Manipulating the maternal microbiome to optimise pregnancy
Date
02 Sep 2025
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MATERNAL IMMUNE ACTIVATION
Pregnancy is a complex process in which several immune, hormonal and metabolic changes occur.1 In tandem with these changes, the maternal microbiome also undergoes significant transformation at various sites of the body, including the gastrointestinal tract, vagina, placenta and oral cavity2 (see Figure 1). These changes may last for up to 6 months post- partum.3
Pregnancy is known to increase vulnerability to infection due to the complex immune and hormonal shifts that occur.4 Therefore, pregnant women are at risk of maternal immune activation, which describes the activation of the pregnant woman’s immune system due to an infectious trigger, such as a virus or bacteria. Subsequent changes within the maternal immune system occur leading to:
• Alterations in cytokine signalling that drive inflammation5
• Epigenetic modifications5
• Modification in healthy function of the placenta5
While a stable and balanced microbiome assists with maintaining a healthy pregnancy, perturbations in maternal microbiome composition may do the opposite, increasing risk of pregnancy complications such as gestational diabetes mellitus (GDM), preeclampsia and preterm birth.2 Additionally, foetal growth and neurodevelopment may be impacted, with emerging evidence suggesting increased occurrence of ASD and ADHD in the offspring.4,6-8
Key highlights
- The maternal microbiome is essential for healthy pregnancy due to its role in modulating immune responses.
- Exposure to infective organisms and release of inflammatory compounds activate the maternal immune system, contributing to dysbiosis.
- Alterations in microbial diversity and function during pregnancy may be linked to maternal gestational diabetes, obesity and preeclampsia, as well as autism spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD) in the offspring.
- Reducing dysbiosis and optimising microbiome balance with strain specific probiotics may mitigate some pregnancy risks and support foetal immune programming and neurodevelopment.
- Co-supplementing probiotics with vitamin D enhances outcomes.