The great obstetrical syndromes and the placenta

Single-cell RNA sequencing identifies CXADR as a fate determinant of the placental exchange surface

The placenta is the critical interface between mother and fetus, and consequently, placental dysfunction underlies many pregnancy complications. Placental formation requires an adequate expansion of trophoblast stem and progenitor cells followed by finely tuned lineage specification events. Here, using single-cell RNA sequencing of mouse trophoblast stem cells during the earliest phases of differentiation, we identify gatekeepers of the stem cell state, notably Nicol1, and uncover unsuspected trajectories of cell lineage diversification as well as regulators of lineage entry points. We show that junctional zone precursors and precursors of one of the two syncytial layers of the mouse placental labyrinth, the Syncytiotrophoblast-I lineage, initially share similar trajectories. Importantly, our functional analysis of one such lineage precursor marker, CXADR, demonstrates that this cell surface protein regulates the differentiation dynamics between the two syncytial layers of the mouse labyrinth, ensuring the correct establishment of the placental exchange surface. Deciphering the mechanisms underlying trophoblast lineage specification will inform our understanding of human pregnancy in health and disease.

Associations between term cesarean delivery in the first pregnancy and second-pregnancy preterm delivery

INTRODUCTION

Cesarean delivery has been shown to increase the risk of preterm delivery in future pregnancies. The association could be a direct result of the procedure, or because the indications that led to the cesarean delivery also increase the risk of preterm delivery in later pregnancies.

MATERIAL AND METHODS

298 901 mothers with first and second singleton deliveries from 1999 to 2020 were investigated using data from the Medical Birth Registry of Norway linked with Statistics Norway. The mothers were categorized by mode of cesarean delivery (total, emergency and planned) and vaginal delivery at term in the first pregnancy. We used log-binomial regression models to estimate relative risks with 95% confidence intervals (CI) of iatrogenic and spontaneous preterm delivery <37 gestational weeks in the second pregnancy. Second, we explored the role of recurrent placental disease in preterm delivery by comparing estimates in mothers with placental disease in neither or both pregnancies.

RESULTS

8243 mothers (2.8%) had a preterm delivery in the second pregnancy. The adjusted relative risk (aRR) of preterm delivery was 1.24 (95% CI 1.17-1.32) after cesarean compared with vaginal delivery in the first pregnancy. The association was stronger in previous planned compared with emergency cesarean delivery (aRR 1.52, 95% CI 1.30-1.77 and aRR 1.21, 95% CI 1.14-1.29, respectively). Spontaneous preterm delivery was not associated with the previous mode of delivery; the risk was confined to iatrogenic preterm delivery after both emergency and planned cesarean delivery (aRR 1.69, 95% CI 1.52-1.87 and aRR 2.65, 95% CI 2.12-3.30, respectively). Mothers with placental disease in both pregnancies had a sixfold increased risk of preterm delivery in the second pregnancy compared with mothers with no placental disease, however, the association between mode of delivery and subsequent preterm delivery was similar in mothers with and without placental disease in the pregnancies.

CONCLUSIONS

Compared with vaginal term delivery in the first pregnancy, cesarean delivery increases the risk of iatrogenic, but not spontaneous preterm delivery in the next pregnancy. Although strongly associated with preterm delivery, placental disease had limited influence on the estimates.

Biomarkers in the prediction of complications in pregnancy after assisted reproductive technology

OBJECTIVES

To compare the temporal changes in mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), placental growth factor (PlGF), and soluble fms-like tyrosine kinase-1 (sFlt-1) across gestation between assisted reproductive technology (ART) pregnancies complicated with great obstetrical syndromes (GOS) or gestational diabetes (GDM) ± large-for-gestational-age (LGA) fetus, and uncomplicated ART pregnancies.

METHODS

This was a prospective longitudinal study of 143 women with singleton pregnancies who conceived through ART at the Department of Obstetrics and Gynecology, Prince of Wales Hospital, the Chinese University of Hong Kong, Hong Kong SAR between December 2017 and January 2020. The participants were followed up at 6-6+3, 11-13+6, 20-24+6, 30-34+6, and 35-37+6 weeks for the measurement of MAP, UtA-PI, PlGF, and sFlt-1. A linear mixed-effects analysis was performed to compare the biomarkers in the GOS, GDM ± LGA, and uncomplicated groups across gestation.

