Analysis Of Related Factors Of Subclinical Hypothyroidism In Pregnancy Women And Its Effects On Pregnancy Outcomes

Objective:To learn the current incidence of subclinical hypothyroidism(SCH) during pregnancy and the related factors in our pupulation; To evaluate the effects of subclinical hypothyroidism(SCH) on pregnancy outcomes including gestational diabetes mel itus, hypertensive disorder complicating pregnancy, placenta previa, placental abruption, premature rupture of membranes, postpartum hemorrhage, preterm birth, small for gestational age, low birth weight; To evaluate the effect of replacement therapy on improving pregnant outcomes of pregnant women complicated with SCH and provide epidemiological evidence of treating for SCH.Methods:Pregnant women who gave singleton live birth between Mar. 2012 and Jul.2015 at the First Affiliated Hospital of Shanxi Medical University were recruited in the study. A person interview was conducted to collect information on demographic characteristics, pregnancy histories, and environmental and lifestyle factors, pregnancy complications(gestational diabetes mel itus, hypertensive disorder complicating pregnancy), delivery conditions, treatment condition of L-T4, and pregnancy outcomes were abstracted from medical records. Epidata3.0 was used to record data, SAS9.2 was used to clean and analyze data. Unconditional logistic regression models were used to explore the related factors of SCH during pregnancy, to investigate the association of SCH during pregnancy and adverse pregnancy outcomes, and evaluated the effect of therapy. Results:1. In this study, we recruited 5174 pregnant women of which 520 were diagnosed SCH(10.05%), 141 were OH(2.73%), 11 were hyperthyroidism(0.21%).2. Chi-square test showed that the differences were statistically significant(P<0.05) in maternal age, education level, history of gestation, pre-pregnancy BMI between pregnant women with SCH and those without SCH. Unconditional logistic regression model showed that pre-pregnancy BMI<18.5(OR=1.383, 95%CI: 1.079~1.773), age≥30 and primiparity(OR=1.473, 95%CI:1.058~2.050) can increase risk of SCH, pregnant women whose age between twenty and twenty five have a lower risk of SCH(OR=0.612, 95%CI:0.417~0.898).3. Compared to pregnant women without SCH, women who developed SCH during pregnancy had a higher incidence of gestational diabetes mel itus(21.73%), anemia(17.12%), premature rupture of membrane(19.42%), women who developed SCH during pregnancy in the first and second trimester had a higher incidence of gestational diabetes mel itus(23.53%), women who developed SCH in the third trimester had a higher incidence of hypertensive disorder complicating pregnancy than in the first and second trimester of pregnancy. Pregnant women with SCH during the whole trimester had a higher incidence of anemia. Treatment of SCH can decrease the incidence of hypertensive disorder complicating pregnancy, The difference were significant. After adjustment for potential confounding factors such as age, BMI before delivery, the logistic regression model was used to find that pregnant women with SCH increased the risk of gestational diabetes mel itus(OR=1.459, 95%CI:1.158~1.837), premature rupture of fetal membranes(OR=1.286, 95%CI:1.017~1.627), anemia(OR=2.244, 95%CI:1.733~2.905), treatment for SCH is useful for hypertensive disorder complicating pregnancy.4. Chi-square test showed that pregnant women developed SCH had a lower incidence of premature birth(3.46%) and fetal distress(8.46%) than those without SCH, these differences were mainly observed among women who developed SCH in the first and second trimester. Pregnancy with SCH for treatment had a lower incidence of premature delivery(1.46%), and women during the third trimester of pregnancy had a lower incidence of low birth weight. After adjustment for potential confounding factors such as age, pre-pregnancy BMI, a significant protective effect was seen for women who had SCH with treatment(OR=0.744, 95%CI: 0.730~0.759). Conclusions:1. Pre-pregnant BMI<18.5, age≥30 and primiparity can both increase the risk of SCH. 20 to 25 years old pregnant women had a lower risk of SCH than those of 25 to 29 years old pregnant women.2. Pregnant women with SCH is a risk factor for gestational diabetes mel itus, premature rupture of membranes occurred, anemia; pregnant women during the late pregnancy had a higher risk of hypertensive disorder complicating pregnancy then during the first and second trimester. Treatment can reduce the risk of hypertensive disorder complicating pregnancy.3. Treatment is the protective factors of preterm delivery, can reduce the risk of the premature birth.