Iodine status in pregnancy: role of dietary habits and geographical origin

A study was conducted on iodine status during pregnancy and its dependence on dietary habits, racial and geographical origin, and time since arrival in Italy. We enrolled 322 consecutive pregnant women: 217 Italians, 62 Eastern Europeans and 43 from Northern and Central Africa. All women completed a food frequency questionnaire on their dietary habits. The urinary iodide concentration (UIC) was determined in spot morning urine samples. In the group as a whole, the median UIC was 83 mu g/l; the UIC was < 50 in 33% and of 150 mu g/l or more in 27%; it was significantly lower in Africans and Eastern Europeans than in Italians (medians 45 and 46 vs. 100 mu g/l, respectively, P = 0.005). For the foreign women, there was a significant correlation between UIC and time since arrival in Italy (r = 0.22, P = 0.02). A significant link emerged between UIC and cow's milk intake (P = 0.0001). Iodine supplements were used by 40% of the women, and UIC were higher in those who did so than in those who did not (median 103 vs. 75 mu g/l, P = 0.03), particularly if the latter did not drink milk (median 98 vs. 42 mu g/l, P = 0.01). Multivariate analysis showed that milk was the only variable influencing UIC (OR 1.29, P = 0.0005). (i) Iodine levels are too low among pregnant women in our region, and particularly in foreign women. (ii) Cow's milk intake is their main source of iodine. (iii) Iodine supplementation is mandatory during pregnancy, particularly for women do not drink milk.