Widespread Vitamin D Deficiency in Urban Massachusetts Newborns and Their Mothers

OBJECTIVE: To determine vitamin D status and associated factors in a cohort of newly delivered infants and their mothers in Boston, Massachusetts.

PATIENTS AND METHODS: Enrollment in this cross-sectional study took place from 2005 to 2007 in an urban Boston teaching hospital with 2500 births per year. A questionnaire and medical-record data were used to identify variables that are potentially associated with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 20 ng/mL). Infant and maternal blood was obtained by venipuncture within 72 hours of birth. The main outcome measure was infant and maternal 25(OH)D status, assessed by competitive protein binding.

RESULTS: We enrolled 459 healthy mother/infant pairs. After subsequent exclusions, analyses were performed on 376 newborns and 433 women. The median infant 25(OH)D level was 17.2 ng/mL (95% confidence interval [CI]: 16.0–18.8; range: <5.0 to 60.8 ng/mL). The median maternal 25(OH)D level was 24.8 ng/mL (95% CI: 23.2–25.8; range: <5.0 to 79.2 ng/mL). Overall, 58.0% of the infants and 35.8% of the mothers were vitamin D deficient (25[OH]D < 20 ng/mL); 38.0% of the infants and 23.1% of the mothers were severely deficient (25[OH]D < 15 ng/mL). Risk factors for infant vitamin D deficiency included maternal deficiency (adjusted odds ratio [aOR]: 5.28 [95% CI: 2.90–9.62]), winter birth (aOR: 3.86 [95% CI: 1.74–8.55]), black race (aOR: 3.36 [95% CI: 1.37–8.25]), and a maternal BMI of ≥35 (aOR: 2.78 [95% CI: 1.18–6.55]). Maternal prenatal-vitamin use throughout the second and third trimesters was protective against infant deficiency (aOR: 0.30 [95% CI: 0.16–0.56]). Similarly, prenatal-vitamin use of ≥5 times per week in the third trimester was protective for mothers (aOR: 0.37 [95% CI: 0.20–0.69]). Despite this, >30% of the women who took prenatal vitamins were still vitamin D deficient at the time of birth.

CONCLUSIONS: A high proportion of infants and their mothers in New England were vitamin D deficient. Prenatal vitamins may not contain enough vitamin D to ensure replete status at the time of birth.