| Study | Reason for exclusion |
|---|---|
| Ala‐Houhala 1986 | 49 healthy, well‐nourished mothers delivering in January 1984 in the maternity wards and outpatient clinic of the Department of Paediatrics of the University Central Hospital of Tampere, Finland (latitude 61°N) and exclusively breastfeeding their infants, were divided in succession into 3 groups: group 1 (n = 17): mothers were given 2000 IU vitamin D3 a day, infants not supplemented; group 2 (n = 16): mothers were given 1000 IU vitamin D3 a day, infants not supplemented; group 3 (n = 16): mothers were not supplemented, and their breast fed infants were given 400 IU of vitamin D2 a day. This is not a randomised trial and the intervention includes mothers at postpartum and their infants. |
| Asemi 2013b | 54 pregnant women aged 18 to 40 years diagnosed with GDM by a 100‐g oral glucose‐tolerance test at 24 to 28 weeks' gestation attending maternity clinics affiliated with Kashan University of Medical Sciences, Kashan, Islamic Republic of Iran. Participants were randomly assigned to 1 of 2 groups: group 1 (n = 27), women received capsules containing 50,000 IU vitamin D (cholecalciferol‐D3) (D‐Vitin 50000; Zahravi Pharm Co) 2 times during the study (at baseline and at day 21 of the intervention): group 2 (n = 27), women received 2 placebos (Barij Essence Co) at the same times. All pregnant women in the study had a diagnosis of gestational diabetes. The type of participant is outside the scope of this review. |
| Asemi 2014 | 56 pregnant women 18 to 40 years of age with gestational diabetes and 24 to 28 weeks' gestation attending prenatal care at maternity clinics affiliated to Kashan University of Medical Sciences, Kashan, Iran were randomly assigned to 1 of 2 groups: group 1 (n = 28) received 1000 mg calcium per day and a 50,000 U vitamin D (cholecalciferol‐D3) pearl twice during the study (at study baseline and on day 21 of the intervention); group 2 (n = 28) received 2 placebos at the same times. Participants were pregnant women with diagnosis of gestational diabetes. The type of participant is outside the scope of this review. |
| Asemi 2015 | 46 women at risk for pre‐eclampsia at 27 weeks' gestation with positive roll‐over test were randomly assigned to receive either the multi mineral‐vitamin D supplements (n = 23) or the placebo (n = 23) for 9 weeks. Study was conducted in Kashan, Iran, during November 2013 to May 2014. Multi mineral‐vitamin D supplements were containing 800 mg calcium, 200 mg magnesium, 8 mg zinc, and 400 IU vitamin D3. Fasting blood samples were taken at baseline and after 9‐week intervention to measure related factors. Newborn's outcomes were determined. This type of intervention is outside the scope of this review. |
| Atkinson 2010 | 120 African American or Caucasian primigravidae women 19 to 40 years of age in their first trimester of pregnancy in Children’s Hospital & Research Center Oakland, California, USA were included in this study. Women who were smokers, had a pre‐pregnancy BMI higher than 30, had a medical condition that affected bone or taking a medication that affected bone were excluded. Participants were randomly assigned to 1 of 3 groups: group 1: 1000 mg of calcium; group 2: 2000 IU vitamin D; group 3: placebo. The intervention started at week 16 of pregnancy until delivery. The type of intervention is outside the scope of this review. |
| Azami 2017 | 90 pregnant women,with least 1 of the risk factors for PE were randomly divided into 3 groups according to randomised selection: Group A received 1 ferrous sulphate tablet (Rooz daru©, Iran) + 1 Claci‐care multimineral‐vitamin D tablet [(VitanePharma©, Germany) contained 800 mg Ca, 200 mg Mg, 8 mg Zn and 400 IU vitamin D3)]per day; Group B received 1 ferrous sulphate tablet (Rooz daru©, Iran,) + 250 mg vitamin C and 55 mg vitamin E, and control group only received Ferrous sulphate daily. This type of intervention is outside the scope of this review. |
| Baqui 2009 | 28 pregnant women were enrolled at a maternal health clinic in inner‐city Dhaka, Bangladesh Aged 18 to 34 years; at 27 to 30 weeks of pregnancy. Participants were randomly assigned to 1 of 2 groups: group 1 (N = 14) were assigned to receive a single dose of vitamin D3 70,000 IU (1.75 mg, where 1 mg = 40,000 IU) on day 0 followed by vitamin D3 35,000 IU (0.875 mg) per week starting on day 7 and continuing until delivery); Group 2 (N = 14), were assigned to receive vitamin D3 14,000 IU (0.350 mg) per week starting on day 0 and continuing until delivery. All participants received vitamin D supplementation in different regimens. The type of intervention is outside the scope of this review. |
