Fetal sex and maternal risk of pre-eclampsia/eclampsia: a systematic review and meta-analysis.
BACKGROUND
A preponderance of male fetuses in pregnancies complicated by pre-eclampsia was described over 40 years ago. Since then, however, there has been conflicting evidence in the literature, with some studies supporting a male preponderance, some demonstrating no relationship with fetal sex, and others reporting increased risk in pregnancies bearing females.


OBJECTIVE
In this context, we sought to conduct a systematic review and meta-analysis to objectively evaluate the relationship between fetal sex and maternal risk of pre-eclampsia/eclampsia.


METHODS
Studies from January 1950 to April 2015 were identified from PUBMED and EMBASE.


METHODS
This systematic review and meta-analysis evaluated 22 articles reporting data on fetal sex and prevalence of pre-eclampsia/eclampsia.


METHODS
Data were extracted by two independent reviewers. Pooled estimates of the relative risk (RR) were calculated by random-effects model.


RESULTS
Male fetus was considered the exposure and prevalence of maternal pre-eclampsia/eclampsia was the outcome of interest. We identified 534 studies through electronic searches and three studies through manual searches. Twenty-two studies fulfilled the inclusion criteria, yielding data on 3 163 735 women. Pooled analyses of these studies showed no association between male fetal sex and maternal risk of pre-eclampsia/eclampsia (RR 1.01; 95% confidence interval, 95% CI 0.97-1.05); however, a subgroup analysis including only studies that evaluated the non-Asian population (n = 2 931 771 women) demonstrated that male fetal sex was associated with increased maternal risk of pre-eclampsia/eclampsia (RR 1.05; 95% CI 1.03-1.06; I2= 10%; P = 0.33).


CONCLUSIONS
Male fetal sex is associated with maternal risk of pre-eclampsia/eclampsia in the non-Asian population.


CONCLUSIONS
Fetal sex is associated with maternal risk of pre-eclampsia/eclampsia in the non-Asian population.
Department of Medicine, University of Toronto, Toronto, ON, Canada.
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D
Jaskolka
Department of Medicine, University of Toronto, Toronto, ON, Canada.|Division of Endocrinology, University of Toronto, Toronto, ON, Canada.|Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada.|Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.
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R
Retnakaran
Department of Medicine, University of Toronto, Toronto, ON, Canada.|Division of Endocrinology, University of Toronto, Toronto, ON, Canada.|Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada.|Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.
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B
Zinman
Department of Medicine, University of Toronto, Toronto, ON, Canada.|Division of Endocrinology, University of Toronto, Toronto, ON, Canada.|Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada.
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CK
Kramer
D005260:Female; D005333:Fetus; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D011247:Pregnancy; D015995:Prevalence; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D012737:Sex Factors
Eclampsia; fetal sex; meta-analysis; pre-eclampsia; systematic review