Elsevier

Obstetrics & Gynecology

Volume 95, Issue 2, February 2000, Pages 215-221
Obstetrics & Gynecology

Original Articles
Determinants of unexplained antepartum fetal deaths

Presented at the 45th Annual Clinical Meeting of the American College of Obstetricians and Gynecologists, Las Vegas, Nevada, April 1997.
https://doi.org/10.1016/S0029-7844(99)00536-0Get rights and content

Abstract

Objective: To assess fetal, maternal, and pregnancy-related determinants of unexplained antepartum fetal death.

Methods: We conducted a hospital-based cohort study of 84,294 births weighing 500 g or more from 1961–1974 and 1978–1996. Unexplained fetal deaths were defined as fetal deaths occurring before labor without evidence of significant fetal, maternal, or placental pathology.

Results: One hundred ninety-six unexplained antepartum fetal deaths accounted for 27.2% of 721 total fetal deaths. Two thirds of the unexplained fetal deaths occurred after 35 weeks’ gestation. The following factors were independently associated with unexplained fetal death: maternal prepregnancy weight greater than 68 kg (adjusted odds ratio [OR] 2.9; 95% confidence interval [CI] 1.85, 4.68), birth weight ratio (defined as ratio of birth weight to mean weight for gestational age) between 0.75 and 0.85 (OR 2.77; 95% CI 1.48, 5.18) or over 1.15 (OR 2.36; 95% CI 1.26, 4.44), fewer than four antenatal visits in women whose fetuses died at 37 weeks or later (OR 2.21; 95% CI 1.08, 4.52), primiparity (OR 1.74; 95% CI 1.26, 2.40), parity of three or more (OR 2.01; 95% CI 1.26, 3.20), low socioeconomic status (OR 1.59; 95% CI 1.14, 2.22), cord loops (OR 1.75; 95% CI 1.04, 2.97) and, for the 1978–1996 period only, maternal age 40 years or more (OR 3.69; 95% CI 1.28, 10.58). Trimester of first antenatal visit, low maternal weight, postdate pregnancy, fetal-to-placental weight ratio, fetal sex, previous fetal death, previous abortion, cigarette smoking, and alcohol use were not significantly associated with unexplained fetal death.

Conclusion: In this study, we identified several factors associated with an increased risk of unexplained fetal death.

Section snippets

Methods

The study cohort comprised infants delivered at the Royal Victoria Hospital in Montreal between 1961 and 1996 excluding those delivered in 1975–1977, for whom computerized data were not available. This teaching hospital serves a socioeconomically and ethnically diverse population. During those years, information on all deliveries was entered into a computerized data bank2 maintained by one of the authors (RHU). Of the 105,201 total births of 500 g or more, there were 196 unexplained fetal

Results

During the years 1961–1974 and 1978–1996, there were 721 fetal deaths among the 105,201 total births of 500 g or more (7.1 per 1000). Of these fetal deaths, 196 (27.2% or 1.9 per 1000 total births) occurred antepartum and could not be explained. Although the rate of fetal deaths, including unexplained fetal deaths, has decreased over the four decades, the proportion that is unexplained has remained fairly constant, between 20.0% and 30.2%. The rate of unexplained fetal deaths per 1000 total

Discussion

The sudden death of a fetus in utero for no apparent reason is a tragedy, particularly when it occurs shortly before the expected delivery date. At our institution, unexplained antepartum fetal deaths currently comprise 25% of all fetal deaths; this proportion has remained fairly constant despite advances in antenatal diagnostic instruments. However, these deaths have received little attention in the literature.3, 4, 5

Yudkin et al3 reported an institutional analysis of 63 unexplained

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