| Bhatia 2010 | 150 consecutive pregnant women pregnant women during their second trimester from 6 villages of a poor socio‐economic region in district Barabanki (latitude 26.8 ºN), Uttar Pradesh, north India. The participants were initially randomised to receive either no dose or 1 dose of 60,000 IU cholecalciferol under observation in the 5th gestational month. This is not a randomised trial and the comparisons are outside the scope of this review. |
| Bhatia 2012 | 299 pregnant women with 12 and 24 weeks of gestation of lower‐middle and middle socio‐economic groups attending the antenatal clinic in Queen Mary Hospital, Chhatrapati Sahuji Maharaj, India, were randomly assigned to 1 of 2 groups, group 1: received 1500 mcg cholecalciferol at induction into the study, or group 2 3000 mcg cholecalciferol at induction as well as at 28 weeks of gestation. All were prescribed 1 g of elemental calcium daily as calcium carbonate without vitamin D. This type of intervention is outside the scope of our review. |
| Bisgaard 2009 | 623 women were recruited at 24 weeks of pregnancy. Women were randomised 1:1 to a daily dose of 2400 IU vitamin D3 supplementation or matching placebo tablets (Camette A/S) from pregnancy week 24 to 1 week postpartum. In addition, all women were instructed to continue supplementation of 400 IU of vitamin D3 during pregnancy as recommended by the Danish National Board of Health; thus, the study is a dose comparison of 2800 IU/day vs 400 IU/day of vitamin D3 supplementation. Both groups received vitamin D. This type of intervention is outside the scope of our review. |
| Chandy 2016 | 230 infants and mothers giving birth in 2 maternity units of the institution, who intended to continue exclusive breast‐feeding until the first 6 months and come to the hospital of birth for immunisation, were eligible, from September 2012 and June 2014 at the King George Medical University, and Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow (latitude 26°N). After maternal blood sample was collected for serum 25(OH)D 2 to 4 days after delivery, mother–infant pairs were randomly assigned at birth to 1 of 3 treatment regimens described below, to be followed for 9 months. Intervention was postpartum. |
| Cockburn 1980 | 1139 pregnant women were assigned to 1 of 2 wards: group 1 (n = 506) Caucasian pregnant women assigned to 1 ward of the Simpson Memorial Maternity Pavilion, Edinburgh, UK during the 9 months from September to May, were given a daily dietary supplement of 400 IU of vitamin D2 from about the 12th week of pregnancy until delivery; group 2 women (n = 633) were assigned to another ward over the same period and were given a placebo containing no vitamin D. This is not a randomised trial. |
| Czech‐Kowalska 2013 | 174 healthy postpartum women who had delivered babies at term in Poland, were randomised to 1 of 2 groups: group 1 (n = 70) received 1200 IU/day vitamin D (cholecalciferol‐D3 as 800 IU/day alone + 400 IU/day from a multiple micronutrient supplements; group 2 (n = 67) received 400 IU/day vitamin D (cholecalciferol‐D3 as placebo + 400 IU/day from multiple micronutrient supplements) during 6 months of lactation. Participants from both groups received vitamin D supplements. The participants were postpartum women. The type of participant and the type of interventions are outside the scope of this review. |
| Das 2010 | 200 consecutive pregnant women attending antenatal clinic of at Queen Mary Hospital in CSMMU (former KGMC) were enrolled into the study after taking informed consent and randomly allocated to 1 of 3 groups: (1) Intervention group 1 vitamin D 1,20,000IU in 3 doses each 8 weeks apart + calcium carbonate containing 500 mg elemental calcium with 250 IU vitamin D twice a day, daily throughout pregnancy; (2) Intervention group 2 vitamin D 60,000IU in 3 doses each 8 weeks apart + calcium carbonate containing 500 mg elemental calcium with 250 IU vitamin D twice a day, daily throughout pregnancy; (3) Comparator agent group 3 calcium carbonate containing 500 mg elemental calcium with 250 IU vitamin D twice a day, daily throughout pregnancy. This is a registry for an ongoing study (open to recruitment). The type of intervention is outside the scope of this review. |
