Study	Reason for exclusion
Aaseth 2001	67 non‐anaemic pregnant women attending prenatal care clinics in Kingsvinger Hospital, in Kingsvinger, Norway were allocated to a daily regimen of either 100 mg Fe or 15 mg Fe. Both groups received iron at different doses. No comparisons allowed within the scope of this review.
Abel 2000	Community‐based study in Vellore district, India using a pre‐post experimental design measuring the impact of an iron supplementation program, helminthic treatment and education intervention in the prevalence of anaemia in the different trimesters of pregnancy. The same pregnant women were not followed. The type of study is not eligible for inclusion in this review.
Adhikari 2009	320 pregnant women attending the Tribhuvan University Teaching Hospital, Nepal for antenatal care were randomised to 1 of 4 groups: group 1: 60 mg elemental iron daily (as ferrous sulphate); group 2: 60 mg elemental iron daily (as ferrous sulphate) with a count of unused pills at antenatal appointments; group 3: 60 mg elemental iron daily (as ferrous sulphate) with education (direct counselling and colour brochure) on iron and anaemia; group 4: 60 mg elemental iron daily (as ferrous sulphate) with pill count and education (direct counselling and colour brochure) on iron and anaemia. In this randomised trial the aim of the intervention was to increase compliance and all 4 intervention groups received daily iron supplements. The type of interventions do not allow for comparisons within the scope of this review.
Afifi 1978	260 pregnant women from Cairo, Egypt (formerly part of United Arab Republic) were randomly allocated to 1 of 2 groups: group 1 received 130 mg elemental iron daily (a slow release ferrous sulphate preparation, Plexafer‐F®) and 360 μg (0.36 mg) folic acid; group 2 received iron (as ferrous sulphate, no dose reported) in addition to 5000 μg (5 mg) folic acid. Both groups received daily iron supplementation in different preparations. The type of interventions do not allow for comparisons within the scope of this review.
Agrawal 2011	75 pregnant women aged 19 to 40 years attending the department of Obstetrics and Gynaecology, Kasturba Hospital, Manipal India, with normal Hb levels between 13‐16 weeks' gestation will be randomly assigned to 2 supplementation groups: group 1: ferrous fumarate with 98.6 mg of elemental iron (Continuous group) 1 capsule daily (all days a week); group 2: ferrous fumarate with 98.6 mg of elemental iron (Intermittent group) 1 capsule daily 4 days a week (i.e. from Monday to Thursday). The supplementation period will start at 13‐16 weeks and continued up to delivery and in postnatal period. The study was excluded because there are 2 groups receiving iron, 1 group daily and the other intermittently. This type of comparison is outside the scope of this review.
Ahn 2006	209 pregnant women between 18 and 45 years of age, attending outpatient obstetric clinics at North York General Hospital and the Hospital for Sick Children in Toronto, Canada were randomly assigned to receive multiple micronutrient supplements containing 60 mg of elemental iron (as ferrous fumarate) (Materna®) or another supplement (PregVit®) to be taken twice daily with the morning dose containing 35 mg of elemental iron (as ferrous fumarate) and the evening dose containing 300 mg calcium, and other vitamins and minerals. Both groups received daily iron in different doses as well as other vitamins and minerals. The type of interventions do not allow for comparisons within the scope of this review.
Alaoddolehei 2012	145 healthy pregnant women 20 to 40 years of age with Hb 110g/L or higher at 20 weeks' gestation attending the Gynecology and Obstetrics Clinic, Babol, Iran, from October 2002 to September 2005 were assigned (on the basis of number given them at first visit) to 1 of 2 groups: group 1 (even numbers, n = 73) received daily iron supplement at 50 mg/day; group 2 (odd numbers, n = 72) received an intermittent dose of 3 times per week (50 mg/each time) from 20th week gestation until delivery. Women with β minor thalassaemia, Hb less than 11 g/dL, more than 1 delivery and diagnosed with internal and infectious diseases were excluded. Blood samples were assessed for complete blood count (Hb, HCT, RBC) , iron, ferritin and zinc at baseline in the first trimester in all participants. Both groups received iron supplements in different regimens.The type of interventions is outside the scope of this review.
Angeles‐Agdeppa 2003	744 apparently healthy pregnant (with less than 20 weeks) and non‐pregnant women of reproductive age (15‐49 years) from the municipalities of Calasiao, Binmaley and Santa Barbara, Philippines who were pregnant or most likely to become pregnant within the 12‐month duration of the study, and who volunteered to participate in the study were provided 2 preparations of iron‐folic acid supplements. Women with severe anaemia or history of malaria were excluded. Non‐pregnant women were prescribed 4 capsules monthly each containing 60 mg of elemental iron and 3500 μg (3.5 mg) folic acid to be taken once weekly before bedtime (to be purchased by the women in local drugstores). Pregnant women received free of cost 4 capsules monthly each containing 120 mg of elemental iron and 3500 μg (3.5 mg) of folic acid to be taken once a week before bedtime until delivery and for 3 months thereafter. Pregnant women seen at the health centres with 20 weeks or more of gestation were advised to take their usual daily dose of iron‐folic acid tablets containing 60 mg of elemental iron and 500 μg (0.5 mg) of folic acid. Women were followed for 12 months. Hb, HCT, MCV, MCHC Hb concentration, serum ferritin, transferrin receptors, prevalence of iron deficiency and anaemia, compliance were assessed at baseline, 4.5, 9 and 12 months. There was not randomisation and the control group was not appropriate for comparisons. The type of comparisons are not relevant for the scope of this review.
Arija 2014	878 non‐anaemic pregnant women older than 18 years of age with ≤ 12 weeks' gestation without anaemia (Hb > 110 g/L), capable of understanding the official State languages (Castilian or Catalan) at early gestation stage, and their subsequent newborns attending 10 Primary Care Centers from Catalunya (Spain) of the Catalunya Sexual and Reproductive Healthcare Service [Atención a la Salud Sexual y Reproductiva (ASSIR)] of the Catalan Institute of Health [Instituto Catalán de la Salud (ICS)] subdivided in 2 strata as a function of the Hb levels at the start of the pregnancy. Women with multiple pregnancy, taking > 10 mg iron during the months prior to week 12, hypersensitivity to egg protein (due to the iron prescription formula contains ovalbumin), previous serious illness (immunosuppressed status) or chronic illness that could affect the nutritional development (e.g. cancer, diabetes), malabsorption, and liver disease such as chronic hepatitis or cirrhosis. Participants are randomly assigned to 1 of 2 groups per stratum starting from around the 12th week of gestation and continuing up to partum: group 1: women will receive of 20 mg elemental iron (150 mg ferrimanitol ovoalbumin); group 2: women will receive 80 mg per day of elemental iron (600 mg ferrimanitol ovoalbumin). The reference dose is the control group: women will receive 40 mg elemental iron (300 mg ferrimanitol ovoalbumin), similar to that routinely prescribed in clinical practice. The study was excluded because all women receive iron supplements. The type of intervention is outside the scope of this review. EudraCT Number: 2012‐005480‐28.
Babior 1985	15 healthy pregnant women 22‐32 years old, in the first trimester of pregnancy from Boston, Massachusetts, USA were randomly assigned to 3 different multiple micronutrient preparations to assess absorption of iron. All women received iron in the multiple micronutrient supplements. The type of interventions is not relevant for the scope of this review.
Balmelli 1974	42 pregnant women attending antenatal care clinic at the Hospital University of Berne, Switzerland were randomly assigned to 1 of 2 groups: group 1 received 37 mg elemental iron (as ferrous sulphate) and succinic acid 3 times daily (total daily dose of 111 mg elemental iron and 555 mg succinic acid); group 2 received 37 mg elemental iron (as ferrous sulphate) and succinic acid 3 times daily (total daily dose of 111 mg elemental iron and 555 mg succinic acid) and 1 tablet 3 times a day containing 100 μg (0.1 mg) folic acid and 100 μg vitamin B12. Both groups received iron supplements. The type of interventions is outside the scope of this review.
Bencaiova 2007	260 women with singleton pregnancy in Zurich, Switzerland, were randomised at 21‐24 weeks of gestation to receive either intravenous iron group (further divided into 2 doses of 200 mg iron saccharate or 3 doses of 200 mg iron) or 80 mg elemental iron (as ferrous sulphate) daily. Both groups received iron in different routes of administration. No comparisons allowed within the scope of this review.
Berger 2003	864 apparently healthy married pregnant and non‐pregnant nulliparous women of reproductive age planning to have a child soon from 19 rural communes of the Thanh Mien district in Hai Duong province, Vietnam were invited to participate and assigned to 1 of the following interventions according to their pregnancy status at baseline: women who were pregnant received free of charge UNICEF tablets containing 60 mg of elemental iron and 250 μg (0.25 mg) of folic acid to be taken daily and women who were non‐pregnant were prescribed pink packs of tablets containing 60 mg of elemental iron and 3500 μg (3.5 mg) of folic acid that they could buy at their village from the Women's Union, to be taken once weekly. If these women became pregnant, women received red packs of tablets containing 120 mg of elemental iron and 3500 μg (3.5 mg) of folic acid free of charge to be taken once weekly. After delivery women were given tablets containing 60 mg of elemental iron and 0.5 mg of folic acid free of charge for 3 months to be taken weekly. Hb concentration, serum ferritin, and serum ferritin receptors, prevalence of anaemia and iron deficiency and compliance were measured at baseline, at 4.5, 9 and 12 months. This is not a randomised study and no comparisons can be made for the aims of this review.
Bergsjo 1987	Planned study registered at the Oxford Database of Perinatal Trials. Author contacted and informed the project was not completed.
Bhatla 2009	109 pregnant non‐anaemic women between 14 and 18 weeks (49% vegetarian) with no prior intake of iron supplements in the Department of Obstetrics and Gynaecology of the All India Institute of Medical Sciences in New Delhi, India were randomly allocated into 1 of 3 different groups: group 1 (n = 37) received the standard Government of India supply of Irofol®  tablets containing 100 mg of elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) folic acid (Nestor Pharmaceuticals Ltd., Faridabad, Haryana, India) to be taken once daily; group 2 (n = 36) received the standard Government of India supply of Irofol® tablets containing 100 mg of elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) folic acid and were instructed to take 2 tablets on any 1 day of the week; 1 before lunch and the other before dinner (total 200 mg elemental iron and 1000 μg (1 mg) folic acid per week) with no tablets taken during the rest of the week; group 3 (n = 36) received Ferium® tablets iron (III)‐hydroxide poly maltose complex tablets daily containing Iron (III) Hydroxide Polymaltose containing 100 mg elemental iron and 350 μg (0.35 mg) folic acid to be taken 1 tablet daily (Emcure Pharmaceuticals Ltd., Pune). All groups received health education regarding the importance of diet in pregnancy, iron‐rich foods and appropriate dietary practices and were instructed to take the tablets 30 min before meals and not with tea, coffee or milk. All women were also advised to take calcium supplements after meals. All groups received iron with different regimens. The type of interventions are not within the scope of this review.
