Unexplained fetal death: Are women with a history of fetal loss at higher risk?

Aims: To identify factors, including the loss of a previous pregnancy before 20 weeks gestation, which are associated withincreased risk of singleton antepartum unexplained fetal death (UFD) in Western Australia (WA) using information recordedin routine data collections.Methods: All fetal deaths in WA from 1990 to 1999 that underwent thorough post-mortem investigations were classified usingthe Perinatal Society of Australia and New Zealand Perinatal Death Classification System. All UFDs were selected as casesand unmatched controls were randomly drawn from all live births in WA occurring during the study period. Demographic andclinical information on cases and controls was obtained from the WA Midwives’ Notification System. Multivariable logisticregression was carried out to determine the independent effect of risk factors and calculate odds ratios.Results: Almost one quarter (22%) of stillbirths were unexplained. Primigravid and primiparous women with a history ofpregnancy loss before 20 weeks were at higher risk of UFD than multiparous women who had not experienced any loss.Women with a history of fetal death (after 20 weeks) had the highest risk of UFD.Conclusion: The current practice of closely monitoring pregnant women with a history of fetal loss or death should continueas this study suggests they may have a higher risk of poor obstetric outcome. Larger studies are needed to confirm theassociation between previous pregnancy loss and UFD.