Crucial nuances in understanding (mis)associations between the neonatal microbiome and Cesarean delivery

Delivery mode and maternal gestational diabetes are important factors in shaping the neonatal initial gut microbiota

Background

The infant gut microbiome's establishment is pivotal for health and immune development. Understanding it unveils insights into growth, development, and maternal microbial interactions. Research often emphasizes gut bacteria, neglecting the phageome.

Methods

To investigate the influence of geographic or maternal factors (mode of delivery, mode of breastfeeding, gestational diabetes mellitus) on the gut microbiota and phages of newborns, we collected fecal samples from 34 pairs of mothers and their infants within 24 hours of delivery from three regions (9 pairs from Enshi, 7 pairs from Hohhot, and 18 pairs from Hulunbuir) using sterile containers. Gut microbiota analysis by Shotgun sequencing was subsequently performed.

Results

Our results showed that geographic location affects maternal gut microbiology (P < 0.05), while the effect on infant gut microbiology was not significant (P = 0.184). Among the maternal factors, mode of delivery had a significant (P < 0.05) effect on the newborn. Specific bacteria (e.g., Bacteroides, Escherichia spp., Phocaeicola vulgatus, Escherichia coli, Staphylococcus hominis, Veillonella spp.), predicted active metabolites, and bacteriophage vOTUs varied with delivery mode. Phocaeicola vulgatus significantly correlated with some metabolites and bacteriophages in the early infant gut (P < 0.05). In the GD group, a strong negative correlation of phage diversity between mother and infants was observed (R = -0.58, P=0.04).

Conclusion

In conclusion, neonatal early gut microbiome (including bacteria and bacteriophages) colonization is profoundly affected by the mode of delivery, and maternal gestational diabetes mellitus. The key bacteria may interact with bacteriophages to influence the levels of specific metabolites. Our study provides new evidence for the study of the infant microbiome, fills a gap in the analysis of the infant gut microbiota regarding the virome, and emphasizes the importance of maternal health for the infant initial gut virome.

Duration of rupture of membranes and microbiome transmission to the newborn: A prospective study

OBJECTIVE

To assess whether labour variables (i.e. individuals characteristics, labour characteristics and medical interventions) impact maternal and newborn microbiomes.

DESIGN

Prospective monocentric study.

SETTING

Saint-Joseph Hospital tertiary maternity unit, in Paris, France.

POPULATION

All consecutive primiparous women with a physiological pregnancy and term labour from 15 April to 1 June 2017.

METHODS

16S ribosomal RNA gene sequencing of the maternal vaginal, newborn skin and newborn oral microbiomes from 58 mother-baby dyads.

MAIN OUTCOME MEASURES

Analysis of the effects of 19 labour variables on the composition and diversity of these microbiomes.

RESULTS

The 19 labour variables explained a significant part of the variability in the vaginal, newborn oral and skin microbiomes (44%-67%). Strikingly, duration of rupture of membranes was the single factor that explained the greatest variability (adjusted R2: 7.7%-8.4%, p ≤ 0.002) and conditioned, by itself, the compositions of the three microbiomes under study. Long duration of rupture of membranes was specifically associated with a lower relative abundance of the Lactobacillus genus (1.7-fold to 68-fold reduction, p < 0.0001) as well as an increase in microbiome diversity, including genera implicated in nosocomial infections. The effects of duration of rupture of membranes were also present in newborns delivered by non-elective caesarean section.

CONCLUSIONS

Maternal and newborn microbiomes were greatly affected by labour variables. Duration of rupture of membranes, even in non-elective caesarean sections, should be considered in epidemiological and microbiological studies, as well as in vaginal seeding practices.