Blot 1980	203 pregnant women attending prenatal care clinics in Antonie Beclere Hospital, Paris, France during their 6th month visit were randomly allocated to either 105 mg of elemental iron with 500 mg of ascorbic acid or a placebo. The intervention group received iron with ascorbic acid in comparison to placebo. The type of intervention do not allow for comparisons within the scope of this review.
Bokhari 2011	33 healthy non‐smokers Caucasian, primiparous, with singleton pregnancy (week 20 to week 30) pregnant women with pre pregnancy BMI between 19.8 and 26 not taking medicines known to influence iron status nor iron supplements and free from gastrointestinal disorders or allergies were randomised to eat 3–4 slices of iron‐rich or control bread daily for 6 weeks. Women with Hb concentrations not within the normal range (below 70 g/L or over 160 g/L) were excluded. Low versus high iron fortified breads were compared. Two 24‐hour‐prompted (multiple‐pass) dietary recalls were completed, and validated algorithms were used to determine the amount of ‘available iron’ from the diet.  Findings from this study show that iron‐rich staple foods can help women reach dietary targets for iron. Further research using fortified staple foods containing higher levels of iron is now warranted to establish physiological benefits. The study was excluded because food fortification is out of the scope of this review. The intervention is outside of the scope of this review.
Bokhari 2012	65 pregnant women 18–45 years between weeks 20 and 30 gestation were recruited from South Manchester University Hospital antenatal clinic, United Kingdom and 33 participants that attended their first appointment were randomised to 1 of 2 groups:group 1 were provided 3–4 slices of functional bread containing flour (Eragrostis tef) that was naturally rich in iron (2.1 mg iron per 50 g slice) and added enzyme phytase or control bread daily for 6 weeks. Participants substituted the bread they would normally eat with the intervention provided. Two 24‐hour‐prompted (multiple‐pass) dietary recalls were completed, and validated algorithms were used to determine the amount of ‘available iron’ from the diet. Levels of total ‘available iron’ were similar in both groups and correlated positively with total dietary iron. This study assessed the effects of an iron rich bread with a control bread. The type of intervention is outside of the scope of this review.
Brown 1972	109 pregnant women attending prenatal care clinics in Manchester, England, United Kingdom were randomly allocated to 1 of 3 groups: group 1 received 1 tablet daily given in 'reminder packs'; group 2 received 1 tablet daily given in loose forms; group 3 received 2 tablets daily given in loose form. Tablets contained 50 mg of elemental iron (as slow release ferrous sulphate) and 400 μg (0.4 mg) of folic acid. All groups received iron daily. The type of interventions do not allow for comparisons within the scope of this review.
Burslem 1968	472 pregnant women attending the booking clinic in Manchester, England, United Kingdom were alternatively allocated to 2 forms of iron: group 1 received 105 mg elemental iron (as a slow release ferrous sulphate preparation) and a tablet containing 5000 μg (5 mg) folic acid daily; group 2 received 3 tablets of combined conventional 60 mg elemental iron (as ferrous sulphate) and 1 tablet containing 5000 μg (5 mg) folic acid for a total of 180 mg elemental iron daily. Both groups received daily iron supplementation in different preparations. The type of interventions do not allow for comparisons within the scope of this review.
Buss 1981	18 pregnant women were randomly assigned to receive either a tablet containing 80 mg of elemental iron with a new mucous membrane vaccine (Tardyferon®) or a tablet containing 80 mg elemental iron with 350 μg (0.35 mg) folic acid (Tardyferon‐Fol®) for a period of 3 months. All women received daily iron. The type of interventions do not allow for comparisons within the scope of this review.
Carrasco 1962	2 liquid preparations were used in this study: 1 with D‐sorbitol and the other without. Both preparations contained vitamin B12, vitamin B6, ferric pyrophosphate and folic acid.The type of interventions do not allow for comparisons within the scope of this review.
Casanueva 2003a	120 singleton pregnant women attending the Instituto Nacional de Perinatologia in Mexico City, Mexico with Hb concentrations higher than 115 g/L at 20 weeks of gestation (equivalent to 105 g/L at sea level) were randomly assigned to 1 of 2 groups: group 1: 1 tablet containing 60 mg of elemental iron (as ferrous sulphate), 200 μg (0.2 mg) folic acid and 1 μg vitamin B12 given daily; group 2: 2 tablets (total 120 mg of elemental iron (as ferrous sulphate), 400 μg (0.4 mg) folic acid, and 2 μg vitamin B12) to be taken once weekly. The groups received either daily supplementation or weekly supplementation at no cost. Supplement tablets were identical in content and were to be ingested from the 20th week of pregnancy until delivery. No comparisons allowed within the scope of this review.
Castren 1968	126 healthy pregnant women attending Maternity Centres of Turku, Finland were assigned to 1 of 2 groups: group 1 (n = 63) received 3 tablets a day providing a total 120 mg elemental iron (as ferrous sulphate) daily; group 2 (n = 63) received 3 tablets a day providing total 120 mg elemental iron (as ferrous sulphate) + 9000 μg (9 mg) folic acid daily from their first visit at 10‐20th week of gestation until term. Both groups received iron. The type of intervention is outside the scope of this review.
Chanarin 1968	206 women attending the antenatal clinic at St. Mary's Hospital, London, United Kingdom with less than 16 weeks pregnant at the first attendance. At the 20th week they were allotted to 1 of 2 groups: group 1 received tablets to be taken once daily containing 260 mg ferrous fumarate; group 2 received tablets to be taken daily containing 260 mg ferrous fumarate and 100 μg (0.1 mg) of folic acid. Iron deficiency was largely eliminated by giving 1 g of intravenous iron dextran as 4 250 mg doses at weekly intervals to all participants in early pregnancy. Both groups received iron. The type of comparison is not within the scope of this review.
Chawla 1995	81 pregnant women with 20 +/‐ weeks of gestation from Ludhiana City, India were divided to 1 of 3 groups: group 1 received 60 mg of elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) of folic acid daily; group 2, 60 mg of elemental iron (as ferrous sulphate) and 2,000,000 IU of vitamin A; group 3, who did not receive any supplements. Supplementation was for a period of 15 weeks. Outcomes measured included Hb, RBC count, total iron binding capacity, transferrin saturation, serum iron, serum vitamin A at baseline and at 36 +/‐ 2 weeks of gestation. Poor methodological quality. Pregnant women who were willing to go to the hospital or centre once a week to collect the iron supplements were included in the groups 1 and 2. The rest of the participants were included in the control group. This is not a randomised trial.
Chew 1996a	256 clinically healthy pregnant women from low SES attending 1 antenatal care clinic in Guatemala City, Guatemala and Hb > 80 g/L were recruited. City of Guatemala is at 1500 m above sea level, so values were adjusted by altitude subtracting 5 g/L in Hb. Participants were randomly assigned to 1 of 2 groups: group 1: daily supervised intake of 60 mg elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) folic acid; group 2: weekly supervised intake of 180 mg of elemental iron (as ferrous sulphate) and 3500 μg (3.5 mg) of folic acid in 1 intake once a week. Supplementation started at different gestational age for each participant. Average gestational age at start was 20.5 weeks until 38th week. All groups received iron with different regimens. The type of interventions are not within the scope of this review
Chew 1996b	120 clinically healthy pregnant women attending 1 antenatal care clinic in Guatemala City, Guatemala with Hb > 80 g/L were recruited. Women were from low SES. City of Guatemala is 1500 m above sea level, so values were adjusted by altitude subtracting 5 g/L in Hb. Participants from low SES were randomly assigned to 1 of 2 groups: group 3: daily unsupervised intake of 60 mg elemental iron (as ferrous sulphate) and 0.5 mg folic acid; or group 4: weekly unsupervised intake of 180 mg of elemental iron (as ferrous sulphate) and 3.5 mg of folic acid in 1 intake once a week. Supplementation started at an average of 20.5 weeks of gestation until 38th week. All groups received iron with different regimens. The type of interventions are not within the scope of this review.
Coelho 2000	100 pregnant women with 20‐34 weeks of gestation attending the antenatal clinic at The Bandra Holy Family Hospital, Bandra, Mumbai India were randomly assigned to 1 of 2 groups: group 1 received 30 mg elemental iron + other essential vitamins and minerals daily; groups 2 received 116 mg elemental iron, folic acid, zinc and vitamin C daily. Outcomes included Hb concentration, maternal weight gain, infant birthweight and maternal compliance and side effects Both groups received iron supplementation. Both groups received daily iron supplementation. The types of interventions do not allow for comparisons within the scope of this review.
Cook 1990	200 women at Kansas University Medical Center, Kansas, USA were randomly assigned to receive 50 mg elemental iron daily given either as Gastric Delivery System (GDS) or conventional ferrous sulphate . Gastrointestinal side effects were evaluated. The participants were non‐pregnant women.
Dawson 1962	2498 pregnant women attending antenatal care clinic in Crumpsal Hospital, Manchester United Kingdom were grouped to receive folic acid or as controls. The assignment was not randomised. Participants whose Hb fell below 100 g/L after 28th week received oral iron if they had not previously received oral iron, had not reached the 36th week of gestation and had a MCHC of less than 30%. If these participants had been receiving oral iron, iron was then provided parenterally. The type of interventions and comparisons are outside the scope of this review.
Dawson 1987	42 healthy women with less than 16 weeks of pregnancy entering prenatal care at the Department of Obstetrics and Gynecology, University of Texas, Texas, USA were randomly assigned to receive either a multiple micronutrient supplement containing 65 mg of elemental iron or 1 multiple micronutrient supplement with no iron, calcium, zinc and copper and pantothenic acid. Both groups received different multiple micronutrient supplement formulations. No comparisons allowed within the scope of this review.
Dijkhuizen 2004	170 pregnant women with less than 20 weeks' gestation from 13 adjacent villages in a rural area in Bogor District, West Java, Indonesia were randomly assigned to receive daily supplementation with B‐carotene (4.5 mg), zinc (30 mg), both, or placebo containing 30 mg elemental iron and 400 μg (0.4 mg) folic acid. Both groups received daily iron and folic acid. The types of interventions do not allow for comparisons within the scope of this review.
Edgar 1956	179 pregnant women with Hb levels below 105 g/L and more than 16 weeks of gestation volunteered for this study and were divided into 4 supplementation groups according to the stage of pregnancy at which iron was introduced: 16th week, 20th week, 24th week, and non‐supplemented controls. 37% of these women were lost to follow‐up and were excluded from the final analysis. This is not a randomised trial.
