Iodine deficiency amongst pregnant women in South-West England

Abstract

Introduction: Iodine 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. Methods: Urine 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, BMI at booking, 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=0.3), so subsequent analyses were carried out as a combined group.

Results: Participants had a mean (SD) age 31(5) years, median (IQR) BMI 24.4(22.0, 28.3) kg/m2, 42% were primiparous, 10% smoked during pregnancy, 35% took iodine containing vitamins. 96% were Caucasian. Median (IQR) UIC was 88.0 (54.3, 157.5) µg/l, which is consistent with iodine deficiency by WHO criteria. A total of 224/308 (73%) of women had UIC values <150µg/l. Increasing milk intake was associated with higher UIC (p=0.021). 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) µg/l, p=0.7. Conclusion: Iodine deficiency in pregnancy is common in South-West England. Measures to develop optimum prevention and treatment strategies are urgently needed.