Iodine Deficiency of Breastfeeding Mothers and Infants from 2012 to 2019 in Zhengzhou, China

To investigate iodine status and characteristics of breastfeeding women and infants in Zhengzhou after the implementation of the new national standard of iodine in edible salt, so as to provide the basis for formulating prevention and control measures. Urine samples from 28,730 infants aged 0–2 years and 17,977 breastfeeding women who received preventive health care in 12 districts/cities of Zhengzhou from 2012 to 2019 were collected to measure urinary iodine concentration (UIC). A total of 350 pairs of unweaned infants and their mothers were included in this study. After the implementation of the new national standard of iodine in edible salt, the iodine deficiency of infants aged 0–2 years showed a trend of decreasing first and then increasing, but generally the iodine nutrition of infants aged 0–2 years was at the appropriate level in 8 years. There was a gradual decrease in iodine deficiency among breastfeeding women over an 8-year period. And the median UIC of breastfeeding women in 8 years was at iodine nutrition appropriate level. In addition, the UIC of breastfeeding mothers was positively associated with that of infants (r = 0.104, P = 0.004). After the implementation of the new national standard of iodine in edible salt, breastfeeding women and infants in Zhengzhou generally were at an appropriate level of iodine nutrition, and there was a significant positive correlation between the UIC of breastfeeding mothers and infants.