Placental findings in singleton stillbirths

Abstract

Objective: To compare placental lesions for stillbirth cases and live birth controls in a population-based study.

Methods: Pathologic 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 were 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, whereas thrombotic lesions were more common in later gestation. Inflammatory lesions were especially common in early live births.

Conclusions: Placental lesions were highly associated with stillbirth compared with 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.

Level of evidence: II.

Figure 1. Study enrollment and inclusion in placenta case-control analyses

This analysis compares placental examination results from singleton stillbirth and live birth pregnancies. A pregnancy was categorized as a stillbirth pregnancy if there were any stillbirths delivered and as a live birth pregnancy if all live births were delivered. A fetal death was defined by Apgar scores of 0 at 1 and 5 minutes and no signs of life by direct observation. Fetal deaths were classified as stillbirths if the best clinical estimate of gestational age at death was 20 or more weeks. Fetal deaths at 18 and 19 weeks without good dating were also included as stillbirths. *Review of only slides or a report from a non-SCRN pathologist, or the placenta having been discarded in labor and delivery before it could be collected by the study staff. †Mummified stillborn babies are those with Grade IV-V maceration among fragmented babies and Grade V maceration among intact babies. ‡Fragmented placenta only, n=66; mummified stillborn only, n=6; both, n=2.

Figure 2A

Acute chorioamnionitis of the placental membranes by gestational age at delivery.

Figure 2B

Acute chorioamnionitis of the chorionic plate by gestational age at delivery.

Figure 3A

Acute funisitis by gestational age at delivery.

Figure 3B

Acute vasculitis of the chorionic plate by gestational age at delivery.

Figure 4

Retroplacental hematoma by gestational age at delivery.

Figure 5

Fetal vascular thrombi of the chorionic plate by gestational age at delivery.