RESULTS

Thirty-three (23.1%) and fifty-five (31.5%) women were diagnosed with GOS and GDM ± LGA, respectively. The GOS group had higher estimated marginal mean log10 MAP mulitples of the median (MoM) across gestation, compared with the uncomplicated group (0.00771 vs -0.02022; P < 0.001), when adjusting for clinical visits and days of embryo transfer. The absolute mean log10 MAP MoM in the GOS group was found to be significantly higher than that of the uncomplicated group at all clinical visits from 6 weeks onwards. Furthermore, the estimated marginal mean log10 PlGF MoM was significantly lower in the GOS group across gestation, compared with the uncomplicated group (-0.04226 vs 0.05566; P = 0.010). The significant difference in log10 PlGF MoM was observed from 11-13+6 to 30-34+6 week of gestation (P < 0.05). However, no significant differences in the estimated marginal means of log10 UtA-PI MoM and log10 sFlt-1 MoM between GOS and uncomplicated groups were observed. GDM ± LGA group had a lower estimated marginal mean log10 PlGF MoM throughout pregnancy compared with the uncomplicated group (-0.01536 vs 0.05572; P = 0.032). In the individual visit analysis, the significant difference was observed at the 20-24+6 and 35-37+6 weeks visits (P < 0.05). There were no significant differences in estimated marginal mean log10 MoM of MAP, UtA-PI, and sFlt-1 between GDM ± LGA and uncomplicated groups during pregnancy.

CONCLUSION

Our study has revealed that among pregnancies conceived through ART, GOS is associated with higher MAP and lower PlGF from early gestation until late third trimester, while GDM ± LGA is associated with lower PlGF during the second half of pregnancy. The same degree of differences in MAP and PlGF persists from early until late gestation in the GOS group and these findings highlight the importance of early screening during the first trimester to identify women who are at risk for developing GOS following ART procedures. Lastly, the potential of PlGF in predicting the development of GDM from the second trimester of pregnancy requires further investigation.

Associations between adverse pregnancy outcomes and cognitive impairment and dementia: a systematic review and meta-analysis

BACKGROUND

Individuals with adverse pregnancy outcomes have an increased risk of cerebrovascular disease, but the association between adverse pregnancy outcomes and cognitive impairment and dementia is less well established. We aimed to synthesise, combine, and assess the growing body of data examining the associations between adverse pregnancy outcomes and mild cognitive impairment and dementia in parous women.

METHODS

In this systematic review and meta-analysis, we searched PubMed (MEDLINE), Web of Science, and Embase from database inception up to July 18, 2024, with no language restrictions, for observational studies or clinical trials that reported mild cognitive impairment or dementia as outcomes and included female individuals or women who had an adverse pregnancy outcome, including hypertensive disorders of pregnancy, gestational diabetes, stillbirth, fetal growth restriction, preterm birth, or placental abruption. We excluded studies of men, nulliparous women, women with pre-pregnancy conditions associated with impaired cognition, and studies examining cognitive impairment within 6 months of pregnancy. Database searches were supplemented by manual review of the reference lists of included studies. If studies met eligibility criteria but did not have sufficient data for meta-analysis (ie, did not report a summary statistic or a hazard ratio [HR] for outcome estimation), they were included in the systematic review and excluded from the meta-analysis. After removing duplicates, two investigators independently screened titles and abstracts using Covidence software, with potentially eligible studies undergoing full-text review by the same reviewers, with further review by a third reviewer and disagreements resolved by discussion and group consensus. Study quality was assessed and summary statistics extracted by two reviewers independently. The primary outcomes of our study were mild cognitive impairment, all-cause dementia, Alzheimer's disease, and vascular dementia. Heterogeneity was measured using the Q test and I2 statistic, and we used random-effects models with inverse-variance weighting to assess the association between adverse pregnancy outcome and primary outcomes with sufficient meta-analysable data via pooled adjusted HRs and 95% CIs. The study protocol was registered with PROSPERO, CRD42023453511.

