Maternal folate, vitamin B12 and homocysteine levels in pregnancies affected by congenital malformations other than neural tube defects

Background—\nPericonceptional use of folic acid prevents most neural tube defects (NTDs).\nWhether folic acid and/or multivitamins can prevent other congenital anomalies is not clear. This\nstudy tested whether maternal blood levels of folate and vitamin B12 in pregnancies affected by\ncongenital malformations excluding NTDs are lower when compared to non-affected pregnancies.\nMethods—\nWe measured pregnancy red cell folate (RCF), vitamin B12, and homocysteine\n(tHcy) concentrations in blood samples taken at the first antenatal clinic in Dublin maternity\nhospitals in 1986–1990 when vitamin supplementation was rare. The cases were mothers who\ndelivered a baby with a congenital malformation other than NTD identified by the Dublin\nEUROCAT Registry; controls were a systematic sample of mothers of offspring without\ncongenital malformations from the same hospitals in the same time period.\nResults—\nThe median maternal levels of RCF and tHcy did not differ significantly between cases\nand controls for any of the congenital malformation groups examined (RCF: all malformations\n275.9 ug/L v controls 271.2; p=0.77; tHcy: all malformations 7.5 umol/L v controls 7.6; p=0.57).\nIn an unadjusted analysis vitamin B12 was significantly higher in case-mothers whose babies had\ncleft palate only (p=0.006), musculoskeletal malformations (p=0.034) and midline defects\n(p=0.039) but not after adjustment for multiple testing.\nConclusions—\nOur data suggest that low maternal folate and B12 levels or high tHcy levels in\nearly pregnancy are not associated with all congenital malformations excluding NTDs.\nFortification with folic acid or B12 may not have a beneficial effect in the prevention of these\nanomalies.