| Dawodu 2013 | 192 Arab women between 12–16 weeks of gestation after their last menstrual period or by ultrasound assessment who had a singleton pregnancy; and planned to receive prenatal and delivery care in primary healthcare clinics affiliated with Tawam Hospital, Al Ain, United Arab Emirates. All participants received vitamin D supplementation in different regimens. The type of intervention is outside the scope of this review. |
| de Menibus 1984 | 77 mother‐child couples were divided into 3 groups, according to whether women were not receiving vitamin D (29 couples) during the last 3 months of pregnancy ending in winter or taking 1000 units of vitamin D in the form of uvesterol (21 pairs) or a single dose of 200,000 units of vitamin D at 7 months (27 pairs). This type of intervention, with no placebo group, is outside the scope of this review. |
| Etemadifar 2015 | 45 pregnant women with confirmed multiple sclerosis who attended an outpatient clinic in Isfahan University of Medical Sciences, Iran aged 20 to 40 years with low serum 25‐hydroxyvitamin D (25(OH)D) levels were randomly allocated to 2 groups in an open‐label randomised, controlled clinical Phase I/II pilot study. 1 group received 50,000 IU/week vitamin D3 (n = 21) or routine care (n = 22) from 12 to 16 weeks of gestation till delivery. This type of participant is outside the scope of this review. |
| Gerais 2015 | 88 women were recruited at different gestational age, the incidence of vitamin D deficiency about 66%. A single daily dose ranging from 1000 IU to 2000 IU according to the level of deficiency were given to the patient for 6 weeks. In our study 34.1% of women had a level below 10 ng/mL This type of intervention, with no placebo group, is outside the scope of this review. |
| Hashemipour 2014 | 160 pregnant women (24 to 26 weeks of gestation) who attended an obstetric clinic in Qazvin, Iran, from December 2011 to March 2012 were randomised, and included in 2 arms. Women in the control group received a multivitamin containing 400 IU vitamin D3 plus 200 mg elemental calcium each day until delivery. Women in the intervention group received a weekly dose of 50,000 IU oral vitamin D3 for 8 weeks (from 26 to 28 weeks of pregnancy) as well as the drug regimen (multivitamin and elemental calcium) given to the control group. Both groups received vitamin D and calcium. This type of intervention is outside the scope of our review. |
| Hossain 2012 | 200 pregnant women who attended the Department of Obstetrics & Gynaecology unit 3, Dow University and Civil Hospital Karachi, Pakistan aged between 18 and 40 years were randomised, and included in 2 arms. Participants were allocated to 1 of 2 groups: group 1 (n = 100) received along with ferrous sulphate, 4000 IU of vitamin D3; group 2 (n = 100) received routine antenatal care (ferrous sulphate and calcium). Both groups received above medications from 20 weeks of pregnancy until delivery. This type of intervention is outside the scope of our review. |
| Ito 1994 | 876 singleton pregnant women with blood pressure lower than 140/90 mmHg at 20 weeks’ gestation, and no evidence of proteinuria, who were attending the obstetric clinic of Kumamoto University Hospital, Japan were divided into 2 groups: group 1 (n = 666) women received conventional antenatal care; group 2 (n = 210 women) were managed under a protocol for the prediction of pre‐eclampsia with an angiotensin sensitivity test and prevention of the condition by calcium supplementation. This is not a randomised trial and the type of intervention is outside the scope of this review. |
| Jamilian 2016 | 60 participants with GDM were divided into 2 groups of either 1000 IU vitamin D3 and 1000 mg EPO or placebo for 6 weeks. At the beginning and end of the study, fasting blood samples were obtained from the participants to measure related variables. The type of participant is outside the scope of this review. |
| Jamilian 2017 | 140 GDM patients. Participants were randomly divided into 4 groups to receive: (1) 1000 mg omega‐3 fatty acids containing 360 mg eicosapentaenoic acid and 240 mg docosahexaenoic acid (DHA) twice a day + vitamin D placebo (n = 35); (2) 50,000 IU vitamin D every 2 weeks + omega‐3 fatty acids placebo (n = 35); (3) 50,000 IU vitamin D every 2 weeks + 1000 mg omega‐3 fatty acids twice a day (n = 35), and (4) vitamin D placebo + omega‐3 fatty acids placebo (n = 35) for 6 weeks. The type of participant is outside the scope of this review. |
