By Mary Dixon Lebeau

You’ve reached the home stretch, your 36th week. All you have to do is sit back, put your feet up, and wait for labor to start, right? Not exactly. First, do you know what your group B strep status is?

“It’s extremely important that every pregnant woman knows her beta strep status before she goes into labor,” says Randy Fink, M.D., an ob/gyn in private practice in Miami. “If your doctor doesn’t test you, go to someone who will.”

What Is Group B Strep?
Group B strep—also known as GBS, beta strep, or, more formally, group B streptococcus—is an very common bacteria found in the vagina or lower intestine of many healthy adult women. “I like to stress that a positive test result is extremely common,” Fink says.

“Unfortunately, when patients hear they tested positive, they think they’ve contracted a terrible disease. It’s simply bacteria,” Fink continues. “It’s not considered a sexually transmitted disease, though it is common in sexually active people.”

And even if you test positive, you’re not sick. “Group B strep is not an infection,” says Ralph Dauterive, M.D., chairman of obstetrics and gynecology at Ochsner Clinic and Foundation in Baton Rouge, LA. But if you’re not sick, why is knowing your status so important? Do you really need another test so late in pregnancy?

The answer is a resounding yes. “The problem isn’t the bacteria,” Fink explains. “The problem is the risk associated with the bacteria.” That risk is group B strep disease—the most common cause of life-threatening infections in newborns, according to the Centers for Disease Control and Prevention (CDC).

How Can It Affect My Baby?
If a mother tests positive for group B strep, her baby can be exposed to the bacteria while passing through the birth canal. Exposure can result in one of two types of group B strep disease. “Early-onset disease” happens within the first week of life and is often noticeable within the first few hours out of the womb. Babies with early-onset disease can develop a variety of illnesses, including pneumonia, sepsis (a blood infection), and meningitis.

“Late-onset disease,” on the other hand, develops in infants between 1 week and 3 months of age.