This sheet is about group B strep infections in pregnancy or while breastfeeding. This information is based on available published literature. It should not take the place of medical care and advice from your healthcare provider.
What are group B strep infections?
Group B strep infections are caused by group B Streptococcus bacteria (also called group B strep or GBS). Most of the time, the bacteria do not cause symptoms or make people feel sick. Some people, including people who are pregnant, have GBS without knowing or having symptoms.
Can GBS be passed to the fetus during pregnancy or at the time of delivery?
When a person is pregnant and passes an infection to the fetus, it is called vertical transmission. Vertical transmission can happen at any time in pregnancy but is usually more likely to happen when someone gets the infection close to delivery.
GBS bacteria can live in the vagina and rectum. Usually, having group B bacteria in these areas of the body does not cause illness. GBS bacteria can be passed to a newborn when they pass through the birth canal (vaginal delivery) or after delivery. GBS infections can be passed to newborns during or after delivery and can cause severe problems.
In newborns, GBS infections can cause GBS disease. Depending on how old the baby is when they develop GBS disease, it can be called ‘early onset’ (within 6 days of birth) or ‘late onset’ (from 7 days of birth up to a few months after birth). Early onset GBS disease can cause meningitis (swelling of the covering around the brain or spinal cord), pneumonia (lung infection), and sepsis (serious disease where the immune system attacks the body instead of the infection). An infant with early onset GBS disease has a higher chance of developing necrotizing enterocolitis (serious condition where tissue in the intestines begins to die, which can lead to a hole in the intestines). Late onset GBS disease can cause meningitis.
What screenings or tests are available to see if I have GBS bacteria before delivery?
The American College of Obstetricians and Gynecologists (ACOG) and the U.S. Centers for Disease Control and Prevention (CDC) recommend that all people get tested for GBS between 36 and 38 weeks of pregnancy. If someone tests positive for GBS bacteria, ACOG and the CDC recommend treatment with antibiotics before giving birth. MotherToBaby has a fact sheet on penicillin G, a medication commonly used to treat GBS here: https://mothertobaby.org/fact-sheets/penicillin-g/.
I have a GBS infection. Can it make it harder for me to get pregnant?
It is not known if having a GBS infection can make it harder to get pregnant. Some other bacterial infections during pregnancy have been associated with trouble getting pregnant. Also, being very sick in general might make it harder to get pregnant. Talk with your healthcare provider about the best way to treat your condition and your plans for pregnancy.
Does having a GBS infection increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. It is not known if GBS infections can increase the chance of miscarriage.
Some bacterial infections that are similar to group B bacteria have been associated with an increased chance of miscarriage. Also, being very sick in general might increase risks to a pregnancy. Talk with your healthcare provider about your condition and the treatment that is right for you during pregnancy.
Does having a GBS infection increase the chance of birth defects?
Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. Studies have not been done to see if having a GBS infection can increase the chance of birth defects.
Would having a GBS infection increase the chance of other pregnancy-related problems?
It is not known if having a GBS infection can increase the chance of other pregnancy-related problems such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth).
One study suggested a link between GBS infection and stillbirth. However, this study cannot confirm that a stillbirth was due to the infection or if other factors were also involved.
Rarely, GBS infections have been linked to necrotizing enterocolitis (serious condition where tissue in the intestines begins to die which can lead to a hole in the intestines) in the newborn.
Some bacterial infections that are similar to group B bacteria during pregnancy have been associated with an increased chance of other pregnancy-related complications, such as preterm delivery and growth restriction (fetus is smaller than expected). Also, being very sick in general might increase risks to a pregnancy. Talk with your healthcare provider about your condition and the treatment that is right for you during pregnancy.
Does having a GBS infection in pregnancy affect future behavior or learning for the child?
Studies have not been done to see if exposure to a GBS infection in pregnancy can affect future behavior or learning for the child.
Breastfeeding while I have a GBS infection:
Strep bacteria can get into breast milk. There is 1 report on 3 preterm infants who developed late onset GBS disease after being exposed to GBS bacteria through breast milk. All infants recovered after treatment with antibiotics.
The benefits of breastfeeding your child might outweigh possible risks. If you have GBS, talk with your healthcare provider as well as your baby’s pediatrician about the best way to feed your baby. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a male has a GBS infection, can it affect male fertility or increase the chance of birth defects?
Studies have not been done to see if a GBS infection could affect male fertility (ability to get partner pregnant) or increase the chance of birth defects. Some other bacterial infections might affect male fertility. Also, being very sick in general may make it harder to get a partner pregnant. Be sure to talk to your healthcare provider about the best way to treat your condition and you and your partner’s plans for pregnancy. For more general information on paternal exposures in pregnancy, please see the MotherToBaby fact sheet at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
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OTIS/MotherToBaby encourages inclusive and person-centered language. While our name still contains a reference to mothers, we are updating our resources with more inclusive terms. Use of the term mother or maternal refers to a person who is pregnant. Use of the term father or paternal refers to a person who contributes sperm.
