Effect of parity on autoimmune thyroid disease / 中华内分泌代谢杂志

ABSTRACT

The objective of this study was to evaluate parity as a risk factor for autoimmune thyroid disease ( AITD) by comparing features of thyroid autoantibodies of pregnant women with different parities. This prospective cohort study included 477 women of first trimester of pregnancy in Peking University International Hospital from October 2016 to April 2017. Subjects were categorized as never parturition group ( n=287) or previously parturition group(n=190). All pregnant women in this study voluntarily signed informed consents. Thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb), thyrotropin (TSH), and free T4 were measured in the first trimester of pregnancy( from 7 to 12 weeks) . Meanwhile, height, weight, blood pressure, gestational weeks and pregnancy history were recorded. Data were statistically analyzed. The positive rates of thyroid autoantibodies including TPOAb and TGAb in previously parturition group were higher than those in no parturition group(10.0％vs 5.2％, P<0.05). The previously parturition group tended to be older and had lower TSH levels than the never pregnant group( P<0.05) . TSH 2.5 mIU/L and 4.0 mIU/L were used as upper reference limits respectively. The rate of abnormality of thyroid function was higher in the never parturition group than those in previously parturition ones ( 33. 33 by 29. 5％, 21. 2％ by 10. 8％) . In both previously parturition and never parturition groups, the commonest diseases of abnormal thyroidal function were SCH and subclinical thyrotoxicosis, and there was significant difference in disease of abnormal thyroidal function abnormal(χ2=15.704, P<0.05 and χ2=14.560, P<0.05). Parity was associated with AITD after adjustment for age, BMI, and gestational week [OR=2.346(1.075-5.121)]. Parity may affect AITD. Pregnant women should be monitored for thyroid function and thyroid autoantibodies even if they did not suffer from thyroid disease in the first pregnancy.