How Oral Bacteria Influence Blood Pressure During Pregnancy
Imagine if a simple mouthful of leafy greens or a routine dental cleaning could hold the key to a healthier pregnancy. For the approximately 10% of pregnant women worldwide who develop hypertensive disorders, this possibility is closer to reality than we once thought. 1 3 Emerging research is revealing a fascinating connection between the microscopic universe of bacteria living in our mouths and the serious blood pressure complications that can arise during pregnancy.
These conditions pose significant risks to both mother and baby, with potential consequences that can extend long after delivery.
The oral microbiome—the diverse community of bacteria, fungi, and viruses that call our mouths home—was once considered largely separate from our systemic health. We now know that these oral inhabitants don't just stay put; they can influence distant organs and bodily processes, including cardiovascular function. For pregnant women, this connection takes on special significance, as hypertensive disorders like preeclampsia pose risks to both mother and baby. 3 4
At the heart of this oral-cardiovascular connection lies a remarkable biochemical pathway that transforms dietary nutrients into powerful blood pressure-regulating compounds.
When you consume nitrate-rich foods like spinach, beetroot, and lettuce, these compounds are rapidly absorbed through your digestive system into your bloodstream. 3
Specialized transporters in your salivary glands actively pull these nitrates from your blood and concentrate them in your saliva. 3
This is where oral bacteria play their crucial role. Select bacteria in your mouth—particularly on the surface of your tongue—possess enzymes called nitrate reductases that convert nitrate to nitrite. 3
Once you swallow this nitrite-rich saliva, it enters a cascade of reactions that ultimately produce nitric oxide (NO)—one of your body's most potent vasodilators, meaning it relaxes and widens blood vessels, thereby lowering blood pressure. 3
This pathway serves as an elegant backup system for nitric oxide production, especially when the primary pathway (which uses the amino acid L-arginine) becomes compromised—as often happens in hypertensive disorders. 3
Research has identified several important genera of oral bacteria involved in this nitrate-reduction process:
| Bacterial Genus | Potential Role in Blood Pressure Regulation | Significance |
|---|---|---|
| Neisseria | Among the most significant contributors to nitrate reduction | Key Player |
| Veillonella | Strong nitrate-reducer; often elevated in hypertensive individuals | Paradoxical |
| Prevotella | Most abundant nitrate-reducing genus; correlated with blood pressure | Key Player |
| Rothia | Associated with oral nitrate reduction | Contributor |
| Staphylococcus | Linked to oral nitrate reduction processes | Contributor |
Table 1: Key Nitrate-Reducing Oral Bacteria 3 4
In a groundbreaking 2025 study published in the International Journal of Oral Science, researchers from Singapore, the U.S., and Australia embarked on a novel approach to understanding pregnancy hypertension. Instead of relying on invasive blood tests, they turned to a more accessible bodily fluid: saliva. 5
The research team recruited 80 pregnant women between 24-34 weeks of gestation, collecting saliva samples which they analyzed using advanced mass spectrometry. This sophisticated technology allowed them to map over 700 metabolites and identify more than 18,000 significant associations between environmental chemicals and metabolic pathways. 5
Participants: 80 pregnant women
Method: Saliva analysis via mass spectrometry
Metabolites Mapped: 700+
Chemicals from food packaging and additives were significantly elevated in the preeclampsia group.
Dopamine, norepinephrine, and epinephrine were all higher, activating stress response and raising BP.
Monoamine oxidase (MAO) was inhibited, disrupting neurotransmitter breakdown.
These specific chemicals were associated with higher stress hormones.
Toluene Styrene Quinoline CoumarinTable 2: Key Findings from the 2025 Saliva Study 5
The researchers discovered that certain chemicals—commonly found in food packaging, additives, or flavorings—were significantly associated with higher levels of stress hormones. These chemicals, including toluene, styrene, quinoline, and coumarin, are known to inhibit an enzyme called monoamine oxidase (MAO). 5
When MAO isn't functioning properly, it leads to an imbalance in neurotransmitters and stress hormones. This imbalance can trigger a cascade of events that ultimately raise blood pressure and increase the risk of preeclampsia. The study provided the first direct evidence that these chemical exposures—detectable in saliva—could be contributing to hypertensive disorders in pregnancy through this specific biological mechanism. 5
The influence of oral bacteria extends beyond blood pressure regulation. Research has detected oral bacteria in places they shouldn't normally be—including the placenta and amniotic fluid. 2 6
In particular, the oral bacterium Fusobacterium nucleatum has been implicated in adverse pregnancy outcomes. 2
These traveling oral bacteria can trigger inflammatory responses that may contribute to complications like preterm birth and stillbirth. The placenta microbiome (the community of bacteria in this temporary organ) more closely resembles the mother's oral microbiome than her gut microbiome, highlighting the special connection between oral and reproductive health. 6
The relationship between oral bacteria and pregnancy complications may also involve psychological factors. A 2024 study in BMJ Mental Health found that the oral microbiome varies significantly with stress and mental health symptoms in pregnant women. 9
Women experiencing high anxiety or depression showed different oral microbiome profiles compared to those with lower symptoms. Those with high PTSD symptoms had particularly distinct microbial communities.
This suggests that psychological stress during pregnancy may shape the oral microbiome in ways that could influence physical health outcomes, including blood pressure regulation. 9
An innovative approach called Prenatal Total Oral Rehabilitation (PTOR) offers promise for improving pregnancy outcomes. This comprehensive dental treatment aims to restore women's oral health to a "disease-free status" before delivery through cleaning, fillings, extractions, root canals, and periodontal treatment as needed. 6
Decreased levels of harmful bacteria like Tannerella forsythia and Treponema denticola
Beneficial changes in immune markers related to preeclampsia risk
Reduced transmission of cavity-causing bacteria to babies
The nitrate-nitrite-NO pathway suggests several practical approaches for managing blood pressure during pregnancy:
| Intervention | Mechanism | Examples | Effectiveness |
|---|---|---|---|
| Nitrate-rich foods | Provides raw material for NO production | Beetroot, spinach, lettuce, celery |
|
| Probiotics | May introduce beneficial nitrate-reducers | Specific bacterial strains (research ongoing) |
|
| Prebiotics | Promotes growth of beneficial oral bacteria | Dietary fibers, certain nutrients |
|
| Oral hygiene | Maintains balanced oral microbiome | Regular brushing, flossing, dental check-ups |
|
Table 3: Dietary and Microbial Interventions for Blood Pressure Health 1 3
While the connections between the oral microbiome and hypertensive pregnancies are compelling, researchers caution that many questions remain unanswered. Current evidence shows association rather than definitive causation, and more studies—particularly large-scale randomized trials—are needed before specific oral microbiome-targeted treatments become standard care. 1 3
Several clinical trials are already underway, including one specifically investigating the role of the oral microbiome in hypertensive pregnancy disorders (study identifier: NCT03930693). 3
The emerging science reveals our oral microbiome as an unexpected partner in maternal health—one that transforms our dietary nutrients into blood pressure-regulating compounds and communicates with distant organs, including the placenta. While not a standalone solution for preventing or treating hypertensive disorders of pregnancy, oral health represents a promising piece of the puzzle.