Ekstrom 1996	176 pregnant women attending Ilula Lutheran Health Centre's antenatal service in Iringa region, Tanzania with 21‐26 weeks of gestational age and Hb > 80 g/L were randomly assigned to receive 120 mg elemental iron (as ferrous sulphate in conventional form) daily or 50 mg elemental iron as gastric delivery system (GDS) daily. Both groups received daily iron supplementation in different preparations. The types of interventions do not allow for comparisons within the scope of this review.
Ekstrom 2002	209 apparently healthy women attending antenatal care clinics in rural areas of Mymemsingh thana, Bangladesh, with fundal height of 14‐22 cm (18‐24 weeks of gestation), who had not used iron supplements prior to the study. Exclusion criteria: women with Hb concentrations < 80 g/L. Each clinic was randomly assigned to 1 of 2 interventions: 60 mg of elemental iron (as ferrous sulphate) and 250 μg (0.25 mg) folic acid given in 1 tablet daily, or 120 mg of elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) folic acid once a week (given in 2 tablets 1 day of the week). Supplementation continued until 6 weeks postpartum. Supplementation started at baseline for 12 weeks. All groups received iron with different regimens. The type of interventions are not within the scope of this review.
Fletcher 1971	643 pregnant women attending antenatal clinic in London, England, United Kingdom were randomly assigned to 1 of 2 groups: group 1 received 200 mg of ferrous sulphate daily; group 2 received 200 mg of ferrous sulphate with 5000 μg (5 mg) of folic acid daily. Both groups received iron. No comparisons allowed within the scope of this review.
Giles 1971	528 pregnant women in the first antenatal care visit at the Royal Women’s Hospital Melbourne, Australia patients were divided in 4 groups: group 1 those attending the antenatal clinic for the first time before 10 weeks of gestation; group 2 those attending the antenatal clinic for the first time from 10‐20 weeks of gestation; group 3 those attending the antenatal clinic for the first time from 20‐30 weeks of gestation; group 4 those attending the antenatal clinic for the first time at or after 30 weeks of gestation. They received a 200 mg ferrous sulphate and 5 a mg folic acid tablet a day, for the remaining of the pregnancy and 5 mg of folic acid were administered to 1 group (n = 265) and a placebo (n = 263) to the other. The study was excluded because both study groups received iron, and the difference was the supplementation or not with 5 mg of folic acid daily. This type of comparison is outside the scope of this review.
Gomber 2002	40 apparently healthy women with singleton pregnancy in their second trimester (between 16‐24 weeks of gestation), living in urban slums, from low SES attending Guru Teg Bahadur Hospital, Delhi, India were randomly assigned to receive 1 tablet containing 100 mg of elemental iron (as ferrous sulphate) with 500 μg (0.5 mg) folic acid daily or once a week. Weekly intake was supervised. Duration of supplementation was 100 days. Hb and HCT concentrations at baseline, at 4 weeks, 8 weeks and 14 weeks of supplementation, serum ferritin concentration, at baseline, at 14 weeks of supplementation and at delivery. Both groups received iron and folic acid in different regimens (daily versus weekly). The type of interventions do not allow for comparisons within the scope of this review.
Goonewardene 2001	92 pregnant women from 14‐24 weeks of gestation attending the university antenatal clinic, in Galle, Sri Lanka were randomly assigned to 1 of 3 regimens: group 1 (n = 26) received a tablet containing 100 mg of elemental iron (as ferrous fumarate), with additional micronutrients once a week; group 2 (n = 35) received the same tablet but 3 times a week; group 3 (n = 31) received the same supplement in a daily fashion. All groups were receiving iron and multiple micronutrients with different regimens (daily, weekly, 3 times a week). The type of interventions do not allow for comparisons within the scope of this review.
Gopalan 2004	900 pregnant women of poor SES attending government antenatal care clinics in New Delhi, India were grouped in 3 groups: group 1 (n = 300) received routine antenatal care; group 2 (n = 300) received 100 mg of elemental iron and 500 μg (0.5 mg) folic acid daily from the 20th week of gestation; group 3 (n = 300) received 100 mg of elemental iron and 500 μg (0.5 mg) folic acid daily from the 20th week of gestation and additionally 900 mg of alpha linolenic acid from the 22nd week of gestation.  Outcomes assessed included birthweight, low birthweight, premature delivery. The study is not reported as randomised and is excluded in the first screening for eligibility.
Goshtasebi 2012	370 pregnant women were randomly assigned to receive either daily or twice weekly iron supplementation during pregnancy. There were no significant differences in initial and delivery Hb and HCT levels between the 2 groups. Ferritin concentrations were significantly lower in the twice‐weekly group at delivery, but hypoferritinaemia (ferritin < 15 microg/L) was not observed in either group. The frequency of nausea, vomiting and constipation was significantly lower in the twice‐weekly group. The type of intervention is not within the scope of this review.
Gringras 1982	40 pregnant women attending antenatal care clinic in Cheshire, England, United Kingdom were given a tablet containing 47 mg of elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) of folic acid daily or a tablet containing 100 mg of elemental iron (as ferrous glycine sulphate) daily. Both groups received iron. No comparisons allowed within the scope of this review.
Grover 1998	200 pregnant women with gestation 16‐24 weeks attending for care in rural health centre in Gazipur village in East Delhi, India from Jan‐Dec 1994 with Hb 70 g/L or more and no tuberculosis, chronic diseases, "toxaemia", bleeding piles were randomly assigned to 1 of 2 groups: group 1: women received 100 mg of elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) of folic acid on alternate days: (data available for 56 women); group 2: women received 100 mg of elemental iron daily (as ferrous sulphate) and 500 μg (0.5 mg) of folic acid (data available for 64 women). It is not clear how the doses were supplied. The type of interventions do not allow for comparisons within the scope of this review.
Guldholt 1991	192 pregnant women in Horsens Hospital, Denmark were consecutively randomised to receive 1 of 2 treatments: group 1: received a daily vitamin‐mineral tablet containing 15 mg of elemental iron; group 2: received a daily vitamin‐mineral tablet containing 100 mg of elemental iron. Both groups received iron in different doses. No comparisons allowed within the scope of this review.
Hampel 1974	65 untreated and 54 treated pregnant women in West Berlin, Germany were assessed during pregnancy for Hb concentrations, iron and folate levels, total iron binding capacity, and RBC count. No data are presented for outcomes prespecified in the review. Women were of different gestational age. No outcomes can be extracted from the paper.
Hanieh 2013	1258 pregnant women older than 16 years of age and with less than 16 week gestation living in 104 communes from Ha Nam province, a malaria‐free province in Viet Nam were assigned at the cluster (commune) level to 1 of 3 groups: group 1 received 60 mg elemental iron plus 400 ug (0.4 mg) folic acid daily; group 2 received 60 mg elemental iron plus 1500 ug (1.5 mg) folic acid per capsule; administered as 2 capsules/week; group 3 received 60 mg elemental iron plus 1500 ug (1.5 mg) plus a variation of the dose of micronutrients in the UNIMMAP daily supplement; administered as 2 capsules/week. Women were excluded if they had a high‐risk pregnancy—multi‐fetal pregnancy (confirmed on palpation or ultrasound), a significant medical condition or if they had severe anaemia (Hb concentration lower than 80 g/L) at enrolment were referred to the commune health station for further management. A placebo control was not contemplated, as it was considered unethical to withhold iron supplementation during pregnancy. Primary outcome was birthweight. The type of intervention is outside the scope of this review.
Hartman‐Craven 2009	In this cross‐over study 2 types of multivitamin supplements were compared: 18 healthy pregnant women 24‐32 weeks' gestation attending a Toronto hospital were recruited and received 2 different supplements in a random order and followed up over 8 hours. Both preparations contained iron and folic acid (although in different doses). The aim of the study was to see whether absorption was improved with a powdered preparation.
Hawkins 1987	No report available of the study results.
Hemminki 1991	2960 pregnant women were recruited by midwives in 27 maternity health centres in Tampere (15 centres) and in 5 neighbouring communities (12 centres) in Finland, and randomised into 2 groups: selective and routine iron supplementation. Routine group: Women received iron throughout pregnancy regardless of Hb level, starting at the latest in the 17th week of gestation. A dose of 100 mg elemental iron per day was recommended, but this could be tailored according to the midwife's judgment. Intervention group: any pregnant women after the 14th week of gestation showing HCT < 0.30 (Hb < 100 g/L) in 2 consecutive visits If the Hb was still less than 100 g/L and/or MCV was less than 82 and a low ferritin was found, 50 mg iron twice a day as ferrous sulphate was recommended. The length of the treatment was to be 2 months or until the HCT was > 10.32 or higher (Hb 110 g/L) or higher). By request of the midwives the treatment schedule was relaxed later during the trial: iron therapy was begun if the mother's HCT was 0.31 or below after the 33rd week. Mothers were followed until the postpartum check‐up, and data were collected by 5 different questionnaires and abstracted from the infant's patient record. There were some changes during the trial. For example in group 2 “By request of the midwives the treatment schedule was relaxed later during the trial “or in group 1, iron doses or compounds “could be tailored according to the midwife's judgment”. The study was excluded because there was not comparable control group because both groups received iron. The routine group received 100 mg of iron as elemental iron and was composed of anaemic and non‐anaemic women. In group 2, anaemic women received 2 doses of 50 mg of iron as ferrous sulphate in slow release form, while for non‐anaemic women it was not clear if women received routine treatment. Group 2 was separated into anaemic and non‐anaemic women. Both groups received iron.
Hermsdorf 1986	120 unselected pregnant women were given 114 mg of elemental iron daily from week 15 until delivery, or not treatment. Only an abstract with insufficient data available.
Horgan 1966	42 apparently healthy pregnant women attending 2 antenatal care clinics in London, England were assigned to 1 of 3 interventions: group 1 received 200 mg ferrous sulphate with 5000 μg (5 mg) of folic acid 3 times a day; group 2 received 350 mg of ferrous aminoate with 50 μg (0.05 mg) folic acid 3 times a day; group 3 received 200 mg of ferrous sulphate with 500 μg (0.5 mg) folic acid once a day. Intervention period was 3 weeks. All groups received daily iron and folic acid. No comparisons allowed within the scope of this review.
Hosokawa 1989	84 anaemic women seeking antenatal care in the Department of Obstetrics and Gynaecology of the Fukui School of Medicine Hospital, Japan were randomly assigned to receive 100 mg of elemental iron (as ferrous sulphate) daily after the evening meal, or the same dose + vitamin C for 4 weeks. Both groups received daily iron. No comparisons allowed within the scope of this review.
