Incidence and risk factors for amniotic-fluid embolism.
OBJECTIVE
To estimate the incidence of amniotic-fluid embolism and to describe risk factors, management, and outcomes.


METHODS
Through a population-based cohort study and nested case-control analysis, using the UK Obstetric Surveillance System, we identified 60 women in the United Kingdom who had an amniotic-fluid embolism between February 2005 and February 2009 and 1,227 women for the control group. We investigated the potential factors underlying amniotic-fluid embolism using an exploratory logistic regression analysis to estimate odds ratios (ORs) and 95% confidence intervals (CIs).


RESULTS
Sixty cases of amniotic-fluid embolism were reported, an estimated incidence of 2.0 per 100,000 deliveries (95% CI 1.5-2.5). Amniotic-fluid embolism occurrence was significantly associated with induction of labor (adjusted OR 3.86, 95% CI 2.04-7.31) and multiple pregnancy (adjusted OR 10.9, 95% CI 2.81-42.7); an increased risk also was noted in older, ethnic-minority women (adjusted OR 9.85, 95% CI 3.57-27.2). Cesarean delivery was associated with postnatal amniotic-fluid embolism (adjusted OR 8.84, 95% CI 3.70-21.1). Twelve women died (case fatality 20%, 95% CI 11-32%); 5 of 37 newborns of women with antenatal amniotic-fluid embolism died (perinatal mortality 135 per 1,000 total births, 95% CI 45-288). Women who died were significantly more likely to be from ethnic-minority groups (adjusted OR 11.8, 95% CI 1.40-99.5).


CONCLUSIONS
High-quality supportive care can result in good maternal outcomes after amniotic-fluid embolism. Clinicians should consider both the risks and benefits of induction and cesarean delivery because more restricted use may result in a decrease in the number of women suffering a potentially fatal amniotic-fluid embolism. The observed increased risk of fatality in ethnic-minority women may be associated with differences in underlying medical conditions or access to care, and clinicians should that ensure appropriate services are provided to minimize this risk.
Knight
Marian
M
From the National Perinatal Epidemiology Unit, University of Oxford, Oxford, United Kingdom; and the Bradford Hospitals NHS Trust, Bradford, United Kingdom.
Tuffnell
Derek
D
Brocklehurst
Peter
P
Spark
Patsy
P
Kurinczuk
Jennifer J
JJ
D000328:Adult; D002585:Cesarean Section / Q000706:statistics & numerical data; D004619:Embolism, Amniotic Fluid / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality / Q000628:therapy; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D016015:Logistic Models; D011159:Population Surveillance; D011247:Pregnancy; D011256:Pregnancy Outcome; D012307:Risk Factors; D006113:United Kingdom / Q000453:epidemiology
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