FINDINGS

Of 11 251 publications identified, 15 studies (including 7 347 202 participants) met inclusion criteria for the systematic review, and 11 studies (6 263 431 participants) had sufficient data for meta-analysis. A history of any adverse pregnancy outcome was associated with higher risk of all-cause dementia (adjusted HR 1·32 [95% CI 1·17-1·49]; I2= 80%), Alzheimer's disease (1·26 [1·04-1·53]; I2=63%), and vascular dementia (1·94 [1·70-2·21]; I2=0%). A history of any hypertensive disorder of pregnancy was significantly associated with all-cause dementia (1·32 [1·11-1·57]; I2=74%) and vascular dementia (1·78 [1·46-2·17]; I2=0%), but not Alzheimer's disease (1·24 [0·98-1·57]; I2=66%). Stillbirth was not significantly associated with higher risk of all-cause dementia (1·26 [95% CI 0·93-1·71]; I2=62%). In individual studies, similar effect directions were observed for preterm birth and fetal growth restriction, but data were insufficient for meta-analysis.

INTERPRETATION

Given their increased risk of dementia, women with a history of adverse pregnancy outcomes should be evaluated for additional dementia risk factors and monitored closely for any signs of cognitive decline. Furthermore, to obtain more reliable findings, future studies should measure both exposures and outcomes prospectively and objectively.

FUNDING

National Institutes of Health, National Institute of Neurological Disorders and Stroke, National Institute on Aging, and National Heart, Lung and Blood Institute.

Fatty Acid Metabolism Disruptions: A Subtle yet Critical Factor in Adverse Pregnancy Outcomes

The establishment and maintenance of pregnancy encompass a series of complex and high-energy-consuming physiological processes, resulting in a significant energy demand. Fatty acids, one of the most essential nutrients, play a crucial role in energy supply via oxidation and perform critical biological functions such as anti-inflammatory and anti-oxidant effects, which substantially impact human health. Disordered fatty acid metabolism can cause anomalies in fetal growth and development, as well as a range of pregnancy problems, which can influence the health of both the mother and the fetus. In this review, we innovatively explore the relationship between fatty acid metabolism abnormalities and pregnancy complications, emphasizing the potential of dietary interventions with polyunsaturated fatty acids in improving pregnancy outcomes. These findings provide important evidence for clinical interventions and enhance the understanding and practical application of health management during pregnancy.

Obstetrical Complications in Venezuelan Refugee and Migrant Women: Analysis of Ecuadorian National Hospital Discharge Data, 2018-2021

An estimated 7.7 million Venezuelans have fled a severe humanitarian crisis in their country, most (70%) to other middle-income host countries in the same Andean region. Migration-related exposures during periconception and other critical gestational periods can adversely impact maternal-perinatal outcomes. Emerging evidence suggests that Venezuelan refugee and migrant women (VRMW) who migrate to Andean host countries are at-risk for delivering preterm and low birthweight infants and for Cesarean-sections. However, relatively few studies have examined obstetrical complications that could contribute to these or other short- and longer-term health outcomes of VRMW and/or their offspring. Our exploratory study analyzed four recent years of national hospital discharge data (2018-2021) from Ecuador to compare the primary discharge diagnoses of VRMW (n = 29,005) and Ecuadorian nationals (n = 1,136,796) for ICD-10 O code obstetrical complications related to or aggravated by pregnancy, childbirth, or the puerperium. Our findings indicated that VRMW were hospitalized for 0.5 days longer than Ecuadorian reference group women and they had higher adjusted odds (aOR) for a primary discharge diagnosis for obstetrical complications including preeclampsia (aOR:1.62, 95% CI:1.55,1.69), preterm labor (aOR:1.20, 95% CI:1.11,1.31), premature rupture of membranes (aOR: 1.72, 95% CI:1.63,1.83), oligohydraminos (aOR:1.24, 95% CI:1.12,1.36), obstructed labor (aOR: 1.39, 95% CI:1.31,1.47), perineal lacerations/other obstetric trauma (aOR:1.76, 95% CI:1.63, 1.91), STIs (aOR:2.59, 95% CI:1.29,2.92), anemia (aOR:1.33, 95% CI:1.24,1.42), and ectopic pregnancy (aOR:1.16 95% CI:1.04,1.28). They had similar aOR for diagnosed gestational diabetes and spontaneous abortion (SAB) compared to the reference group but a reduced aOR for genitourinary infections (aOR:0.79, 95% CI:0.74,0.84) and early pregnancy hemorrhage not ending in SAB (aOR:0.43, 95% CI:0.36,0.51). Our findings underscore the vulnerability of VRMW for a number of potentially serious obstetrical complications with the potential to adversely impact the short- and longer-term health of mothers and their offspring. Future studies should collect more detailed information on the migration status, experiences, and exposures of MRMW that influence their risk for obstetrical complications. These are needed to expand our findings to better understand why they have excess risk for these and to inform social and public health policies, programs and targeted interventions aimed at reducing the risk of this vulnerable refugee and migrant group.