Hossain 2014	200 pregnant women attending the outpatient obstetric clinic at the Civil Hospital Karachi in Karachi, Pakistan with 20 weeks or less of gestation, a singleton pregnancy, and normoglycaemic and normotensive at the time of antenatal booking were randomly allocated to 1 of 2 groups: group 1 (n = 100) received routine antenatal care, which included ferrous sulphate 200 mg, twice daily, and 600 mg of calcium lactate daily; group 2 (n = 100) received routine antenatal care regimen and an oral liquid formulation (400 IU/drop) of vitamin D3 at a daily dose of 4000 IU (10 drops daily) starting at completed 20 weeks of gestation. Women with history of gestational diabetes, hypertension, thyroid disorder, chronic liver disease, and evidence of fetal anomaly in current pregnancy were excluded. Both groups received iron. the type of interventions is outside the scope of this review.
Itam 2003	266 pregnant women from Calabar coastal southeastern Nigeria were randomly assigned to 1 of 3 groups: group 1 received a supplement containing iron (as 300 mg ferrous fumarate), 5000 ug (5 mg) folic acid, 10 ug vitamin B12, 25 mg vitamin C, 0.3 mg zinc sulphate and 0.3 mg magnesium sulphate; group 2 received iron (as 200mg ferrous sulphate) and 5000 ug (5 mg) folic acid once daily; group 3 received iron (as 200 mg ferrous sulphate) 3 times daily and 5000 ug (5 mg) folic acid once daily. The intervention lasted from 18th week of gestation till term. There were also 2 subgroups under each major group anaemic and non‐anaemic groups. Blood samples were collected from each participant on admission into the study and every 2 weeks and analysed for packed cell volume (HCT), Hb, MCHC, reticulocytes and ferritin levels. All participants received iron at different doses and regimens. The type of intervention is outside the scope of this review.
Iyengar 1970	800 pregnant women with less than 24 weeks of gestation and Hb > 85 g/L in India were assigned by rotation to 1 of 4 groups: group 1 received placebo tablets; group 2 received 30 mg of elemental iron as ferrous fumarate in a single tablet daily; group 3 received 30 mg of elemental iron (as ferrous fumarate) with 500 μg (0.5 mg) folic acid in a single tablet; group 4 received in addition to iron and folic acid, 2 μg of vitamin B12 in a single tablet. Loss to follow‐up was 65%. This is not a randomised trial.
Kaestel 2005	2100 pregnant women (22 +/‐ 7 weeks' gestation at entry) attending antenatal clinics in Bissau, Guinea‐Bissau or who were identified by The Bandim Health project were randomly assigned to receive daily multi micronutrient tablet containing 1 RDA of 15 micronutrients, or daily multi micronutrients containing 2 times the RDA except for iron that was maintained at 1 RDA or a conventional prenatal daily iron (60 mg elemental iron) and 400 μg (0.4 mg) folic acid supplement. In a follow‐up analysis (Andersen 2010), of the previous study a 2‐year follow‐up examined the effects of the interventions on fetal loss and under 2 mortality. 2169 women were recruited from 4 suburban districts followed by the Bandim Health project in collaboration with the Danish Epidemiology Science Centre in Guinea‐Bissau. Women with severe anaemia (Hb less than 70 g/L) received 60 mg elemental iron daily in addition to the intervention. All participants received impregnated bed net at inclusion and were provided weekly anti‐malarial prophylaxis with chloroquine phosphate (300 mg base) throughout pregnancy. Also women with more than 10 parasite per 200 leucocytes were offered anti‐malarial treatment with chloroquine. All groups receive iron and folic acid daily. No comparisons allowed within the scope of this review.
Kann 1988	36 healthy non‐anaemic pregnant women in second or third trimesters of gestation were randomly assigned to receive 1 of 4 groups: group 1 received a tablet (Stuartnatal® 1 + 1) containing 65 mg elemental iron, 1000 μg (1 mg) folic acid and 12 additional micronutrients daily; group 2 received a tablet (Stuart Prenatal®) containing 60 mg elemental iron, 800 μg (0.8 mg) folic acid and 11 additional micronutrients; group 3 received a tablet (Materna®) containing 60 mg elemental iron, 1000 μg (1 mg) folic acid and 17 additional micronutrients daily; group 4 received a tablet (Natalins Rx®) containing 60 mg elemental iron, 1000 μg (1 mg) folic acid and 14 additional micronutrients daily. All participants received iron and multiple micronutrients. No comparisons allowed within the scope of this review.
Khambalia 2009	In this randomised trial carried out in Bangladesh childless, non‐pregnant married women under 40 were randomised to receive food supplements (sprinkles) containing either iron and folic acid or folic acid alone. 272 women were randomised and women were followed up for 9 months. If women became pregnant they were withdrawn from the study and ALL pregnant women received both iron and folic acid. The study was excluded as it focused on a non‐pregnant population.
Kulkarni 2010	This study was secondary analysis of the data from the Christian 2003 (C) study included in the review.
Kumar 2005	220 pregnant women with a singleton pregnancy and Hb between 80‐110 g/L at 16‐24 weeks' gestation from New Delhi, India were randomly allocated to receive daily oral iron therapy of 100 mg elemental iron (as ferrous sulphate) with 500 μg (0.5 mg) folic acid or 250 mg of iron sorbitol intramuscularly and repeated at an interval of 4‐6 weeks. This trial compares the effects of daily oral iron with 2 injections of high dose parenteral iron. No comparisons allowed within the scope of this review.
Lira 1989	199 pregnant women with less than 16 weeks' gestation attending antenatal care at the Hospital Clinica Universidad Catolica ein Santiago, Chile were randomly assigned to 1 of 2 groups: group 1 (n = 78) received 105 mg elemental iron (as ferrous sulphate) and 500 mg ascorbic acid; group 2 (n = 75) received 105 mg elemental iron (as ferrous sulphate), 500 mg ascorbic acid and 350 ug (0.35 mg) folic acid daily. There were 36 losses to follow‐up. Both groups received iron. The type of interventions provided is outside the scope of this review.
Liu 1996	395 healthy, anaemic and non‐anaemic, pregnant women attending prenatal care at 2 outpatient clinics in Xianjiang, China. Women with Hb < 80 g/L were excluded. Maternal age was 25.15 ± 2.28 years. Women were randomly assigned to 1 of 3 groups: group 1: 60 mg elemental iron (as ferrous sulphate) and 250 μg (0.25 mg) of folic acid daily; group 2: 120 mg of elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) of folic acid daily; group 3: 120 mg elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) of folic acid once weekly. All women randomised to treatments received iron. A control group that received no iron was composed of women who did not want to participate in the study and did not receive any iron supplements.
Ma 2008	366 pregnant women between 20‐35 years of age women in rural China with 12–24 weeks' gestation; with Hb 105 g/L or lower, all receiving 60 mg elemental iron and 400 μg (0.4 mg) folic acid were randomly assigned to 1 of 4 groups: group 1 (n = 93) received daily 60 mg elemental iron (as ferrous sulphate) and 400 μg (0.4 mg) folic acid; group 2 (n = 91) received daily 60 mg elemental iron (as ferrous sulphate), 400 μg (0.4 mg) folic acid + 2000 μg retinol (as retinyl palmitate); group 3 (n = 91) received daily 60 mg elemental iron (as ferrous sulphate), 400 μg (0.4 mg) folic acid + 1.0 mg riboflavin; group 4 (n = 91) received daily 60 mg elemental iron (as ferrous sulphate), 400 μg (0.4 mg) folic acid, 2000 μg retinol (as retinyl palmitate) + 1.0 mg riboflavin. The intervention lasted 2 months. All groups received iron. The type of comparisons are outside the scope of this review.
Madan 1999	109 apparently healthy pregnant women with 16‐24 weeks of gestation who had not received iron supplements were randomly assigned to 1 of 3 groups: group 1 received 60 mg of elemental iron + 500 μg (0.5 mg) of folic acid once daily; group 2 received 120 mg of elemental iron + 500 μg (0.5 mg) of folic acid once daily; group 3 received 120 mg of elemental iron twice daily + 500 μg (0.5 mg) of folic acid. Duration of supplementation was 12‐14 weeks. All participants received iron and folic acid daily. No comparisons are allowed within the scope of this review.
Marin 2012	360 pregnant women 16 years or older from La Plata, Buenos Aires province, Argentina or who lived in the region for over a year; and who voluntary accepted to participate in the study (consent agreement) were randomly assigned to 1 of 2 groups: group 1 (n = 174) received free medicines from the health centre near their homes consisting of 60 mg of elemental iron (as ferrous sulphate) once (prophylaxis) or twice (treatment) daily and 5000 ug (5 mg) folic acid daily; group 2 (n = 186) were contacted monthly by a member of the health team in order to personalise free iron dispense 60 mg of elemental iron (as ferrous sulphate) once (prophylaxis) or twice (treatment) daily and 5000 ug (5 mg) folic acid daily during all pregnancy period until 45 days after the delivery. This medicine was always dispensed by that same health professional either through the health centre, or in case that the patient did not attend her periodical consultation, drugs were dispensed at the participant's home. All women received iron and folic acid. The difference was on the access to the supplements or the personalised assistance and delivery of the intervention. The type of interventions are outside the scope of this review.
Mbaye 2006	1035 pregnant women attending mother and child health clinics near the town of Farafenni, The Gambia were randomised to receive either folic acid (500‐1500 μg/day) together with oral iron (47 mg of ferrous sulphate per tablet) or oral iron alone (60 mg of ferrous sulphate per tablet) daily for 14 days. All women received treatment with 3 tablets of SP (25 mg of pyrimethamine and 500 mg of sulphadoxine). Both groups received iron daily. No comparisons allowed within the scope of this review.
McKenna 2002	102 healthy pregnant women attending antenatal clinics at the Royal Jubilee Maternity Hospital in Belfast, Ireland with a singleton pregnancy and Hb > 104 g/L and known gestational age of less than 20 weeks who were non‐compliers with routine prescription of 200 mg of ferrous sulphate daily, were randomly assigned to receive 2 sachets of 24 mL each of Spatone® water containing 10 mg of elemental iron or placebo. Participants were instructed to take the 2 sachets daily half an hour before breakfast diluting it in orange juice. Primary outcomes were compliance and side effects. Duration of intervention was from week 22 to week 28 of gestation. The intervention is not an iron supplement but an iron‐fortified water product.
Menon 1962	273 healthy pregnant women with 16‐24 weeks of gestation and Hb concentrations at or above 105 g/L attending antenatal care clinics were divided in order in which they were registered in 3 groups: group 1 was given 5 g of ferrous sulphate daily; group 2 received 5000 μg (5 mg) of folic acid daily; group 3 received 5 g of ferrous sulphate and 5000 μg (5 mg) of folic acid daily. All participants were given 3 multivitamin tablets daily containing vitamin A, vitamin B, C and D. The study was not randomised.
