Histopathological examination of the placenta in twin pregnancies

Outcomes of dichorionic twin pregnancies with fused versus separate placentas

PURPOSE

In a certain proportion of dichorionic twin pregnancies, the two placentas are fused. The clinical significance of this finding remains unclear. Our objective was to compare outcomes of dichorionic twin pregnancies with fused versus separate placentas as determined on first-trimester ultrasound.

METHODS

Retrospective study of patients with dichorionic twins followed at a tertiary center between 2014 and 2022. The co-primary outcomes were fetal growth restriction and preeclampsia. Associations between fused placentas and the study outcomes were estimated using multivariable Poisson regression and were reported as adjusted relative risk (aRR) with a 95%-confidence interval (CI).

RESULTS

Of the 328 eligible patients, 175 (53.4%) and 153 (46.6%) had fused and separate placentas, respectively. Compared with pregnancies with separate placentas, patients with fused placentas had a lower risk of preeclampsia [aRR 0.48 (95%-CI 0.24-0.97)] but a higher risk of fetal growth restriction [aRR 1.23 (95%-CI 1.02-1.48)] and admission to the neonatal intensive care unit [aRR 1.31 (95%-CI 1.01-1.71)]. In addition, pregnancies with fused placentas were more likely to have a total placental weight below the 10th percentile than those with separate placentas [aRR 1.93 (95%-CI 1.16-3.21)].

DISCUSSION

Dichorionic twin pregnancies with fused placentas have a lower risk of preeclampsia but are more likely to be complicated by fetal growth restriction, observations that may be attributed to the lower total placentas mass in pregnancies with fused compared with separate placentas. Fused placentas can be used as a potential biomarker for the prediction of pregnancy complications in dichorionic twin pregnancies.

Monochorionic Twins: TTTS, TAPS, and Selective Fetal Growth Restriction

With an increasing incidence of twin gestations, understanding the inherent risks associated with these pregnancies is essential in modern obstetrics. The unique differences in placentation in monochorionic twins leads to unique complications, including twin-to-twin transfusion syndrome, the twin anemia-polycythemia sequence, and selective fetal growth restriction. Not only does the understanding of the monochorionic placenta lead to an understanding of the pathophysiology of the complications of monochorionic twins, but it also has led to the development of highly effective directed fetal therapy via fetoscopic laser coagulation used in twin-to-twin transfusion syndrome.

Abnormal umbilical cord insertion and birth weight discordancy in monochorionic diamniotic twins: A retrospective study

To investigate the relationship between abnormal umbilical cord insertion and birthweight discordance in monochorionic diamnionic (MCDA) twins. A total of 137 pairs of MCDAs were retrospectively analyzed who delivered and survived in Hangzhou Women's Hospital from January 2016 to December 2021. According to different insertion methods, they were divided into normal cord insertion group (n = 57), marginal cord insertion (MCI) group (n = 34) and velamentous cord insertion (VCI) group (n = 46). The correlation was analyzed between different insertion methods of umbilical cord and the discordant birth weight of MCDAs. The gestational age of delivery with velamentous cord insertion was significantly earlier than those with normal and marginal insertion (P < .05). There were significant differences in birthweight between large fetus (F1) and small fetus (F2) with different umbilical insertion methods (P < .05). The birthweight of F1 and F2 in normal insertion group was significantly higher than those in MCI and VCI group (P < .05). Logistic regression analysis showed that VCI was significantly associated with birth weight in F1/F2, birthweight discordance ≥ 20%, and birthweight discordance ≥ 25%, however MCI and VCI were not an independent factor for discordance in birthweight of MCDAs (P > .05). Umbilical cord insertion method can lead to inconsistency in birthweight of MCDA twins, however they were not an independent factor for discordance in birthweight.

Isolated fetal neural tube defects associate with increased risk of placental pathology: Evidence from the Collaborative Perinatal Project

INTRODUCTION

Neural tube defects (NTDs) are amongst the most common congenital anomalies and are associated with significant postnatal morbidity, but also with a higher incidence of low birthweight and fetal growth restriction. Despite the placenta being a critical determinant of fetal growth, placental development has not been extensively studied in fetuses with NTDs.

METHODS

We performed a matched case-cohort study using data from the Collaborative Perinatal Project to assess the risk of placental pathology in pregnancies with an isolated fetal NTD (cases; n = 74) compared to those without any congenital anomalies (controls; n = 148). We hypothesised that cases would be at an increased risk of placental pathology compared to controls. Data were analysed using adjusted generalized linear and nominal logistic regression models. Results are presented as adjusted β or adjusted odds ratio (aOR; 95% confidence interval).