| Kachhawa 2014 | 243 pregnant patients attending the antenatal clinic, between 18 to 40 years old and with gestational age between 12 to 16 weeks were randomised into 4 groups in a ratio of 1:1:1:1. Group 1 active control group received 600 units of vitamin D per day, group 2: 1000 units/day, group 3: 2000 units/day and group 4: 4000 units per day. This type of intervention is outside the scope of our review. |
| Karamali 2014 | 60 women in Arak, Iran, with GDM were divided into 2 groups to receive Ca + vitamin D supplements or placebo. Individuals in the Ca + vitamin D group (n 30) received 1000 mg Ca/day and 2 pearls containing 1250 μg (50 000 IU) of cholecalciferol (vitamin D3) during the intervention (one at study baseline and another at day 21 of the intervention); those in the placebo group (n 30) received 2 placebos of vitamin D at the mentioned times and placebos of Ca every day for 6 weeks. The type of participant is outside the scope of this review. |
| Karamali 2015 | 60 pregnant women Arak, Iran at risk for pre‐eclampsia according to abnormal uterine artery Doppler waveform were randomly divided into 2 groups to receive 50,000 IU vitamin D supplements (n = 30) or receive placebo (n = 30) every 2 weeks from 20 to 32 weeks of gestation. All pregnant women were also taking 400 μg/day folic acid from the start of pregnancy, 60 mg/day ferrous sulphate from the second trimester, and a multivitamin mineral capsule (containing 400 IU vitamin D) from the second half of pregnancy. The type of participant is outside the scope of this review. |
| Kermack 2017 | 111 couples were recruited for a 6‐week intervention prior to oocyte retrieval consisted of a daily drink, containing 2 g of DHA plus EPA and 10 mcg of vitamin D, and olive oil and olive oil spreads, all in unmarked containers. The control group received a placebo drink and sun flower oil and spreads, again in unmarked containers. 55 couples were randomised to the treatment group and 56 to placebo. Following IVF, embryos were cultured in an Embryoscope and validated morphokinetic markers of embryo quality were recorded; day 3 and 5 KIDScores (Known Implantation Data Score) were calculated for individual embryos. This type of intervention is outside the scope of our review. |
| Kiely 2015 | 144 pregnant women aged older than 18 years of age, with no more than 18 weeks' gestation, in good general health, with low‐risk pregnancy and not consuming > 10 mcg/day vitamin D from supplements were randomised in a 3‐arm, parallel, double‐blind, placebo‐controlled dose‐response intervention study with vitamin D. Group 1 received 10 mcg (400 IU) vitamin D3 once daily taken from baseline visit (approximately 15 weeks' gestation) until endpoint (delivery). Group 2 received 20 mcg (800 IU) vitamin D3 once daily from baseline visit (approximately 15 weeks' gestation) until endpoint (delivery). Group 3 (placebo) received a placebo capsule containing 0 mcg (0 IU) of vitamin D3 taken from baseline visit (approximately 15 weeks' gestation) until endpoint (delivery). The primary outcome was serum 25‐hydroxyvitamin D in pregnant women and cord blood. Women were permitted to continue with self‐administration of antenatal supplements containing ≤ 10 μg vitamin D per day. This type of intervention is outside the scope of our review. |
| Lalooha 2012 | Participants were randomly assigned to 1 of 2 groups: group 1: vitamin D capsule 50,000 U weekly for 8 weeks from 28 gestational age and multivitamin tablet include 400 IU vitamin D daily till termination; group 2: multivitamin tab include 400 IU vitamin D daily till termination. This type of intervention is outside the scope of our review. |
| Li 2016 | 103 pregnant GDM women were eligible to participate, using a permuted block randomisation method stratified according to their baseline 1‐hour OGTT results, all participants in their second trimester were randomly assigned to consume 2 servings (100 g per serving) of either plain yogurt (PY) drink (‘PY’ without any vitamin D3 supplement, from Mengniu Dairy, Hohhot, China) or VDY drink (‘PY’ supplemented with 500 IU vitamin D3, from Mengniu Dairy, Hohhot, China), with 1 serving at breakfast and the other 1 at dinner, on a daily basis for a period of 16 weeks. The type of participant is outside the scope of this review. |