Metz 1965	355 Bantu and white pregnant women attending antenatal clinics at the Baragwanath and South Rand Hospitals, Johannesburg, South Africa were allocated by random numbers to 1 of 3 groups: group 1 received 200 mg of iron by mouth; group 2 received 5000 μg (5 mg) of folic acid daily by mouth in addition to the iron; group 3 received 50 μg of vitamin B12 by mouth in addition to the folic acid and iron. In the white participants, supplementation was started after the 24th week while Bantu participants started after the 28th. Both groups received iron. The type of comparisons are outside the scope of this review,
Milman 2005	427 healthy Danish pregnant women living in the northeastern part of Copenhagen County, Denmark were randomly allocated to receive iron (as ferrous fumarate) in daily doses of 20 mg (n = 105), 40 mg (n = 108), 60 mg (n = 106), and 80 mg (n = 108) from 18 weeks of gestation. Hb, serum ferritin, and serum soluble transferrin receptor concentrations were measured at 18 weeks (inclusion), 32 weeks, and 39 weeks of gestation and 8 weeks postpartum. All women received iron daily. No comparisons allowed within the scope of this review.
Milman 2014	80 healthy ethnic Danish pregnant women, urban and rural residents attending the antenatal care clinic, were allocated in 2 groups to compare the effects of oral ferrous bisglycinate 25 mg iron/day vs ferrous sulphate 50 mg iron/day. Women were allocated to ferrous bisglycinate 25 mg elemental iron (Aminojern®) (n = 40) or ferrous sulphate 50 mg elemental iron (n = 40) from 15 to 19 weeks of gestation to delivery. Haematological status (Hb, red blood cell indices) and iron status (plasma iron, plasma transferrin, plasma transferrin saturation, and plasma ferritin) were measured at 15‐19 weeks (baseline), 27‐28 weeks and 36‐37 weeks of gestation. The study was excluded because both study groups received iron. This type of comparison is outside the scope of this review.
Mitra 2012	959 low‐income postpartum girls and women aged 13 years and older, between 2 and 6 weeks after delivery, and certified for WIC from 11 clinics selected the Mississippi Primary Health Care Association and the Mississippi Department of Health, in Mississippi, United States of America. The clinics were randomised to 1 of 3 groups: group 1 (n = 364, 4 clinics) women received universal anaemia screening and treatment of anaemic women as iron supplement containing 65 mg of elemental Fe (as 325 mg ferrous sulphate); group 2, (n = 348, 3 clinics) received universal iron supplements daily containing 65 mg of elemental Fe (as 325 mg ferrous sulphate) for 2 months to all low‐income women; group 3, (n = 247, 4 clinics) only women at high risk and diagnosis of anaemia were treated iron supplement containing 65 mg of elemental Fe (as 325 mg ferrous sulphate (control). Supplements were provided free of charge to the women in the control group. All study participants within each clinic received the same treatment. Women were followed up at 6 months after delivery. Hb was measured at baseline and at follow‐up. The primary outcome variable was the proportion of women with anaemia after treatment. The participants were post partum women. The type of participants is outside the scope of this review.
Morgan 1961	356 pregnant women attending 2 different antenatal care clinics at the King Edward Memorial Hospital for Women in Subiaco, Australia received according to the clinic they visited, either no treatment or 100 mg of elemental iron (as ferrous gluconate) daily. No systematic allocation was used in this open trial.
Morrison 1977	105 pregnant women attending the University Unit, Mater Misericordiae Mothers' Hospital, South Brisbane, Australia, with normal height, weight and nutrition for the Australian population and with no previous adverse medical, surgical or obstetrical history were allotted by random selection to 1 of 4 types of supplements: group 1 received 50 mg of elemental iron (as dried ferrous sulphate) daily; group 2 received 80 mg elemental iron (as dried ferrous sulphate) with 300 μg (0.3 mg) folic acid daily; group 3 received 105 mg elemental iron (as ferrous sulphate); group 4 received 105 mg of elemental iron (as ferrous sulphate) with 300 μg (0.3 mg) of folic acid. All groups received iron daily. No comparisons allowed within the scope of this review.
Mukhopadhyay 2004	111 apparently healthy pregnant women with less than 20 weeks and no prior intake of iron supplements during this pregnancy with Hb equal or higher than 100 g/L and singleton pregnancy in New Delhi, India were randomly assigned to 1 of 2 groups: group 1 received 2 tablets of 100 mg elemental iron and 500 μg (0.5 mg) folic acid each (total 200 mg elemental iron and 1000 μg (1 mg) folic acid, to be taken only once a week, 1 tablet before lunch and another tablet before dinner; group 2 received 1 tablet of 100 mg elemental iron and 500 μg (0.5 mg) folic acid daily. Women were advised to take the supplements 30 minutes before the meals and not with tea, coffee or milk. Also, women were advised to take calcium supplements after meals (500 mg elemental calcium twice daily). Iron supplementation started between 14 and 20 weeks until delivery. Deworming, if required, was carried out with Mebendazole 100 mg twice a day for 3 days in the second trimester. Both groups received iron and folic acid in different regimens (daily versus weekly).
Mumtaz 2000	191 anaemic pregnant women between the ages of 17‐35 years of age, and uneventful obstetric history attending the Maternity wing of the Federal Government Services Hospital in Islamabad and the Maternal & Child Health Clinic at the Christian Mission Hospital in Taxila, Pakistan were randomly assigned to 1 of 2 interventions: group 1 received 40 mg elemental iron (as ferrous sulphate) with 1000 μg (1 mg) of folic acid once daily; group 2 received 40 mg elemental iron (as ferrous sulphate) with 1000 μg (1 mg) of folic acid on 2 days of the week and placebo the rest of the days. Participants and care providers were blinded to the treatments. Outcomes measured included Hb concentration and serum ferritin at baseline and during the 3 following consecutive visits as well as compliance and weight. Change in Hb Z‐scores after supplementation was the main outcome variable, in women from different gestational ages and duration of intervention. Both groups received iron and folic acid in different regimens (daily versus bi‐weekly).
Nguyen 2008	167 pregnant women with less than 20 weeks of gestation who called either Motherisk General Information line or the Motherisk Nausea and Vomiting of Pregnancy (NVP) Helpline (Hospital for Sick Children, Toronto) and had not started taking or had discontinued any multivitamin due to adverse events were randomly assigned to 1 of 2 groups: group 1 were provided,  a small‐size supplement (PregVit®), containing 35 mg elemental iron (as ferrous fumarate) and multivitamins; group 2 who received high iron content, small size supplement (Orifer F®) containing 60 mg elemental iron (as ferrous sulphate) and multivitamins. Follow‐up interviews documented pill intake and adverse events. Participants from both groups received iron in different amounts and compounds.
Nogueira 2002	74 low‐income pregnant adolescents ranging from 13‐18 years of age attending antenatal care at the Evangelina Rosa Maternity Hospital in Teresina, Piaui State, Brazil were distributed into 5 groups: group 1 received 120 mg elemental iron (as ferrous sulphate) and 250 μg (0.25 mg) of folic acid daily; group 2 received 80 mg elemental iron (as ferrous sulphate) and 250 μg (0.25 mg) folic acid daily; group 3 received 120 mg of elemental iron, with 5 mg of zinc sulphate and 250 μg (0.25 mg) of folic acid daily; group 4 received 80 mg of elemental iron (as ferrous sulphate), with 5 mg of zinc sulphate and 250 μg (0.25 mg) of folic acid daily; group 5 received 120 mg elemental iron (as ferrous sulphate, routine regime locally). All groups received iron and 2 groups received zinc in addition to iron and folic acid. No comparisons allowed within the scope of this review.
Ogunbode 1984	80 apparently healthy non‐anaemic pregnant women attending University College Hospital and Inalende Maternity Hospital in Ibadan, Nigeria during the first and second trimesters of pregnancy were randomly allocated to 1 of 2 groups: group 1 (n = 39) received 1 tablet Ferrograd Folic 500 Plus® daily, a sustained‐released formulation containing ferrous sulphate and folic acid (composition is not available); group 2 (n = 41) received a capsule containing 200 mg ferrous sulphate and 5000 μg (5 mg) of folic acid. All patients were also provided 25 mg weekly of pyrimethamine throughout pregnancy as an anti‐malarial agent. Patients who became anaemic during pregnancy were excluded from the study and analysis. Outcomes measured included reticulocyte count, HCT, anaemia, and side effects. Both groups received iron and folic acid supplements, thus making the comparisons not suitable for this review.
Ogunbode 1992	315 apparently healthy pregnant women attending 4 prenatal care clinics in 4 geographical areas of Nigeria with mild to moderate anaemia (as defined by HCT between 26% to 34%) and 18‐28 weeks of gestation, single pregnancies, no complications and who consented to participate in the study were randomly allocated to 1 of 2 groups: group 1 (n = 159) received 1 daily capsule of a multiple micronutrient supplement Chemiron® containing 300 mg of ferrous fumarate, 5000 μg (5 mg) folic acid, 10 μg vitamin B12, 25 mg of vitamin C, 0.3 mg magnesium sulphate and 0.3 mg of zinc sulphate; group 2 (n = 156) received a capsule containing 200 mg ferrous sulphate and 5000 μg (5 mg) of folic acid. All patients were also provided 600 mg of chloroquine to be taken under supervision and 25 mg weekly of pyrimethamine throughout pregnancy. Patients who became anaemic during pregnancy were excluded of the study and analysis. Outcomes measured included blood Hb, anaemia, HCT, serum ferritin levels, side effects. A second published study followed these same women and their infants. Both groups received iron and folic acid supplements, thus making the comparisons not suitable for this review.
Ortega‐Soler 1998	41 healthy pregnant women, attending prenatal care clinics at Hospital Diego Paroissien in La Matanza, Province of Buenos Aires, Argentina with serum ferritin below 50 mg/mL were assigned to 1 of 2 groups: group 1 received 100 mg of elemental iron daily (as ferric maltosate); group 2 received no treatment. Supplementation started at 21 +/‐ 7 weeks of gestation until birth. Maternal outcomes measured included: Hb, erythrocyte protoporphyrin, serum ferritin at baseline and term, dietary intake. The iron intake was unsupervised and compliance was not reported. The trial is not randomised nor quasi‐randomised so it does not fill the inclusion criteria for this review.
Osifo 1970	52 pregnant women 18‐40 years of age with 15‐22 weeks of gestation attending routine prenatal care in the village of Osegere, Nigeria with no complications were divided into 3 groups based on the day of the week convenient to them to attend the weekly clinic: group 1 received iron supplements (200 mg ferrous sulphate) 3 times a day; group 2 received iron supplements (200 mg ferrous sulphate) 3 times a day plus a tablet containing 5000 µg (5 mg) folic acid daily; group 3 received iron supplements (200 mg ferrous sulphate) 3 times a day plus a tablet containing 5000 µg (5 mg) folic acid daily and 800 mg of cholorique sulphate (Nivaquine; May & Baker Ltd, Dagenham, Essex) at first and 25 mg of pyrimethamine (Daraprim; Burroughs Wellcome, 10 Lancaster Onike Road, Yaba, Lagos, Nigeria) weekly. Blood samples were collected each week and assessed for Hb and HCT concentrations. The study is not randomised and all the women received iron supplements. The type of study design and the type of interventions are outside the scope of this review.
