Study	Reason for exclusion
Coelingh Benninck 1979	We have been unable to locate the full text, and this is the only report, an abstract, we have. It does not provide enough information for assessment for inclusion.
Lumeng 1976	Reasons for excluding this study were: (1) there was no control group (i.e. a non‐vitamin B6 supplemented group) and (2) only biochemical outcomes were studied. 33 antenatal women were randomly assigned to multivitamin supplements containing 2.5, 4 or 10 mg pyridoxine.