Placental factor in spontaneous term labor in uncomplicated pregnancy

The Placenta and Neonatal Encephalopathy with a Focus on Hypoxic-Ischemic Encephalopathy

Background: Placental examination is important for its diagnostic immediacy to correlate with maternal and/or fetal complications and parturitional difficulties. In a broader context, clinicopathologic studies of the placenta have addressed a range of pathogenetic questions that have led to conclusive and inconclusive results and interpretations. Methods: Recent standardized morphologic criteria and terminology of placental lesions have facilitated the ability to compare findings from studies that have focused on complications and outcomes of pregnancy. This review is an evaluation of recent studies on placental lesions associated with hypoxic-ischemic encephalopathy (HIE). Conclusion: No apparent consensus exists on whether it is fetal inflammation with the release of cytokines or chronic maternal and/or fetal vascular malperfusion is responsible for HIE with a lowering of the threshold for hypoxic ischemia. The counter argument is that HIE occurs solely as an intrapartum event. Additional investigation is necessary.

Pregnancy Complications, Correlation With Placental Pathology and Neonatal Outcomes

Purpose

We aimed to clarify and contribute to a better comprehension of associations and correlations between placental histological findings, pregnancy evolution, and neonatal outcomes.

Study Design

This is a longitudinal and prospective observational study, performed between May 2015 and May 2019, on 506 pregnant women. Clinical data related to pregnancy outcome, neonatal health status, and placental histology were primarily collected. Twin pregnancies or malformed newborns were excluded and therefore the study was conducted on 439 cases. These cases have been then subdivided into the following study groups: (a) 282 placentas from pathological pregnancies; and, (b) a control group of 157 pregnancies over 33 weeks of gestational age, defined as physiological or normal pregnancies due to the absence of maternal, fetal, and early neonatal pathologies, most of which had undergone elective cesarean section for maternal or fetal indication.

Results

A normal placenta was present in 57.5% of normal pregnancies and in 42.5% of pathological pregnancies. In contrast, placental pathology was present in 26.2% of normal pregnancies and 73.8% of pathological pregnancies. Comparison of the neonatal health status with the pregnancy outcome showed that, among the 191 newborns classified as normal, 98 (51.3%) were born from a normal pregnancy, while 93 (48.7%) were born from mothers with a pathological pregnancy. Among the 248 pathological infants, 59 (23.8%) were born from a mother with a normal pregnancy, while 189 (76.2%) were born from pregnancies defined as pathological.

Conclusion

Placental histology must be better understood in the context of natural history of disease. Retrospective awareness of placental damage is useful in prevention in successive pregnancy, but their early identification in the evolving pregnancy could help in association with biological markers or more sophisticated instruments for early diagnosis.

Passively inhaled tobacco smoke - pregnancy and neonatal outcomes in correlation with placental histopathology

INTRODUCTION

We aimed to investigate the effect of maternal passive smoking (MPS) during pregnancy-on placental pathology and pregnancy outcomes.

METHODS

A prospective case-control study. We recruited low-risk laboring women at 37+0-41 + 0 weeks between 9/2019-7/2020. MPS was defined as exposure to in-house spouse tobacco smoking of >20 cigarettes/day in the absence of maternal active-smoking. In attempt to "purify" the effect of MPS on placental pathology-we excluded cases with preeclampsia, diabetes, suspected fetal growth restriction (FGR), preterm labor, and illicit drug use. Maternal characteristics, pregnancy outcomes, and placental pathology were compared between the MPS group and a control group matched for gestational age, maternal age, and delivery date. Placental lesions were classified according to the "Amsterdam" criteria. The study was powered to detect a 33% difference in placental malperfusion lesions. Multivariable regression was performed to identify independent associations with placental malperfusion lesions.

RESULTS

In labor, the MPS group (n = 115) had higher rates of meconium stained amniotic fluid (MSAF, p < 0.001) and non-reassuring fetal heart-rate (NRFHR,p = 0.006), compared to controls (n = 115). Neonates in the MPS group had higher rates of undiagnosed FGR (p = 0.01) and NICU admissions (p = 0.004). The MPS group had higher rates of placental-hypoplasia (p = 0.02) and fetal vascular malperfusion (FVM) lesions (p = 0.04). In regression analysis MPS was associated with FVM lesions independent of background confounders (aOR = 1.24 95% CI 1.10-2.65).

DISCUSSION

In otherwise low-risk pregnancies, MPS was associated with higher rates of MSAF, NRFHR, undiagnosed FGR, and NICU admissions, probably mediated via placental FVM. These worrisome findings mandate patient counseling and further investigation in larger population-based studies.

