Vitamin D status and bone health in immigrant versus Swedish women during pregnancy and the post-partum period

Objective: We evaluated the association between vitamin D status and bone health in pregnant and post-partum immigrant versus Swedish women. Methods: We consecutively recruited 41 immigrant and 19 age-matched healthy native Swedish women. Serum 25-hydroxy vitamin D-3 [25(OH)D] and parathyroid hormone (PTH) were analyzed at pregnancy week 12 and 6-12 months postpartum. Dual X-ray absorptiometry (DXA) of the hip and lumbar spine, and peripheral quantitative computed tomography (pQCT) of the radius and tibia were analyzed 6-12 months postpartum. Results: The mean +/- SD 25(OH)D in gestational week 12 was 20 +/- 11 nmol/L among the immigrants and 60 +/- 17 nmol/L among the Swedish women (p<0.001). The postpartum 25(OH)D was 29 +/- 18 nmol/L among the immigrants and 53 +/- 19 nmol/L among the Swedish women (p=0.003). BMD measured with DXA and pQCT did not differ significantly between groups. The ratio of cortical and trabecular density, a potential sign of osteomalacia, did not differ between groups. There were no significant correlations between 25(OH)D and the bone density measurements. Conclusions: Immigrant young women in Sweden are at a high risk of persistent and pronounced 25(OH)D deficiency. However, radiological measures of bone health were not affected by persisting low 25(OH)D. The health consequences of 25(OH)D deficiency should be studied in future studies.