Significant Shifts in Oral Microbiome During Pregnancy Could Contribute to Tooth Loss

A popular saying suggests that “if you give birth to a child, your teeth will fall out.” While pregnancy is known to elevate the risk of dental issues, the underlying reasons remain somewhat unclear. Recent studies indicate that the oral microbiome alters during pregnancy, becoming less diverse and potentially more susceptible to inflammation.

Hormonal changes during pregnancy are often cited as the main culprits for the increased risk of conditions like periodontal disease and tooth decay. Moreover, there’s a widespread belief that the fetus extracts calcium from the mother’s teeth, a notion that lacks scientific backing.

Disruption of the oral microbiome, which comprises over 700 bacterial species, can lead to dental issues regardless of pregnancy status. However, Yoram Luzon and his team from Bar-Ilan University in Israel aimed to explore whether this typically stable ecosystem shifts during pregnancy. They collected saliva samples from 346 Israeli women across all three trimesters: 11-14 weeks, 24-28 weeks, and 32-38 weeks.

Their investigation revealed a decrease in species diversity in saliva samples starting from the transition between the first and second trimesters, continuing to decline throughout the pregnancy. A notable characteristic was the reduction in the number of species, with Akkermansia muciniphila, often hailed as a beneficial bacterium, declining alongside an increase in pro-inflammatory bacteria like Gammaproteobacteria and Synergystobacteria.

“While the oral microbiome is generally stable, we have noted a gradual decrease in its diversity over the years,” Louzoun observes. “Pregnancy accelerates this slow evolution, allowing changes that typically take years to manifest in just nine months.”

Despite being relatively minor overall, numerous factors may contribute to these changes. “Pregnancy involves a multitude of hormonal shifts and inflammation, leading to alterations in your microbiome,” explains Lindsay Edwards from King’s College London. “Dietary changes are frequent during pregnancy, and various factors such as nausea, medication cessation, and altered eating habits all play a role.”

The participants filled out questionnaires regarding their diets and health, allowing the researchers to identify similar yet distinct effects among different women. This included those who followed a gluten-free diet, took antibiotics, experienced stress, or were current or former smokers. “Many women quit smoking during pregnancy, but their prior smoking habits can impact their microbiome,” notes Dr. Luzon, emphasizing the potential long-term effects.

A parallel study found similar changes in the oral microbiomes of 154 pregnant women in Russia during their second and third trimesters.

Although pregnancy heightens the risk of dental complications, particularly in the early stages, Luzon does not definitively link oral microbiome changes to these issues. “We can’t conclude whether these microbiome alterations are beneficial or detrimental, but they are undoubtedly changing rapidly,” he states.

Conversely, Edwards suggests that shifts in microbial composition might be a contributing factor, highlighting that saliva tends to become more acidic during pregnancy, altering the types of bacteria present.

Valentina Biagioli and her colleagues from the University of Genoa in Italy assert that changes in the oral microbiome may correlate with variations in systemic hormone levels, as both systems potentially influence each other. “There exists a plausible biological link connecting the observed microbiome changes to prevalent dental issues during pregnancy, such as tooth loss,” she comments.

Disruption in the oral microbiome has been noted to relate to pregnancy complications. Consequently, establishing what constitutes an optimal microbiome during pregnancy could serve as a benchmark for monitoring pregnancy progression. “Once we establish the baseline oral microbiome of pregnancy, deviations can be detected,” Louzoun states.

Moreover, ongoing research aims to elucidate this microbiome’s role in the immune system, affecting both the health of the pregnant woman and her unborn child. “The microbiome is instrumental in shaping the immune system, fostering a reciprocal relationship,” Edwards explains.

In light of this, enhancing our understanding of how to sustain a healthy oral microbiome (e.g., via good dental hygiene and a balanced, nutritious diet) could yield significant benefits. “Microbiome changes may influence the inflammatory state of expectant parents and better prepare the child’s immune system, potentially affecting long-term health, allergies, infection susceptibility, and chronic inflammatory conditions,” cautions Edwards.