Many pregnant women in the UK are not meeting adequate iodine requirements

February 19, 2014

According to a new study, the majority of women in the UK do not meet the higher iodine requirements of pregnancy, which can have a negative effect on fetal brain development.

The observational study measured the iodine concentration in urine samples of 100 pregnant women, bet- ween 19 and 47 years of age, in the first trimester and used a questionnaire to collected information on the participants’ lifestyle (1). The study results showed that all women were mildly to moderately iodine defi- cient: the median urinary iodine concentration was 85.3 mg/l, compared to a recommended range of 150–249 mg/l. The urinary iodine concentration was significantly higher in women taking an iodine-containing prenatal supplement than in those not taking such a supplement. Increased milk intake also improved the iodine status.

The researchers commented that these findings give cause for concern. Women of childbearing age and pregnant women should be given advice on how to improve their iodine status through dietary means. Iodine is a key component of the thyroid hormones, which are crucial for brain development, particularly during gestation and early life. Iodine deficiency, once endemic in the UK, was eradicated by the concurrent in- crease in milk-iodine concentration and milk consumption in the post-war years, but data is now emerging that suggests that this may no longer be the case, at least in women of childbearing age. The UK has never introduced a national iodine-fortification program (e.g., iodized salt) to ensure adequate population iodine intake, as has been done in many countries worldwide (2).


  1. Bath S. C. et al. Iodine deficiency in pregnant women living in the South East of the UK: the influence of diet and nutritional supplements on iodine status. British Journal of Nutrition. Published online January 2014.
  2. Zimmermann M. B. Iodine deficiency. Endocr Rev. 2009; 30:376–408.