The Hidden Relationship between Intestinal Microbiota and Immunological Modifications in Preeclampsia Pathogenesis

Preeclampsia is a multifactorial gestational syndrome characterized by increased blood pressure during pregnancy associated with multiorgan involvement. The impact of this disease on maternal and neonatal health is significant, as it can lead to various fetal comorbidities and contribute to the development of maternal comorbidities later in life. Consistent evidence has shown that the microbiota acts as a regulator of the immune system, and it may, therefore, influence the development of preeclampsia by modulating immune factors. This narrative review aims to investigate the role of the immune system in the pathogenesis of preeclampsia and to summarize the most recent literature on the possible link between preeclampsia and alterations in the intestinal microbiota. To this end, we conducted a literature search, aiming to perform a narrative review, on PubMed and Embase from January 1990 to March 2024, focusing on the latest studies that highlight the main differences in microbial composition between patients with and without preeclampsia, as well as the effects of microbial metabolites on the immune system. From the review of 28 studies assessing the intestinal microbiota in preeclamptic women, preeclampsia could be associated with a state of dysbiosis. Moreover, these patients showed higher plasmatic levels of endotoxin, pro-inflammatory cytokines, and T helper 17 cells; however, the findings on specific microbes and metabolites that could cause immune imbalances in preeclampsia are still preliminary.

Preeclampsia and neonatal outcomes in pregnancies with maternal congenital heart disease: A nationwide cohort study from Norway

INTRODUCTION

The prevalence of congenital heart disease (CHD) among women of reproductive age is rising. We aimed to investigate the risk of preeclampsia and adverse neonatal outcomes in pregnancies of mothers with CHD compared to pregnancies of mothers without heart disease.

MATERIAL AND METHODS

In a nationwide cohort of pregnancies in Norway 1994-2014, we retrieved information on maternal heart disease, the course of pregnancy, and neonatal outcomes from national registries. Comparing pregnancies with maternal CHD to pregnancies without maternal heart disease, we used Cox regression to estimate the adjusted hazard ratio (aHR) for preeclampsia and log-binomial regression to estimate the adjusted risk ratio (aRR) for adverse neonatal outcomes. The estimates were adjusted for maternal age and year of childbirth and presented with 95% confidence intervals (CIs).

RESULTS

Among 1 218 452 pregnancies, 2425 had mild maternal CHD, and 603 had moderate/severe CHD. Compared to pregnancies without maternal heart disease, the risk of preeclampsia was increased in pregnancies with mild and moderate/severe maternal CHD (aHR1.37, 95% CI 1.14-1.65 and aHR 1.62, 95% CI 1.13-2.32). The risk of preterm birth was increased in pregnancies with mild maternal CHD (aRR 1.33, 95% CI 1.15-1.54) and further increased with moderate/severe CHD (aRR 2.49, 95% CI 2.03-3.07). Maternal CHD was associated with elevated risks of both spontaneous and iatrogenic preterm birth. The risk of infants small-for-gestational-age was slightly increased with mild maternal CHD (aRR 1.12, 95% CI 1.00-1.26) and increased with moderate/severe CHD (aRR 1.63, 95% CI 1.36-1.95). The prevalence of stillbirth was 3.9 per 1000 pregnancies without maternal heart disease, 5.6 per 1000 with mild maternal CHD, and 6.8 per 1000 with moderate/severe maternal CHD. Still, there were too few cases to report a significant difference. There were no maternal deaths in women with CHD.

CONCLUSIONS

Moderate/severe maternal CHD in pregnancy was associated with increased risks of preeclampsia, preterm birth, and infants small-for-gestational-age. Mild maternal CHD was associated with less increased risks. For women with moderate/severe CHD, their risk of preeclampsia and adverse neonatal outcomes should be evaluated together with their cardiac risk in pregnancy, and follow-up in pregnancy should be ascertained.

