Maternal serum cobalamin at 18 weeks of pregnancy predicts infant cobalamin status at 6 months-A prospective, observational study

Abstract

Background: An adequate maternal cobalamin status is crucial for fetal and infant neurodevelopment. Pregnancyinduced physiologic changes make evaluation of maternal cobalamin status in pregnancy difficult. Objective:We have investigated maternal cobalamin status during pregnancy in order to establish a maternal cobalamin concentration which secures an optimal infant cobalamin status during the first 6 mo of life. Methods: In an observational, prospective study, markers of cobalamin status including serum cobalamin, plasma total homocysteine (tHcy), and plasma methylmalonic acid (MMA) were assessed in healthy pregnant women (n = 114) from week 18 of pregnancy through 6 mo postpartum and related to infant cobalamin status at 6 mo. Healthy, never-pregnant women aged 18-40 y (n = 123) were included as controls. Results: Compared to controls, all markers of cobalamin statuswere lower in pregnantwomen. Median serumcobalamin concentration progressively decreased from week 18 to week 36 of pregnancy (356 to 302 pmol/L, P < 0.001) and increased by > 40% by 6 wk postpartum (518 pmol/L). The metabolic markers increased from week 18 of pregnancy to 6 wk postpartum: median plasma tHcy 3.9 to 7.7 μmol/L (P < 0.001), and MMA 0.13 to 0.17 μmol/L (P < 0.001). The serum cobalamin concentration of infants at age 6 mo correlated with maternal serum cobalamin concentration during pregnancy and postpartum(rho = 0.36-0.55, P < 0.001). A maternal serumcobalamin concentration < 394 pmol/L during week 18 of pregnancy was associated with an increased risk (OR: 4.2; 95% CI: 1.5, 11.5) of infant biochemical cobalamin deficiency at 6 mo (defined as tHcy ≥6.5 μmol/L). Conclusions: The maternal serum cobalamin concentration in early pregnancy is a strong predictor for later maternal and infant cobalamin status. To secure an optimal infant cobalamin status during the first 6 mo of life, we recommend a maternal serum cobalamin concentration > 394 pmol/L at week 18 of pregnancy. This should be confirmed in an intervention study.