Maternal smoking and the vitamin D-parathyroid hormone system during the perinatal period.

Objective: To evaluate the effect of smoking on the vitamin D-parathyroid hormone (PTH) system during the perinatal period.

Study Design: Sixty-one healthy women with singleton pregnancies and their newborns participated in a cohort study. We compared serum PTH and BsmI polymorphism of the vitamin D receptor gene, 25 hydroxyvitamin D (25(OH)D), 1,25 dihydroxyvitamin D, calcium, phosphorus, and bone alkaline phosphatase (bALP) in a smoking group (n = 32) versus a non-smoking group (n = 29), controlling for lifestyle confounders.