Vitamin B(12) Status in Pregnant Adolescents and Their Infants

Vitamin B(12) deficiency has been associated with increased risk of adverse pregnancy outcomes. Few prospective studies have investigated the burden or determinants of vitamin B(12) deficiency early in life, particularly among pregnant adolescents and their children. The objectives of this study were to determine the prevalence of vitamin B(12) deficiency and to examine associations between maternal and neonatal vitamin B(12) status in a cohort study of healthy pregnant adolescents. Serum vitamin B(12) and folate concentrations were measured in adolescents at mid-gestation (n = 124; 26.4 ± 3.5 weeks) and delivery (n = 131; 40.0 ± 1.3 weeks), and in neonates at birth using cord blood. Linear regression was used to examine associations between maternal and neonatal vitamin B(12) status. Although the prevalence of vitamin B(12) deficiency (<148.0 pmol/L; 1.6%) in adolescents was low during pregnancy, 22.6% of adolescents were vitamin B(12) insufficient (<221.0 pmol/L; 22.6%) at mid-gestation. Maternal vitamin B(12) concentrations significantly decreased from mid-gestation to delivery (p < 0.0001), and 53.4% had insufficient vitamin B(12) status at delivery. Maternal vitamin B(12) concentrations (p < 0.001) and vitamin B(12) deficiency (p = 0.002) at delivery were significantly associated with infant vitamin B(12) concentrations in multivariate analyses, adjusting for gestational age, maternal age, parity, smoking status, relationship status, prenatal supplement use, pre-pregnancy body mass index, race, and intake of vitamin B(12) and folate. Maternal vitamin B(12) concentrations significantly decreased during pregnancy and predicted neonatal vitamin B(12) status in a cohort of healthy pregnant adolescents.