The Relationship Between Hypothyroidism,Abnormal Thyroid Autoantibodies And Adverse Pregnancy Outcomes

Objective To investigate the prevalence of hypothyroidism and thyroid autoantibody abnormality in pregnant women at different stages of pregnancy;To assess the impact of hypothyroidism,especially subclinical hypothyroidism on adverse pregnancy outcomes;To explore whether thyroid autoantibody abnormalities have adverse effects on pregnancy outcomes in pregnant women.Methods 1632 pregnant women admitted to obstetric ward in Shanghai Jiao Tong University Affiliated Sixth People’s Hospital from January 2016 to October 2016 were collected.The general biology data,menstrual history,thyroid function,blood routine,and biochemical laboratory records were collected at the same time.Both the delivery of patients and the adverse outcome of pregnancy were recorded.According to the levels of thyroid hormones,pregnant women were divided into normal and abnormal thyroid function group.The abnormal thyroid function group consisted of hypothyroidism and hyperthyroidism group.The hypothyroidism group included subclinical hypothyroidism,clinical hypothyroidism and isolated low T₄ group;Meanwhile the hyperthyroidism group included subclinical hypothyroidism and clinical hypothyroidism group.According to TPOAb level,pregnant women were also divided into thyroid autoantibody-negative and-positive group.The pregnancy adverse outcomes of poor pregnancy were compared between different groups,respectively.Results The prevalence of hypothyroidism in early,middle and late trimester of pregnancy were 14.5%,15.9%,22.3%,respectively;The TPOAb positive rate were8.8%,9.4%,5.0%,respectively.Among all 1418 cases,287 were reported adverse pregnancy outcome,accounting for 15.4%,of which the top three are preterm birth,gestational hypertension,postpartum hemorrhage.According to the classification of thyroid hormone levels,there were significant differences in TPOAb levels among the six groups（p<0.05）.Substantial differences were also found in the prevalence of gestational hypertension between the normal,the hypothyroidism and the hyperthyroidism group（p<0.05）.There were significant differences in the prevalence of total adverse pregnancy outcome,premature birth,threatened abortion,placental abruption among the normal,the subclinical hypothyroidism,the clinical hypothyroidism and the isolated low T₄ group（p<0.05）.Between the normal and the subclinical hypothyroidism group,significant differences were shown in the total adverse pregnancy outcomes,threatened abortion and gestational hypertension（p<0.05）.The prevalence of threatened abortion,premature delivery and postpartum hemorrhage in TPOAb positive pregnant women was considerably higher than that in TPOAb negative pregnant women（p<0.05）.Conclusion The prevalence of hypothyroidism in pregnant women increased with the process of pregnancy period,while TPOAb positive rate decreased with the pregnancy cycle.Hypothyroidism could cause a significant increase in the incidence of adverse outcomes in pregnant women,and subclinical hypothyroidism increased the incidence of pregnant women suffering from total adverse incomes,threatened abortion,gestational hypertension.TPOAb positive is an independent risk factor for threatened abortion,premature birth,postpartum hemorrhage.