High prevalence of vitamin D deficiency in pregnant non-Western women in The Hague, Netherlands.

BACKGROUND Vitamin D deficiency is common in dark-skinned persons living in northern countries. Vitamin D deficiency during pregnancy may have serious consequences for both mother and child. OBJECTIVE The objective was to ascertain the prevalence of vitamin D deficiency in pregnant women of several ethnic backgrounds who were living in The Hague, a large city in the Netherlands. DESIGN Midwives whose practice was visited by a large number of non-Western immigrants added the assessment of serum 25-hydroxyvitamin D [25(OH)D] to the standard blood test given to women who visited the practice during week 12 of pregnancy. Subsequently, the Municipal Health Service collected additional data from the midwives' files (June 2002 through March 2004): background variables, use of tobacco or alcohol or drugs, and infectious diseases. The women were grouped ethnically as Western, Turkish, Moroccan, and other non-Western. RESULTS The vitamin D concentrations of 358 women were found in the midwives' files. Of these women, 29% were Western, 22% were Turkish, and 19% were Moroccan. Mean serum 25(OH)D concentrations in Turkish (15.2 +/- 12.1 nmol/L), Moroccan (20.1 +/- 13.5 nmol/L), and other non-Western women (26.3 +/- 25.9 nmol/L) were significantly (P </= 0.001) lower than those in Western women (52.7 +/- 21.6 nmol/L). Serum 25(OH)D was below the detection limit in 22% of the Turkish women. The differences between ethnic groups were not confounded by other determinants such as age, socioeconomic status, or parity. CONCLUSIONS The prevalence of vitamin D deficiency in pregnant non-Western women in the Netherlands is very high, and screening should be recommended.