Analysis Of Types Of Hyperthyroidism In Pregnancy And Its Effects On Maternal And Neonatal Outcomes

Objective To analyze the types of hyperthyroidism in pregnancy and the onset and remission time of gestational transient thyrotoxicosis(GTT).Moreover,to investigate the changes of thyrotrophin receptor antibody(TRAb)levels and its effects on the recovery of thyroid function and pregnancy outcomes.Methods 306 pregnant women were enrolled who underwent regular examination at Jiangsu Province Hospital between December 2014 and September 2017 and were diagnosed as hyperthyroidism in this study.Pregnant women with positive thyroid peroxidase antibody(TPOAb),assisted reproduce technology,and recognized systemic autoimmune diseases were excluded.Then 267 subjects were divided into two groups according to the results of TRAb level: TRAb-positive and TRAb-negative groups.340 normal pregnant women were selected for control.TSH and FT4 levels were monitored every 2-4 weeks in all subjects and TRAb levels were measured at least once in every trimester and after delivery in TRAb-positive pregnant women.Followed up patients,recorded the adverse outcomes of mothers and offspring,and compared the incidence of outcomes between different groups.Results Of all pregnant women with hyperthyroidism,41.83% had hyperthyroidism before pregnancy and 58.17% were diagnosed with hyperthyroidism during pregnancy.In pregnant women with hyperthyroidism before pregnancy,52.34% were GD,13.28% were hashitoxicosis,and 34.38% were hyperthyroidism caused by other reasons.Among women diagnosed with hyperthyroidism during pregnancy,58.43% were GTT,23.03% were GD,8.99% were hashitoxicosis,and 9.55% were hyperthyroidism caused by other reasons.The onset time of GTT was no more than 16 weeks of pregnancy and 43.27% of GTT occurred at 8-12 weeks of pregnancy.In GTT,33.65% and 44.23% of TSH returned to normal at 14-19 and 20-27 weeks of pregnancy,respectively.Most of high level of FT4 returned to normal at 8-13 and 14-19 weeks of pregnancy with the proportion of 28.85% and 53.85%,respectively.The proportion of pregnant women with a euthyroid state was significantly higher in TRAb-negative group than in TRAb-positive group.In TRAb-negative group,18.24% of pregnant women were treated with ATD,but none of the 104 pregnant women with GTT received ATD treatment.And 49.07% of pregnant women in TRAb-positive group were treated with ATD.As pregnancy progressed,there was a gradual decrease in TRAb levels which may increase after delivery.The incidences of abortion,pregnancy-induced hypertension,placental abruption,preeclampsia,preterm birth,postpartum hemorrhage,LBW and neonatal hyperthyroidism and hypothyroidism were significantly higher in TRAb-positive group than those in TRAb-negative group.The rates of postpartum hemorrhage,cesarean section,and pregnancy-induced hypertension in hyperthyroidism group were significantly higher than in the control group.Conclusion It is necessary to identify the cause of hyperthyroidism in pregnancy once it is diagnosed.The onset time of GTT was in the first half of pregnancy and GTT can be resolved in the second half of pregnancy without ATD treatment.GTT was not associated with adverse pregnancy outcomes.High TRAb levels can affect the recovery of thyroid function and pass through placenta and thus increase the incidence of maternal and neonatal adverse outcomes,so it should be important to measure TRAb during pregnancy.Most pregnant women with GD required ATD treatment.However,ATD should be prudent to use considered it can cross placenta which may lead to fetal or neonatal hypothyroidism.