| MacDonald 1986 | This trial was registered in 1986 on the Oxford Database of Perinatal Trials and reports the recruitment and follow‐up completed in 1979. The registration form reports a randomised controlled trial to assess the efficacy of calcium and vitamin D supplementation versus placebo in the prevention of maternal and fetal hypocalcaemia. The reports indicates that the sample size was 55 Asian women with morbidity and laboratory results as primary outcomes but no further information is available. |
| March 2010 | 226 healthy pregnant women from Greater Vancouver, British Columbia, Canada, from 13 to 24 weeks of gestation were randomly allocated to 10, 25, or 50 mg vitamin D/d from 13 to 24 weeks of gestation until 8 weeks postpartum, with no infant supplementation. Mother and infant blood was collected at 8 weeks postpartum (n = 76, n = 76, and n = 74, respectively). The overall study retention rate from beginning to end was 76% (n = 172). This type of intervention, with no placebo group, is outside the scope of this review. |
| Marya 1981 | 45 Hindu pregnant women were randomly assigned to 1 of 2 groups: group 1 (n = 25) received tablets containing 1200 IU vitamin D and 375 mg calcium daily throughout the 3rd trimester; group 2 (n = 20) received oral single dose of 600,000 IU vitamin D2 once during 7th month and 8th month (total 2 doses). This group was compared with group 3 (n = 75) who had not received vitamin D supplements during pregnancy. The results were also compared with data from 25 non pregnant, non‐lactating healthy women. The randomised study compares 2 doses of vitamin D supplementation. The type of study, type of participants and types of interventions are outside the scope of this review. |
| McLean 2012 | Pregnant women, aged 18 years or more, with less than 20 weeks’ gestation at recruitment. Participants will be randomly assigned to 1 of 2 groups: group 1: received high‐dose vitamin D supplementation (5000 IU/day); group 2: standard dose pregnancy vitamin supplementation (400 IU vitamin D daily), administered as an oral capsule, from the time of the first antenatal clinic visit (around 12 weeks’ gestation) until delivery. This type of intervention is outside the scope of this review. |
| Mojibian 2015 | 500 women with gestational age 12 to 16 weeks and serum 25 hydroxy vitamin D (25 (OH) D ) less than 30 ng/mL randomly categorized in 2 groups: group A received 400 IU vitamin D daily and group B 50,000 IU vitamin D every 2 weeks orally until delivery. Maternal and neonatal outcomes were assessed in 2 groups. This intervention had no placebo group. |
| Mozzafari 2010 | Women between 20 to 45 years old with gestational diabetes at their recent pregnancy, from the list of GDM Diabetes Research Center of Yazd University, and without thyroid disease, kidney disease, bone disease, PCO, liver disease and not using anti‐epilepsy drugs, glucocorticoids, and statins. Exclusion criteria: risk of any illness that requires medication and lack of any willingness to co‐operate, were randomly assigned to 1 of 2 groups: group 1: intramuscular injection of vitamin D with 300,000 IU dose; group 2: control: not receive any intervention. The type of participant is outside the scope of this review. |
| Mutlu 2013 | 91 pregnant women aged 16 to 42 years were admitted to Kocaeli Maternity and Children Hospital between April 2011 and April 2012. The participants were randomly divided into 3 groups: 600 IU/d (control group; n = 31); 1,200 IU/d (n = 31), and 2,000 IU/d (n = 32) of vitamin D. All groups received vitamin D supplements. This type of comparison is outside the scope of our review. |
| Nausheen 2014 | 315 pregnant women aged 15 to 45 years with less than 16 weeks of gestation in a hospital in Pakistan. Pregnant women with pre‐existing type 1 or type II diabetes, pre‐existing hypertension, multiple fetuses,babies (twins, triplets) or with a diagnosis of pregnancy with a fetal anomaly in scan will be excluded. Participants were randomly assigned to 1 of 3 groups: groups 1 received a dose of 400 IU/day till the time of delivery; group 2 received 2000 IU/day till the time of delivery; group 3 received 4000 IU/day till the time of delivery. This type of intervention is outside the scope of this review. |
| Niramitmahapanya 2017 | 76 Thai lactating mothers and their breast‐fed infants were studied with maternal 25 hydroxyvitamin D 25 (OH) D levels of 10‐30 ng/mL determined using Liquid Chromatography Mass Spectrometry Tandem (LC‐MS/MS). 1 group received vitamin D3 1800 IU/day supplementation for 6 weeks, and members of the other group were given a placebo. 25 (OH) D level of colostrum and 6‐week serum from breast‐fed milk were measured by High Performance Liquid Chromatography (HPLC). The data from the 2 groups were analysed and compared. The type of participant is outside the scope of this review. |
