Maternal vitamin D status throughout and after pregnancy.

Prospective longitudinal study of vitamin D status and its risk factors in 75 pregnant women from early pregnancy until 6 months postpartum, by serial measurement of serum 25 (OH) vitamin D levels. The serum levels at booking were not significantly different between nationalities (p = 0.06), parity (p = 0.2), education levels (p = 0.4), dress code (p > 0.5), consumption of vitamin D fortified milk (p = 0.2) or, fatty fish (p = 0.5), sun-exposed body surface area (p = 0.3), weekly time exposed to the sun (p = 0.08) or the sun exposure index (p = 0.2). Vitamin D status progressively worsened as the proportion with adequate serum levels fell from 31% at the antenatal visit, to 23% after birth and 17%, 6 months later (p = 0.02). While 80% of mothers who were exclusively breast-feeding had low vitamin D levels 6 months after delivery, this occurred in only 67% of those partially breast-feeding (p = 0.6).