Prevention in Newborns
The two most important ways to prevent early-onset group B strep (GBS) disease are:
- Testing pregnant women for GBS bacteria late in pregnancy (ideally between 35 and 37 weeks pregnant)
- Giving antibiotics during labor to women at increased risk, including those who test positive for GBS bacteria
Testing Pregnant Women
Doctors should test pregnant women for GBS bacteria when they are 35 to 37 weeks pregnant. About 1 in every 4 pregnant women carry GBS bacteria in their body. Women who test positive are not sick, but are at increased risk for passing the bacteria to their babies during birth.
The test is simple and does not hurt. Clinicians use a sterile swab (“Q-tip”) to collect a sample from the vagina and the rectum. They send the sample to a laboratory for testing.
A woman may test positive for the bacteria at some times and not others. That is why doctors should test pregnant women between 35 to 37 weeks of every pregnancy.
Note: Clinicians do not need to test women who had a previous baby who developed GBS disease. These women should receive antibiotics no matter what.
Antibiotics are very effective at preventing GBS disease in newborns. Consider the following examples.
Tanya tests positive for GBS bacteria and gets antibiotics during labor. Her baby has a 1 in 4,000 chance of developing GBS disease.
Maria tests positive for GBS bacteria and does not get antibiotics during labor. Her baby has a 1 in 200 chance of developing GBS disease.
This means Maria’s baby is 20 times more likely to get GBS disease compared to Tanya’s baby.
Antibiotics during Labor
Pregnant women should receive antibiotics through the vein (IV) during labor if:
- They test positive for GBS bacteria during their current pregnancy
- They have GBS bacteria in their urine anytime during their current pregnancy
- They had a previous baby who developed GBS disease
Pregnant women who do not know if they are positive for GBS bacteria when labor starts should receive antibiotics if they have:
- Labor starting at less than 37 weeks (preterm labor)
- Prolonged membrane rupture (water breaking 18 or more hours before delivery)
- Fever during labor
Giving antibiotics to pregnant women during labor helps protect their babies from infection. The antibiotics help during labor only — because the bacteria can grow back quickly; doctors cannot give antibiotics before labor begins. Penicillin is the most common antibiotic that doctors prescribe, but they can also give other antibiotics to women who are severely allergic to penicillin. Women should tell their doctor or nurse about any allergies during a checkup and try to make a plan for delivery. When arriving at the hospital, women should remind their doctor and any staff if they have any allergies to medicines.
Penicillin is very safe and effective at preventing the spread of GBS bacteria to newborns during birth. About 1 in every 10 women have mild side effects from receiving penicillin. There is a rare chance (about 1 in every 10,000 women) of having a severe allergic reaction that requires emergency treatment.
Researchers have not identified an effective strategy for preventing late-onset GBS disease. Unfortunately, giving women antibiotics during labor does not prevent late-onset disease.
Currently, there is no vaccine to help pregnant women protect their newborns from GBS bacteria and disease. Researchers are working on developing a vaccine, which may become available in the future.
The following strategies are not effective at preventing GBS disease in babies:
- Taking antibiotics by mouth
- Taking antibiotics before labor begins
- Using birth canal washes with the disinfectant chlorhexidine
To date, receiving antibiotics through the vein during labor is the only proven strategy to protect a baby from early-onset GBS disease.