The fecal microbiota of gravidas with fetal growth restriction newborns characterized by metagenomic sequencing

Intestinal flora and pregnancy complications: Current insights and future prospects

Numerous studies have demonstrated the pivotal roles of intestinal microbiota in many physiopathological processes through complex interactions with the host. As a unique period in a woman's lifespan, pregnancy is characterized by changes in hormones, immunity, and metabolism. The gut microbiota also changes during this period and plays a crucial role in maintaining a healthy pregnancy. Consequently, anomalies in the composition and function of the gut microbiota, namely, gut microbiota dysbiosis, can predispose individuals to various pregnancy complications, posing substantial risks to both maternal and neonatal health. However, there are still many controversies in this field, such as "sterile womb" versus "in utero colonization." Therefore, a thorough understanding of the roles and mechanisms of gut microbiota in pregnancy and its complications is essential to safeguard the health of both mother and child. This review provides a comprehensive overview of the changes in gut microbiota during pregnancy, its abnormalities in common pregnancy complications, and potential etiological implications. It also explores the potential of gut microbiota in diagnosing and treating pregnancy complications and examines the possibility of gut-derived bacteria residing in the uterus/placenta. Our aim is to expand knowledge in maternal and infant health from the gut microbiota perspective, aiding in developing new preventive and therapeutic strategies for pregnancy complications based on intestinal microecology.

ÁP, Alvarez AM. From gut to placenta: understanding how the maternal microbiome models life-long conditions

The microbiome -defined as the microbiota (bacteria, archaea, lower and higher eukaryotes), their genomes, and the surrounding environmental conditions- has a well-described range of physiological functions. Thus, an imbalance of the microbiota composition -dysbiosis- has been associated with pregnancy complications or adverse fetal outcomes. Although there is controversy about the existence or absence of a microbiome in the placenta and fetus during healthy pregnancy, it is known that gut microbiota can produce bioactive metabolites that can enter the maternal circulation and may be actively or passively transferred through the placenta. Furthermore, the evidence suggests that such metabolites have some effect on the fetus. Since the microbiome can influence the epigenome, and modifications of the epigenome could be responsible for fetal programming, it can be experimentally supported that the maternal microbiome and its metabolites could be involved in fetal programming. The developmental origin of health and disease (DOHaD) approach looks to understand how exposure to environmental factors during periods of high plasticity in the early stages of life (e.g., gestational period) influences the program for disease risk in the progeny. Therefore, according to the DOHaD approach, the influence of maternal microbiota in disease development must be explored. Here, we described some of the diseases of adulthood that could be related to alterations in the maternal microbiota. In summary, this review aims to highlight the influence of maternal microbiota on both fetal development and postnatal life, suggesting that dysbiosis on this microbiota could be related to adulthood morbidity.

Silicone breast implants may contribute to early-onset fetal growth restriction

INTRODUCTION

There are many studies showing that silicone breast implants may affect lactation, but few analyzed whether these implants affect placentation. We observed that many mothers with growth-restricted pregnancies had inflammatory conditions, such as silicone breast implants or giardiasis.

METHODS

This single-center cohort study assessed the prevalence of inflammatory conditions in normotensive growth-restricted singleton pregnancies. Next, we stratified the patients according to the presence or absence of silicone breast implants, to determine whether these implants influence fetal growth restriction onset or severity.

RESULTS

Twelve (32%) of the 38 participants underwent cosmetic breast augmentation 4-18 years before pregnancy. Half of the patients with and 38% without silicone breast implants had giardiasis. Half of the mothers with and 35% without silicone breast implants had autoantibodies. Silicone breast implants were associated with a 70% increased risk of fetal growth restriction before 32 weeks' gestation (95% confidence interval [CI], 1.2-2.5). Fetal growth restriction was diagnosed significantly earlier in mothers with than in those without silicone breast implants, respectively at 27 (95% CI, 25-30) and 30 weeks' gestation (95% CI, 29-32). Silicone breast implants also tripled the risk of fetuses being below the third percentile, but the difference was not significant.

CONCLUSION

Our results suggest that the association of inflammatory conditions, such as silicone breast implants, giardiasis, and autoantibodies may contribute to placental insufficiency. Silicone breast implants older than four years increased the risk of early-onset fetal growth restriction. Studies with large samples are needed to validate our findings and define whether silicone-related fetal growth restriction should be included in autoimmune/inflammatory syndrome induced by adjuvants (ASIA) criteria. Key Points • Fetal growth restriction (FGR), responsible for 30% of stillbirths, is the most common cause of prematurity and intrapartum asphyxia. • In this study, including 38 mothers with normotensive FGR, all participants had 2-4 inflammatory conditions, such as giardiasis, sinusitis, candidiasis, dysbiosis, extreme fear or autoantibodies. • Silicone breast implants were associated with a 70% increased risk of fetal growth restriction before 32 weeks' gestation. • FGR was diagnosed at 27 weeks' gestation (95% CI, 25-30) in mothers with and at 30 weeks' gestation (95% CI, 29-32) in mothers without silicone breast implants.

Evaluating Current Molecular Techniques and Evidence in Assessing Microbiome in Placenta-Related Health and Disorders in Pregnancy

The microbiome is of great interest due to its potential influence on the occurrence and treatment of some human illnesses. It may be regarded as disruptions to the delicate equilibrium that humans ordinarily maintain with their microorganisms or the microbiota in their environment. The focus of this review is on the methodologies and current understanding of the functional microbiome in pregnancy outcomes. We present how novel techniques bring new insights to the contemporary field of maternal-fetal medicine with a critical analysis. The maternal microbiome in late pregnancy has been extensively studied, although data on maternal microbial changes during the first trimester are rare. Research has demonstrated that, in healthy pregnancies, the origin of the placental microbiota is oral (gut) rather than vaginal. Implantation, placental development, and maternal adaptation to pregnancy are complex processes in which fetal and maternal cells interact. Microbiome dysbiosis or microbial metabolites are rising as potential moderators of antenatal illnesses related to the placenta, such as fetal growth restriction, preeclampsia, and others, including gestational diabetes and preterm deliveries. However, because of the presence of antimicrobial components, it is likely that the bacteria identified in placental tissue are (fragments of) bacteria that have been destroyed by the placenta's immune cells. Using genomic techniques (metagenomics, metatranscriptomics, and metaproteomics), it may be possible to predict some properties of a microorganism's genome and the biochemical (epigenetic DNA modification) and physical components of the placenta as its environment. Despite the results described in this review, this subject needs further research on some major and crucial aspects. The phases of an in utero translocation of the maternal gut microbiota to the fetus should be explored. With a predictive knowledge of the impacts of the disturbance on microbial communities that influence human health and the environment, genomics may hold the answer to the development of novel therapies for the health of pregnant women.