Study On The Relationship Between Thyroid Autoantibodies,Iodine,Bisphenol A And Pregnancy Outcomes

Background:Thyroid autoantibodies positivity may be associated with miscarriage,premature birth,gestational diabetes(GDM)and other adverse pregnancy outcomes.Iodine is an essential trace element for human body and the main raw material for thyroid hormone synthesis.Abnormal iodine nutritional status and bisphenol A(BPA)exposure may not only influence maternal thyroid disease,but also directly cause adverse pregnancy outcomes.However,the relationship between thyroid autoantibodies positivity,abnormal iodine status,BPA exposure and adverse pregnancy outcomes remains unclear.Objective:To investigate the relationship between euthyroid women with anti-thyroid peroxidase antibody(TPOAb)positivity,abnormal iodine status,BPA exposure and adverse pregnancy outcomes.Method:This study was a cohort study involving pregnant women admitted to Peking University International Hospital from October 2016 to December 2019.All pregnant women who met the inclusion and exclusion criteria signed informed consent.The general conditions of pregnant women at baseline were recorded,thyroid function and biochemical indexes were measured.Follow-up was conducted during the second and third trimester of pregnancy until delivery,and the outcomes of delivery and fetal conditions were recorded.1 A total of 938 pregnant women were enrolled and divided into euthyroid group(n=837)and euthyroid women with TPOAb positivity group(n=101)according to thyroid function and TPOAb.2 A total of 726 pregnant women were enrolled.Urinary iodine was detected during the first trimester of pregnancy.According to different levels of urinary iodine,pregnant women were divided into three groups:iodine deficiency group(n=390),iodine adequate group(n=206),and more than iodine adequate and iodine excess group(n=130).3 A total of 262 pregnant women were enrolled.BPA were detected during the first trimester of pregnancy.According to the median of BPA,they were divided into low level group(n=131)and high level(n=131)group.The association between euthyroid women with TPOAb positivity,abnormal iodine status,BPA exposure and adverse pregnancy outcomes were evaluated.Restricted cubic spline regression was used to judge the nonlinear correlation between variables;multivariate logistic regression models were used to evaluate the association between euthyroid women with TPOAb positivity,abnormal iodine status,BPA exposure and adverse pregnancy outcomes.Result:1 There were no differences in the incidence of GDM,spontaneous abortion,premature rupture of membrane(PROM),hypertensive disorders of pregnancy(HDP),premature birth,fetal embarrassment,small for gestational age(SGA),low birth weight and macrosomia between euthyroid group and euthyroid women with TPOAb positivity group.Euthyroid women with TPOAb positivity was not associated with an increased risk of adverse pregnancy and fetal outcomes.However,in euthyroid women with a female fetus,TPOAb positivity was independently associated with preterm birth(OR:4.511,95%CI:1.075-18.926)after adjustment for potential confounding factors.2 The incidence of TPOAb positivity,thyroglobulin antibody(TGAb)positivity and thyroid autoimmunity(TAI)in iodine deficiency group were higher than that in iodine adequate group,and more than iodine adequate and iodine excess group.After adjustment for age,body mass index,parity,and history of spontaneous abortion,iodine deficiency was found to be an independent risk factor for TPOAb positivity,TGAb positivity,and TAI(OR:3.646,95%CI:1.658-8.017;OR:3.109,95%CI:1.465-6.599;OR:2.885,95%CI:1.539-5.407).Abnormality of iodine nutritional status was not found to be a risk factor for GDM,subclinical hypothyroidism(SCH),hypothyroidemia,spontaneous abortion,PROM,HDP,preterm birth,fetal distress,low birth weight,macrosomia,and SGA in the general population and different sex fetuses' groups.3 There were no differences in the incidence of GDM,SCH,hypothyroxidemia,TAI,spontaneous abortion,PROM,HDP,preterm delivery,fetal distress,low birth weight,macrosomia and SGA among different levels of BPA groups.After adjusting for potential confounders,high level of BPA was not a risk factor for adverse pregnancy outcomes.After adjusting for urinary iodine and TPOAb concentrations,there was a non-linear correlation between urinary BPA and free thyroxine(FT4)level(P overall<0.05,P non-linear<0.05).There was a non-linear correlation between urinary BPA and FT4 levels in different sex fetuses' groups,TPOAb positivity and TgAb positivity pregnant women(P overall<0.05,P non-linear<0.05).Conclusion:1 In euthyroid women with a female fetus,TPOAb positivity was associated with preterm births.2 Iodine deficiency in early pregnancy was a risk factor for thyroid antibodies positivity during pregnancy.The relationship between urine iodine and the concentration of TPOAb and TGAb was similar to U-shaped curve.3 Exposure to BPA in first trimester of pregnancy did not increase adverse pregnancy outcomes.There was a non-linear correlation between BPA exposure and FT4 levels.In clinical practice,the association between thyroid autoantibodies positivity,abnormal iodine status,BPA exposure and adverse pregnancy outcomes during pregnancy should be concerned.