RESULTS

Cases had lower placental weight (β = -22.2 g [-37.8 to -6.6]), surface area (β = -9.6 cm² [-18.3 to -1.0]) and birth length z-scores (β = -0.4 [-0.7 to -0.001]) compared to controls. Cases were more likely to have a single umbilical artery (vs. two; 6 [8.1%] vs. 1 [0.7%]; aOR = 301 [52.6-1726]), placental hypermaturity (9 [12.2%] vs. 5 [3.4%]; aOR = 6.8 [3.1-14.7]), many (vs. few) Hofbauer cells (9 [12.2%] vs. 7 [4.7%]; aOR = 3.02 [1.2-7.3]), and stromal fibrosis (9 [12.2%] vs. 10 [6.8%]; aOR = 3.0 [1.4-6.3]) in placental terminal villi compared to controls.

CONCLUSIONS

Fetuses with isolated NTDs may be at increased risk of placental pathology, which could be contributing to poor fetal growth in these pregnancies and subsequent postnatal morbidities.

Discordant Clinical Outcomes in a Monozygotic Dichorionic-Diamniotic Twin Pregnancy with Probable Zika Virus Exposure. Case Report

Prenatal exposure to Zika virus (ZIKV) is associated with congenital anomalies of the brain and the eye and neurodevelopmental sequelae. The spectrum of disease outcomes may relate to timing of infection as well as genetic and environmental factors. Congenital infections occurring in twin pregnancies can inform the clinical spectrum of these conditions and provide unique information regarding timing of infection and in utero environment with disease pathophysiology. Herein, we report a monozygotic dichorionic-diamniotic twin pregnancy with probable prenatal ZIKV exposure identified through the Colombian ZIKV disease surveillance system. Multidisciplinary clinical evaluations were provided to the twins during their first three years of life through a national program for children with in utero ZIKV exposure. Laboratory evidence of congenital infection as well as microcephaly, brain, eye, and neurodevelopmental compromise related to prenatal ZIKV infection were identified in only one infant of the twin pregnancy. This is the first report of monozygotic twins discordant for Zika-associated birth defects. The evaluation of the pathophysiology of discordance in disease outcome for congenital infections in twin pregnancies may lead to a better understanding of potential complex environmental and genetic interactions between the mother, her offspring, and an infectious exposure.

The spectrum of brain malformations and disruptions in twins

Twins have an increased risk for congenital malformations and disruptions, including defects in brain morphogenesis. We analyzed data on brain imaging, zygosity, sex, and fetal demise in 56 proband twins and 7 less affected co-twins with abnormal brain imaging and compared them to population-based data and to a literature series. We separated our series into malformations of cortical development (MCD, N = 39), cerebellar malformations without MCD (N = 13), and brain disruptions (N = 11). The MCD group included 37/39 (95%) with polymicrogyria (PMG), 8/39 (21%) with pia-ependymal clefts (schizencephaly), and 15/39 (38%) with periventricular nodular heterotopia (PNH) including 2 with PNH but not PMG. Cerebellar malformations were found in 19 individuals including 13 with a cerebellar malformation only and another 6 with cerebellar malformation and MCD. The pattern varied from diffuse cerebellar hypoplasia to classic Dandy-Walker malformation. Brain disruptions were seen in 11 individuals with hydranencephaly, porencephaly, or white matter loss without cysts. Our series included an expected statistically significant excess of monozygotic (MZ) twin pairs (22/41 MZ, 54%) compared to population data (482/1448 MZ, 33.3%; p = .0110), and an unexpected statistically significant excess of dizygotic (DZ) twins (19/41, 46%) compared to the literature cohort (1/46 DZ, 2%; p < .0001. Recurrent association with twin-twin transfusion syndrome, intrauterine growth retardation, and other prenatal factors support disruption of vascular perfusion as the most likely unifying cause.

Placental Anatomy and Function in Twin Gestations

With an increasing incidence of twin gestations, understanding the inherent risks associated with these pregnancies is essential in modern obstetrics. The unique differences in placentation in twins contribute to the increased risks. Monochorionic twins are susceptible to complications because of their unique placental architecture, including twin-to-twin transfusion syndrome, the twin anemia-polycythemia sequence, selective intrauterine growth restriction, and the twin reversed arterial perfusion sequence. Knowing the clinical correlations of placental anatomy in these gestations helps perinatal pathologists perform a more informed placental evaluation, allowing for better care for the mother and her children.

