Iodine Supplementation in Pregnancy in an Iodine-Deficient Region: A Cross-Sectional Survey

Abstract

Iodine deficiency is a common problem in pregnant women and may have implications for maternal and child health. Iodine supplementation during pregnancy has been recommended by several scientific societies. We undertook a cross-sectional survey to assess the efficacy of these recommendations in a European iodine-deficient region. Urinary iodine concentrations (UIC) were determined in pregnant women before (n = 203) and after (n = 136) the implementation of guidelines for iodine supplementation in pregnancy. Iodine supplementation (200 μg/day) reduced the proportion of pregnant women with severe iodine deficiency (37.4% to 18.0%, p = 0.0002). The median UIC increased from 67.6 µg/L to 106.8 µg/L but remained below the recommended target level (>150 µg/L) for pregnant women. In conclusion, iodine supplementation in pregnant women improved iodine status in this iodine-deficient region but was insufficient to achieve recommended iodine levels in pregnancy. Additional measures, such as the adjustment of the dose or timing of supplementation, or universal salt iodization, may be needed.

Keywords: iodine deficiency; pregnancy; supplementation; thyroid hormones.

Figure 1

Distribution of urinary iodine concentration (UIC) in untreated (n = 203) and iodine-supplemented (n = 111) pregnant women, studied in 2006/07 and 2018/19, respectively. Supplementation with a daily dose of 200 µg iodine resulted in a shift towards a higher UIC in pregnancy (chi-square test p < 0.0001). For clarity, UIC higher than 150 µg/L have been grouped together. Bars represent percentages (%) of total and error bars represent 95% confidence intervals.