Osrin 2005	1200 healthy pregnant women with a singleton pregnancy and less than 20 weeks' gestation attending an antenatal clinic at Janakpur zonal hospital in Nepal, were randomly assigned to receive routine 60 mg elemental iron daily and 400 μg (0.4 mg) folic acid supplements or a multiple micronutrient supplement containing 15 vitamins and minerals including 30 mg elemental iron and 400 μg (0.4 mg) folic acid. Both groups received iron and folic acid. No comparisons allowed within the scope of this review.
Parkkali 2013	4326 non‐high risk pregnant women 18 years of age or older attending prenatal care consultation at the 2 health centres (1° de Maio and Machava) in Maputo, Mozambique, a setting of endemic malaria and high prevalence of HIV. In this pragmatic randomised controlled trial to compare 2 iron administration policies were evaluated. Participants randomly allocated to 1 of 2 groups: group 1 (n = 2184) received routine iron 60 mg (as ferrous sulphate) and 400 μg (0.4 mg) of folic acid daily throughout pregnancy; group 2 (n = 2142) were assigned to the selective intervention (i.e, regular screening for Hb level and treatment for anaemia only after diagnosis) where they were screened and treated for anaemia and daily intake of 1000 µg (1 mg) of folic acid). In group 2 (selective iron group), women’s Hb levels were measured at each visit by the study nurses using a rapid Hb measure, HemoCue Hb 201+, (Hemocue AB, Ängelholm, Sweden). If the Hb was 90 g/L or more, they received 30 tablets of 1000 µg (1 mg) of folic acid per day. If their Hb was below the cut‐off of < 90 g/L Hb, they received a monthly double dose of iron (60 mg + 60 mg) for the treatment of anaemia. The usual care recommendations at the time of the trial included daily 60 mg elemental iron + 400 μg folic acid) throughout pregnancy; 1 dose of mebendazol 500 mg for intestinal parasite; 3 doses of sulphadoxine pyrimethamine for malaria prophylaxis (started around 20 weeks' gestation, or when quickening occurs or when the fetal heart is heard); Hb measurement (Lovibond is routinely used) and syphilis screening at the first prenatal visit and 3 doses of tetanus vaccine (at the fifth and seventh months and at delivery). Women received different doses of iron and folic acid. The comparisons in this study are outside the scope of this review.
Payne 1968	200 pregnant women attending antenatal clinics in Glasgow, Scotland with less than 20 weeks' gestation, whose antenatal care was undertaken wholly by the hospital antenatal clinic and who subsequently had a normal delivery, were randomly allocated to receive 200 mg of ferrous sulphate daily or 200 mg of ferrous sulphate with 1700 μg (1.7 mg) of folic acid daily throughout pregnancy. Both groups received iron. No comparisons allowed within the scope of this review.
Peña‐Rosas 2003	116 pregnant women of 10‐30 week of gestational age attended antenatal care clinics in Trujillo, Venezuela were randomly allocated to receive a 120 mg oral dose of iron (as ferrous sulphate) and 500 μg (0.5 mg) of folic acid weekly (n = 52) or 60 mg elemental iron (as ferrous sulphate) and 250 μg (0.25 mg) folic acid and a placebo twice weekly (n = 44). Hb, HCT, serum ferritin and transferrin saturation were estimated at baseline and at 36‐39 week of gestation. All groups received iron and folic acid in 2 intermittent regimens with no control group. No comparisons allowed within the scope of this review.
Picha 1975	In a randomised double‐blind study the new effervescent iron tablet Loesferron® was tested in 57 postpartum women. The participants were not pregnant women.
Pita Martin 1999	203 healthy pregnant women with normal blood pressure at first visit, attending antenatal care clinic at Diego Paroissien Hospitalin the Province of Buenos Aires, Argentina were included in the study, but in this review only 41 women who were randomised and completed the study were included in the analysis. Participants were assigned to 1 of 3 groups: group 1 received 60 mg of elemental iron (as ferrous fumarate) daily; group 2 received 60 mg elemental iron (as ferrous fumarate) every 3 days; group 3 received no treatment. Supplementation started at 8‐28 weeks until 34‐37 weeks of gestation. Outcomes: maternal: Hb, HCT, erythroporphyrin, serum ferritin concentration at baseline and at 34‐37 weeks' gestation, premature delivery, birthweight. Unsupervised. Compliance not reported.   Women from control group (group 3) were not assigned randomly. These women were recruited but due to delays in the acquisition of the iron tablets and the progression of their pregnancies without supplementation they were left as controls in the study.
Powers 1985	81 pregnant 14‐36 weeks of gestation or lactating (1‐20 months postpartum) women with Hb less than 140 g/L living in a village in The Gambia were allocated to 1 of 4 groups: group 1 received daily placebo; group 2 received 5 mg riboflavin; group 3 received 30 mg ferrous sulphate; group 4 received 30 mg ferrous sulphate + 5 mg riboflavin. At the beginning of the study and at 3 and 6 weeks thereafter women were examined clinically and blood samples collected for haematological and biochemical measurements. This is not a randomised trial.
Quintero 2004	107 healthy pregnant women with 6‐20 weeks of gestation who had not received iron supplements during the current pregnancy attending 19 health units in the State of Morelos, Mexico were randomly assigned by block pairs to receive either 120 mg of elemental iron (as ferrous sulphate) in a single dose daily or once weekly. Hb concentration, prevalence of anaemia and nutrient consumption at baseline and after 10 weeks of supplementation were measured. Both groups received iron in different regimens (daily versus weekly). Gestational ages were variable among the participants.
Rae 1970	In this quasi‐randomised trial, pregnant women attending antenatal clinic at the Department of Obstetrics and Department of Haematology, Walton Hospital, Liverpool, United Kingdom were assigned to 1 of 2 groups: group 1 received 200 mg ferrous gluconate 3 times a day throughout pregnancy; group 2 received 200 mg ferrous gluconate + 5000 μg (5 mg) 3 times a day. Both groups received iron daily. The type of comparison is outside of the scope of this review.
Ramakrishnan 2003	873 pregnant women living near Cuernavaca, Morelos, Mexico with less than 13 weeks of gestation who did not use micronutrient supplements were randomly assigned to receive a daily multiple micronutrient supplement or a daily iron‐only supplement. Both supplements contained 60 mg of elemental iron (as ferrous sulphate). Supplement intake was supervised by trained workers from registration until delivery by home visits 6 days a week. No comparison allowed within the scope of this review.
Rayado 1997	394 healthy non‐anaemic adult pregnant women with 24‐32 weeks of gestation and singleton pregnancy from Fuentalabra, Spain were randomly assigned to 1 of 2 groups: group 1 received 40 mg of elemental iron (as iron mannitol albumin) daily; group 2 received 40 mg elemental iron (as iron protein succinylate) daily. Both groups received iron daily. No comparisons allowed within the scope of this review.
Reddaiah 1989	110 pregnant women attending the antenatal clinic at Comprehensive Rura Health Services Project Hospital, Ballabgarh, India, with 16‐24 weeks of gestation were randomly assigned to 1 of 3 groups: group 1 received 60 mg elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) of folic acid daily; group 2 received 120 mg elemental iron (as ferrous sulphate) with 500 μg (0.5 mg) of folic acid daily; group 3 received 240 mg elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) of folic acid daily. All groups received iron daily. No comparisons allowed within the scope of this review.
Ridwan 1996	176 pregnant women with 8‐24 weeks of gestation attending antenatal care at 6 health centres in West Java, Indonesia. Health centres were randomised to 1 of 2 interventions: weekly regimen, where women received 120 mg of elemental iron (as ferrous sulphate) with 500 μg (0.5 mg) of folic acid; or daily regimen where women received 60 mg of elemental iron (as ferrous sulphate) with 250 μg (0.25 mg) of folic acid daily until week 28‐32 of gestation. Supplementation started at 8‐24 weeks until 28‐32 weeks of gestation. Both groups received iron in different regimens.
Robinson 1998	680 pregnant women served by 11 health centres from 5 sub‐districts on or near the western end of the island of Seram in the Province of Maluku, Indonesia were assigned to 1 of 2 interventions: group 1 received 60 mg of elemental iron (as ferrous sulphate) with 250 μg (0.25 mg) of folic acid daily by a traditional birth attendant; group 2 received 120 mg of elemental iron (as ferrous sulphate) with 500 μg (0.5 mg) of folic acid once a week by the traditional home visiting birth attendants. A control group was formed by participants receiving traditional iron supplements (60 mg elemental iron) with folic acid from health centres, self‐administered without incentive. Groups 1 and 2 both received iron in different regimens. The control group was not assigned the traditional iron supplement.
Rolschau 1979	36 pregnant women were selected consecutively, paired 2 and 2, and allotted to 2 groups, 1 of which was supplied daily with 5000 ug (5 mg) folic acid, and the second with tablets without folic acid, from the 23rd week of pregnancy. The type of comparison is outside the scope of this review.
Roth 1980	23 pregnant women were assigned to 1 of 2 groups during August 1976 and September 1977: group 1 (n = 11) received a supplement daily 'Tardyferon‐Fol ®" containing 80 mg ferrous sulphate and 350 ug (0.35 mg) folic acid; group 2 (n = 12) received a supplement daily' Tardyferon®" containing 80 mg ferrous sulphate. Both groups received iron. The type of intervention is outside the scope of this review.
Roztocil 1994	84 non‐anaemic pregnant women at Mazarik University Brno in Czech Republic were treated from 20‐24 weeks with 1 capsule of Actiferrin Compositum®, and from 36 weeks to delivery with 2 capsules. The group was compared with 57 non‐anaemic pregnant women who received no supplements. The supplement contained 34.5 mg of elemental iron (as ferrous sulphate), 500 μg (0.5 mg) of folic acid, and 0.3 mg of cyanocobalamin. This is not a randomised trial. No comparisons allowed within the scope of this review.
Rukhsana 2006	90 pregnant women attending the Department of Obstetrics and Gynaecology Jinnah Postgraduate Medical Centre Karachi, with clinical sings of anaemia (Hb < 110 g/L) were randomly assigned to 1 of 3 supplementation groups (30 women in each group): group 1 received 60 mg iron/daily; group 2 60 mg iron/once a week; group 3 120 mg iron/once a week for 12 weeks. Hb, RBC count, red cell indices and reticulocyte count were measured and results compared to baseline to 12 weeks and between groups. The study was excluded because there were 3 groups receiving iron, 1 group daily and the other 2 intermittently. This type of comparison is outside the scope of this review.