Fused placentas: Till birth do us part

Twinning and placental fusion occur at a low frequency in species like humans and mice. They are linked to reduced birth weight and intertwin growth discrepancy with important consequences for perinatal survival. Despite this, little is known about the histological characteristics of the twin or fused placenta and how these relate to fetal growth. In this case report, we characterise the histological changes of a fused mouse placenta showing intertwin growth discrepancy. Our study demonstrates that morphological changes in the placental exchange and endocrine regions and elevated calcification levels may contribute to the intertwin growth discrepancy observed in mouse pregnancy.

Cause of intrauterine and neonatal death in twin pregnancies (CoDiT): development of a novel classification system

OBJECTIVE

Twin pregnancies have a significantly higher perinatal mortality than singleton pregnancies. Current classification systems for perinatal death lack twin-specific categories, potentially leading to loss of important information regarding cause of death. We introduce and test a classification system designed to assign a cause of death in twin pregnancies (CoDiT).

DESIGN

Retrospective cross-sectional study.

SETTING

Tertiary maternity unit in England with a perinatal pathology service.

POPULATION

Twin pregnancies in the West Midlands affected by fetal or neonatal demise of one or both twins between 1 January 2005 and 31 December 2016 in which postmortem examination was undertaken.

METHODS

A multidisciplinary panel designed CoDiT by adapting the most appropriate elements of singleton classification systems. The system was tested by assigning cause of death in 265 fetal and neonatal deaths from 144 twin pregnancies. Cause of death was validated by another obstetrician blinded to the original classification.

MAIN OUTCOME MEASURES

Inter-rater, intra-rater, inter-disciplinary agreement and cause of death.

RESULTS

Cohen's Kappa demonstrated 'strong' (>0.8) inter-rater, intra-rater and inter-disciplinary agreement (95% CI 0.70-0.91). The commonest cause of death irrespective of chorionicity was the placenta; twin-to-twin transfusion syndrome (TTTS) was the commonest placental cause in monochorionic twins and acute chorioamnionitis in dichorionic twins.

CONCLUSIONS

This novel classification system records causes of death in twin pregnancies from postmortem reports with high inter-user agreement. We highlight differences in aetiology of death between monochorionic and dichorionic twins.

TWEETABLE ABSTRACT

New classification system for #twin cause of death 'CoDiT' shows high rater agreement.

The impact of placental pathology discordance in multiple gestation pregnancies on bronchopulmonary dysplasia-associated pulmonary hypertension

Bronchopulmonary dysplasia-associated pulmonary hypertension (BPD-PH) may either be concordant or discordant between multiple gestation births. Abnormal placental development, particularly maternal vascular malperfusion, may account for discordance in BPD-PH through fetal programming mechanisms. Maternal vascular malperfusion is a placental histologic lesion associated with intrauterine growth restriction and BPD-PH. We conducted a retrospective longitudinal cohort study of infants born <29 weeks gestation with available placental histology at Prentice Women's Hospital in Chicago from 2005-2012. The primary outcome was discordant BPD-PH associated with placental maternal vascular malperfusion. We secondarily assessed whether the risk of BPD-PH and placental lesions was different among infants of multiple (compared to singleton) gestations. The cohort consisted of 135 multiple gestation infants and 355 singletons. In a separate cohort of 39 singletons and 35 multiples, associations between 12 cytokines and angiogenic growth factors in cord blood plasma for biomarker discordance, maternal vascular malperfusion, and bronchopulmonary dysplasia were explored. Among multiples, discordant maternal vascular malperfusion was not associated with BPD-PH (OR = 1.9 (0.52, 6.9); p = 0.33) in infants exposed to placental maternal vascular malperfusion. However, singleton infants were more likely to develop BPD-PH (compared to multiples) after adjusting for mode of delivery, chorioamnionitis, chronic hypertension, placental abruption, small-for-gestational age birth weight, and gestational age (aOR = 2.7 (1.2, 5.8); p = 0.038). Singletons were more likely to be small-for-gestational age (11% vs 4%, p = 0.025) and have placental lesions compared to their multiple-gestation counterparts (96% vs 81%, p < 0.001), principally severe maternal vascular malperfusion (17% vs 4%, p < 0.001) and chronic inflammation (32% vs 11%, p < 0.001). Increased risk of BPD-PH in singleton pregnancies <29 weeks gestation compared to multiples may be related to increased frequency of these histologic lesions. Placental pathology in singleton and multiple gestation pregnancies may serve as an early biomarker to predict BPD-PH.