Stillbirth, hypertensive disorders of pregnancy, and placental pathology

Abstract

Introduction: Stillbirth, preeclampsia, and gestational hypertension (PE/GH) have similar clinical risk factors and redundant placental pathology. We aim to discern if stillbirth with PE/GH has a particular phenotype by comparing stillbirths with and without PE/GH.

Methods: Secondary analysis of the Stillbirth Collaborative Research Network, a population-based cohort study of all stillbirths and a sample of live births from 2006 to 2008 in five catchment areas. We compared placental pathology between stillbirths and with and without PE/GH, stratified by term or preterm. We also compared placental pathology between stillbirths and live births with PE/GH.

Results: 79/518 stillbirths and 140/1200 live births had PE/GH. Amongst preterm stillbirths, there was higher feto-placental ratio in PE/GH pregnancies (OR 1.24 [1.11, 1.37] per unit increase), and there were more parenchymal infarctions (OR 5.77 [3.18, 10.47]). Among PE/GH pregnancies, stillbirths had increased maternal and fetal vascular lesions, including retroplacental hematoma, parenchymal infarction, fibrin deposition, fetal vascular thrombi, and avascular villi.

Discussion: Stillbirth pregnancies are overwhelmingly associated with placental lesions. Parenchymal infarctions are more common in PE/GH preterm stillbirths, but there is significant overlap in lesions found in stillbirths and PE/GH.

Keywords: Placental pathology; Preeclampsia; Stillbirth.

Figure 1

This analysis compares placental examination results for subgroups of singleton stillbirth and live birth pregnancies, with particular focus on PE/GH. 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. * A placenta examination was deemed inadequate for this analysis if conducted by a pathologist other than those trained to follow the Stillbirth Collaborative Research Network placental exam protocol or if only slides were available for review. Mummified stillborn fetuses were those with Grade IV-V maceration among fragmented fetuses and Grade V maceration among intact fetuses. Two stillborn fetuses were both fragmented and macerated.

Figure 2

Hematoxylin and eosin micrographs of placental chorionic villi, 100× magnification. A) Normal term; B) distal villous hypoplasia; C) immature distal villi; D) massive perivillous fibrin deposition.