Nguyen 2008.

Methods	Randomized controlled trial
Participants	The study location was The Hospital for Sick Children, Toronto, ON, Canada 92 participants were randomized to the intervention group and 75 participants were randomized to the control group The inclusion criteria were pregnant women who had not started any multivitamin due to adverse events such as nausea, vomiting, constipation, diarrhea, calling the Motherisk program at The Hospital for Sick Kids in Toronto The exclusion criteria were pregnancy progressed past 20 gestational weeks, hypersensitivity to any of the ingredients in the study drugs, hemochromatosis, hemosiderosis or hemolytic anemia
Interventions	Intervention: SMALL LOW IRON DOSE TABLET Small low‐dose iron tablets were used as the intervention in this study. PregVit a prenatal multivitamin that contains 35 mg elemental iron, as ferrous fumarate was prescribed for intervention group patients. The multiple vitamins and minerals are formulated into 2 small tablets, and is taken as 2 tablets per day. After enrolment, subjects received a 1‐week follow‐up telephone call and then were interviewed by telephone on a monthly basis until the end of pregnancy. Each interview documented obstetrical and medical information, adherence based on pill intake recall, and any reported adverse events. The date(s) of discontinuation at any time(s) during study participation was documented as the date(s) reported by the subject during the monthly interview Control: SMALL 60 MG MULTIVITAMIN TABLET A small‐sized high‐dose (60 mg) multivitamin administered once daily was used as the control in this study
Outcomes	The measures of adherence were measured by monthly telephone interview until the end of pregnancy. The date and time of discontinuation of the drug was documented by the interviewer The patient outcomes were adverse events. Data were collected by making telephone calls to the patients on a monthly basis until the end of the pregnancy
Notes	―
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A computer‐generated randomization table was used. "Based on a computer‐generated randomization table, women were randomized to one of two groups" (pg 3)
Allocation concealment (selection bias)	Unclear risk	No information was provided about how allocation was handled
Selective reporting (reporting bias)	Unclear risk	No protocol available; although it appears that everything was reported it is difficult to determine this without a protocol
Other bias	Low risk	The study seems to be free of other types of bias
Blinding of outcome assessment (detection bias) Adherence measure	Unclear risk	(PRIMARY) SELF REPORT ‐ INTERVIEW ‐ No information on blinding given. There is insufficient information to permit judgment of 'Low risk' or 'High risk'
Blinding of outcome assessment (detection bias) Patient outcome	Unclear risk	(PRIMARY) ADVERSE EFFECTS ‐ No information on blinding given. There is insufficient information to permit judgment of 'Low risk' or 'High risk'
Blinding of participants (performance bias) Adherence measure	High risk	(PRIMARY) SELF REPORT ‐ INTERVIEW ‐ This is a subjective measure; there is no information on blinding
Blinding of participants (performance bias) Patient outcome	High risk	(PRIMARY) ADVERSE EFFECTS ‐ This is a subjective measure; there is no information on blinding
Blinding of personnel (performance bias) Adherence measure	Unclear risk	(PRIMARY) SELF REPORT ‐ INTERVIEW ‐ No information on blinding given. There is insufficient information to permit judgment of 'Low risk' or 'High risk'
Blinding of personnel (performance bias) Patient outcome	Unclear risk	(PRIMARY) ADVERSE EFFECTS ‐ No information on blinding given. There is insufficient information to permit judgment of 'Low risk' or 'High risk'
Incomplete outcome data (attrition bias) Adherence measure	High risk	(PRIMARY) SELF REPORT ‐ INTERVIEW ‐ imbalance in numbers and the reason for the dropout could be related to the outcome (NVP)
Incomplete outcome data (attrition bias) Patient outcome	High risk	(PRIMARY) ADVERSE EFFECTS ‐ imbalance in numbers and the reason for the dropout could be related to the outcome (NVP)