Background Genetic abnormalities have been associated with 6 to 13% of stillbirths, but the true prevalence may be higher. Unlike karyotype analysis, microarray analysis does not require live cells, and it detects small deletions and duplications called copy-number variants. Methods The Stillbirth Collaborative Research Network conducted a population-based study of stillbirth in five geographic catchment areas. Standardized postmortem examinations and karyotype analyses were performed. A single-nucleotide polymorphism array was used to detect copy-number variants of at least 500 kb in placental or fetal tissue. Variants that were not identified in any of three databases of apparently unaffected persons were then classified into three groups: probably benign, clinical significance unknown, or pathogenic. We compared the results of karyotype and microarray analyses of samples obtained after delivery. Results In our analysis of samples from 532 stillbirths, microarray analysis yielded results more often than did karyotype analysis (87.4% vs. 70.5%, P<0.001) and provided better detection of genetic abnormalities (aneuploidy or pathogenic copy-number variants, 8.3% vs. 5.8%; P = 0.007). Microarray analysis also identified more genetic abnormalities among 443 antepartum stillbirths (8.8% vs. 6.5%, P = 0.02) and 67 stillbirths with congenital anomalies (29.9% vs. 19.4%, P = 0.008). As compared with karyotype analysis, microarray analysis provided a relative increase in the diagnosis of genetic abnormalities of 41.9% in all stillbirths, 34.5% in antepartum stillbirths, and 53.8% in stillbirths with anomalies. Conclusions Microarray analysis is more likely than karyotype analysis to provide a genetic diagnosis, primarily because of its success with nonviable tissue, and is especially valuable in analyses of stillbirths with congenital anomalies or in cases in which karyotype results cannot be obtained. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development.)

Objective To compare placental lesions for stillbirth cases and live birth controls in a population-based study. Methods Pathological examinations were performed on placentas from singleton pregnancies using a standard protocol. Data were analyzed overall and within gestational age groups at delivery. Results Placentas from 518 stillbirths and 1,200 live births were studied. Single umbilical artery was present in 7.7% of stillbirths and 1.7% of live births, velamentous cord insertion was present in 5% of stillbirths and 1.1% of live births, diffuse terminal villous immaturity was present in 10.3% of stillbirths and 2.3% of live births, inflammation (eg, acute chorioamnionitis of placental membranes) was present in 30.4% of stillbirths and 12% of live births, vascular degenerative changes in chorionic plate was present in 55.7% of stillbirths and 0.5% of live births, retroplacental hematoma was present in 23.8% of stillbirths and 4.2% of live births, intraparenchymal thrombi was present in 19.7% of stillbirths and 13.3% of live births, parenchymal infarction was present in 10.9% of stillbirths and 4.4% of live births, fibrin deposition was present in 9.2% of stillbirths and 1.5% of live births, fetal vascular thrombi was present in 23% of stillbirths and 7% of live births, avascular villi was present in 7.6% of stillbirths and 2.0% of live births, and hydrops was present in 6.4% of stillbirths and 1.0% of live births. Among stillbirths, inflammation and retroplacental hematoma were more common in placentas from early deliveries, while thrombotic lesions were more common in later gestation. Inflammatory lesions were especially common in early live births. Conclusion Placental lesions were highly associated with stillbirth compared to live births. All lesions associated with stillbirth were found in live births but often with variations by gestational age at delivery. Knowledge of lesion prevalence within gestational age groups in both stillbirths and live birth controls contributes to an understanding of the association between placental abnormality and stillbirth. Précis Placental lesions are highly associated with stillbirth compared to live births but all lesions associated with stillbirths are found in live births; prevalence varies by gestational age at delivery.