Vitamin D Supplementation During Pregnancy and Bone Status in Children at Birth and at One Year of Age

Overview

Vitamin D deficiency is frequently reported in pregnant women despite recommendation of daily vitamin D supplementation of 400IU/d. Recent studies have shown that in the absence of sun exposure these doses are seldom able to achieve 25(OH)D optimal serum levels. We hypothesize that larger doses of vitamin D are needed to be supplemented to all women during pregnancy. We hypothesize that this may have advantageous effects on maternal vitamin D and bone reserve as well on offspring vitamin D and bone status at birth and possible further on. The aim of the present study is to compare vitamin D and bone status of infants born to mothers supplemented with 400IU/d (present recommendations) and 2000IU/d vitamin D during the third trimester of pregnancy.

This is a prospective randomized controlled study. 120 pregnant women will be recruited at 27 weeks gestation and randomized into two treatment groups; 400IU/d or 2000IU/d vitamin D supplementation from 27 weeks until delivery. 25-hydroxyvitamin D (25OHD), parathyroid hormone (PTH), urinary calcium/creatinine and serum calcium and alkaline phosphatase (ALP) levels will be assessed in mothers at 27 weeks and at delivery. 25OHD, calcium and ALP levels, and urinary calcium/creatinine will be evaluated in offspring at birth and at one year age. Vitamin D and calcium intake and sun exposure will be evaluated in mothers and offsprings. Quantitative ultrasound (QUS) measurement of tibia and radius will be performed to newborns and at the age of one year. Bone status of newborns at birth and at one year age in children will be compared between the 2 groups.