Study	Reason for exclusion
Bjerre 1967	Folic acid was supplemented in combination with other micronutrients versus placebo.
Colman 1974	Study was to assess efficacy of folic acid supplementation in the form of food fortification.
Colman 1975	Study was to assess efficacy of folic acid supplementation in the form of food fortification.
Ellison 2004	Both the intervention and control group received folic acid supplementation, and groups were compared on duration of folic acid therapy. One group was given supplementation till 16 weeks of pregnancy and the other group received it till end of pregnancy.
Giles 1960	There was no randomisation and intervention participants were compared with historical controls.
Gregory 2001	Folate in pregnant women was compared with non‐pregnant controls.
Hague 1998	Published abstract of a protocol, however, study was abandoned without completion.
Hamilton 1973	Nothing has been mentioned about randomisation nor the word is used. It seems this is not a randomised controlled trial.
Hekmatdoost 2011	This study compares 1: 5 methyltetrahydrofolate with folic acid.
Hibbard 1969	Folic acid 1.5 mg was compared with folic acid 15 mg.
Khanna 1977	Included patients were already receiving iron and then therapeutic folic acid was added among women who were found to have anaemia.
Klinger 2006	Effect on folic acid on placental apoptosis was assessed.
Kristoffersen 1979	Only a published abstract with insufficient information was available.
Ma 2008	Folic acid and iron was given along with retinol and riboflavin.
Manizheh 2009	High‐dose of folate was compared with low‐dose folate.
Melli 2008	Onlt published abstract with insufficient information was available.
Ouma 2006	Association of folic acid supplementation and sulfadoxine pyrimethamine was observed.
Polatti 1992	Both the intervention and control groups received folic acid supplementation. Assessed the effectiveness of folic acid when given from 12 week of pregnancy compared with given from 20 weeks of pregnancy.
Taylor 1979	Experimental group was given Iron and folate and were compared with no therapy group.
Taylor 1981	Experimental group was given Iron and folate and were compared with no therapy group.
Tchernia 1982a	In this paper they have reviewed and re‐analysed the results of 3 different trials.
Thomson 1982	Published abstract with insufficient information was only available.
Ulrich 1999	Half of the participants were selected and allotted to the group based on randomisation, while other half of the study population was selected from the hospitals who delivered during the study period. Effect of folic acid was observed on development of congential anomalies.
Wang 2012	This study compares folic acid, iron‐folic acid or multi‐micronutrients. Effect of folic acid alone cannot be determined.
Zeng 2008	Both the intervention and control group were given folic acid and the intervention group also received iron.