Arthropods to Eutherians: A Historical and Contemporary Comparison of Sparse Prenatal Microbial Communities Among Animalia Species

Since the advent of next-generation sequencing, investigators worldwide have sought to discern whether a functional and biologically or clinically relevant prenatal microbiome exists. One line of research has led to the hypothesis that microbial DNA detected in utero/in ovo or prior to birth/hatching is a result of contamination and does not belong to viable and functional microbes. Many of these preliminary evaluations have been conducted in humans, mice, and nonhuman primates due to sample and specimen availability. However, a comprehensive review of the literature across animal species suggests organisms that maintain an obligate relationship with microbes may act as better models for interrogating the selective pressures placed on vertical microbial transfer over traditional laboratory species. To date, studies in humans and viviparous laboratory species have failed to illustrate the clear presence and transfer of functional microbes in utero. Until a ground truth regarding the status and relevance of prenatal microbes can be ascertained, it is salient to conduct parallel investigations into the prevalence of a functional prenatal microbiome across the developmental lifespan of multiple organisms in the kingdom Animalia. This comprehensive understanding is necessary not only to determine the role of vertically transmitted microbes and their products in early human health but also to understand their full One Health impact. This review is among the first to compile such comprehensive primary conclusions from the original investigator's conclusions, and hence collectively illustrates that prenatal microbial transfer is supported by experimental evidence arising from over a long and rigorous scientific history encompassing a breadth of species from kingdom Animalia.

Delivery by cesarean section leads to heavier adult bodyweight in prairie voles (Microtus ochrogaster)

Delivery by cesarean section now makes up 32.1 % of all births in the United States. Meta-analyses have estimated that delivery by cesarean section is associated with a > 50 % increased risk for childhood obesity by 5 years of age. While this association is independent of maternal obesity, breastfeeding, and heritable factors, studies in humans have been unable to test for a causal role of cesarean delivery in this regard. Here, we set out to use an animal model to experimentally test whether delivery by cesarean section would increase offspring weight in adulthood. Delivery by cesarean section may exert neurodevelopmental consequences by impacting hormones that are important at birth as well as during metabolic regulation in later life, such as oxytocin and vasopressin. The prairie vole (Microtus ochrogaster) has long been studied to investigate the roles of oxytocin and vasopressin in brain development and social behavior. Here, we establish that prairie voles tolerate a range of ambient temperatures, including conventional 22° housing, which makes them translationally appropriate for studies of diet-induced obesity. We also studied vole offspring for their growth, sucrose preference, home cage locomotor activity, and food consumption after birth by either cesarean section or vaginal delivery. At sacrifice, we collected measures of weight, length, and adipose tissue to analyze body composition in adulthood. Voles delivered by cesarean section had consistently greater bodyweights than those born vaginally, despite having lower food consumption and greater locomotive activity. Cesarean-delivered animals were also longer, though this did not explain their greater body weights. While cesarean delivery had no effect on vasopressin, it resulted in less oxytocin immunoreactivity within the hypothalamus in adulthood. These results support the case that cesarean section delivery plays a causal role in increasing offspring body weight, potentially by affecting the oxytocin system.

A jump into the deep end - Women's strategies on the way to VBAC in Poland

PROBLEM

In Poland, as in other high-income countries, the rate of caesarean sections (CS) is alarmingly high. Promoting vaginal birth after caesarean section (VBAC) is one of the ways that may help to decrease CS rate. Despite the recommendations by the Polish Association of Gynaecologists and Obstetricians that one previous CS should not be an indication for a subsequent one and VBAC should be promoted, the rate of VBAC in Poland remains low.

BACKGROUND

Research shows that in countries with high VBAC rates women felt supported by healthcare personnel to have VBAC.

AIM

This study aims to explore the elements of Polish maternity services that contribute to or hinder women's chances of having a VBAC.

METHODS

The study used qualitative methods of research based on semi-structured interviews. We interviewed 22 women. Each woman was interviewed twice, once during pregnancy and then between 6 and 12 weeks after she had given birth.

FINDING

Women who planned vaginal birth after one previous CS engaged in various strategies such as seeking supportive personnel, opting for fee-for-service dedicated midwifery care or traveled long distances to give birth in facilities supporting VBAC.