| Pandey 2015 | 20 women with 25 (OH) D < 20 ng/mL & Hb = 8‐10 g/dL were randomised into groups using a computerised program (8 patients in iron alone group and 12 pregnant mothers in iron + vitamin D group). Recruited pregnant mothers received group iron + vitamin D: tablets containing fixed dose combination of vitamin D (1000 IU) + ferrous ascorbate (100 mg of elemental iron) + folic acid (1 mg) + vit B12 (7.5 mcg) (1 tablet/day) for 12 weeks. Group iron alone: tablets containing fixed dose combination of ferrous ascorbate (100 mg of elemental iron) + folic acid (1.1 mg) (1 tablet/day) for 12 weeks. This type of intervention is outside the scope of this review. |
| Qian 2015 | 60 pregnant women at risk for pre‐eclampsia, experiencing their first pregnancy, aged between 20 and 32 years, between 18 and 20 weeks' gestation, and pregnant with a single fetus were eligible. Each pregnant woman selected for the study showed the following abnormalities on uterine artery Doppler, qualifying them as high‐risk: average resistance index (RI) > 0.67, pulsatility index (PI) > 1.65, and incisura at early diastole phase. Pregnant women were randomised into 2 groups to take either cholecalciferol supplements (n = 30) or placebo (n = 30). This study was retracted due to having data very similar to another paper. |
| Razavi 2017 | 120 women with GDM were randomly divided into 4 groups to receive: 1) 1000 mg omega‐3 fatty acids containing 180 mg eicosapentaenoicacid (EPA) and 120 mg docosahexaenoic acid (DHA) twice a day + vitamin D placebo (n = 30); 2) 50,000 IU vitamin D every 2 weeks + omega‐3 fatty acids placebo (n = 30); 3) 50,000 IU vitamin D every 2 weeks + 1000 mg omega‐3 fatty acids twice a day (n = 30) and 4) vitamin D placebo + omega‐3 fatty acids placebo (n = 30) for 6 weeks. The type of participant is outside the scope of this review. |
| Rostami 2018 | 1600 and 900 first trimester pregnant women, aged 18 to 40 years, with gestational age < 14 weeks, with singleton pregnancy in Masjed‐Soleiman, Khuzestan province,Iran were randomised by levels of vitamin D in serum to: Moderate deficiency
Severe deficiency
Pregnant women with normal vitamin D status were the controls. All women were allowed to consumed multivitamins containing no more than 400 IU per day of vitamin D3. This type of intervention is outside the scope of this review. |
| Shakiba 2013 | 51 healthy pregnant women from the beginning of their second trimester of pregnancy during the autumn and winter of 2009 in recruited from 2 primary care clinics in Yazd (31°53’50”N/54°22’04”E), Iran. Participants were distributed in 3 groups according to their serum 25(OH)D at the beginning of the second trimester of pregnancy. Participants with low concentrations (25(OH)D levels < 20 ng/mL) (n = 17) were treated with 200,000 IU (50,000 IU/week for 4 weeks) of vitamin D (as (cholecalciferol‐D3), followed by supplementation with 50,000 IU/month vitamin D (cholecalciferol‐D3). The other 34 participants were randomly assigned to 1 of 2 groups: group 1 received 50,000 IU/month vitamin D (cholecalciferol‐D3); group 2 received 100,000 IU/month vitamin D (50,000 IU every 2 weeks) of vitamin D (cholecalciferol‐D3) supplementation. All participants received vitamin D supplements. The type of study design and the type of intervention are outside the scope of this review. |
| Shi 2017 | 602 women with singleton pregnancy who were diagnosed of pre‐eclampsia in Cangzhou Central Hospital participated in the present trial and were divided into 2 groups using stratified permuted‐block randomisation method with diastolic blood pressure as a factor: (1) nifedipine + VD group (n = 298), given 1 capsule containing nifedipine (10 mg per capsule) and VD (200 IU per capsule) every 15 min orally, up to 4 doses, until blood pressure was equal to or below 150/100 mmHg; (2) nifedipine + placebo group (n = 304), given 1 capsule containing nifedipine (10 mg per capsule) plus glucose (20 mg per capsule) as placebo every 15 minutes orally, up to 4 doses, until blood pressure was equal to or below 150/100 mmHg. The type of participant is outside the scope of this review. |
