Vitamin B12 and Folate Status in Pregnant Females and Their Infants in Norway: Secondary Analysis from the Mommy's Food Study

Background: Vitamin B12 and folate are essential micronutrients important for normal infant growth and development. Objectives: The aims were to describe vitamin B12 and folate status in pregnant females and their infants according to commonly used status cutoffs and examine the associations between maternal status, maternal supplement use, and breastfeeding and infant status.Methods: Pregnant females were recruited at 18 wk gestation in Bergen, Norway. Maternal vitamin B12 and folate status were measured at gestational weeks 18 (n = 136) and 36 (n = 116), and infant status was measured at ages 3 (n = 73) and 6 (n = 74) mo.Results: At gestational weeks 18 and 36, respectively, 4.4% and 2.6% of the mothers had plasma cobalamin concentrations <148 pmol/L, 0.7% and 6.9% had methylmalonic acid (MMA) concentrations >0.26 mu mol/L, and 3.7% and 30% had folate concentrations <10 nmol/L. None of the females had total homocysteine (t-Hcy) concentrations >13 mu mol/L or 3 combined indicator of vitamin B12 (cB12) <-0.5. At 3 and 6 mo, respectively, 4.1% and 5.4% of the infants had cobalamin concentrations <148 pmol/L, 63% and 74% had t-Hcy concentrations >6.5 mu mol/L, 59% and 66% had MMA concentrations >0.26 mu mol/L, and 47% and 60% had cB12 >-0.5. None of the infants had folate concentrations <10 nmol/L. Several of the vitamin B12 biomarkers in infants were associated with maternal vitamin B12 status during pregnancy. Breastfed infants had lower vitamin B12 status (as indicated by plasma cobalamin, t-Hcy, and cB12) than nonbreastfed infants at both 3 and 6 mo. Use of supplements during pregnancy was associated with better vitamin B12 status among infants at 3 and 6 mo, as indicated by infants' cobalamin and t-Hcy concentrations.Conclusions: Subclinical vitamin B12 deficiency among infants was common and associated with maternal vitamin B12 status during pregnancy and breastfeeding. Among the mothers, an increase in biochemical folate deficiency was discovered toward the end of gestation. Further studies are needed to investigate clinical consequences. This trial was registered at clinicaltrials.gov as NCT02610959.