title: Maternal early-pregnancy thyroid function is associated with subsequent hypertensive disorders of pregnancy: the generation R study.
abstract: BACKGROUND
  Hypertensive disorders during pregnancy are associated with a wide range of maternal and fetal complications, and only a few risk factors are known for the development of these disorders during pregnancy. Conflicting and limited data are available on the relationship between thyroid (dys)function and the risk of hypertensive disorders of pregnancy.
  
  
  OBJECTIVE
  The objective of the investigation was to study the associations between early-pregnancy thyroid dysfunction, thyroid function within the normal range, and the risk of hypertensive disorders.
  
  
  METHODS
  In early pregnancy, serum TSH, free T4 (FT4), and thyroperoxidase antibody (TPOAb) levels were determined in 5153 pregnant women. No interventions were done. The associations of thyroid function with the risk of hypertensive disorders were studied.
  
  
  METHODS
  Mean blood pressures and hypertensive disorders, including pregnancy-induced hypertension (n = 209) and preeclampsia (n = 136), were measured.
  
  
  RESULTS
  Hyperthyroid mothers had a higher risk of hypertensive disorders [odds ratio (OR) 3.40 [95% confidence interval (CI) 1.46-7.91], P = .005], which was mainly due to an increased risk of pregnancy-induced hypertension [OR 4.18 (95% CI 1.57-11.1), P = .004]. Hypothyroidism and hypothyroxinemia were not associated with hypertensive disorders. Within the normal range, the high-normal FT4 levels were associated with an increased risk of hypertensive disorders [OR 1.62 (95% CI 1.06-2.47), P = .03], which was mainly due to an increased risk of preeclampsia [OR 2.06 (95% CI 1.04-4.08), P = .04]. The TPOAb status was not associated with hypertensive disorders.
  
  
  CONCLUSIONS
  We show that biochemical hyperthyroidism and also high-normal FT4 levels during early pregnancy are associated with an increased risk of hypertensive disorders. These data demonstrate that these associations are even seen for a mild variation in thyroid function within the normal range.
authors.affiliation: The Generation R Study Group (M.M., T.I.M.K., S.S.-T., R.G., V.W.V.J.) and Departments of Internal Medicine (M.M., T.I.M.K., Y.B.d.R., W.E.V., T.J.V., R.P.P.), Epidemiology (R.G., A.H., V.W.V.J.), and Immunology (H.H.), Erasmus Medical Center, 3015 GE Rotterdam, The Netherlands; and Departments of Obstetrics and Gynecology (S.S.-T., W.V., E.A.P.S.), Pediatrics (R.G., S.M.P.F.d.M.K.-S., J.J.B.-S., H.T., V.W.V.J.), Clinical Chemistry (Y.B.d.R.), and Child and Adolescent Psychiatry (H.T.), Erasmus Medical Center, Sophia Children's Hospital, 3000 DR Rotterdam, The Netherlands.
authors.forename: Marco
authors.initials: M
authors.lastname: Medici
authors.forename: Tim I M
authors.initials: TI
authors.lastname: Korevaar
authors.forename: Sarah
authors.initials: S
authors.lastname: Schalekamp-Timmermans
authors.forename: Romy
authors.initials: R
authors.lastname: Gaillard
authors.forename: Yolanda B
authors.initials: YB
authors.lastname: de Rijke
authors.forename: W Edward
authors.initials: WE
authors.lastname: Visser
authors.forename: Willy
authors.initials: W
authors.lastname: Visser
authors.forename: Sabine M P F
authors.initials: SM
authors.lastname: de Muinck Keizer-Schrama
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.forename: Herbert
authors.initials: H
authors.lastname: Hooijkaas
authors.forename: Jacoba J
authors.initials: JJ
authors.lastname: Bongers-Schokking
authors.forename: Henning
authors.initials: H
authors.lastname: Tiemeier
authors.forename: Vincent W V
authors.initials: VW
authors.lastname: Jaddoe
authors.forename: Theo J
authors.initials: TJ
authors.lastname: Visser
authors.forename: Robin P
authors.initials: RP
authors.lastname: Peeters
authors.forename: Eric A P
authors.initials: EA
authors.lastname: Steegers
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000503:physiopathology*; D007455:Iodine / Q000097:blood / Q000652:urine; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D018570:Risk Assessment; D013959:Thyroid Diseases / Q000503:physiopathology*; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000503:physiopathology*; D013967:Thyroiditis, Autoimmune / Q000150:complications
chemical_list: D007455:Iodine