Rybo 1971	117 pregnant women between 20‐29 weeks of gestation were alternatively assigned during 3 consecutive 2 weeks periods to receive daily tablets containing 200 mg of elemental iron (as ferrous sulphate), 200 mg of elemental iron (as a sustained released iron) or placebo. After each 2‐week treatment period women were questioned about possible side effects. No side effects are reported by group assigned. No comparisons are allowed within the scope of this review.
Sachdeva 1993	In this study carried out in rural India 66 pregnant women from low‐ and middle‐income groups received nutritional supplements. Women in both groups received both iron and folic acid supplements. In addition, women in the experimental group received a calcium supplement, individual and group counselling and a booklet about nutrition in pregnancy. All women received iron and folic acid supplements (the dose and regimen were not clear) and it was not clear that allocation to groups was random.
Saha 2007	100 pregnant women aged 20‐40 years at 14 to 27 weeks' gestation, with Hb < 90 g/L, and serum ferritin < 12 μg/L, attending the Department of Pharmacology and the Department of Obstetrics and Gynaecology at the Postgraduate Institute of Medical Education and Research, Chandigarh, India were randomly assigned to 1 of 2 groups: group 1 received 100 mg elemental iron (as iron polymaltose complex) and 500 μg (0.5 mg) folic acid daily; group 2 received 120 mg elemental iron (as ferrous sulphate) and 500 μg (0.5 mg) folic acid daily for 8 weeks. Both groups received iron and folic acid. No comparisons can be made within the scope of this review.
Sandstad 2003	233 pregnant women attending their second antenatal care visit at the University Health Services of Oslo, Norway with serum ferritin concentration < 60 μg/L were randomised to 2 different iron preparations: group 1 received 1 tablet containing 60 mg of elemental iron (as ferrous sulphate) daily; group 2 received 3 tablets each containing 1.2 mg of heme iron from porcine blood plus 8 mg of elemental iron (as ferrous fumarate) per tablet (total 3.6 heme iron and 24 mg elemental iron) daily. A third group (n = 93) of pregnant women who had been given advice to take or not the iron supplements according to the centre recommendations were enrolled in the trial at 6 weeks postpartum and served as control. The study groups were not randomised to the interventions and no comparisons can be made within the scope of this review.
Schoorl 2012	25 pregnant women in the third trimester of pregnancy with suspected IDE during pregnancy (Hb ≤ 110g/L, Ret‐He < 29.6 pg, zinc protoporphyrin > 75 mol/mol hem) participated in the study, receiving ferrous fumarate (200 mg 2 times a day, approx. 200 mg iron a day) according to local practice during 4 weeks. From the first trimester of pregnancy, 400 ug of folic acid was given as supplement in a multivitamin tablet (Centrum® Materna). Blood samples were drawn to establish haemocytometric parameters to evaluate RBC and reticulocyte Hb content. The study was excluded because there was a single group of women receiving iron during the third trimester of pregnancy without control, placebo or other intervention groups. There was not randomisation. This type of interventions is outside the scope of this review.
Seck 2008	221 apparently healthy pregnant women, had not used iron supplements prior to enrolment, who were 12 to 16 weeks were recruited from 6 health centres in Dakar, Senegal during their first prenatal visit, and randomly assigned to receive either a prescription to purchase iron/folic acid tablets to be taken daily, according to official policy, or to receive free tablets. Compliance was assessed 20 weeks after enrolment through interviews and pill count. All women received iron. No comparisons allowed within the scope of this review.
Shatrugna 1999	115 healthy pregnant women with 20‐28 weeks of gestation attending the antenatal clinic of the National Institute of Nutrition, Government Maternity Hospital, India were randomly assigned to 1 of 11 different formulations and doses of iron and then undergo iron tolerance tests. They received ferrous sulphate tablets containing 60 mg, 12 mg, and 180 mg of elemental iron; formulations containing 60 mg of elemental iron as pure ferrous sulphate salt, ferrous fumarate tablets, ferrous fumarate syrup, excipients added to pure ferrous sulphate salts; powdered ferrous sulphate tablets, iron tablets distributed by the National Nutritional Anaemia Prophylaxis Programme and pure ferrous salt in gelatin capsules. All women received iron. No comparisons allowed within the scope of this review.
Sinha 2011	50 pregnant women between 16‐20 weeks of gestation with Hb equal or greater than 100 g/L in Allahabad, in the north Indian state of Uttar Pradesh, India were randomly assigned to 1 of 2 groups: group 1 (n = 22): women received 2 doses of 400 mg iron sucrose infusion, 1 at 16‐20 weeks' gestation and a second infusion at 28‐32 weeks' gestation; group 2 (n = 28): women received 100 mg oral ferrous ascorbate daily starting at 16‐20 weeks' gestation. The type of intervention is outside the scope of this review.
Sjostedt 1977	300 pregnant women attending the Maternity Welfare Center, in Oulu, Finland before the 5th month of pregnancy were randomly assigned to 1 of 3 groups: group 1 received 100 mg of elemental iron (as sustained‐release tablets) daily; group 2 received 200 mg of elemental iron daily (as sustained‐release tablets); group 3 received 200 mg of elemental iron daily (as rapidly disintegrating ferrous sulphate tablets). All groups received iron in different doses and formulations.
Sood 1979	151 healthy pregnant women with Hb > 50 g/L who had not received iron supplements during the last 6 months from Delhi and Vellore, India were divided in 1 of 3 strata according to Hb concentration (50‐79 g/L; 80‐109 g/L;110 g/L and above) and within each strata were allocated randomly to 1 of 5 interventions: group 1 received 120 mg of elemental iron (as ferrous sulphate) 6 days a week; group 2 received 100 mg of elemental iron (as iron dextran complex) intramuscular twice per week; group 3 received iron as group 1 + pteroylmonoglutamic acid 5 mg/d 6 days a week + cyanocobalamin 100 μg intramuscular once per 14 d; group 4 received 100 mg of elemental iron intramuscular + pteroylmonoglutamic acid + cyanocobalamin 100 μg intramuscular; group 5 received iron dextran complex intramuscular in a single total dose infusion + 5 mg/d pteroylmonoglutamic acid + 100 μg intramuscular cyanocobalamin once per 14 days. All groups received iron at different doses and routes. No comparisons allowed within the scope of this review.
Srisupandit 1983	567 pregnant women 16‐30 years of age with 18‐26 weeks' gestation attending antenatal care clinic, in the department of Obstetrics and Gynecology of the Siriraj Hospital, Thailand were randomly assigned to 1 of 3 groups; group 1 received 60 mg elemental iron daily; group 2 received 180 mg elemental iron daily; group 3 received 180 mg elemental iron and 5000 ug (5 mg) folic acid daily. The intervention lasted 3 months. THere were 101 losses to follow‐up. All participants received iron. The type of interventions is outside the scope of this review.
Steer 1992	Trial abandoned. No data available.
Stone 1975	248 healthy pregnant women attending hospital antenatal clinic in London, England, were allocated randomly to receive 105 mg of elemental iron (as ferrous sulphate slow release dose) and 350 μg (0.35 mg) of folic acid daily or 80 mg of elemental iron (as ferrous fumarate) and 400 μg (0.4 mg) of folic acid daily in a standard preparation. Both groups received iron in different doses and preparations. No comparisons allowed within the scope of this review.
Swain 2011	100 women with uncomplicated pregnancy were assigned to received either injectable iron sucrose (400 mg diluted in 400 mL of normal saline) over 2‐3 hours or to receive oral dose of 100 mg elemental iron daily. The interventions in this trial are outside of the scope of this review.
Tampakoudis 1996	82 pregnant women with Hb concentrations 140 g/L or above attending clinic in Thessaloniki, Greece were randomised to receive 80 mg iron protein succinylate daily or a placebo. Serial Hb, HCT and serum erythropoietin were measured from maternal blood and cord blood on delivery; serum ferritin measured in frequent intervals. Abstract only available. Insufficient information to assess characteristics of the trial.
Tan 1995	285 healthy middle‐class pregnant women with Hb concentration above 100 g/L attending antenatal clinic at the University Hospital at Kuala Lumpur, Malaysia were assigned to receive daily iron supplements or no treatment. Abstract only available. No additional information was available, including doses, regimens or any other characteristics of the trial.
Tange 1993	128 anaemic and non‐anaemic pregnant females aged 10‐19 years old, with an average gestation of 16 weeks, were grouped for 3 levels of iron supplementation: group 1 (n = 42 non‐anaemic participants) received placebo (no iron); group 2 (n = 41 anaemic and non‐anaemic participants) received 22 mg of elemental iron daily; group 3 (n = 45 anaemic and non‐anaemic participants) received 55 mg elemental iron daily.  Women were supplemented from 16 weeks until delivery. Outcomes assessed included Hb, HCT, RBC count, MCV, serum iron, serum transferring and serum, ferritin measured every 4 weeks. The study is not reported as randomised and is excluded in the first screening for eligibility.
Thane‐Toe 1982	135 healthy pregnant women between 22‐28 weeks of gestation attending antenatal clinic in Burma, were randomly assigned to receive a daily dose of 60 mg, 120 mg or 240 mg of elemental iron (as ferrous sulphate). A control group was composed by 47 apparently healthy adults (17 males and 30 single women). Control groups are not appropriate. No comparisons allowed within the scope of this review.
Thomsen 1993	52 healthy non‐anaemic nulliparous women with normal singleton pregnancy and serum ferritin levels above 15 mg/L at 16th week in Herlev, Denmark were randomly assigned to receive either a daily tablet containing 18 mg elemental iron or a daily tablet containing 100 mg of elemental iron from 16 weeks until delivery. All women received 300 μg (0.3 mg) of folic acid daily. All women received iron in different doses. No comparisons allowed within the scope of this review.
Trigg 1976	158 pregnant women seeking antenatal care with general practitioners in the former South‐east England Faculty of the Royal College of General Practitioners, in South England, United Kingdom were assigned to 1 of 2 groups: group 1 (n = 76) received 50 mg ferrous sulphate daily to 76 pregnant women was compared with giving ferrous sulphate 50 mg daily + 500 μg (0.5 mg) folic acid. After the first test, patients were randomly allocated to 1 of the 2 treatments which was either a minimum of 50 mg of ferrous sulphate daily or a minimum of 50 mg of ferrous sulphate plus 500 μg (0.5 mg) of folic acid daily, and afterwards allocation was in sequence. Both groups received iron. The type of comparison is not within the scope of this review.
Vogel 1963	191 consecutive pregnant when attending antenatal care clinics and at 32 weeks of gestation were divided in 2 groups by alternate allocation by clinic: group 1 received 140 mg of elemental iron daily (as ferrous gluconate) in 4 tablets; group 2 received 150 mg elemental iron daily (as ferrous glutamate) in 3 tablets. All women received iron in different dose and number of tablets. No comparisons allowed within the scope of this review.
