During your last trimester of pregnancy, you get a test for group B strep (also called GBS). GBS is a common type of bacteria that can cause infection. Usually, GBS is not serious for adults, but it can hurt newborns. It’s important to get this test and know the results so you can protect your baby.
Many people carry GBS — in fact about 1 in 4 (25 percent) pregnant women are carriers. Being a carrier does not mean you have an infection, it means you have this bacteria in your body. GBS bacteria naturally live in the intestines and the urinary and genital tracts. You can’t get it from food, water or things you touch. You can’t catch it from another person, and you can’t get it from having sex. GBS in adults usually doesn’t have any symptoms. But sometimes it can cause minor infections, like a bladder or urinary tract infection (UTI).
If you’re pregnant and have a GBS infection, it can pass to your baby during labor and birth and can make your baby very sick.
Testing and treatment for GBS
You prenatal care provider tests you for GBS at 35 to 37 weeks of pregnancy. The test is a simple swab of your vagina and rectum. If you have GBS, your provider gives you antibiotics during labor and birth to help prevent your baby from getting infected. Your provider gives you the antibiotics through an IV.
Penicillin is the best antibiotic for most women. If you’re allergic to penicillin, you can get a different medicine. It’s not helpful to your baby if you get treatment for GBS early in your pregnancy. The bacteria can return quickly, so you could have it again by the time you go into labor.
If you have GBS, remind your providers at the hospital when you go to have your baby. This way you can be treated quickly. Treatment works best when it begins at least 4 hours before childbirth. If you have GBS and you’re having a scheduled c-section before labor starts and before your water breaks, you probably don’t need antibiotics.
What are the chances you can pass GBS to your baby?
If you have GBS during childbirth and it’s not treated, there’s a 1 to 2 in 100 chance (1 to 2 percent) that your baby will get the infection. The chances are higher if you have any of these risk factors:
- Your baby is premature. This means your baby is born before 37 weeks of pregnancy.
- Your water breaks (also called ruptured membranes) 18 hours or more before you have your baby.
- You have a fever (100.4 F or higher) during labor.
- You’ve already had a baby with a GBS infection.
- You had a UTI during your pregnancy that was caused by GBS.
If you have GBS and you’re treated during labor and birth, your treatment helps protect your baby from the infection.
Visit marchofdimes.org for more information.