title: Effects of subclinical hypothyroidism on maternal and perinatal outcomes during pregnancy: a single-center cohort study of a Chinese population.
abstract: OBJECTIVE
  Adverse maternal outcomes and perinatal complications are closely associated with overt maternal hypothyroidism, but whether these complications occur in women with subclinical hypothyroidism (SCH) during pregnancy remains controversial. The aim of this study was to evaluate the effects of SCH on maternal and perinatal outcomes during pregnancy.
  
  
  METHODS
  A prospective study of data from 8012 pregnant women (371 women with SCH, 7641 euthyroid women) was performed. Maternal serum samples were collected in different trimesters to examine thyroid hormone concentrations. SCH was defined as a thyroid stimulating hormone concentration exceeding the trimester-specific reference value with a normal free thyroxine concentration. The occurrence of maternal outcomes, including gestational hypertension (GH), gestational diabetes mellitus, placenta previa, placental abruption, prelabor rupture of membranes (PROM), and premature delivery; and perinatal outcomes, including intrauterine growth restriction (IUGR), fetal distress, low birth weight (LBW; live birth weight ≤ 2500 g), stillbirth, and malformation, was recorded. Logistic regression with adjustment for confounding demographic and medical factors was used to determine the risks of adverse outcomes in patients with SCH.
  
  
  RESULTS
  Compared with euthyroid status, SCH was associated with higher rates of GH (1.819% vs. 3.504%, P = 0.020; χ2 = 7.345; odds ratio (OR), 2.243; 95% confidence interval (CI), 1.251-4.024), PROM (4.973% vs. 8.625%, P = 0.002; χ2 = 72.102; adjusted OR, 6.014; 95% CI, 3.975-9.099), IUGR (1.008% vs. 2.965%, <0.001; χ2 = 13.272; adjusted OR, 3.336; 95% CI, 1.745-6.377), and LBW (1.885% vs. 4.582%, P<0.001; χ2 = 13.558; adjusted OR, 2.919; 95% CI, 1.650-5.163).
  
  
  CONCLUSIONS
  The results of this study indicate that pregnant women with SCH had increased risks of GH and PROM, and their fetuses and infants had increased risks of IUGR and LBW. Thus, routine maternal thyroid function testing is necessary to improve maternal and perinatal outcomes.
authors.affiliation: Department of Endocrinology, Third Affiliated Hospital, Wenzhou Medical University, Ruian, Zhejiang, China.
authors.forename: Liang-Miao
authors.initials: LM
authors.lastname: Chen
authors.affiliation: Department of Endocrinology, Third Affiliated Hospital, Wenzhou Medical University, Ruian, Zhejiang, China.
authors.forename: Wen-Jun
authors.initials: WJ
authors.lastname: Du
authors.affiliation: Department of Endocrinology, Third Affiliated Hospital, Wenzhou Medical University, Ruian, Zhejiang, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Dai
authors.affiliation: Department of Endocrinology, Third Affiliated Hospital, Wenzhou Medical University, Ruian, Zhejiang, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Endocrinology, Third Affiliated Hospital, Wenzhou Medical University, Ruian, Zhejiang, China.
authors.forename: Guang-Xin
authors.initials: GX
authors.lastname: Si
authors.affiliation: Department of Endocrinology, Third Affiliated Hospital, Wenzhou Medical University, Ruian, Zhejiang, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Endocrinology, Third Affiliated Hospital, Wenzhou Medical University, Ruian, Zhejiang, China.
authors.forename: En-Ling
authors.initials: EL
authors.lastname: Ye
authors.affiliation: Department of Endocrinology, Third Affiliated Hospital, Wenzhou Medical University, Ruian, Zhejiang, China.
authors.forename: Qing-Shou
authors.initials: QS
authors.lastname: Chen
authors.affiliation: Department of Endocrinology, Third Affiliated Hospital, Wenzhou Medical University, Ruian, Zhejiang, China.
authors.forename: Le-Chu
authors.initials: LC
authors.lastname: Yu
authors.affiliation: Chinese-American Research Institute for Diabetic Complications, Wenzhou Medical University, Wenzhou, China; Ruian Center of the Chinese-American Research Institute for Diabetic Complications, Third Affiliated Hospital, Wenzhou Medical University, Wenzhou, China.
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Endocrinology, Third Affiliated Hospital, Wenzhou Medical University, Ruian, Zhejiang, China; Chinese-American Research Institute for Diabetic Complications, Wenzhou Medical University, Wenzhou, China; Ruian Center of the Chinese-American Research Institute for Diabetic Complications, Third Affiliated Hospital, Wenzhou Medical University, Wenzhou, China.
authors.forename: Xue-Mian
authors.initials: XM
authors.lastname: Lu
mesh_terms: D000328:Adult; D002681:China; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000150:complications; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D011256:Pregnancy Outcome / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors; D013963:Thyroid Hormones / Q000097:blood*
chemical_list: D013963:Thyroid Hormones