| Simsek 2011 | Women with gestational diabetes, defined by the WHO criteria: fasting glucose ≥ 7.0 mmol/L or; oral glucose tolerance test: 75 g glucose, 2‐hour glucose ≥ 7.8 mmol/L recognised during pregnancy with a written informed consent, aged between 18 to 42 years. Participants will be randomly assigned to 1 of 2 groups: group 1: cholecalciferol 15,000 IU once a week during pregnancy; group 2: placebo. Per communication with the author, this study was not completed due to low recruitment. |
| Soheilykhah 2013 | 120 women with gestational age less than 12 weeks without gestational diabetes, history of PCO, BMI less than 30 kg/m2 before pregnancy, no vitamin D supplementation in the past 6 months were randomised into 2 groups: supplementation with 50,000 IU of vitamin D monthly (2000 IU daily) or 50,000 IU every 2 weeks (4000 IU daily). Maternal and neonatal outcomes were assessed in 2 groups. This intervention had no placebo group. |
| Stephensen 2011 | Pregnant women less than 20 weeks' gestation and over 18 years of age with no use of medications known to affect vitamin D metabolism, diagnosis of type 1 diabetes, history of thyroid, renal, or liver disease, problems with digestion or absorption participated in the study at USDA Western Human Nutrition Research Center and clinicians at UC Davis Medical Center. They were distributed into 2 groups, receiving: either 400 IU or 2000 IU of vitamin D per day for the duration of their pregnancy. Both groups received vitamin D supplements. This type of intervention is outside the scope of our review. |
| Sudfeld 2017 | 2300 HIV‐infected pregnant women receiving triple‐drug ART under Option B+ in Dar es Salaam Tanzania. HIV‐infected pregnant women of 12 to 27 weeks' gestation were randomised to either: 1) 3000 IU vitamin D3 taken daily from randomisation in pregnancy until trial discharge at 12 months postpartum; or 2) a matching placebo regimen. Maternal participants are followed‐up at monthly clinic visits during pregnancy, at delivery, and then with their children at monthly postpartum clinic visits. The type of participant is outside the scope of this review. |
| Taheri 2014 | 229 women 18 to 35 years old, who were confirmed to be vitamin D deficient (vitamin D < 75 nmol/L), were randomised into the intervention, and control groups and after 15 weeks consumption of the supplement (2000 IU/day oral vitamin D) and placebo. The study was conducted among reproductive women in a high‐risk population for vitamin D deficiency. The participants of the study were not pregnant women. The type of participant is outside the scope of this review. |
| Thiele 2014 | 16 pregnant women at 24 to 28 weeks' gestation were enrolled. The control group (N = 8) received a prenatal vitamin containing 400 IU vitamin D daily, plus a placebo capsule. The experimental group (N = 8) received the same prenatal vitamin with an additional capsule containing 3400 IU vitamin D, for a total of 3800 IU daily. This study had no placebo group, therefore, this type of intervention is outside the scope of this review. |
| Valizadeh 2016 | 96 women with GDM at weeks 12 to 32 of gestation, age > 16 years, singleton pregnancy were randomly assigned to either the intervention (n = 48) or control group (n = 48). Patients were referred from primary health centres affiliated with Zanjan University of Medical Sciences, as well as private obstetric clinics throughout the city. The type of participant is outside the scope of this review. |
| von Hurst 2009 | 235 South Asian women, aged 23 to 68 years, living in Auckland, New Zealand were recruited for the study and those who were insulin resistant ‐ homeostasis model assessment 1 (HOMA1) > 1.93 and had serum 25‐hydroxyvitamin D concentration < 50 nmol/L were randomly assigned to 1 of 2 groups: group 1 (n = 42) received 100 μg (4000 IU) vitamin D(3); group 2 (n = 39) received a placebo daily for 6 months. The study participants were non‐pregnant women. The type of participant is outside the scope of this review. |
| Wagner 2006a | 494 apparently healthy pregnant women (16 to 45 years of age) with 12 to 16 weeks' gestation of singletons attending prenatal care in Medical University of South Carolina, Charleston, United States were randomised into 1 of 3 groups stratified by race: group 1 received 400 IU vitamin D (cholecalciferol‐D3)/day; group 2 received 2000 IU vitamin D (cholecalciferol‐D3)/day; and group 3 received 4000 IU vitamin D (cholecalciferol‐D3)/day until delivery. All women received daily multiple micronutrients supplements. All women received vitamin D supplementation at different doses. The type of intervention is outside the scope of this review. |
