title: Treatment of thyroid disorders before conception and in early pregnancy: a systematic review.
abstract: BACKGROUND
  Thyroid disorders are associated with pregnancy complications. Universal screening is currently not recommended because of a lack of evidence on the effectiveness of treatment. Women with hyperthyroidism and hypothyroidism evidently require treatment but this is less clear for women with subclinical hypothyroidism and thyroid autoimmunity. Therefore, we conducted a systematic review to provide a comprehensive overview on the available treatment interventions.
  
  
  METHODS
  Relevant studies were identified by searching Medline, EMBASE and Cochrane Controlled Trials Register, published until December 2011.
  
  
  RESULTS
  From a total of 7334 primary selected titles, 22 articles were included for the systematic review and 11 were appropriate for meta-analyses. Eight studies reported on hyperthyroidism. Propylthiouracil (PTU) and methimazole reduce the risk for preterm delivery [risk ratio (RR): 0.23, confidence interval (CI): 0.1-0.52], pre-eclampsia (RR: 0.23, CI: 0.06-0.89) and low birthweight (RR: 0.38, CI: 0.22-0.66). The nine studies that reported on clinical hypothyroidism showed that levothyroxine is effective in reducing the risk for miscarriage (RR: 0.19, CI: 0.08-0.39) and preterm delivery (RR: 0.41, CI: 0.24-0.68). For treatment of subclinical hypothyroidism, current evidence is insufficient. The five studies available on thyroid autoimmunity showed a not significant reduction in miscarriage (RR: 0.58, CI: 0.32-1.06), but significant reduction in preterm birth by treatment with levothyoxine (RR: 0.31, CI: 0.11-0.90).
  
  
  CONCLUSIONS
  For hyperthyroidism, methimazole and PTU are effective in preventing pregnancy complications. For clinical hypothyroidism, treatment with levothyroxine is recommended. For subclinical hypothyroidism and thyroid autoimmunity, evidence is insufficient to recommend treatment with levothyroxine. The overall lack of evidence precludes a recommendation for universal screening and is only justified in a research setting.
authors.affiliation: Academic Medical Centre, Centre for Reproductive Medicine, Department of Obstetrics and Gynaecology, Q3-120, Meibergdreef 9, 1100 DD Amsterdam,  The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Vissenberg
authors.forename: E
authors.initials: E
authors.lastname: van den Boogaard
authors.forename: M
authors.initials: M
authors.lastname: van Wely
authors.forename: J A
authors.initials: JA
authors.lastname: van der Post
authors.forename: E
authors.initials: E
authors.lastname: Fliers
authors.forename: P H
authors.initials: PH
authors.lastname: Bisschop
authors.forename: M
authors.initials: M
authors.lastname: Goddijn
mesh_terms: D000022:Abortion, Spontaneous / Q000517:prevention & control; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000188:drug therapy*; D007037:Hypothyroidism / Q000188:drug therapy*; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D011225:Pre-Eclampsia / Q000517:prevention & control; D016742:Preconception Care; D011247:Pregnancy; D011248:Pregnancy Complications / Q000188:drug therapy*; D047928:Premature Birth / Q000517:prevention & control