Objective: To investigate the iodine status of lactating women and the influence on infants during the first 24 weeks postpartum in Tianjin City.
Methods: The iodine concentration of human milk and urine were measured from 438 lactating women and their exclusive breastfeeding infants.
Results: Significant difference was found between the levels of BMIC according to the time of collecting samples( P < 0. 001). The BMIC was lower at the 24th week postpartum with a M( P25-P75) of 123. 5 μg/L( 83. 1-177. 6 μg/L) and the level of lactating women's UIC was lower at the 4th week postpartum with the M( P25-P75) of 87 μg/L( 52-159 μg/L). Besides that, the level of infants ' UIC was lower at the 12th week postpartum with the M( P25-P75) of 191 μg/L( 130-302 μg/L). Lactating women's BMIC and UIC( r = 0. 238, P <0. 001), lactating women's BMIC and infants' UIC( r = 0. 257, P < 0. 001), lactating women's UIC and infants' UIC( r = 0. 148, P < 0. 001) were significantly positive correlated. According to different time of collecting samples, the levels of infants' UIC were significant different categorized by BMIC at 4th, 12th, 24th week postpartum( P <0. 05).
Conclusion: The BMIC gradually decreased during the first 24 weeks postpartum in Tianjin, but still been in the sufficient iodine status. The iodine status of lactating women can affect their infants' iodine status.
Keywords: human milk; infant; iodine status; lactating women; spot urine.