| Wagner 2006b | This is an analysis of data from 2 randomised controlled trials by the same research group (Wagner 2006a; Wagner 2010a). In Wagner 2006a, women were randomised to 400, 2000, or 4000 IU vitamin D (cholecalciferol‐D3)/day, stratified by race. In Wagner 2010a, participants were randomised to 2000 or 4000 IU vitamin D (cholecalciferol‐D3)/day. |
| Wagner 2013 | 258 women, exclusively breastfeeding (n = 201) and formula‐feeding (n = 57) women participating in a prospective, randomised controlled trial of vitamin D supplementation were compared at baseline 1 month postpartum (V1), at 4 months (V4), and 7 months postpartum (V7) on the basis of vitamin D status (measured by total circulating 25(OH)D concentration) and BMI. The type of intervention is outside the scope of this review. |
| Weiss 2009 | 881 pregnant women with either a personal history of asthma or allergies or a similar history in the spouse or partner, between 18 and 40 years of age and at an estimated gestational age between 10 and 18 weeks, were recruited at a scheduled obstetrical prenatal visit at 3 clinical centres: Boston Medical Center (Boston, MA), Washington University at Saint Louis (St. Louis, MO), and Kaiser Permanente Southern California Region (San Diego, CA). Participants were randomised to either vitamin D (cholecalciferol, 4000 IU/day; equivalent to 100 μg/day) or placebo. All pregnant mother participants received prenatal vitamins containing 400 IU (10 μg/day) of cholecalciferol; thus, the vitamin D arm received a total of 4400 IU/day (110 μg/day) and the placebo arm received 400 IU/day (10 μg/day). Both groups received vitamin D supplements. This type of intervention is outside the scope of our review. |
| Yap 2014 | 179 pregnant women 18 years of age or older, with singleton pregnancy, with plasma 25‐hydroxivitamin D (25OHD) concentrations lower than 32 ng/mL, less than 20 weeks of gestation were randomly assigned to 1 of 2 groups: group 1 (n = 89) received 5000 IU/d of vitamin D (cholecalciferol‐D3) until delivery; group 2 (n = 90) received 400 IU/d of vitamin D (cholecalciferol‐D3) until delivery. Outcomes included glycaemia and glucose tolerance, gestational diabetes at 26‐28 weeks of gestation; neonatal 25OHD, maternal hypertension, mode of delivery, prematurity, birthweight, crown‐heel length, occipitofrontal head circumference. All participants received vitamin D supplements at different doses. The type of intervention is outside the scope of this review. |
| Yazdchi 2016 | 76 pregnant women without a prior diagnosis of glucose intolerance in the first trimester were asked to participate in a 75‐g OGTT at 24‐28 weeks of gestation. Diagnosis of GDM was based on the International Association of Diabetes and Pregnancy Study Groups criteria. Patients were recruited from Al‐Zahra Hospital, the academic outpatient centre of the Tabriz University of Medical Sciences, Tabriz, Iran. Participants in the vitamin D group received oral capsules containing 50,000 IU vitamin D 3 (D‐Vitin50000; Zahravi Pharm Co., Iran), once every 2 weeks for 2 months, for a total of 4 capsules. Those in the placebo group received placebos composed of paraffin oil (Dana Pharm Co., Iran) using the same schedule, for a total of 4 placebos. The type of participant is outside the scope of this review. |
| Zhang 2016 | 133 pregnant women with GDM during weeks 24 to 28 of pregnancy. The patients were randomly divided into 4 groups. The control group (n = 20) received a placebo (sucrose; 1 granule/day), the low‐dosage group (n = 38) received the daily recommended intake of 200 IU vitamin D (calciferol) daily, the medium‐dosage group (n = 38) received 50,000 IU monthly (2000 IU daily for 25 days) and the high‐dosage group (n = 37) received 50,000 IU every 2 weeks (4000 IU daily for 12.5 days). The general characteristics and dietary intakes of the patients with GDM were similar between each group. High‐dose vitamin D supplementation (50,000 IU every 2 weeks) significantly improved insulin resistance in pregnant women with GDM. The type of participant is outside the scope of this review. |
BMI: body mass index Ca: calcium DHA: docosahexaenoic DRI: dietary references intakes EPA: eicosapentaenoic acid FPG: fasting plasma glucose GDM: gestational diabetes mellitus Hb: haemoglobin IU: international units IVF: in vitro fertilisation mcg: microgram OGTT: oral glucose tolerance test PCO: polycystic ovary syndrome PTH: parathyroid hormone 25OHD: 25‐hydroxycholecalciferol