Wali 2002	60 iron‐deficient anaemic pregnant women with the gestational age of 12‐34 weeks were randomly assigned to 1 of 3 groups: group 1 (n = 15) received intravenous 500 mg of iron sucrose for storage; group 2 (n = 20) received intravenous iron sucrose according to deficit calculated as per formula with 200 mg of iron was given for storage; group 3 received intramuscular iron Sorbitol in the dose used as practice. All groups received iron intravenously or intramuscularly.
Weil 1977	29 attending a clinic at University of Basel, Switzerland between May and November 1976 with 20 weeks' gestation were randomly assigned in 1 of 2 groups: group 1 (n = 15) received 80 mg elemental iron slow release as ferrous sulphate (Tardyferon®); group 2 (n = 14) received 80 mg elemental iron slow release as ferrous sulphate + 350 μg (0.35 mg) folic acid (gino‐Tardyferon®) until term. Women who had already taken multiple micronutrient supplements containing folic acid were excluded from the study. Both groups received iron. The type of interventions is outside the scope of this review.
West 2014	28,516 pregnant women were provided supplements containing 15 micronutrients (14,374) or iron–folic acid alone (14,142), taken daily from early pregnancy to 12 weeks postpartum, to assess effects of antenatal multiple micronutrient vs iron–folic acid supplementation on 6‐month infant mortality and adverse birth outcomes. Surveillance included 127,282 women; 44,567 became pregnant and were included in the analysis and delivered 28,516 live‐born infants. Median gestation at enrolment was 9 weeks. The study was excluded because it was conceived to assess effects of antenatal multiple micronutrient vs iron–folic acid supplementation on 6‐month infant mortality and adverse birth outcomes and it is not possible to evaluate the role of iron alone on the proposed outcomes. This type of interventions is outside the scope of this review.
Willoughby 1966	350 consecutive pregnant women attending antenatal care clinic were allocated to 1 of 5 groups: group 1 received no hematinic supplements; group 2 received 105 mg of elemental iron daily (as iron chelate aminoates); group 3 received 105 mg of elemental iron daily with 100 μg (0.1 mg) of folic acid; group 4 received 105 mg of elemental iron daily with 300 μg (0.3 mg) of folic acid; group 5 received 105 mg of elemental iron daily with 450 μg (0.45 mg) of folic acid. All women received a multivitamin preparation (Vivatel®) free of folic acid. This is not a randomised trial.
Willoughby 1968	68 pregnant women attending antenatal care clinic in Queen Mother's Hospital in Scotland, were randomly allocated to receive 195 mg of elemental iron alone daily or 195 mg of elemental iron in conjunction with 300 μg (0.3 mg) of folic acid daily. Both groups received iron. No comparisons allowed within the scope of this review.
Winichagoon 2003	484 healthy pregnant women with 13‐17 weeks of gestation who had not received iron supplements before enrolling in the study, and who had a Hb concentration > 80 g/L attending antenatal care clinics at the district hospital and 7 health centres from 54 villages in the Province of Khon‐Kaen in northeast Thailand. The villages were grouped according to size and then randomised in 4 clusters to 1 of 3 interventions: group 1 received a daily regimen providing 60 mg of elemental iron (as ferrous sulphate) with 250 μg (0.25 mg) of folic acid daily; group 2 received 120 mg of elemental iron with 3500 μg (3.5 mg) of folic acid once a week; group 3 received 180 mg of elemental iron (as ferrous sulphate) with 3500 μg (3.5 mg) of folic acid once a week. Supplementation started at 15 +/‐ 2 weeks until delivery. All groups receive iron in different regimens (weekly versus daily) or doses. No comparisons allowed within the scope of this review.
Wu 1998	369 pregnant women attending antenatal care at Beijing Hospital, China were divided into 2 groups according to their initial Hb concentrations. Women with Hb 110 g/L or above were randomly assigned to 1 of 2 groups: group 1 (n = 96) received 1 daily tablet of maternal supplement containing 60 mg of elemental iron in addition to other micronutrients including calcium and magnesium; group 2 (n = 95) served as control and received no supplements. Another group of women with Hb < 110 g/L (treatment group) were randomly assigned to 1 of 3 groups: group 1 received 1 tablet of maternal supplement daily; group 2 received 0.9 g of ferrous sulphate daily; group 3 received 1 tablet of Ferroids, a sustained released preparation daily. In the preventive group, women entered the study from 20‐24 gestational weeks. In the treatment groups, women less than 36 gestational weeks were accepted. No comparisons allowed within the scope of this review. This is not a randomised trial.
Yecta 2011	210 pregnant women with 17–20 weeks' gestation and singleton pregnancies, no known disease, and Hb levels higher than 110 g/L attending local public healthcare centres at 7 prenatal healthcare clinics between September 2007 and February 2009 in the urban regions of Urmia city North West Iran were randomly assigned to 1 of 3 groups: group 1 (n = 70) received 2 iron supplementation tablets once weekly providing 100 mg elemental iron per week (as ferrous sulfate); group 2 (n = 70) received 1 tablet twice weekly providing 100 mg elemental iron per week (as ferrous sulfate); group 3 (n = 70) received 1 tablet daily containing 50 mg elemental iron per day (as ferrous sulfate). No additional micronutrients were supplied. Hb and serum ferritin levels were measured at 20, 28, and 38 weeks. Pregnancy and birth outcomes (pregnancy termination, method of delivery, birthweight, stillbirth) were reported. All participants received iron in different regimens. The type of interventions is outside the scope of this review.
Young 2000	413 healthy non‐severely anaemic pregnant women attending antenatal care at Ekwendeni Hospital or its mobile clinics in northern Malawi with less than 30 weeks of gestation at their first visit, stratified by initial Hb concentration before randomisation. Supplementation starting time variable (22.2 +/‐ 4.8 weeks) and ending time variable (32.2 +/‐ 4.4 weeks of gestation). Participants were randomly assigned within each anaemia grade category to 1 of 2 interventions: group 1 received 120 mg of elemental iron (as ferrous sulphate) with 500 ?g (0.5 mg) of folic acid once a week; group 2 received 60 mg of elemental iron (as ferrous sulphate) with 250 ?g (0.25 mg) of folic acid daily. Outcomes: maternal: Hb concentration at baseline and after 8 weeks of supplementation; compliance, presence of side effects, and prevalence of anaemia. All women received iron and folic acid in  different regimens (daily versus weekly). No comparisons allowed within the scope of this review.
Young 2010	This trial examines the relative differences in heme (animal‐based) and non‐heme (ferrous sulphate) iron utilisation in 20 non‐smoking, pregnant women (19 yeas or older; n = 10) and adolescents (18 years of age or younger; n = 10) from the Strong Midwifery Group and the Rochester Adolescent Maternity Program in Rochester, NY, USA and 12 healthy, non‐smoking, non‐pregnant women ages 18–27 years recruited in 2009 from Ithaca, NY, USA. Women were randomly assigned to receive both an animal‐based heme meal (intrinsically labelled 58Fe pork) and labelled ferrous sulphate (57Fe) fed on alternate days. The type of design and the comparisons of this study are outside the scope of this review.
Yu 1998	51 healthy pregnant women with 18‐22 weeks of gestation who had not taken supplements or medication in the previous 6 months attending public health centre in Ulsan, South Korea were randomly assigned to 1 of 2 groups: group 1 received 160 mg of elemental iron (as ferrous sulphate) in 1 intake once a week; group 2 received 80 mg of elemental iron (as ferrous sulphate) daily. Women with low Hb were assigned by the trialists to daily regimen. Supplementation started at 20.1 weeks and 20.2 weeks of gestation for groups 1 and 2, respectively. Both groups receive iron in different regimens (weekly versus daily). No comparisons allowed within the scope of this review.
Zamani 2008	152 healthy, non‐anaemic pregnant women aged 18‐38 years, 15‐16 weeks’ gestation (gestation estimated by menstrual dates and ultrasound) attending 2 clinics for prenatal care in Isfahan, Iran. ("In Iran, it is mandatory to prescribe iron (1 tablet containing 45 mg elemental iron (as ferrous sulphate) per day) and folic acid supplements to pregnant women after the 15th‐ 18th week of gestation"). Exclusion criteria: current anaemia (Hb < 110 g/L), past history of anaemia, thalassaemia, or other blood disorders, history of previous obstetric problems (haemorrhage, pregnancy‐induced hypertension, diabetes) or any other chronic systemic disorder. Participants were assigned to 1 of 2 groups: group 1 (experimental group) received 2 tablets of 45 mg elemental iron (as ferrous sulphate) taken on a single day each week. “Women in the trial group were instructed to choose any day of the week and to take 2 tablets of 45 mg elemental iron (as ferrous sulphate) each on the same day every week, 1 in the morning and 1 before dinner” i.e. 90 mg of “elemental iron (as ferrous sulphate) 1 day per week in 2 takes”. (Supplied as 8 tablets every 4 weeks) for 16 weeks (from recruitment at 16‐18 weeks); group 2 (control group) were to take 1 tablet containing 45 mg elemental iron (as ferrous sulphate) daily for 16 weeks (from recruitment at 16‐18 weeks). Supplied as 28 tablets every 4 weeks. Both groups receive iron in different regimens (weekly versus daily). No comparisons allowed within the scope of this review.
Zhou 2009	180 anaemic women (Hb < 110 g/L) attending antenatal care at the Children, Youth and Women's Health Service, Adelaide, Australia with 24‐32 weeks of gestation and a singleton pregnancy. Women were excluded if they were taking iron or vitamins and minerals supplements, had presumptive diagnosis of non iron‐deficiency‐related anaemia, history of thalassaemia, drug or alcohol abuse and/or diabetes requiring insulin or a known fetal abnormality. Women were randomly assigned to receive a daily dose of 20, 40 or 80 mg of elemental iron (as ferrous sulphate) for 8 weeks or until birth. The primary outcomes measured were Hb levels, anaemia at the end of the intervention and gastrointestinal side effects during treatment. All women received iron at different doses. No comparisons allowed within the scope of this review.
Zutschi 2004	200 apparently pregnant women with 24‐26 weeks of gestation, with singleton pregnancy and moderate anaemia (Hb > 80 g/L and < 110 g/L) were randomly assigned to receive injectable iron‐sorbitol‐citrate in 3 intramuscular doses of 150 mg each at 4 weeks intervals or 100 mg of elemental iron daily. Hb concentrations were measured at baseline, every 4 weeks and at delivery. The study compares 2 routes of iron administration. Both groups receive iron. No comparisons allowed within the scope of this review.

BMI: body mass index
 Fe: iron
 Hb: haemoglobin
 HCT: hematocrit (same as PCV: packed cell volume)
 IDE: iron‐deficient erythropoiesis
 IU: international units
 MCV: mean corpuscular (or cell) haemoglobin concentration
 RBC: red blood cell
 RDA: Recommended Dietary Allowance
 SES: socioeconomic status