Iodine deficiency amongst pregnant women in South-West England

IntroductionIodine deficiency in pregnancy may impair foetal neurological development. The UK population is generally thought to be iodine sufficient; however, recent studies have questioned this assumption. Our study aimed to explore the prevalence of iodine deficiency in a cohort of pregnant mothers from South-West England. MethodsUrine samples were obtained from 308 women participating in a study of breech presentation in late pregnancy. They had no known thyroid disease and a singleton pregnancy at 36-38 weeks' gestation. Samples were analysed for urinary iodine concentrations (UIC). Baseline data included age, parity, smoking status, ethnicity, body mass index (BMI) at booking, prenatal vitamin use and a dietary questionnaire. There was no difference in median UIC between women with (n = 156) or without (n = 152) a breech presentation (P = 03), so subsequent analyses were carried out as a combined group. ResultsParticipants had a mean (SD) age 31(5) years, median (IQR) BMI 244 (220, 283) kg/m(2); 42% were primiparous, 10% smoked during pregnancy, and 35% took iodine-containing vitamins. Ninety-six per cent were Caucasian. Median (IQR) UIC was 880 (543, 1575) g/l, which is consistent with iodine deficiency by WHO criteria. A total of 224/308 (73%) of women had UIC values <150 g/l. Increasing milk intake was associated with higher UIC (P = 002). There was no difference in median (IQR) UIC between those women who took iodine-containing vitamins (n = 108) and those who did not (n = 200): 88 (54, 168) vs 88 (54, 150) g/l, P = 07. ConclusionIodine deficiency in pregnancy is common in South-West England. Measures to develop optimum prevention and treatment strategies are urgently needed.