Iodine deficiency in pregnant women living in the South East of the UK: the influence of diet and nutritional supplements on iodine status

Abstract

Iodine is a key component of the thyroid hormones which are crucial for brain development. Adequate intake of iodine in pregnancy is important as in utero deficiency may have lifelong consequences for the offspring. Data on the iodine status of UK pregnant women are sparse, and there are no such data for pregnant women in the South East of the UK. A total of 100 pregnant women were recruited to a cross-sectional study carried out at the Royal Surrey County Hospital, Guildford, at their first-trimester visit for an ultrasound scan. The participants provided a spot-urine sample (for the measurement of urinary iodine concentration (UIC) and creatinine concentration) and 24 h iodine excretion was estimated from the urinary iodine:creatinine ratio. Women completed a general questionnaire and a FFQ. The median UIC (85·3 mg/l) indicated that the group was iodine deficient by World Health Organisation criteria. The median values of the iodine:creatinine ratio (122·9 mg/g) and of the estimated 24 h iodine excretion (151·2 mg/d) were also suggestive of iodine deficiency. UIC was significantly higher in women taking an iodine-containing prenatal supplement (n 42) than in those not taking such a supplement (P,0·001). In the adjusted analyses, milk intake, maternal age and iodine-containing prenatal supplement use were positively associated with the estimated 24 h urinary iodine excretion. Our finding of iodine deficiency in these women gives cause for concern. We suggest that women of childbearing age and pregnant women should be given advice on how to improve their iodine status through dietary means. A national survey of iodine status in UK pregnant women is required.

Iodine deficiency during pregnancy: a national cross-sectional survey in Latvia

“…Several recent studies have suggested suboptimal iodine status in pregnant women living in areas with only partial coverage of iodized salt, such as Italy, the UK and the USA (25)(26)(27) . In a limited number of studies, long-term iodization before pregnancy showed more favourable effects on thyroid function than did short-term iodization and the early initiation of iodine supplements was more effective than beginning treatment in late pregnancy (28) .…”

Milk as an Essential Source of Iodine in Latvian Population

“…Studies conducted in the United Kingdom, the United States and Italy, areas known for partial coverage of iodised salt, also suggest suboptimal iodine status in pregnant women (Marchioni et al, 2008;Bath et al, 2014;Hollowell et al, 1998). This deficiency can occur during pregnancy, when the maternal need for thyroid hormone increases due to the transfer of iodine and thyroid hormone to the foetus and the increase in renal iodine clearance (Zimmermann et al, 2008).…”

Revisiting the Iodine Global Network’s definition of iodine status by country

“…Pregnant women using I supplements had a higher median UIC than non-supplement users (126 v. 66 µg/l, respectively). A UK study of 100 pregnant women found a similar median UIC of 85·3 µg/l, being higher in I supplement users than in non-supplement users (111 v. 61 µg/l, respectively) (20) . A UK study of educated women of childbearing age (n 57) found a median UIC of 63·1 µg/l (21) , remarkably similar to a comparable New Zealand study in 2010 of fifty highly educated women who had a median UIC of 65 µg/l (17) .…”

“…Pregnant women 100 85·3-whole group Bath et al (20) 34 85-whole group Brough et al (15) 111-supplement users 126-supplement users 61-non-supplement users 66-non-supplement users Women of childbearing age 57 63·1 Bath et al (21) 50 65 Shukri et al…”