Premature birth is the No.1 killer of babies in America, and of the approximately 4,300,000 live births in the U.S. each year, about 12.3 percent are preterm.
The cause of prematurity — birth before the 37th week of pregnancy — is often a puzzle to experts, but a study at the Perelman School of Medicine at the University of Pennsylvania may have found the key: bacteria in the mom's cervix.
Depending on the specific type of bacteria in the mom's vagina and cervix, her risk of giving premature birth may be increased or reduced. Researchers theorize that by either eliminating the "bad" bacteria or increasing the "good" bacteria, they could prevent premature births.
"For the first time in eight years, the number of pre-term babies in the United States actually increased in 2016," said lead author Michal Elovitz, M.D.
"Unfortunately, there are underlying causes that doctors still don't understand," he said. "Decoding the causes of prematurity has been a riddle that's stumped researchers and clinicians for years, but our new study is finally shedding some light on a path toward offering treatment to women we can identify as being at-risk."
In the study, researchers examined vaginal swabs from a sample of 2,000 pregnant women, taken at three distinct points in pregnancy, to determine the types of microbes that were present.
Analysis showed that among the many specific types of bacteria, some, such as certain Bifidobacterium and Lactobacillus species, actually lowered the risk of spontaneous preterm birth. Others, specifically several anaerobic bacteria, significantly increased the risk.
Bifidobacterium and Lactobacillus are two types of probiotic bacteria that are found in the gastrointestinal tract. Both play an important role in the immune and digestive systems.
Anaerobic bacteria, which do not require oxygen to grow, are also found in the digestive tract, and they play a role in several conditions, including appendicitis and diverticulitis.
Elovitz says the new findings are the result of a new approach to studying the problem of prematurity, examining the cervix and vagina instead of limiting the study to the uterus, as conventional wisdom would suggest.
Although the authors say more research is needed they suggest their findings could mean that treatments targeting harmful cervical bacteria, or replenishing the protective bacteria could be used to prevent premature birth in the immediate future.