Abstract
Factor V Leiden (FVL) and prothrombin gene mutation (PGM) are common inherited thrombophilias. Retrospective studies variably suggest a link between maternal FVL/PGM and placenta-mediated pregnancy complications including pregnancy loss, small for gestational age, pre-eclampsia and placental abruption. Prospective cohort studies provide a superior methodologic design but require larger sample sizes to detect important effects. We undertook a systematic review and a meta-analysis of prospective cohort studies to estimate the association of maternal FVL or PGM carrier status and placenta-mediated pregnancy complications. A comprehensive search strategy was run in Medline and Embase. Inclusion criteria were: (1) prospective cohort design; (2) clearly defined outcomes including one of the following: pregnancy loss, small for gestational age, pre-eclampsia or placental abruption; (3) maternal FVL or PGM carrier status; (4) sufficient data for calculation of odds ratios (ORs). We identified 322 titles, reviewed 30 articles for inclusion and exclusion criteria, and included ten studies in the meta-analysis. The odds of pregnancy loss in women with FVL (absolute risk 4.2%) was 52% higher (OR = 1.52, 95% confidence interval [CI] 1.06-2.19) as compared with women without FVL (absolute risk 3.2%). There was no significant association between FVL and pre-eclampsia (OR = 1.23, 95% CI 0.89-1.70) or between FVL and SGA (OR = 1.0, 95% CI 0.80-1.25). PGM was not associated with pre-eclampsia (OR = 1.25, 95% CI 0.79-1.99) or SGA (OR 1.25, 95% CI 0.92-1.70). Women with FVL appear to be at a small absolute increased risk of late pregnancy loss. Women with FVL and PGM appear not to be at increased risk of pre-eclampsia or birth of SGA infants. Please see later in the article for the Editors' Summary.
Highlights
Pregnancy loss, pre-eclampsia, small for gestational age (SGA) pregnancies, and placental abruption are distressing and often devastating pregnancy outcomes for women, their families, and society [1,2,3]
The search was updated in February 2010.We identified the following relevant MeSH and free terms for the exposures and outcomes by literature review and by recommendations from experts in the field (MAR, MC): Thrombophilia, activated protein C resistance (APCR), factor V Leiden (FVL), and prothrombin gene mutation (PGM) (PGM, PGV, G202110A, G1691A) for the exposure
Selection Criteria Using a structured question format to aid our literature search strategy, we reviewed all potentially relevant articles that satisfied all of the following criteria: (1) unselected pregnant women enrolled prospectively in the first or second trimester of pregnancy; (2) women investigated for FVL or PGM carrier status; and (3) reported any of the following placenta-mediated pregnancy complication outcomes: pregnancy loss, pre-eclampsia, placenta abruption, or SGA
Summary
Pre-eclampsia, small for gestational age (SGA) pregnancies, and placental abruption are distressing and often devastating pregnancy outcomes for women, their families, and society [1,2,3]. Retrospective studies variably suggest a link between maternal FVL/PGM and placenta-mediated pregnancy complications including pregnancy loss, small for gestational age, pre-eclampsia and placental abruption. We undertook a systematic review and a meta-analysis of prospective cohort studies to estimate the association of maternal FVL or PGM carrier status and placenta-mediated pregnancy complications. A better way to determine whether thrombophilia and pregnancy problems are associated is to recruit groups of women with and without thrombophilia and follow them during pregnancy to see whether they develop complications —‘‘prospective cohort studies.’’ In this study, the researchers undertake a systematic review (a search that uses predefined criteria to identify all the research on a given topic) and meta-analysis (a statistical method for combining the results of studies) of prospective cohort studies to estimate the risk of placentamediated pregnancy complications in women with FVL or PGM
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