title: Hypothyroxinemia and TPO-antibody positivity are risk factors for premature delivery: the generation R study.
abstract: BACKGROUND
  Premature delivery is an important risk factor for child mortality and psychiatric, metabolic, and cardiovascular disease later in life. In the majority of cases, the cause of prematurity cannot be identified. Currently, it remains controversial whether abnormal maternal thyroid function during pregnancy increases the risk of premature delivery. Therefore, we investigated the relation between maternal serum thyroid parameters and the risk of premature delivery in a large prospective population-based study.
  
  
  METHODS
  Serum TSH, free T4 (FT4), T4, and TPO antibodies (TPOAbs) were determined during early pregnancy in 5971 pregnant women from the Generation R study. Data were available on maternal age, parity, smoking, socioeconomic status, ethnicity, maternal anthropometrics, and urinary iodine levels.
  
  
  RESULTS
  Of all women, 5.0% had a premature delivery (<37 weeks), 4.4% had a spontaneous premature delivery, and 1.4% had a very premature delivery (<34 weeks). High TSH levels and subclinical hypothyroidism were associated with premature delivery but not with spontaneous premature delivery. Maternal hypothyroxinemia was associated with a 2.5-fold increased risk of premature delivery, a 3.4-fold increased risk of spontaneous premature delivery, and a 3.6-fold increased risk of very premature delivery (all P < .01). TPOAb positivity was associated with a 1.7-fold increased risk of premature delivery (P = .01), a 2.1-fold increased risk of spontaneous premature delivery (P = .02), and a 2.5-fold increased risk of very premature delivery (P = .04). These effects remained similar after correction for TSH and FT4 levels.
  
  
  CONCLUSIONS
  Hypothyroxinemia and TPOAb positivity are associated with an increased risk of premature delivery. The increased risk in TPOAb-positive women seems to be independent of thyroid function.
authors.affiliation: MD, MSc, Room D 430, Department of Internal Medicine, Erasmus Medical Centre, Dr Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands. m.medici@erasmusmc.nl.
authors.forename: Tim I M
authors.initials: TI
authors.lastname: Korevaar
authors.forename: Sarah
authors.initials: S
authors.lastname: Schalekamp-Timmermans
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: H Alec
authors.initials: HA
authors.lastname: Ross
authors.forename: Herbert
authors.initials: H
authors.lastname: Hooijkaas
authors.forename: Henning
authors.initials: H
authors.lastname: Tiemeier
authors.forename: Jacoba J
authors.initials: JJ
authors.lastname: Bongers-Schokking
authors.forename: Vincent W V
authors.initials: VW
authors.lastname: Jaddoe
authors.forename: Theo J
authors.initials: TJ
authors.lastname: Visser
authors.forename: Eric A P
authors.initials: EA
authors.lastname: Steegers
authors.forename: Marco
authors.initials: M
authors.lastname: Medici
authors.forename: Robin P
authors.initials: RP
authors.lastname: Peeters
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000453:epidemiology / Q000276:immunology; D006801:Humans; D006980:Hyperthyroidism / Q000453:epidemiology / Q000276:immunology; D007037:Hypothyroidism / Q000453:epidemiology* / Q000276:immunology; D007231:Infant, Newborn; D007455:Iodine / Q000652:urine; D008297:Male; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology; D047928:Premature Birth / Q000453:epidemiology* / Q000276:immunology; D011446:Prospective Studies; D012307:Risk Factors; D013974:Thyroxine / Q000097:blood / Q000276:immunology*; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D007455:Iodine; D013974:Thyroxine