Iodine Status In Lactating Women And Infants During The Period Of 12 Weeks Postpartum

Objective 1. To evaluate the pregnant women’s iodine nutrition status in Tianjin City. 2. To know well about women and neonates’ iodine nutritional status. 3. To know the fluctuation in breast milk iodine concentration(BMIC) during the period of 12 weeks postpartum, providing theoretical basis for iodine deficiency prevention and cure. 4. To explore the relations between BMIC, urinary iodine concentration(UIC) for lactating women and infants.Methods 1. Before the implementation of universal salt iodization, Tianjin was a mild iodine deficiency area. Present studies have basically eliminated iodine deficiency, and iodine sufficient areas were chosen as the study areas. 2. Pregnant women aged 18~45 in the third trimester in Tianjin Baodi Hospital were enrolled. Inclusion criteria were as follows: Women had no endocrine diseases, other autoimmune diseases, heart diseases and family genetic diseases, lived locally over 5 years, and no iodine contained medication. 3. Demographics information were recorded and informed consent forms were signed. 4. Pregnant women’s midstream urine, urine and breast milk of lactating women and infants during the period of 12 weeks postpartum were collected. Urinary iodine concentrations were measured by national standard method, breast milk iodine content was measured by ICP-MS.Results 1. Median urinary iodine concentration(MUIC) of 220 late-stage pregnant women in the survey was 95.67 μg/L, and UIC of 124 pregnant women(80.3%) were less than 150 μg/L, indicating iodine deficiency. In the 12 weeks postpartum, MUIC of 175 pairs of mother and neonatal were 115.2 μg/L and 185.90 μg/L, respectively, which indicated adequate iodine nutrition. 2. Median of milk iodine content was 219.1 μg/L, according to the WHO recommended levels of 150-150 μg/L, and it was sufficient. 3. There is a significant difference in the UIC of pregnant women, lactating women and their babies(P < 0.001). 4. Median of breast milk iodine content in 4 weeks, 8 weeks, 12 weeks were 294.1 μg/L, 219.1μg/L, 173.7μg/L, respectively MUIC of lactating women in 4 weeks, 8 weeks, 12 weeks WERE129.9 μg/L, 107.7 μg/L, 113.4 μg/L, respectively. MUIC of infant in 4 weeks, 8 weeks, 12 weeks were 269.1μg/L, 194.1μg/L, 157.4 μg/L, According to the 100μg/L of urine iodineconcentrations standard, lactating women and their infants were adequate iodine status in the three period of postpartum. 5. There were significant differences in the UIC of lactating women and infants in the 4wk, 8wk and 12 wk after the postpartum(P < 0.001). 6. In the 4 weeks, 8 weeks, 12 weeks, the difference of milk iodine median was statistically significant(P < 0.001), and breast milk iodine concentration(BMIC) had a declining trend over time(R2 = 0.176, P < 0.001), at the same time, three times of infant urinary iodine was negatively correlated with time(rs =-0.39, P < 0.001), no correlation was found between UIC of lactating women and the time(P > 0.05). 7. There was a positive correlation between BMIC and UIC of infants(R2 = 0.06, P = 0.06).Conclusions 1. A large proportion of pregnant women in the optimal iodine area are iodine deficiency, we should give more attention to the special populations in the background of USI to ensure the appropriate iodine intake. 2. In the 12 weeks postpartum, BMIC has a decline trend over time. Over 4wk, the value of BMIC is highest. It suggests BMIC fluctuate in different periods. 3. There are significant differences among UIC of pregnant women, lactating women and infants. It illustrated that people in different special physiological period, UIC will change accordingly, and iodine excretion of absorption will also change. So we should give high attention to the special groups, to avoid the threat posed by its inappropriate iodine nutritional status. 5. We should focus on neonatal urinary iodine and its growth and development. Effects on neonates’ growth and development of iodine excess should be further studied.