title: Preconception TSH and pregnancy outcomes: a population-based cohort study in 184 611 women.
abstract: BACKGROUND
  Whether subclinical hypothyroidism adversely impacts pregnancy outcomes is inconclusive, and limited data are available on the optimal TSH range in women planning pregnancy.
  
  
  OBJECTIVE
  To investigate the association between maternal preconception TSH levels and pregnancy outcomes.
  
  
  METHODS
  Population-based cohort study.
  
  
  METHODS
  From 2010 to 2012, the free National Pre-pregnancy Checkups Project recruited 248 501 pairs of volunteer couples across China, of which 184 611 women, who subsequently became pregnant, were studied. Maternal TSH was measured within 6 months prior to conception. Participants were grouped according to TSH: 0·48-2·49 mIU/l (n = 133 232, 72%), 2·50-4·28 mIU/l (n = 44 239, 24%) and 4·29-10·0 mIU/l (n = 7140, 4%). Multivariable logistic regression models were used to study the association between TSH and pregnancy outcomes.
  
  
  RESULTS
  Pregnancy loss, gestational age (GA), delivery modes and birthweight.
  
  
  RESULTS
  The overall incidence of adverse pregnancy outcomes was 28·6%. Compared with TSH 0·48-2·50 mIU/l, TSH 2·50-4·29 mIU/l was associated with spontaneous abortion [aOR: 1·10, 95% confidence interval (CI): 1·03-1·18], preterm birth (aOR: 1·09, 95% CI: 1·04-1·15) and operative vaginal delivery (aOR: 1·15, 95% CI: 1·09-1·21), while TSH 4·29-10 mIU/l was correlated with spontaneous abortion (aOR: 1·15, 95% CI: 1·10-1·22), stillbirth (aOR: 1·58, 95% CI: 1·10-2·28), preterm birth (aOR: 1·20, 95% CI: 1·08-1·34), caesarean section (aOR: 1·15, 95% CI: 1·10-1·22) and large for gestational age (LGA) infants (aOR: 1·12, 95% CI: 1·04-1·21).
  
  
  CONCLUSIONS
  Preconception TSH elevation was associated with increased risk of adverse pregnancy outcomes, even within the normal nonpregnant range.
authors.affiliation: Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Shi
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Huijuan
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Fengying
authors.initials: F
authors.lastname: Gong
authors.affiliation: Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Linjie
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Clinical Laboratory, Beijing Shijitan Hospital, Capital Medical University, Beijing, China.
authors.forename: Man
authors.initials: M
authors.lastname: Zhang
authors.affiliation: School of Public Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of pediatric health care, Hebei Center for Women and Children's Health, Shijiazhuang, China.
authors.forename: Chengsheng
authors.initials: C
authors.lastname: Yan
authors.affiliation: School of Software Engineering, University of Science and Technology Beijing, Beijing, China.
authors.forename: Jianqiang
authors.initials: J
authors.lastname: Li
authors.affiliation: Tsinghua National Laboratory for Information Science and Technology, Tsinghua University, Beijing, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Research Association for Women and Children's Health, Secretariat, Beijing, China.
authors.forename: Shikun
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Hui
authors.identifier: http://orcid.org/0000-0001-6512-2955
authors.initials: H
authors.lastname: Pan
mesh_terms: D000022:Abortion, Spontaneous; D000328:Adult; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D036861:Delivery, Obstetric; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis / Q000453:epidemiology*; D011256:Pregnancy Outcome / Q000453:epidemiology*; D013972:Thyrotropin / Q000097:blood*; D055815:Young Adult
chemical_list: D013972:Thyrotropin