胎次对自身免疫性甲状腺疾病的影响

Effect of parity on autoimmune thyroid disease

本研究通过比较不同胎次妊娠妇女甲状腺自身抗体的变化，探讨胎次对自身免疫性甲状腺疾病的影响。纳入从2016年10月至2017年4月在北京大学国际医院建档的妊娠妇女477例，包括头胎妊娠妇女（主要指初产妇）287例，二胎及以上妊娠妇女（主要指经产妇）190例，参加研究的妊娠妇女均自愿参加并签署项目知情同意书。妊娠早期（7周到12周）行甲状腺功能和甲状腺自身抗体检测，并记录身高、体重、血压、孕周数、孕产史。收集数据进行统计学分析。二胎及以上妊娠妇女的甲状腺自身抗体包括甲状腺过氧化物酶抗体（TPOAb）和甲状腺球蛋白抗体（TGAb）均阳性的比例高于头胎妊娠妇女（10.0%对5.2%, P〈0.05）。二胎及以上妊娠妇女TSH水平低于头胎妊娠妇女，年龄高于头胎妊娠妇女，均具有显著性差异（P〈0.05）。分别以TSH 2.5 mIU/L和4.0 mIU/L为参考值上限进行甲状腺功能异常状态的分析，发现二胎及以上妊娠妇女组甲状腺功能异常的比例均高于头胎妊娠妇女组（分别为33.3%对29.5%，21.2%对10.8%），头胎妊娠妇女组和二胎及以上妊娠妇女组甲状腺功能异常常见的均是亚临床甲状腺功能减退（subclinical hypothyroidism, SCH）和亚临床甲状腺毒症，两组间甲状腺功能异常状态均存在差异（分别为χ^2＝15.704，P〈0.05, χ^2＝14.560，P〈0.05）。调整了年龄、孕周、BMI后，多次生产是甲状腺自身抗体阳性的危险因素[OR＝2.346（1.075～5.121）]。胎次可能影响甲状腺自身免疫性疾病。本研究提示妊娠妇女即使首次妊娠未罹患甲状腺疾病，再次妊娠时也应该监测甲状腺功能和甲状腺自身抗体。

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（χ^2=15.704, P〈0.05 and χ^2=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.