The gut microbiome refers to the trillions of microorganisms, including bacteria, viruses, fungi, and other microbes, that inhabit the gastrointestinal tract. Emerging research suggests that the gut microbiome can play a role in influencing various aspects of health, including pregnancy. The human indigenous gut microbiome can play a critical role in overall health and may be especially important for mother and fetus during pregnancy.  

During pregnancy, in birth and later in breastfeeding, mothers pass on gut microbiota to their infants, which starts to colonize the babies’ guts and then contributes to more diversification of the gut microbiota. When that early colonization is disturbed, there is an increased risk of developing a range of conditions later in life, including obesity, allergies and cardiovascular diseases. Dysbiosis of the gut microbiome during pregnancy is associated with gestational diabetes, preeclampsia and restricted fetal growth among others [1,2,3]. While not a consensus in the biomedical field, manipulating the composition of the maternal gut microbiome during pregnancy with probiotics could result in improved maternal health and pregnancy outcomes [1].

Only limited evidence is available to thoroughly understand the changes in gut microbiota during pregnancy and its impact on maternal and fetal health. However, according to the available literature, low-grade inflammation at the intestinal mucosa as well as hormonal changes, might be responsible for gut microbiota alteration during pregnancy. In addition, adult human gut microbiota can be influenced by many factors, including body mass index (BMI), medications, diseases, environment, and lifestyle (diet, physical activity, smoking, and drinking habits). Pre-pregnancy exposure to these factors can lead to structural and functional alteration in maternal gut microbiota during pregnancy. A growing body of evidence shows that diet is one of the most powerful factors driving the gut microbiota. This is why maternal nutrition during pregnancy is believed to be crucial to supporting mothers’ health while also promoting adequate infant growth and development [4,5].

While the field is still evolving, here are some ways in which the gut microbiome may affect pregnancy:

  • Immune System Regulation: The gut microbiome has a significant impact on the immune system. During pregnancy, the immune system undergoes changes to tolerate the developing fetus [6]. Imbalances in the gut microbiome may influence immune responses, potentially contributing to complications such as preterm birth or preeclampsia.
  • Inflammation: Imbalances in the gut microbiota can lead to inflammation, which may affect pregnancy outcomes. Chronic inflammation has been linked to conditions like gestational diabetes and preterm birth [2,3].
  • Nutrient Metabolism: The gut microbiome plays a role in the metabolism of nutrients. Changes in the composition of the gut microbiota may influence how the body processes and absorbs nutrients, which can impact the health of both the mother and the developing fetus [4].
  • Hormonal Regulation: Gut microbes can interact with hormones, and this interaction may influence hormonal regulation during pregnancy. Hormones play a crucial role in maintaining a healthy pregnancy, and any disruption in their balance could lead to complications.
  • Maternal Mental Health: There is a bidirectional communication pathway between the gut and the brain known as the gut-brain axis. The gut microbiome can influence mental health, and maternal stress or mental health during pregnancy can affect the developing fetus.
  • Metabolites Production: Gut bacteria produce various metabolites, such as short-chain fatty acids, which can have systemic effects. These metabolites are considered postbiotics and may play a role in supporting a healthy pregnancy by influencing immune function and inflammation. 


Final Thoughts

It’s important to note that the research on this topic is still in its early stages, and our understanding of the complex interactions between the gut microbiome and pregnancy is continually evolving. Factors such as diet, antibiotic use, and overall health can influence the composition of the gut microbiome, and these factors may, in turn, impact pregnancy outcomes. However, in terms of impact on offspring, current thought is that the effect of the maternal gut microbiome on the fetus is not significant [3]. 

While there is growing interest in this area, more research is needed to fully understand the mechanisms and potential therapeutic interventions related to the gut microbiome and pregnancy. Pregnant individuals should consult with healthcare professionals for personalized advice based on their specific health conditions and needs.



[1] Zakaria, Z. Z., Al-Rumaihi, S., Al-Absi, R. S., Farah, H., Elamin, M., Nader, R., Bouabidi, S., Suleiman, S. E., Nasr, S., & Al-Asmakh, M. (2022). Physiological Changes and Interactions Between Microbiome and the Host During Pregnancy. Frontiers in cellular and infection microbiology, 12, 824925.

[2] Gorczyca, K., Obuchowska, A., Kimber-Trojnar, Ż., Wierzchowska-Opoka, M., & Leszczyńska-Gorzelak, B. (2022). Changes in the Gut Microbiome and Pathologies in Pregnancy. International journal of environmental research and public health, 19(16), 9961.

[3] Yao Y, Cai X, Chen C, Fang H, Zhao Y, Fei W, Chen F and Zheng C (2020). The Role of Microbiomes in Pregnant Women and Offspring: Research Progress of Recent Years. Front. Pharmacol. 11:643. https://doi:10.3389/fphar.2020.00643

[4] Sinha T. 2023. The maternal gut microbiome during pregnancy and its role in maternal and infant health. Current Opinion in Microbiology.

[5] Izaskun García-Mantrana, Marta Selma-Royo, Sonia González, Anna Parra-Llorca, Cecilia Martínez-Costa & María Carmen Collado (2020) Distinct maternal microbiota clusters are associated with diet during pregnancy: impact on neonatal microbiota and infant growth during the first 18 months of life, Gut Microbes, 11:4, 962-978, https://doi:10.1080/19490976.2020.1730294

[6] Koren, O., Konnikova, L., Brodin, P. et al. The maternal gut microbiome in pregnancy: implications for the developing immune system. Nat Rev Gastroenterol Hepatol 21, 35–45 (2024).