Low plasma vitamin B-12 is associated with a lower pregnancy-associated rise in plasma free choline in Canadian pregnant women and lower postnatal growth rates in their male infants.

BACKGROUND

Choline needs are increased in pregnancy. Choline can be used as a source of methyl for homocysteine remethylation to methionine, but choline synthesis requires methyls from methionine. Vitamin B-12 deficiency increases choline use for homocysteine methylation.

OBJECTIVES

We investigated whether poor vitamin B-12 status occurs and contributes to low plasma choline and altered biomarkers of choline synthesis in pregnant women. With the use of a post hoc analysis, we addressed the association of maternal plasma vitamin B-12 status with postnatal growth rates in term infants.

DESIGN

Blood was analyzed for a prospective study of 264 and 220 pregnant women at 16 and 36 wk of gestation, respectively, and 88 nonpregnant women as a reference.

RESULTS

The proportion of women with a plasma total vitamin B-12 concentration <148 pmol/L (deficient) or 148-220 pmol/L (marginal) increased with pregnancy and pregnancy duration, which affected 3% and 9% of nonpregnant women, 10% and 21% of women at 16 wk of gestation, and 23% and 35% of women at 36 wk of gestation, respectively. Plasma free choline, betaine, and dimethylglycine were lower in women at 36 wk of gestation with a deficient or marginal compared with sufficient plasma total vitamin B-12 concentration (>220 pmol/L). Plasma total vitamin B-12 was positively associated with the increase in plasma free choline from midgestation to late gestation (P < 0.001). The postnatal growth rate to 9 mo was lower in infant boys of women classified as total vitamin B-12 deficient compared with sufficient.

CONCLUSION

This study shows that maternal vitamin B-12 status is related to choline status in late gestation in a folate-replete population and may be a determinant of infant growth even in the absence of undernutrition.