Association of Low Serum 25-Hydroxyvitamin D Levels in Pregnancy with Glucose Homeostasis and Obstetric and Newborn Outcomes

Objective: To evaluate the association of maternal serum 25-hydroxyvitamin D (25[OH]D) status with glucose homeostasis and obstetric and newborn outcomes in women screened for gestational diabetes mellitus (GDM).Methods: Consecutive women were screened for GDM at 24 to 28 weeks' gestation during the months of maximal sunlight exposure in Spain (June through September). Serum 25(OH)D levels and parameters of glucose homeostasis were measured. Outcomes of the delivery and newborn were collected.Results: Two hundred sixty-six women were screened. Vitamin D deficiency (25[OH]D <20 ng/mL) was observed in 157 women (59%). We observed an inverse correlation between 25(OH)D levels and hemoglobin A1c, homeostasis model assessment of insulin resistance, serum insulin, and fasting and 1-hour oral glucose tolerance test glucose levels (P<.001). With a 25(OH)D concentration less than 20 ng/mL, the odds ratios were 3.31 for premature birth (95% confidence interval, 1.52-7.19; P<.002) and 3.93 for cesarean delivery (95%...