Pregnant Women Are Iodine Deficient While School-Aged Children Demonstrate Adequate Iodine Status in Sarawak, Malaysia

Pregnant women at risk for iodine deficiency but adequate iodine intake in school-aged children of Zhejiang Province, China

The median urinary iodine concentration (UIC) of school-aged children has been commonly used as a surrogate to assess iodine status of a population including pregnant women. However, pregnant women have higher iodine requirements than children due to increased production of thyroid hormones. The aim of the study was to evaluate the iodine status of pregnant women and children as well as their household salt iodine concentration (SIC) in Quzhou, Zhejiang Province, China. Eligible pregnant women and children from all six counties of Quzhou in 2021 were recruited into the study. They were asked to complete a socio-demographic questionnaire and provide both a spot urine and a household table salt sample for the determination of UIC and SIC. A total of 629 pregnant women (mean age and gestation weeks of 29.6 years and 21.6 weeks, respectively) and 1273 school-aged children (mean age of 9 years and 49.8% of them were females) were included in the study. The overall median UIC of pregnant women and children in our sample was 127 (82, 193) μg/L and 222 (147, 327) μg/L, respectively, indicating sufficient iodine status in children but a risk of mild-to-moderate iodine deficiency in pregnant women. Distribution of iodine nutrition in children varied significantly according to their sex and age (P < 0.05). The rate of adequately household iodised salt samples (18-33 mg/kg) provided by pregnant women and children was 92.4% and 90.6%, respectively. In conclusion, our results indicated a risk of insufficient iodine status in pregnant population of China, but iodine sufficiency in school-aged children. Our data also suggested that median UIC of children may not be used as a surrogate to assess iodine status in pregnant women.

Noncompliance to iodine supplementation recommendation is a risk factor for iodine insufficiency in Portuguese pregnant women: results from the IoMum cohort

PURPOSE

After a recommendation for iodine supplementation in pregnancy has been issued in 2013 in Portugal, there were no studies covering iodine status in pregnancy in the country. The aim of this study was to assess iodine status in pregnant women in Porto region and its association with iodine supplementation.

METHODS

A cross-sectional study was conducted at Centro Hospitalar Universitário São João, Porto, from April 2018 to April 2019. Pregnant women attending the 1st trimester ultrasound scan were invited to participate. Exclusion criteria were levothyroxine use, gestational age < 10 and ≥ 14 weeks, non-evolutive pregnancy at recruitment and non-signing of informed consent. Urinary iodine concentration (UIC) was measured in random spot urine by inductively coupled plasma-mass spectrometry.

RESULTS

Median UIC was 104 μg/L (IQR 62-189) in the overall population (n = 481) of which 19% had UIC < 50 µg/L. Forty three percent (n = 206) were not taking an iodine-containing supplement (ICS) and median UIC values were 146 µg/L (IQR 81-260) and 74 µg/L (IQR 42-113) in ICS users and non-users, respectively (p < 0.001). Not using an ICS was an independent risk factor for iodine insufficiency [adjusted OR (95% CI) = 6.00 (2.74, 13.16); p < 0.001]. Iodised salt use was associated with increased median iodine-to-creatinine ratio (p < 0.014).

CONCLUSIONS

A low compliance to iodine supplementation recommendation in pregnancy accounted for a mild-to-moderately iodine deficiency. Our results evidence the need to support iodine supplementation among pregnant women in countries with low household coverage of iodised salt. Trial registration number NCT04010708, registered on the 8th July 2019.