Maternal vitamin B-12 status in early pregnancy and its association with birth outcomes in Canadian mother-newborn Dyads

Vitamin B-12 (B-12) is a co-enzyme essential for fetal growth and development. Lower maternal B-12 status has been associated with preterm birth (<37 gestational weeks) and low birth weight (<2500 g), which are linked to morbidity and mortality across the lifespan. In Canada, 17-25 % of women in early pregnancy had a serum total B-12 concentration <148 pmol/l and maternal total B-12 concentration decreased throughout pregnancy. This study aimed to determine the association between maternal B-12 status and birth outcomes in Canadian mother-newborn dyads. A secondary analysis of 709 mother-newborn dyads in British Columbia (BC), Canada, was conducted. Bio-banked first- (n 656) and second-trimester (n 709) maternal serum samples of apparently healthy South Asian (50 %) and European (50 %) women from the BC Prenatal Genetic Screening Program were quantified for B-12 biomarkers (total B-12, holotranscobalamin (holoTC), methylmalonic acid (MMA) and total homocysteine (tHcy)). Obstetric history and birth outcome data were obtained from the BC Perinatal Data Registry. All associations were determined using multiple linear regression. Maternal serum total B-12, holoTC, MMA and tHcy had a mean weekly decrease of 3 center dot 64 pmol/l, 1 center dot 04 pmol/l, 1 center dot 44 nmol/l and 0 center dot 104 mu mol/l, respectively (P < 0 center dot 001). Despite a total B-12 concentration <148 pmol/l among 20-25 % of the women, maternal B-12 biomarker concentrations were not associated with birth weight z-score, head circumference z-score and gestational age at birth (P > 0 center dot 05). Additional research in women at high risk of adverse birth outcomes and the association between maternal B-12 status and functional, for example, cognitive, outcomes is needed.