Prevention of Pregnancy Complications Using a Multimodal Lifestyle, Screening, and Medical Model

Prevention of pregnancy complications related to the "great obstetrical syndromes" (preeclampsia, fetal growth restriction, spontaneous preterm labor, and stillbirth) is a global research and clinical management priority. These syndromes share many common pathophysiological mechanisms that may contribute to altered placental development and function. The resulting adverse pregnancy outcomes are associated with increased maternal and perinatal morbidity and mortality and increased post-partum risk of cardiometabolic disease. Maternal nutritional and environmental factors are known to play a significant role in altering bidirectional communication between fetal-derived trophoblast cells and maternal decidual cells and contribute to abnormal placentation. As a result, lifestyle-based interventions have increasingly been recommended before, during, and after pregnancy, in order to reduce maternal and perinatal morbidity and mortality and decrease long-term risk. Antenatal screening strategies have been developed following extensive studies in diverse populations. Multivariate preeclampsia screening using a combination of maternal, biophysical, and serum biochemical markers is recommended at 11-14 weeks' gestation and can be performed at the same time as the first-trimester ultrasound and blood tests. Women identified as high-risk can be offered prophylactic low dose aspirin and monitored with angiogenic factor assessment from 22 weeks' gestation, in combination with clinical assessment, serum biochemistry, and ultrasound. Lifestyle factors can be reassessed during counseling related to antenatal screening interventions. The integration of lifestyle interventions, pregnancy screening, and medical management represents a conceptual advance in pregnancy care that has the potential to significantly reduce pregnancy complications and associated later life cardiometabolic adverse outcomes.

Syncytiotrophoblast Markers Are Downregulated in Placentas from Idiopathic Stillbirths

The trophoblast cells are responsible for the transfer of nutrients between the mother and the foetus and play a major role in placental endocrine function by producing and releasing large amounts of hormones and growth factors. Syncytiotrophoblast cells (STB), formed by the fusion of mononuclear cytotrophoblasts (CTB), constitute the interface between the foetus and the mother and are essential for all of these functions. We performed transcriptome analysis of human placental samples from two control groups-live births (LB), and stillbirths (SB) with a clinically recognised cause-and from our study group, idiopathic stillbirths (iSB). We identified 1172 DEGs in iSB, when comparing with the LB group; however, when we compared iSB with the SB group, only 15 and 12 genes were down- and upregulated in iSB, respectively. An assessment of these DEGs identified 15 commonly downregulated genes in iSB. Among these, several syncytiotrophoblast markers, like genes from the PSG and CSH families, as well as ALPP, KISS1, and CRH, were significantly downregulated in placental samples from iSB. The transcriptome analysis revealed underlying differences at a molecular level involving the syncytiotrophoblast. This suggests that defects in the syncytial layer may underlie unexplained stillbirths, therefore offering insights to improve clinical obstetrics practice.

Melatonin-mediated actions and circadian functions that improve implantation, fetal health and pregnancy outcome

This review summarizes data related to the potential importance of the ubiquitously functioning antioxidant, melatonin, in resisting oxidative stress and protecting against common pathophysiological disorders that accompany implantation, gestation and fetal development. Melatonin from the maternal pineal gland, but also trophoblasts in the placenta, perhaps in the mitochondria, produce this molecule as a hedge against impairment of the uteroplacental unit. We also discuss the role of circadian disruption on reproductive disorders of pregnancy. The common disorders of pregnancy, i.e., stillborn fetus, recurrent fetal loss, preeclampsia, fetal growth retardation, premature delivery, and fetal teratology are all conditions in which elevated oxidative stress plays a role and experimental supplementation with melatonin has been shown to reduce the frequency or severity of these conditions. Moreover, circadian disruption often occurs during pregnancy and has a negative impact on fetal health; conversely, melatonin has circadian rhythm synchronizing actions to overcome the consequences of chronodisruption which often appear postnatally. In view of the extensive findings supporting the ability of melatonin, an endogenously-produced and non-toxic molecule, to protect against experimental placental, fetal, and maternal pathologies, it should be given serious consideration as a supplement to forestall the disorders of pregnancy. Until recently, the collective idea was that melatonin supplements should be avoided during pregnancy. The data summarized herein suggests otherwise. The current findings coupled with the evidence, published elsewhere, showing that melatonin is highly protective of the fertilized oocyte from oxidative damage argues in favor of its use for improving pregnancy outcome generally.