title: Inter-pregnancy interval and risk of recurrent pre-eclampsia: systematic review and meta-analysis.
abstract: BACKGROUND
  Women with a history of pre-eclampsia have a higher risk of developing pre-eclampsia in subsequent pregnancies. However, the role of the inter-pregnancy interval on this association is unclear.
  
  
  OBJECTIVE
  To explore the effect of inter-pregnancy interval on the risk of recurrent pre-eclampsia or eclampia.
  
  
  METHODS
  MEDLINE, EMBASE and LILACS were searched (inception to July 2015).
  
  
  METHODS
  Cohort studies assessing the risk of recurrent pre-eclampsia in the immediate subsequent pregnancy according to different birth intervals.
  
  
  METHODS
  Two reviewers independently performed screening, data extraction, methodological and quality assessment. Meta-analysis of adjusted odds ratios (aOR) with 95 % confidence intervals (CI) was used to measure the association between various interval lengths and recurrent pre-eclampsia or eclampsia.
  
  
  RESULTS
  We identified 1769 articles and finally included four studies with a total of 77,561 women. The meta-analysis of two studies showed that compared to inter-pregnancy intervals of 2-4 years, the aOR for recurrent pre-eclampsia was 1.01 [95 % CI 0.95 to 1.07, I(2) 0 %] with intervals of less than 2 years and 1.10 [95 % CI 1.02 to 1.19, I(2) 0 %] with intervals longer than 4 years.
  
  
  CONCLUSIONS
  Compared to inter-pregnancy intervals of 2 to 4 years, shorter intervals are not associated with an increased risk of recurrent pre-eclampsia but longer intervals appear to increase the risk. The results of this review should be interpreted with caution as included studies are observational and thus subject to possible confounding factors.
authors.affiliation: Department of Mother and Child Health Research, Institute for Clinical Effectiveness and Health Policy (IECS), Emilio Ravignani 2024, Buenos Aires, Argentina. gcormick@iecs.org.ar.|Centro de Investigaciones en Epidemiología y Salud Pública (CIESP, CONICET-IECS), Buenos Aires, Argentina. gcormick@iecs.org.ar.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Cormick
authors.affiliation: Department of Reproductive Health and Research, World Health Organization, Avenue Appia 20, Geneva, 1211, Switzerland.
authors.forename: Ana Pilar
authors.initials: AP
authors.lastname: Betrán
authors.affiliation: Centro de Investigaciones en Epidemiología y Salud Pública (CIESP, CONICET-IECS), Buenos Aires, Argentina.|Argentine Cochrane Branch, Institute for Clinical Effectiveness and Health Policy (IECS), Emilio Ravignani 2024, Buenos Aires, Argentina.
authors.forename: Agustín
authors.initials: A
authors.lastname: Ciapponi
authors.affiliation: Department of Obstetrics and Gynaecology, Stellenbosch University and Tygerberg Hospital, Cape Town, South Africa.
authors.forename: David R
authors.initials: DR
authors.lastname: Hall
authors.affiliation: Effective Care Research Unit, Eastern Cape Department of Health, University of the Witwatersrand, University of Fort Hare, Walter Sisulu University, East London, South Africa.
authors.forename: G Justus
authors.initials: GJ
authors.lastname: Hofmeyr
mesh_terms: D000328:Adult; D001721:Birth Intervals; D015331:Cohort Studies; D016208:Databases, Factual; D004461:Eclampsia / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D057286:Electronic Health Records; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D008297:Male; D064887:Observational Studies as Topic; D011225:Pre-Eclampsia / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D011247:Pregnancy; D012008:Recurrence; D012306:Risk; D055502:Secondary Prevention; D012747:Sexual Partners
keywords: Birth interval; Birth spacing; Eclampsia; Hypertensive disorders of pregnancy; Inter-pregnancy interval; Meta-analysis; Pre-eclampsia; Recurrence; Systematic review