The Effect of Iodine Nutrition during Pregnancy on Their Neonatal Physical Growth and Thyroid Function in Iodine Deficient Area

Background: The impact of mild to moderate iodine deficiency is still controversial. We aimed to explore the effects of mild-to-moderate iodine deficiency during pregnancy on neonatal physical growth and TSH. Methods: : 2613 pregnant women and their infants were enrolled in this prospective cohort study. Spot urine and venous blood samples were collected to determine urinary iodine concentration (UIC) and thyroid-stimulating hormone (TSH). Heel blood samples of neonates were collected within 72 hours after birth to determine neonatal TSH. Results: : The median UIC was 116 (64, 190) μg/L and 63.9% of pregnant women had UIC < 150μg/L, indicating mild-to-moderate iodine deficiency. Lower birth weight and WFA Z-scoreswere found in neonates with maternal UIC ranged 100-149μg/L during pregnancy(both P < 0.05), and were associated with parity (0 or ≥ 1), delivery week (< 37wks or ≥ 37wks) and delivery way (all P < 0.05). 40.4% neonates had TSH ≥ 5.0mIU/L. Neonatal TSH increased by 0.28mIU/L per unit in neonates with nulliparous mother than multiparous, 1.12mIU/L higher in term neonates than preterm and 0.44mIU/L higher in neonates born via NVD than CS (all P < 0.05), respectively. The rate of neonatal TSH ≥ 5.0mIU/L was 1.103 folds positively associated with Maternal TSH and 1.178 times higher related to parity equals 0, 2.485 times higher in term neonates than preterm and 1.444 times higher in neonates born via NVD than CS (all P <0.05). Conclusions: : The iodine nutrition in pregnant women in Shunde was mild-to-moderate deficient. Lower birth weight and WFA Z-scores in neonates were related to maternal UIC within 100-149μg/L.BMI of pregnant women, parity, neonatal gender, delivery week and way affected neonatal birth weight and WFA Z-scores. High maternal TSH led to high neonatal TSH. Maternal age, parity, delivery week and way had effects on neonatal TSH and neonatal TSH ≥ 5.0mIU/L.