**2.4 Review of existing literature on vaginal seeding, including studies on microbiome composition, immune development, and health outcomes**

In recent years, several studies have investigated the impact of vaginal seeding on the neonatal microbiome composition, immune development, and various health outcomes. Here, we review the existing literature on vaginal seeding, highlighting key findings and insights in these areas.

Microbiome composition: Studies examining the neonatal microbiome composition following vaginal seeding have reported varying results. Some studies have shown that vaginal seeding leads to an increased abundance of bacteria associated with vaginal birth, such as Lactobacillus and Bifidobacterium species, in the gut and other body sites of C-section-born infants. These findings suggest that vaginal seeding can help establish a microbial community resembling that of infants born vaginally [19–23].

However, other studies have reported inconsistent or limited effects of vaginal seeding on the neonatal microbiome composition. Methodological differences, including variations in the timing and techniques of vaginal fluid transfer, sample collection methods, and analysis techniques, may contribute to the discrepancies in findings. Larger, well-controlled studies with standardized protocols are needed to further elucidate the impact of vaginal seeding on the neonatal microbiome composition [19–23].

Immune development: The influence of vaginal seeding on immune development in newborns has also been explored. Some studies have suggested that vaginal seeding may promote immune maturation such as indicated by changes in immune cell populations, cytokine profiles, and immune markers. These findings indicate that exposure to maternal vaginal microbiota through vaginal seeding may play a role in modulating immune responses and promoting immune tolerance.

However, the clinical significance and long-term implications of these immune changes remain unclear. Further, research is needed to establish a clear link between vaginal seeding and immune development, considering factors such as the timing and frequency of vaginal seeding, potential variations in immune outcomes, and the interplay with other factors influencing immune development [19–23].

Health outcomes: The potential impact of vaginal seeding on health outcomes in C-section-born infants has been a topic of interest. Some observational studies have reported associations between vaginal seeding and a reduced risk of certain health conditions, including allergies, asthma, and autoimmune disorders. These findings suggest that vaginal seeding may have long-term health benefits by influencing the neonatal microbiome and immune system [23–25].

However, the evidence on health outcomes and the clinical significance of these associations is limited and often based on small-scale studies or anecdotal reports. Larger, well-designed studies, including randomized controlled trials, are needed to further investigate the potential benefits and long-term effects of vaginal seeding on health outcomes. It is essential to consider potential confounding factors, such as breastfeeding practices and other early life exposures, when assessing the impact of vaginal seeding on health outcomes [23–27].

In summary, the existing literature on vaginal seeding indicates a potential influence on the neonatal microbiome composition, immune development, and health outcomes. While some studies suggest positive associations between vaginal seeding and beneficial outcomes, the evidence is limited, and conflicting results have been reported. Further, research, including larger-scale studies with standardized protocols, is necessary to establish a clearer understanding of the effects of vaginal seeding on the neonatal microbiome, immune development, and long-term health outcomes.

Despite the growing interest in vaginal seeding, there are several gaps in the current knowledge that need to be addressed through further research. These gaps include:

Lack of standardized protocols: There is a lack of standardized protocols for assessing the maternal vaginal microbiota, including methods for sample collection, processing, and analysis. Standardized protocols are crucial for ensuring consistency across studies and facilitating comparisons between different research findings [23–25].

Variations in vaginal seeding practices: Vaginal seeding practices vary widely across studies, including differences in the timing and techniques of vaginal fluid transfer, the selection of participants, and the criteria for determining eligibility. These variations make it difficult to draw definitive conclusions or compare results between studies. Standardized protocols for vaginal seeding are needed to establish consistency in practice and facilitate meaningful comparisons [25–29].

Small sample sizes: Many studies investigating vaginal seeding have relatively small sample sizes, which may limit the generalizability and statistical power of the findings. Larger-scale studies with adequate sample sizes are required to provide more robust evidence regarding the effects of vaginal seeding on the neonatal microbiome, immune development, and health outcomes.

Long-term follow-up studies: There are not enough long-term follow-up studies to evaluate the consequences of vaginal seeding after birth. Longitudinal studies that track infants exposed to vaginal seeding over an extended period are needed to evaluate the persistence of any observed effects and to assess potential health outcomes, including allergies, asthma, autoimmune disorders, and metabolic conditions.

Limited diversity of participants: Many studies on vaginal seeding have primarily focused on populations from developed countries, limiting the generalizability of the *Vaginal Seeding in Term Cesarean Section Is a Mandatory Condition for Improvement… DOI: http://dx.doi.org/10.5772/intechopen.114043*

findings to other populations and settings. It is essential to include diverse populations, including those from different geographical regions and with varying sociocultural backgrounds, to understand the broader implications of vaginal seeding [25–29].

Safety concerns and screening protocols: Safety concerns regarding the potential transmission of harmful microorganisms during vaginal seeding need to be addressed. Standardized protocols for evaluating the maternal vaginal microbiota, including screening for infections and identification of potential pathogens, are necessary to ensure the safety of vaginal seeding procedures.

Mechanistic understanding: While studies have explored the effects of vaginal seeding on the neonatal microbiome and immune development, the underlying mechanisms are not well understood. Further, research is needed to elucidate the specific pathways through which vaginal seeding influences these processes and to identify the key microbial factors driving any observed effects. Addressing these gaps in the current knowledge will provide a more comprehensive understanding of vaginal seeding and its implications for neonatal health [29–31]. Large-scale, well-controlled studies with standardized protocols, long-term follow-up, diverse populations, and a focus on safety considerations are crucial for advancing our understanding of the potential benefits, risks, and mechanisms of action associated with vaginal seeding.
