The Relationship Between Different Thyroid Peroxidase Antibody Titers In Late Pregnancy And Neonatal Hypothyroidism

Objective: On the basis of analyzing the thyroid disease related indicators of pregnant women who had a normal thyroid function and positive thyroid peroxidase antibody and their newborns.The impact of different thyroid peroxidase antibody titers during late pregnancy on neonatal hypothyroidism was explored.To understand the correlation between peroxidase antibody and thyroid dysfunction,and to provide the theoretical basis for the necessity of thyroid function screening and the necessity of intervention.Method: The pregnant women who had all normal pregnancy tests except for thyroid disease at third trimester and their newborns were recruited for study between January 2015 and December 2016.The epidemiological data and thyroid disease related indicators of pregnant women and their newborns were selected as analysis data.All women were divided into three groups according to their TPO-Ab titers on the first pregnancy test at third trimester.The differences of thyroid related indicators were compared among three groups.A logistics regression model was used to analyze the influencing factors of neonatal hypothyroidism.The correlation between pregnant women's thyroid related indicators and their newborns' thyroid related indicators was also explored.Results: There were 207 pregnant women at third trimester in the study.The average of TPO-Ab was 79.5±16.7IU/mL.According to TPO-Ab titers,the pregnant women were divided into three groups.There were 96 women in the control group,78 women in the low titer group and 33 women in the high titer group.There were no differences in age,gestational weeks and BMI among three groups.The mean values of TSH,TG-Ab,FT3 and FT4 in pregnant women were 2.2±1.4uIU/mL,50.4±25.0IU/mL,3.1±1.3pmol/L and 14.1±2.9pmol/L respectively.There were no differences in FT3 and FT4 among three groups.However,TSH in low titer and high titer group were both higher than that in the control group(F=9.363,P<0.001).TG-Ab of women in high titer group was higher than that in other two groups(F=159.040,P<0.001).213 cases of newborn were delivered out successfully by 207 pregnant women.The mean values of TPO-Ab,TG-Ab,TSH,FT3 and FT4 in newborns were 29.9±15.7IU/mL,24.4±4.5IU/mL,3.7±2.3uIU/mL,3.6±1.6pmol/L and 19.8±6.5pmol/L respectively.The newborn was in the same groups as their mother.The Apgar scores and birthweight of newborns in the high titer group were both higher than that in other two groups(F=7.236,P=0.001;F=4.646,P=0.011).TPO-Ab and TSH of newborns in high titer group were obviously higher than that in other two groups(F=908.543,P<0.001;F=100.818,P<0.001),but newborns' FT4 in the high titer group was lower than that in other two groups(F=107.735,P<0.001).There were 15 newborns diagnosed as neonatal hypothyroidism.Of all thyroid disease related indicators,only TPO-Ab in pregnant women was the risk factor of neonatal hypothyroidism(OR=1.278,P<0.001).TPO-Ab in pregnant women had no correlation with their newborns' TG-Ab and FT3.However,there was a positive correlation existed between TPO-Ab in pregnant women and their newborns' TPO-Ab and TSH(r2=0.793,P<0.001;r2=0.597,P<0.001).Conclusion: TPO-Ab of women in late pregnancy is the risk factor of neonatal hypothyroidism.It also has a positive relationship with their newborns' TPO-Ab and TSH.