Is advanced maternal age associated with placental vascular malperfusion? A prospective study from a single tertiary center

PURPOSE

Pregnancy at advanced maternal age (AMA) has become more common. There has been concern regarding the adverse effect deferring pregnancy might have on pregnancy outcomes. We aimed to prospectively study the effect of AMA on placental pathology.

METHODS

A prospective case-control study was performed in a single university center. Placental histopathology, maternal demographics, labor characteristics, and neonatal outcomes of pregnancies with AMA were collected and compared to matched controls. We defined AMA as maternal age > 35 years at delivery. In attempt to isolate the effect of maternal age, we excluded cases complicated by preterm birth, hypertensive disorders, diabetes mellitus, small for gestational age, and congenital/genetic anomalies.

RESULTS

The study group included 110 AMA patients that were matched with controls. The groups did not differ in maternal demographics, but the AMA group had a higher rate of assisted reproductive technologies (ART) as compared to the control group (p < 0.001). Placentas in the AMA group were characterized by a higher rate of maternal vascular lesions (MVM) (39.1% vs. 24.5%, p = 0.003), but not fetal vascular malperfusion lesions (p = 0.576). In multivariable analysis maternal age was associated with placental MVM lesions independent of all other maternal demographics (aOR 1.18 95% CI 1.06-3.17). Neonatal outcomes did not significantly differ between the groups.

CONCLUSIONS

After excluding all background morbidities-AMA was associated with a higher rate of placental MVM lesions vs. controls. These findings suggest an independent effect of AMA on placental function. Large prospective trials are needed to study the clinical importance of these findings.

Reduced fetal movements at term in singleton low risk pregnancies-Is there an association with placental histopathological findings?

INTRODUCTION

Maternal perception of fetal movements has long been considered an indicator of fetal well-being. A sudden decrease in the number of fetal movements is suggestive of fetal compromise. We aimed to determine whether the maternal perception of reduced fetal movements (RFM) is associated with placental pathological lesions in a low-risk term population.

MATERIAL AND METHODS

Our study was a case-control study that was performed in a single university center. Placental histopathology, maternal demographics, labor characteristics, and neonatal outcomes of term, singleton pregnancies with maternal perception of RFM during the 2 weeks prior to delivery were collected. To isolate the effect of RFM on placental pathology, we excluded cases complicated by preterm birth, hypertensive disorders, diabetes mellitus, small-for-gestational-age and congenital/genetic anomalies. We compared pregnancy outcomes and placental pathology between the RFM group and a control group matched for gestational age and mode of delivery. Placental lesions were classified according to the "Amsterdam" criteria. Composite adverse neonatal outcome was defined as one or more of the following: sepsis, transfusion, hypoglycemia, phototherapy, respiratory morbidity, cerebral morbidity, necrotizing enterocolitis and fetal/neonatal death. Multivariable regression analysis was performed to identify independent associations with adverse neonatal outcome.

RESULTS

We included patients who gave birth from January 2008 until May 2019. The study group included 203 term pregnancies with RFM during the 2 weeks prior to delivery, which was matched with 203 controls. The RFM group was characterized by a higher rate of placental weight <10th percentile (22.6% vs. 3.9%, P < .001), a higher rate of maternal vascular malperfusion lesions (30.5% vs. 18.7%, P = .007) and lesions of maternal inflammatory response (43.3% vs. 29.5%, P = .005). At delivery, the RFM group had higher rates of cesarean delivery due to non-reassuring fetal heart rate monitoring (P = .01), 5-minute Apgar score ≤7 (P = .03), neonatal intensive care unit admissions (P < .001) and composite adverse neonatal outcomes (P = .007). Using multivariable analysis, RFM (adjusted odds ratio [aOR] 1.7, 95% confidence interval [CI] 1.1-4.8), and placental maternal vascular malperfusion lesions (aOR 1.2, 95% CI 1.0-2.9) were independently associated with adverse neonatal outcome.

CONCLUSIONS

After excluding important placental-related morbidities, RFM was associated with a higher rate of placental weight <10th percentile and placental maternal vascular malperfusion lesions vs. controls. This study suggests a placental involvement in the association between RFM at term and adverse pregnancy outcomes.

The association between isolated oligohydramnios at term and placental pathology in correlation with pregnancy outcomes

INTRODUCTION

Isolated term oligohydramnios (ITO) is an obstetrical complication of which the etiology, management, and clinical importance are controversial. In attempt to deepen our understanding, we aimed to study placental pathology and pregnancy outcomes in pregnancies complicated by ITO.

