Chanarin 1968.

Methods	This was a RCT in which women attending the antenatal clinic at St. Mary's hospital (London) took part in the study.
Participants	206 women took part in this study. They all were less than 16 weeks of pregnancy. Women were given 1 g of IV Iron dextran as 4 250 mg doses at weekly intervals. At the 20th week they were assigned in to groups (n = 206).
Interventions	Ferrous fumarate 260 mg (n = 101). Ferrous fumarate 260 mg and 100 µg folic acid (n = 105).
Outcomes	Changes in haemoglobin (n = 206), serum iron (n = 206), serum folate (n = 206) and red cell folate levels (n = 206).
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Allotted to one of the two groups".
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit any judgement.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Quote: "The survey being conducted as a blind trial". Comment: probably not done.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Insufficient information to permit any judgment.
Selective reporting (reporting bias)	Unclear risk	Insufficient information to permit any judgment.
Other bias	Unclear risk	No other bias identified but insufficient information available to fully assess this 'Risk of bias' domain.