CONCLUSIONS

Polish maternity services do not support women on the way to vaginal birth after surgery. Access to VBAC in Poland is highly unequal and dependent on women's social and financial resources such as access to private care, place of residence, or social relationships. Efforts should be made to make access to VBAC more universal.

Effects of maternal type 1 diabetes and confounding factors on neonatal microbiomes

AIMS/HYPOTHESIS

Body niche-specific microbiota in maternal-neonatal dyads from gravidae with type 1 diabetes have not been quantitatively and functionally examined. Similarly, the impact of pregnancy-specific factors, such as the presence of comorbidities known to occur more frequently among gravidae with type 1 diabetes, including Caesarean delivery, as well as antibiotic prophylaxis, level of glycaemic control during each trimester of pregnancy and insulin administration, has not been adequately considered. The aims of this study were to characterise the maternal and neonatal microbiomes, assess aspects of microbiota transfer from the maternal microbiomes to the neonatal microbiome and explore the impact of type 1 diabetes and confounding factors on the microbiomes.

METHODS

In this observational case-control study, we characterised microbiome community composition and function using 16S rRNA amplicon sequencing in a total of 514 vaginal, rectal and ear-skin swabs and stool samples derived from 92 maternal-neonatal dyads (including 50 gravidae with type 1 diabetes) and in-depth clinical metadata from throughout pregnancy and delivery.

RESULTS

Type 1 diabetes-specific microbiota were identified among gravidae with type 1 diabetes and their neonates. Neonatal microbiome profiles of ear-skin swabs and stool samples were established, indicating the taxa more prevalent among neonates born to mothers with type 1 diabetes compared with neonates born to control mothers. Without taking into account the type 1 diabetes status of mothers, both delivery mode and intrapartum antibiotic prophylaxis were found to have an influence on neonatal microbiota composition (both p=0.001). In the logistic regression analysis involving all confounding variables, neonatal ear-skin microbiome variation was explained by maternal type 1 diabetes status (p=0.020) and small for gestational age birthweight (p=0.050). Moreover, in women with type 1 diabetes, a relationship was found between HbA1c levels >55 mmol/mol (>7.2%) measured in the first trimester of pregnancy and neonatal ear-skin microbiota composition (p=0.008). In the PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) assessment, pathways concerning carbohydrate biosynthesis were predicted as key elements of the microbial functional profiles dysregulated in type 1 diabetes. Additionally, in SourceTracker analysis, we found that, on average, 81.0% of neonatal microbiota was attributed to maternal sources. An increase in the contribution of maternal rectum microbiota and decrease in the contribution of maternal cervix microbiota were found in ear-skin samples of vaginally delivered neonates of mothers with type 1 diabetes compared with neonates born to control mothers (83.2% vs 59.5% and 0.7% vs 5.2%, respectively).

CONCLUSIONS/INTERPRETATION

These findings indicate that, in addition to maternal type 1 diabetes, glycaemic dysregulation before/in the first trimester of pregnancy, mode of delivery and intrapartum antibiotic prophylaxis may contribute to the inoculation and formation of the neonatal microbiomes.

DATA AVAILABILITY

The BioProject (PRJNA961636) and associated SRA metadata are available at http://www.ncbi.nlm.nih.gov/bioproject/961636 . Processed data on probiotic supplementation and the PICRUSt analysis are available in the Mendeley Data Repository ( https://doi.org/10.17632/g68rwnnrfk.1 ).

