The Inlfuence Of Subclinical Hypothyroidism On Pregnancy And Its Outcomes

【Objective】Subclinical hypothyroidism (SCH) during pregnancy has a high morbidity in clinicalwork, but the influence on pregnancy and its outcomes was not very clear. In this researchwe propose to know the prevalence of SCH during pregnancy in Jinan city; Analyse therelationship between SCH and adverse outcomes of pregnancy such as abortion, prematurebirth, gestational hypertension, placental abruption, fetal growth restriction and low birthweight; Discuss whether serum TSH of pregnant women is affected by weeks of gestation,weight, age, pregnant season and the correlation between TPOAb and their educationdegree; Research the effect of LT4replacement therapy on improving pregnant outcomesand maternity complications of pregnant women with SCH; Provide related support fordiagnosis, screening and treatment of SCH during pregnancy.【Method】1. In this study, we screened582obstetric outpatient pregnant women of GeneralHospital of Jinan Military Command from May2010to May2011. Tested their thyroidfunction at the first antenatal visit. According to the results assessed by standard laboratoryreference ranges, we classified them into different groups. Gave them observation andtreatment until the end of pregnancy.2. The pregnant women who were diagnosed to be overt hypothyroidism, overthyperthyroidism and subclinical hyperthyroidism were transferred to endocrine clinic.Women who were subclinical hypothyroidism were divided into SCH group.3. We divided107pregnant women with SCH into treatment group and observationgroup, and randomly chose54normal pregnant women in the same period as the controlgroup. We tested thyroid function every month for the treatment group and observationgroup. The treatment group were given LT4replacement therapy and adjusted doseaccording to the test results. In order to know the incidence of adverse pregnant outcomesin each group, evaluate the influence of SCH and the effect of LT4replacement therapy.4. According to the results of thyroid function tests of all the pregnant women, weanalysed whether serum TSH is affected by pregnant season, weeks of gestation, bodymass index(BMI), and age; and wanted to know the influence of mother’s education degreeto TPOAb positive. 5. We extracted umbilical blood of the newborn for the thyroid function test, in orderto know the influence of the pregnant women’s thyroid function to the fetus. At the sametime, we wanted to know the relationship of the umbilical blood detection and thecongenital hypothyroidism.6. During the3months after delivery, we still tested the thyroid function of thetreatment group every month and adjusted LT4dose according to the test results. By thisway, we can compare the variation tendency of the dosage of LT4.【Results】1. In this study, we screened582pregnant women of which107were diagnosed to beSCH (morbidity was18.38%),3were OH (morbidity was0.52%),2were overthyperthyroidism (morbidity was0.34%).2. There were four types in SCH group, their morbidity respectively were:①subclinical hypothyroidism group (increased serum TSH, normal FT4):26.17%(28/107)②isolated hypothyroxinemia (normal serum TSH, reduced FT4):12.15%(13/107)③isolated TPOAb positive:17.76%(19/107)④increased serum TSH with TPOAbpositive:43.93%(47/107).3. Serum TSH、TPOAb of treatment group and observation group were obviouslyhigher than control group, serum FT4was obviously lower than control group, thedifference was statistically significant (P <0.05). The thyroid function of treatment groupwere controlled in normal range after curing by LT4, compared with the control group, thedifference was not statistically significant (P>0.05).4. The morbidity of premature birth and low birth weight in observation group wereobviously higher than treatment group and control group, the difference was statisticallysignificant (P <0.05), but made no sense in the statistics (P>0.05) in other adverseoutcomes of pregnancy.5. Screening serum TSH at the first antenatal visit. The incidence of the increasedserum TSH in each age group made no sense in the statistics (P>0.05); The incidence ofthe increased serum TSH in overweight group and obese group were obviously higher thanmoderate group and lighter weight group, the difference were statistically significant (P<0.05); At the same time, we knew serum TSH was positive correlation with body massindex. 6. Screening serum TPOAb at the first antenatal visit. We found that the incidence ofTPOAb positive in lower than junior high school group and higher than master group wereobviously higher than high school and technical secondary school group、college andbachelor degree group, the difference were statistically significant (P <0.05).7. In observation group, serum TSH level in the second and the third trimester wereobviously higher than in the first trimester, the difference was statistically significant (P<0.05); Serum TSH level in the first and fourth quarter were obviously higher than in thesecond and third quarter, the difference was statistically significant (P <0.05).8. The serum TSH and TPOAb level of pregnant women were significant positivecorrelation with the corresponding level in umbilical blood of the newborn; The thyroidfunction test of umbilical blood had no correlation with congenital hypothyroidism.9. The postpartum dosage of LT4was significantly reduced than in the second and thethird trimester, the difference was statistically significant (P <0.05). But compared with thefirst trimester, the difference was not statistically significant (P>0.05).【Conclusion】1. SCH during pregnancy has a high morbidity, the one that serum TSH increasedwith TPOAb positive is the highest in all the SCH types. Screening in pregnancy should bestrengthened.2. Pregnancy with SCH are related with adverse pregnant outcomes, such as pretermdelivery and low birth weight. We can obviously reduce the occurrence through the timelyand effective replacement therapy. It is significant to keep women with normal thyroidfunction during pregnancy.3. Serum TSH level is connected with pregnant women’sBMI, weeks of gestation andgravid season, but has no correlation with women’s age. Serum TPOAb is related withmother’s education degree.4. The thyroid function test of umbilical blood is influenced by maternal level. So itmakes no sense with the screening of congenital hypothyroidism.5. We shoud sequentially monitor thyroid function after delivery, and adjust LT4therapeutic dose timely.