MATERIALS AND METHODS

- Maternal demographics, neonatal outcomes, and placental histopathology reports of all pregnancies complicated by ITO at 37^0/7 to 41^0/7 weeks were reviewed. Excluded were cases complicated by hypertensive disorders, intrauterine fetal growth restriction, placental abruption, and deliveries of undiagnosed small for gestational age neonates. Results were compared between the ITO group and a control group matched for gestational age and mode of delivery. Placental lesions were classified according to the current "Amsterdam" criteria. Composite adverse neonatal outcome was defined as one or more of the following early complications: neonatal intensive care unit admission, sepsis, blood transfusion, phototherapy, respiratory morbidity, cerebral morbidity, necrotizing enterocolitis, or death.

RESULTS

The study group included 108 patients with ITO that were compared to matched controls. Placentas from the ITO group were characterized by higher rates of placental weights <10th centile (p < 0.001), abnormal cord insertion (p < 0.001), and maternal vascular malperfusion (MVM) lesions (p < 0.001). Neonates from the ITO group had lower birth weights (p < 0.002), and worse composite adverse neonatal outcome (p = 0.028) compared to controls.

CONCLUSION

- The current study demonstrates higher rates of placental MVM lesions, and worse neonatal outcome in pregnancies complicated by ITO. These novel findings suggest that ITO should be seen as part of the "placental insufficiency" spectrum.

Placental and intra-amniotic inflammation are associated with altered fetal immune responses at birth

INTRODUCTION

High-grade placental inflammation is associated with preterm birth and poor neonatal outcomes. Recent reports suggest that low-grade placental inflammation is common in uncomplicated pregnancies. The relationship between placental inflammation and innate immune anti-microbial responses is unknown. In this study we sought to identify any association between placental inflammation and fetal immune responses.

METHODS

Cord blood samples collected from late preterm and full-term Caesarean section deliveries (n = 44) were exposed to various immune challenges (resiquimod, LPS, PGN, poly (I:C), cGAMP, and 5'ppp-dsRNA) and production of inflammatory mediators (G-CSF, IFN-γ, IL-1β, IL-6, IL-8, IL-10, and TNF-α) was measured by multiplex assay. Hospital histology reports were used to assess the extent of inflammation in the placenta.

RESULTS

Almost half (47.7%) of placentae examined here showed histological evidence of inflammation. Resiquimod, LPS, and PGN elicited strong inflammatory responses in neonatal cord blood, while poly (I:C), cGAMP, and 5'ppp-dsRNA elicited weaker responses. Fetuses with evidence of chorioamnionitis and fetal inflammatory reaction in their placentae had significantly increased immune responses to cGAMP and 5'ppp-dsRNA (ligands for STING and RIG-I, respectively) and significantly decreased immune responses to poly (I:C) (a TLR3 agonist). Interestingly, STING, RIG-I, and TLR3 are all involved in viral response pathways, suggesting that fetuses exposed to chorioamnionitis or fetal inflammatory reaction might respond differently to viruses postnatally.

CONCLUSION

Our data suggest that low-level placental inflammation is associated with altered innate cytokine responses at birth.

The frequency and type of placental histologic lesions in term pregnancies with normal outcome

Objective To determine the frequency and type of histopathologic lesions in placentas delivered by women with a normal pregnancy outcome. Methods This retrospective cohort study included placental samples from 944 women with a singleton gestation who delivered at term without obstetrical complications. Placental lesions were classified into the following four categories as defined by the Society for Pediatric Pathology and by our unit: (1) acute placental inflammation, (2) chronic placental inflammation, (3) maternal vascular malperfusion and (4) fetal vascular malperfusion. Results (1) Seventy-eight percent of the placentas had lesions consistent with inflammatory or vascular lesions; (2) acute inflammatory lesions were the most prevalent, observed in 42.3% of the placentas, but only 1.0% of the lesions were severe; (3) acute inflammatory lesions were more common in the placentas of women with labor than in those without labor; (4) chronic inflammatory lesions of the placenta were present in 29.9%; and (5) maternal and fetal vascular lesions of malperfusion were detected in 35.7% and 19.7%, respectively. Two or more lesions with maternal or fetal vascular features consistent with malperfusion (high-burden lesions) were present in 7.4% and 0.7%, respectively. Conclusion Most placentas had lesions consistent with inflammatory or vascular lesions, but severe and/or high-burden lesions were infrequent. Mild placental lesions may be interpreted either as acute changes associated with parturition or as representative of a subclinical pathological process (intra-amniotic infection or sterile intra-amniotic inflammation) that did not affect the clinical course of pregnancy.