The Impact of Cesarean Section Delivery on Intestinal Microbiota: Mechanisms, Consequences, and Perspectives-A Systematic Review

The relationship between cesarean section (CS) delivery and intestinal microbiota is increasingly studied. CS-born infants display distinct gut microbial compositions due to the absence of maternal birth canal microorganisms. These alterations potentially link to long-term health implications like immune-related disorders and allergies. This correlation underscores the intricate connection between birth mode and the establishment of diverse intestinal microbiota. A systematic literature review was conducted on the PubMed, Scopus, and Web of Science databases by analyzing the articles and examining the intricate interactions between CS delivery and the infant's intestinal microbiota. The analysis, based on a wide-ranging selection of studies, elucidates the multifaceted dynamics involved in CS-associated shifts in the establishment of fetal microbiota. We also explore the potential ramifications of these microbial changes on neonatal health and development, providing a comprehensive overview for clinicians and researchers. By synthesizing current findings, this review contributes to a deeper understanding of the interplay between delivery mode and early microbial colonization, paving the way for informed clinical decisions and future investigations in the field of perinatal medicine.

Machine-learning analysis of cross-study samples according to the gut microbiome in 12 infant cohorts

IMPORTANCE

There are challenges in merging microbiome data from diverse research groups due to the intricate and multifaceted nature of such data. To address this, we utilized a combination of machine-learning (ML) models to analyze 16S sequencing data from a substantial set of gut microbiome samples, sourced from 12 distinct infant cohorts that were gathered prospectively. Our initial focus was on the mode of delivery due to its prior association with changes in infant gut microbiomes. Through ML analysis, we demonstrated the effective merging and comparison of various gut microbiome data sets, facilitating the identification of robust microbiome biomarkers applicable across varied study populations.

Microbial transmission, colonisation and succession: from pregnancy to infancy

The microbiome has been proven to be associated with many diseases and has been used as a biomarker and target in disease prevention and intervention. Currently, the vital role of the microbiome in pregnant women and newborns is increasingly emphasised. In this review, we discuss the interplay of the microbiome and the corresponding immune mechanism between mothers and their offspring during the perinatal period. We aim to present a comprehensive picture of microbial transmission and potential immune imprinting before and after delivery. In addition, we discuss the possibility of in utero microbial colonisation during pregnancy, which has been highly debated in recent studies, and highlight the importance of the microbiome in infant development during the first 3 years of life. This holistic view of the role of the microbial interplay between mothers and infants will refine our current understanding of pregnancy complications as well as diseases in early life and will greatly facilitate the microbiome-based prenatal diagnosis and treatment of mother-infant-related diseases.

Construction of a nomogram model for predicting infectious intrapartum fever

OBJECTIVES

To investigate influencing factors of intrapartum fever during vaginal delivery and to construct a prediction model for infectious intrapartum fever.

METHODS

A total of 444 patients with intrapartum fever admitted in Ningbo Women and Children's Hospital from January 2020 to December 2021 were enrolled. The clinical data and laboratory findings were compared between patients with infectious intrapartum fever and non-infectious intrapartum fever, and the factors associated with intrapartum fever were analyzed with a multivariate logistic regression model. A prediction nomogram model was constructed based on the factors of intrapartum fever and its predictive efficiency was evaluated by correction curve and receiver operator characteristic curve.

RESULTS

In the 444 cases, 182 (41.0%) had definite intrauterine infection and 262 (59.0%) had no infectious intrapartum fever. Univariate analysis showed that the length of hospital stay before induced labor, the time of induced abortion, misoprostol administration, autoimmune diseases, white blood cell count (WBC) and hypersensitive C-reactive protein (hs-CRP) levels were significantly different between the two groups (all P<0.05). Multivariate analysis showed that misoprostol administration and autoimmune diseases were protective factors (OR=0.31 and 0.36, both P<0.05) for infectious intrapartum fever, while high WBC and hs-CRP were risk factors (OR=1.20 and 1.09, both P<0.05). The area under the curve of nomogram model for predicting infectious intrapartum fever was 0.823, and the calibration curve validation showed that the predicted and measured values were in general agreement.

CONCLUSIONS

Multiple factors cause intrapartum fever. The nomogram model constructed in this study has good predictive accuracy for infectious intrapartum fever.