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Medical student’s pilot study investigates relationship between obesity during pregnancy and potentially harmful bacteria that may predict negative birth outcomes

Catherine Doss

12 Mar 2024

Woman wearing a white lab coat working with instruments in a lab — While investigating the relationship between obesity and negative birth outcomes, Kelly Ingram discovered that two types of vaginal bacteria were part of the equation. Photo by Ryan Anderson for Virginia Tech.

It is well documented that women who are overweight or obese are more likely to have pregnancy complications such as pre-term birth, gestational hypertension, diabetes, or preeclampsia than women of healthy weight. Kelly Ingram, a fourth-year student at the Virginia Tech Carilion School of Medicine, recently completed a research study examining the impact of obesity on the bacteria in a woman’s vaginal microbiome as a possible reason why.

“Lower total estrogen levels in obese pregnant women potentially dampens the mechanism that initiates a dynamic relationship in the vaginal environment and among vaginal bacteria in pregnant women,” Ingram said. “This may be associated with a bacterial imbalance and unfavorable pregnancy outcomes.”

Ingram’s research project earned her a Letter of Distinction at the school’s 2024 Student Research Symposium.

Project overview

“We hypothesized that estrogen and glycogen levels would be lower, vaginal pH would be higher, and vaginal microbiome diversity would be greater during pregnancy in obese and overweight women compared to healthy weight women,” Ingram said.

Her research involved collecting a series of samples from pregnant women measuring the above criteria at four gestational time points and a fifth round of samples when their babies were born. Her sample of 67 pregnant women was evenly divided among women of healthy weight, women who were overweight, and women who were obese. She then looked at all of their pregnancy outcomes to see if there were any differences.

With the help of a research assistant, Embelle Ngalame Eko, Ingram meticulously kept track of each of the participants, when their check-ups were scheduled, and was able to see them and their babies soon after birth.

“I was pleasantly surprised about how excited these women were to participate in this research study. It was fun getting to know them,” Ingram said.

Findings

“The big things that we found were that the greatest differences in our variables were at a really early time point: 10 to 14 weeks gestation,” Ingram said.

She also made another interesting discovery. Two types of vaginal bacteria were significantly increased in overweight and obese participants. In addition, for women who had pregnancy complications, the same two bacteria were elevated.

“It was super exciting that we were able to make this discovery with our relatively small sample size and that it was statistically significant,” Ingram said.

“Kelly’s work, from its conception was thoughtfully conceived to not only generate mechanistic insight into the role of the vaginal environment on birth outcomes, but also to define tractable targets for reducing risk for poor birth outcomes,” said Brittany Howell, assistant professor at the Fralin Biomedical Research Institute at VTC and one of Ingram’s two research mentors.

In another, smaller part of the study, Ingram collected skin and oral swabs from the babies right after they were delivered to see what types of bacteria were being transferred from the mother to the baby during delivery. She, Howell, and her second research mentor, Jaclyn Nunziato, associate professor of OB-GYN at the medical school, will present their findings at an international conference in Scotland this spring.

“Kelly exemplifies the qualities of diligence, accountability, self-motivation, and remarkable aptitude making her one of the most impressive students I have had the privilege of working with,” Nunziato said. “Her commitment to academic excellence and her passion for advancing medical knowledge are truly commendable.”

Significance of research

Ingram’s research reveals the profound impact of maternal pre-pregnancy weight and transfer of the microbiome from mother to infant, both of which are crucial factors influencing infant health.

The ultimate goal would be to test for some of the variables Ingram studied during a woman’s early prenatal visits and recommend treatment options in order to lower the risk of pregnancy complications.

“The next step, though, is to do a much larger research study with a more diverse population specifically looking at the two bacteria that were present.”