The Microbiome’s Murky Role in Pregnancy Loss and Complication

The microbiome’s role in pregnancy is not always clear. Researchers have recently found that the same vaginal bacteriacan have opposite effects on different pregnancy complications, even among the same population of women.

It could take more than two to make a healthy baby — many, many more.

Researchers are beginning to better understand how the millions of bacteria that make up the vaginal microbiome help shape a normal pregnancy — as well as the devastating complications that may arise when that microbial community is off balance.

study published recently by scientists at Temple University and Fred Hutchinson Cancer Research Center found that the very same bacteria can have entirely different effects on women’s risk of premature delivery or miscarriage. And that dichotomy — one bacteria causing help and harm — has researchers both baffled and intrigued.

It’s long been understood that the wrong mix of vaginal bacteria can increase the risk of premature delivery, when a baby is born earlier than 37 weeks gestation. More than 450,000 babies are born premature every year in the U.S., according to the Centers for Disease Control and Prevention. Preterm birth contributed to 35 percent of all infant deaths in 2010, more than any other single cause.

Normally, the vaginal environment is dominated by a few key bacterial species from the genus Lactobacillus, said Dr. David Fredricks, Fred Hutch’s resident vaginal microbiome expert. When that community is out of whack, bacterial vaginosis can result. . .  reader_3