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The association of stillbirth with placental abnormalities in growth-restricted and normally grown fetuses.

ABSTRACT: BACKGROUND:Stillbirth, defined as foetal death ?20 weeks' gestation, is associated with poor foetal growth and is often attributed to placental abnormalities, which are also associated with poor foetal growth. Evaluating inter-relationships between placental abnormalities, poor foetal growth, and stillbirth may improve our understanding of the underlying mechanisms for some causes of stillbirth. OBJECTIVE:Our primary objective was to determine whether poor foetal growth, operationalised as small for gestational age (SGA), mediates the relationship between placental abnormalities and stillbirth. METHODS:We used data from the Stillbirth Collaborative Research Network study, a population-based case-control study conducted from 2006-2008. Our analysis included 266 stillbirths and 1135 livebirths. We evaluated associations of stillbirth with five types of placental characteristics (developmental disorders, maternal and foetal inflammatory responses, and maternal and foetal circulatory disorders) and examined mediation of these relationships by SGA. We also assessed exposure-mediator interaction. Models were adjusted for maternal age, race/ethnicity, education, body mass index, parity, and smoking status. RESULTS:All five placental abnormalities were more prevalent in cases than controls. After adjustment for potential confounders, maternal inflammatory response (odds ratio [OR] 2.58, 95% confidence interval [CI] 1.77, 3.75), maternal circulatory disorders OR 4.14, 95% CI 2.93, 5.84, and foetal circulatory disorders OR 4.58, 95% CI 3.11, 6.74 were strongly associated with stillbirth, and the relationships did not appear to be mediated by SGA status. Associations for developmental disorders and foetal inflammatory response diverged for SGA and non-SGA births, and strong associations were only observed when SGA was not present. CONCLUSIONS:Foetal growth did not mediate the relationships between placental abnormalities and stillbirth. The relationships of stillbirth with maternal and foetal circulatory disorders and maternal inflammatory response appear to be independent of poor foetal growth, while developmental disorders and foetal inflammatory response likely interact with foetal growth to affect stillbirth risk.

SUBMITTER: Freedman AA

PROVIDER: S-EPMC6662619 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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The association of stillbirth with placental abnormalities in growth-restricted and normally grown fetuses.

Freedman Alexa A AA Silver Robert M RM Gibbins Karen J KJ Hogue Carol J CJ Goldenberg Robert L RL Dudley Donald J DJ Pinar Halit H Drews-Botsch Carolyn C

Paediatric and perinatal epidemiology 20190701 4

<h4>Background</h4>Stillbirth, defined as foetal death ≥20 weeks' gestation, is associated with poor foetal growth and is often attributed to placental abnormalities, which are also associated with poor foetal growth. Evaluating inter-relationships between placental abnormalities, poor foetal growth, and stillbirth may improve our understanding of the underlying mechanisms for some causes of stillbirth.<h4>Objective</h4>Our primary objective was to determine whether poor foetal growth, operation ...[more]

PMID: 31347723

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Project description:BackgroundWorldwide, stillbirth is one of the leading causes of death. Altered fetal growth and placental abnormalities are the strongest and most prevalent known risk factors for stillbirth. The aim of this study was to identify patterns of association between placental abnormalities, fetal growth, and stillbirth.Methods and findingsPopulation-based case-control study of all stillbirths and a representative sample of live births in 59 hospitals in 5 geographic areas in the U.S. Fetal growth abnormalities were categorized as small (<10th percentile) and large (>90th percentile) for gestational age at death (stillbirth) or delivery (live birth) using a published algorithm. Placental examination by perinatal pathologists was performed using a standardized protocol. Data were weighted to account for the sampling design. Among 319 singleton stillbirths and 1119 singleton live births at ?24 weeks at death or delivery respectively, 25 placental findings were investigated. Fifteen findings were significantly associated with stillbirth. Ten of the 15 were also associated with fetal growth abnormalities (single umbilical artery; velamentous insertion; terminal villous immaturity; retroplacental hematoma; parenchymal infarction; intraparenchymal thrombus; avascular villi; placental edema; placental weight; ratio birth weight/placental weight) while 5 of the 15 associated with stillbirth were not associated with fetal growth abnormalities (acute chorioamnionitis of placental membranes; acute chorioamionitis of chorionic plate; chorionic plate vascular degenerative changes; perivillous, intervillous fibrin, fibrinoid deposition; fetal vascular thrombi in the chorionic plate). Five patterns were observed: placental findings associated with (1) stillbirth but not fetal growth abnormalities; (2) fetal growth abnormalities in stillbirths only; (3) fetal growth abnormalities in live births only; (4) fetal growth abnormalities in stillbirths and live births in a similar manner; (5) a different pattern of fetal growth abnormalities in stillbirths and live births.ConclusionsThe patterns of association between placental abnormalities, fetal growth, and stillbirth provide insights into the mechanism of impaired placental function and stillbirth. They also suggest implications for clinical care, especially for placental findings amenable to prenatal diagnosis using ultrasound that may be associated with term stillbirths.

Project description:ObjectiveUmbilical cord abnormalities are commonly cited as a cause of stillbirth, but details regarding these stillbirths are rare. Our objective was to characterize stillbirths associated with umbilical cord abnormalities using rigorous criteria and to examine associated risk factors.MethodsThe Stillbirth Collaborative Research Network conducted a case-control study of stillbirth and live births from 2006 to 2008. We analyzed stillbirths that underwent complete fetal and placental evaluations and cause of death analysis using the INCODE (Initial Causes of Fetal Death) classification system. Umbilical cord abnormality was defined as cord entrapment (defined as nuchal, body, shoulder cord accompanied by evidence of cord occlusion on pathologic examination); knots, torsions, or strictures with thrombi, or other obstruction by pathologic examination; cord prolapse; vasa previa; and compromised fetal microcirculation, which is defined as a histopathologic finding that represents objective evidence of vascular obstruction and can be used to indirectly confirm umbilical cord abnormalities when suspected as a cause for stillbirth. We compared demographic and clinical factors between women with stillbirths associated with umbilical cord abnormalities and those associated with other causes, as well as with live births. Secondarily, we analyzed the subset of pregnancies with a low umbilical cord index.ResultsOf 496 stillbirths with complete cause of death analysis by INCODE, 94 (19%, 95% CI 16-23%) were associated with umbilical cord abnormality. Forty-five (48%) had compromised fetal microcirculation, 27 (29%) had cord entrapment, 26 (27%) knots, torsions, or stricture, and five (5%) had cord prolapse. No cases of vasa previa occurred. With few exceptions, maternal characteristics were similar between umbilical cord abnormality stillbirths and non-umbilical cord abnormality stillbirths and between umbilical cord abnormality stillbirths and live births, including among a subanalysis of those with hypo-coiled umbilical cords.ConclusionUmbilical cord abnormalities are an important risk factor for stillbirth, accounting for 19% of cases, even when using rigorous criteria. Few specific maternal and clinical characteristics were associated with risk.

Dataset Information

The association of stillbirth with placental abnormalities in growth-restricted and normally grown fetuses.

Publications

The association of stillbirth with placental abnormalities in growth-restricted and normally grown fetuses.

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