Risk factors for maternal vitamin D deficiency and preterm birth overlap but the distribution of 25-hydroxyvitamin D (25(OH)D) levels among preterm infants is not known. We aimed to determine associations between 25(OH)D levels and gestational age.
We measured umbilical cord plasma levels of 25(OH)D from 471 infants born at Brigham and Women’s Hospital in Boston. We used generalized estimating equations to determine whether preterm (<37 weeks’ gestation) or very preterm (<32 weeks’ gestation) infants had greater odds of 25(OH)D levels < 20 ng/ml than more mature infants. We adjusted for potential confounding by season of birth, maternal age, race, marital status and singleton or multiple gestation.
Mean cord plasma 25(OH)D level was 34.0 ng/ml (range 4.1 to 95.3, and SD 14.1). Infants born before 32 weeks’ gestation had increased odds of 25(OH)D levels < 20 ng/ml in unadjusted (OR 2.2, 95% CI 1.1, 4.3) and adjusted models (OR 2.4, 95% CI 1.2, 5.3) compared to more mature infants.
Infants born < 32 weeks’ gestation are at higher risk than more mature infants for low 25(OH)D levels. Further investigation of the relationships between low 25(OH)D levels and preterm birth and its sequelae is thus warranted.