Objective To evaluate the effects of maternal iodine nutrition levels on postpartum thyroid function, and to provide clinical evidence for accurate iodine supplementation in women with subclinical hypothyroidism during pregnancy. Methods This study collected single-pregnant women who had no history of thyroid diseases before pregnancy in our city. Thyroid function and urinary iodine results were continuously recorded during pregnancy and lactation. All subjects were divided into subclinical hypothyroidism group and euthyroidism group according to their thyroid function during pregnancy. The relationship between urinary iodine levels during pregnancy and lactation with postpartum thyroid function were analyzed. Results A total of 148 maternal women were collected, including 41 cases of subclinical hypothyroidism group and 107 cases of euthyroidism group. The urinary iodine level in pregnant women was higher than that in lactation ( median 174.75 vs 149.89μg/L, P<0.05) . However, the iodine deficiency ratio(23.6％) during pregnancy was higher than that during lactation (5.4％). There were significant differences in the change of urinary iodine in each time interval during pregnancy and lactation ( P<0.05). A total of 56 maternal women developed postpartum thyroiditis ( PPT). The incidence of PPT in pregnant women with TPOAb-positive in early pregnancy was higher than that in TPOAb-negative patients (χ2=10.811, P=0.001) . The urinary iodine concentration in the 12-month postpartum period was lower in women with PPT than that in womenwithoutPPT(P<0.05).Coxregressionanalysisshowedthatiodinedeficiencyduringlactation(HR=3.870, 95％CI 1.595-9.392, P=0.003) and TPOAb positive in early pregnancy (HR=3.679, 95％ CI 1.466-9.233, P<0.05) increased the risk of PPT. Subgroup analysis also showed a similar risk increase of PPT in women with hypothyroidism during pregnancy (HR=8.318, 95％CI 2.383-29.029, P<0.05). However, this association was not found in euthyroidism group. Conclusion The urinary iodine level of women during pregnancy and lactation in our iodine suitable areas is within normal range, but attention should still be paid to the effect of iodine deficiency on breast-feeding women, especially among those with subclinical hypothyroidism.

Objective To investigate the associations of urinary iodine concentration ( UIC) and blood selenium levels with subclinical hypothyroidism and thyroid antibodies during the first half pregnancy in women. Methods A total of 239 pregnant women(7-20 weeks)were selected. The baseline data were collected, and serum TSH, FT4 , thyroid peroxidase antibody ( TPOAb), thyroglobulin antibody ( TgAb), blood selenium, and urinary iodine concentration(UIC) levels were measured. Results The median level of urinary iodine among 239 women was 156. 96 μg/ L. The distributions of pregnant women with iodine deficiency, iodine adequate, more-than-adequate or excessive iodine intake were 43. 9％ , 38. 9％ , 17. 2％ , respectively. The percentage of more-than-adequate and excessive iodine in women with subclinical hypothyroidism was higher than that in women with euthyroidism. The serum TSH level in women with UIC≥250 μg/ L was higher than those with 150≤UIC<250 μg/ L and UIC<150 μg/ L (P<0. 05). The serum TSH level in women with blood selenium<95 μg/ L was higher than those with selenium≥95μg/ L(P<0. 05). Logistic regression analysis showed that the risk of subclinical hypothyroidism in women with UIC≥250 μg/ L was increased by 3. 498 fold(95％ CI 1. 588-7. 704)as compared with those with 150≤UIC<250 μg/ L. The risk of subclinical hypothyroidism in women with blood selenium <80 μg/ L was increased by 2. 667 fold (95％ CI 1. 123-6. 331) compared with those with 90 ≤ selenium < 100 μg/ L. After adjusting for age, gestational weeks, residential district, TPOAb, TgAb, taking compound nutritional supplements, more-than-adequate and excessive iodine still increased the risk of subclinical hypothyroidism(OR= 3. 014, 95％ CI 1. 310-6. 938). Women with UIC≥250 μg/ L and blood selenium <95 μg/ L revealed the increased risk of subclinical hypothyroidism as compared to those with 150≤UIC<250 μg/ L and selenium≥95 μg/ L(OR=5. 429, 95％ CI 1. 929-15. 281). After adjusting for age, gestational weeks, residential district, TPOAb, TgAb, taking compound nutritional supplements, the fingdings still existed. Conclusion The nutrient condition of iodine and selenium of the pregnant women in Tianjin during the first half pregnancy should be noticed. The individualized supplement of iodine and selenium, if needed, should be performed to decrease the risk of subclinical hypothyroidism.

Objective:To evaluate the effects of subclinical hypothyroidism during pregnancy treated with LT 4 on the growth and neuropsychology of offspring aged 0-36 months. Methods:A maternal-infant cohort was established in healthy singleton pregnant women aged 20-45 years without history of thyroid disease. Women developing subclinical hypothyroidism during pregnancy were treated with LT4. The weight, length, and head circumference of the offspring were recorded between 0 to 36 months after birth. Meanwhile, infant nutrition and family support were investigated. The Neuropsychological Development Questionnaire of 0-6 year old children was used to evaluate the neurodevelopment of offspring.Results:A total of 186 mother-infant pairs were included. All subjects were divided into the euthyroidism(ETH) group( n=136) and subclinical hypothyroidism(SHT) group( n=50) according to maternal thyroid function during pregnancy. The Z-scores(adjusted by months of age and gender) of weight, length, weight/length at birth, weight/length at 1 month, head circumference at 6 months, length at 8 months, weight/length at 24 months of SHT group were lower than those of the ETH group( P<0.05). Furthermore, the language competence of the SHT offspring at 12 months of age was also lower than that of the ETH group( P<0.05). Maternal subclinical hypothyroidism treated with LT 4 did not significantly affect preterm delivery, low birth weight, and developmental quotient <85, but reduced the risk of macrosomia(AOR 0.206, 95% CI 0.046-0.929, P=0.040). Conclusion:Although women with subclinical hypothyroidism received LT 4 treatment during pregnancy, the offspring still may suffer adverse effects on their growth and neural development.