Altered vitamin-D metabolism in pregnancy.

Low levels of plasma-25-hydroxy-vitamin-D (25-OHD) (less than 16 nmol/1) were found in 33% of a group of pregnant women studied in South London. Non-White women in the last 10 weeks of pregnancy had significantly reduced levels compared with non-pregnant controls (P less than 0.02). Plasma-25-OHD was unrelated to dietary vitamin-D intake, age, parity, social class, plasma-calcium, and plasma-albumin. Reduction of plasma-25-OHD could contribute to the fall in plasma-calcium during pregnancy, and may result from enhanced maternal metabolism or increased utilisation of vitamin D by the fetus.