By Mariya Petrova, PhD, Senior Science Educator, Winclove Probiotics
The past few decades have witnessed significant advancements in microbiome research, particularly concerning gut microbiota and its impact on our overall health. While there is a growing body of knowledge about various microbial niches, including in the oral cavity and on the skin, one area that has not received as much attention is the role of microbes in women’s health. Women’s health and the specific impact of their unique microbiotas throughout their lifespan remains largely underexplored. This is particularly concerning during pregnancy, a critical period in which women nurture and carry the next generation. Research in this area is still evolving, and the significance of microbes during this transformative period has often been overlooked. Nevertheless, the microbes that mothers pass on to their newborns play a vital role in early development.
Looking into the importance of mother microbes two distinct microbial niches play a major role during pregnancy, but also for the early development of the newborn – the vaginal and the gut microbiota. Even though this blog focus mostly on the gut microbiota, speaking for women’s health and pregnancy without briefly touching on the vaginal microbiota is impossible. As someone who actively participates in conferences and focuses on women’s health, I can confidently say that progress has been made in understanding the role of vaginal microbiota in pregnancy, although many questions remain, and new questions are frequently raised. Multiple studies have highlighted the importance of an optimal Lactobacillus-dominated vaginal microbiota in relation to preterm birth, shedding light on the potential implications for maternal and neonatal outcomes. However, one important question arises regarding the gut microbiota and its influence not only during pregnancy but also in the earlier stages of conception, as well as fertility and infertility. Gaining insights into the gut microbiota during this critical phase of women’s health can provide essential information on maintaining a healthy pregnancy and ensuring the well-being of both mother and baby. Furthermore, it opens avenues for considering appropriate probiotic interventions that could support maternal health during this vital period.
Before exploring pregnancy and the role of microbes, it’s essential to understand how microbes contribute to successful conception. Fertility and infertility have been a growing area of research in recent years1. It’s fascinating to think that microbes influence the future of the next generation. We now know that both the vaginal and endometrial microbiomes play a role in infertility and in successful in vitrofertilization (IVF)2–5. A diverse non-optimal vaginal microbiome, characterized by numerous non-beneficial bacteria and a low amount of Lactobacillus species is linked to reduced fertility and IVF failure. In other words, bacterial vaginosis (BV), whether asymptomatic or symptomatic, can be a contributing factor for a woman’s inability to conceive. For example, the presence of BV –associated bacteria such as Gardnerella, Prevotella, and Atopobium, as well as Escherichia, Enterococcus, and Streptococcus, are commonly detected in women with recurrent implantation failure and women who are less likely to achieve pregnancy following IVF2–7. Less known is that the gut microbiota also plays a role in female fertility. The gut microbiota plays a major role in the reproductive endocrine system throughout a woman’s lifetime by interacting with estrogen, androgens, insulin, and other hormones. Imbalance of the gut microbiota composition can lead to several infertility issues such as polycystic ovary syndrome (PCOS), and endometriosis but the exact mechanisms of action are still unknown8–10. For example, studies suggest that insulin resistance, sex hormone concentrations, and obesity may affect the diversity and composition of gut microbiota in women with PCOS8–10. Of interest, interventions with probiotics have been studied for their effects on infertility by targeting the gut microbiota and the above‑mentioned mechanisms. For example, a recent meta-analysis reports that probiotics have a significant impact on the regulation of hormonal and inflammatory indicators, with a significant decrease in the free androgen index and malondialdehyde, and demonstrated an improvement in the body weight, insulin, HOMA-IR, triglycerides, cholesterol, and testosterone of PCOS patients 11.
During pregnancy, the gut microbiota also plays a crucial role by influencing both maternal and fetal health. Some of the key functions of the gut microbiota during pregnancy include but are not limited to:
- Immune modulation: The gut microbiota helps to regulate the immune system, which is particularly important during pregnancy as the immune response must adapt to protect both the mother and the developing fetus.
- Nutrient absorption: The microbiota aids in the digestion and absorption of essential nutrients, including vitamins and minerals that are vital for the health of both the mother and baby. For instance, certain gut microbes are involved in synthesizing folate, which is crucial for fetal development.
- Metabolic regulation: Pregnancy induces significant metabolic changes, and the gut microbiota plays a role in regulating these changes, including energy metabolism and glucose homeostasis.
- Influence on baby’s microbiome: The gut microbiota can affect the colonization of the baby’s microbiome during birth and early infancy. A diverse maternal microbiota can lead to a more diverse microbiome in the newborn, which is linked to better health outcomes.
- Impact on mental health: Via the gut-brain axis the gut microbiota can influence mood and mental health. During pregnancy a healthy microbiota may help regulate stress and anxiety levels.
When looking at the composition of the gut microbiota during the first trimester of pregnancy, it resembles that of a healthy non-pregnant woman. Subsequently, the gut microbiome composition changes dramatically over gestation. From the second to the third trimester, a progressive reduction in α-diversity and an increase in β-diversity occurs12. These findings during pregnancy could be due to progressive weight gain (within the normal range) considered beneficial for fetal growth. Butyrate-producing bacteria, known for anti-inflammatory properties, decrease, whereas the amount of bifidobacteria, Proteobacteria, and lactic acid-producing bacteria increase13. As gestation progresses, the gut microbiome is gradually enriched with bacteria that promote weight gain and the production and storage of energy, which are essential for fetal growth and future breastfeeding 14–17. However, changes in the composition of the microbiota during pregnancy may also be associated with an unhealthy increase in adipose mass, blood glucose levels, insulin resistance, and the circulation of pro-inflammatory cytokines in the pregnant woman. As such, the gut microbiota during pregnancy can play a role in several health complications, such as gestational diabetes and hypertension, which, if untreated, may lead to preeclampsia. In that regard, a lesser known fact is that pregnancy and metabolic syndrome have the same core – insulin resistance and weight gain- and women’s body goes through the same metabolic changes14,15. Furthermore, some of the latest research points out that gut microbiota can also be used a predictor of early onset gestational diabetes as changes in microbial composition and SCFAs can be seen already at week 12 in women who develop gestation diabetes (normally diagnosed only at week 26-28). Therefore, targeting the gut microbiota, for example with probiotics, can benefit the mother’s general well-being but also focus on more specific indications such as gestational diabetes.
Maternal gut microbiome dysbiosis also seems to be related to adverse pregnancy outcomes. From years of research, we can now conclude that strong evidence for a relationship between the vaginal microbiota and preterm birth exists18–22. However, the role of the maternal gut microbiome in triggering preterm birth remains poorly studied and understood. For example, in a recent study, the researchers collected fecal samples from 41 women susceptible to preterm labor and found a different gut microbiome composition than those delivered at term23. Opportunistic pathogens, such as Porphyromonas, Streptococcus, Fusobacterium, and Veillonella ssp. were most represented, whereas Coprococcus and Gemmiger ssp. were significantly depleted in the preterm group. Interestingly, oral bacteria were the dominant community, suggesting that the oral cavity may represent an endogenous reservoir for the gut microbiome, and that bacteria could migrate through the digestive tract23. More research is needed to address the role of the gut microbiota during pregnancy.
In conclusion, maintaining a healthy balance of gut microbiota through a nutritious diet, probiotics, and prebiotics can thus be beneficial before conception and during pregnancy for both the mother and the developing child.
References:
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