Key takeaways: About 1 in 4 pregnant people carry group B strep (GBS) without symptoms. Screening late in pregnancy and IV antibiotics during labor greatly reduce early-onset GBS infection in babies. Late-onset infection can still occur up to about 3 months, so know the warning signs.
Group B Streptococcus (GBS) is a type of bacteria that lives harmlessly in the intestines or vagina of many healthy adults. During birth, it can be passed to the baby and occasionally cause serious infections such as sepsis, pneumonia, or meningitis.
Screening in Pregnancy
ACOG recommends GBS screening for all pregnant people between 36 0/7 and 37 6/7 weeks of pregnancy, using a swab of the vagina and rectum. The CDC reports that about 1 in 4 pregnant people carry GBS.
Antibiotics During Labor
If you test positive, or have certain risk factors (such as GBS in your urine during pregnancy, a previous baby with GBS disease, or unknown status with preterm labor, prolonged rupture of membranes, or fever), you’ll be offered IV antibiotics during labor. Penicillin or ampicillin is usually used. Other antibiotics are available for people with penicillin allergy; allergy testing may be recommended.
Antibiotics in labor significantly reduce the risk of early-onset GBS disease. Since this approach became widespread, early-onset GBS disease in the U.S. has declined substantially.
After Birth
Babies whose parent was GBS-positive are observed in the hospital. Depending on whether antibiotics were given adequately (typically at least 4 hours before birth) and on other risk factors, your baby may simply be monitored or may need blood tests. Many hospitals use risk calculators to guide care.
Early-Onset vs. Late-Onset GBS
- Early-onset: in the first week of life, usually within 24 hours. Antibiotics in labor help prevent it.
- Late-onset: from 1 week to about 3 months of age. Antibiotics in labor don’t prevent late-onset disease. It can come from the birthing parent or other sources.
Warning Signs at Home
Call your baby’s doctor right away or go to the emergency room if your baby:
- Has a fever of 100.4°F or higher rectally, or a low temperature.
- Is feeding poorly or refusing feeds.
- Is unusually sleepy, floppy, or hard to wake.
- Is very irritable or has a high-pitched cry.
- Has trouble breathing, grunting, or fast breathing.
- Has a bulging soft spot or seizures.
- Has blue, gray, or mottled skin.
Breastfeeding
GBS isn’t a reason to avoid breastfeeding. Rarely, late-onset GBS has been linked to breast milk, but breastfeeding is recommended in nearly all cases. Talk with your doctor if your baby develops GBS infection.
The Bottom Line
GBS is common in adults and usually harmless, but it can cause serious infections in newborns. Screening and antibiotics in labor prevent most early-onset cases. Watch for warning signs in the first 3 months.
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Sources
- American College of Obstetricians and Gynecologists. Committee Opinion No. 797: Prevention of group B streptococcal early-onset disease in newborns. Obstet Gynecol. 2020;135(2):e51-e72.
- Puopolo KM, Lynfield R, Cummings JJ; Committee on Fetus and Newborn; Committee on Infectious Diseases. Management of infants at risk for group B streptococcal disease. Pediatrics. 2019;144(2):e20191881.
- Centers for Disease Control and Prevention. Group B strep: about GBS; fast facts. https://www.cdc.gov/group-b-strep
- Pantell RH, Roberts KB, Adams WG, et al; Subcommittee on Febrile Infants. Evaluation and management of well-appearing febrile infants 8 to 60 days old. Pediatrics. 2021;148(2):e2021052228.
This article is for general education and is not a substitute for individualized medical advice. Always talk with your baby’s health care provider or your own provider about your specific situation. If you think your baby or you may have a medical emergency, call 911.
