The Impact of the COVID-19 Pandemic on Iodine Nutrition Status of Pregnant Women and Infants/Toddlers: Repeated Cross-Sectional Studies in Zhengzhou, China.

Iodine nutrition in pregnant women and infants/toddlers is a critical public health indicator, yet the impact of the COVID-19 pandemic on iodine status remains unclear. Using data (2014-2022) from 139,163 pregnant women and 30,761 infants/toddlers aged 0-2 years in Zhengzhou, we explored effects of the pandemic on iodine nutrition through stratified inter-group analyses and seasonal autoregressive integrated moving average (SARIMA) modeling. Pregnant women and infants/toddlers had adequate iodine, with urinary iodine concentration (UIC) of 192.66 μg/L and 213.19 μg/L, respectively, both exceeding WHO thresholds for iodine sufficiency (150 μg/L for pregnant women and 100 μg/L for infants/toddlers). During the pandemic, significantly lower UICs were observed in urban pregnant women aged ≤ 30 years (2nd/3rd trimesters), rural pregnant women (1st/2nd trimesters), and rural infants (0-12 months) on formula/mixed feeding, compared with those in pre-pandemic. Notably, rural breastfed infants/toddlers had higher UICs during the pandemic than those before. Pre-pandemic data (2014-2019) yielded well-fitting SARIMA models, SARIMA(2,0,3)(2,1,2) for pregnant women and SARIMA(2,1,3)(1,2,2) for infants/toddlers, but incorporating pandemic data (2020-2022) worsened their fits, indicating that UIC patterns during the pandemic deviated from the pre-pandemic trends predicted by the model. These findings suggest that UICs of urban pregnant women aged ≤ 30 years in their 2nd/3rd trimesters, rural pregnant women in their 1st/2nd trimesters, and rural infants/toddlers were likely affected by the COVID-19 pandemic, highlighting the need for targeted monitoring during similar events.