OBJECTIVE: To estimate the risk of stillbirth among pregnancies complicated by a major isolated congenital anomaly detected by antenatal ultrasonography and the influence of incidental growth restriction.
METHODS: A retrospective cohort study of all consecutive singleton pregnancies undergoing routine anatomic survey between 1990 and 2009 was performed. Stillbirth rates among fetuses with an ultrasound-detected isolated major congenital anomaly were compared with fetuses without major anomalies. Stillbirth rates were calculated per 1,000 ongoing pregnancies. Exclusion criteria included delivery before 24 weeks of gestation, multiple fetal anomalies, minor anomalies, and chromosomal abnormalities. Analyses were stratified by gestational age at delivery (before 32 weeks compared with 32 weeks of gestation or after) and birth weight less than the 10th percentile. We adjusted for confounders using logistic regression.
RESULTS: Among 65,308 singleton pregnancies delivered at 24 weeks of gestation or after, 873 pregnancies with an isolated major congenital anomaly (1.3%) were identified. The overall stillbirth rate among fetuses with a major anomaly was 55 per 1,000 compared with 4 per 1,000 in nonanomalous fetuses (adjusted odds ratio [OR] 15.17, 95% confidence interval [CI] 11.03–20.86). Stillbirth risk in anomalous fetuses was similar before 32 weeks of gestation (26/1,000) and 32 weeks of gestation or after (31/1,000). Among growth-restricted fetuses, the stillbirth rate increased among anomalous (127/1,000) and nonanomalous fetuses (18/1,000), and congenital anomalies remained associated with higher rates of stillbirth (adjusted OR 8.20, 95% CI 5.27–12.74).
CONCLUSION: The stillbirth rate is increased in anomalous fetuses regardless of incidental growth restriction. These risks can assist practitioners in designing care plans for anomalous fetuses who have elevated and competing risks of stillbirth and neonatal death.
LEVEL OF EVIDENCE: II
The risk of stillbirth is increased in fetuses with ultrasound-detected isolated congenital anomalies, independent of incidental growth restriction.
Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
Corresponding author: Heather A. Frey, MD, Department of Obstetrics and Gynecology, Washington University in St Louis, Campus Box 8064, 660 S Euclid Avenue, St Louis, MO 63110; e-mail: FreyH@wudosis.wustl.edu.
Dr. Frey is supported by a training grant from the Eunice Kennedy Shriver National Institute of Child Health and Human Development T32 grant (5 T32 HD055172-05), and this publication was supported by the Washington University CTSA grant (UL1 TR000448).
Presented as a poster at the 33rd Annual Meeting of the Society of Maternal Fetal Medicine, February 11–16, 2013, San Francisco, California.
Financial Disclosure The authors did not report any potential conflicts of interest.