Vitamin D status of pregnant and non-pregnant women of reproductive age living in Hanoi City and the Hai Duong province of Vietnam

Vitamin D insufficiency during pregnancy has been associated with a number of adverse outcomes for both mother and child. Vitamin D insufficiency has been well described in many populations of both pregnant and non-pregnant women of childbearing age, but there is a lack of data on women living in South-East Asia. We measured plasma 25-hydroxyvitamin D in a representative sample of pregnant (n = 64) and non-pregnant (n = 477) women (1549 years) living in Hanoi City (n = 270) and rural Hai Duong Province (n = 271) in northern Vietnam. Mean 25-hydroxyvitamin D (95% confidence interval) concentration was 81 (79, 84) nmol L-1. Mean 25-hydroxyvitamin D concentration differed between urban and rural (78 vs. 85 nmol L-1; P = 0.016), farming and non-farming (89 vs. 77 nmol L-1; P < 0.001) but not pregnant and non-pregnant or older vs. younger women. Only one woman had a 25-hydroxyvitamin D less than 25 nmol L-1, a concentration indicative of vitamin D deficiency. Of the women, 7% and 48% of the women were vitamin D insufficient based on cut-offs for plasma 25-hydroxyvitamin D of 50 and 75 nmol L-1, respectively. Mean plasma 25-hydroxyvitamin D concentrations of these Vietnamese women were much higher than those reported in other studies of pregnant and non-pregnant women in the region.