Group B streptococcus and pregnancy

Health advice, Questions/answers, Third trimester

Have you just found out that you are a carrier of group B streptococcus (GBS)? Don’t panic! This is a common occurrence in late pregnancy, and there are simple measures you can take to protect your baby.

What is Group B Streptococcus?

GBS is a bacterium that is naturally present in the body, particularly in the intestines, vagina, and rectum. Approximately 10 to 30% of women are carriers without knowing it and without symptoms.

GBS Transmission to the Baby During Delivery

In pregnant women, GBS can be transmitted to the baby during childbirth. It is estimated that 15 to 40% of pregnant women carry the bacteria, and among them, 40 to 70% will pass it on to their newborn. Of the babies who become colonized, 1 to 2% will develop an infection within the first 7 days of life, with 95% of cases occurring in the first 24 hours. These infections may include meningitis, pneumonia, or sepsis, and can lead to irreversible damage.

Screening and prevention

A simple vaginal and anal swab is recommended between 35 and 37 weeks of pregnancy to check for the presence of GBS.

If the test is positive, preventive intravenous antibiotics will be offered during labor or after your water breaks, ideally at least four hours before delivery. The administration takes only a few minutes and may be repeated, depending on the antibiotic used. This measure significantly reduces the risk of transmission.

When is treatment started immediately, even without test results?

  • If you’ve previously had a baby infected with Group B Streptococcus (GBS);
  • If you go into labor prematurely and your GBS status is unknown;
  • If your membranes have been ruptured for more than 18 hours;
  • If you develop a fever during labor (≥ 38 °C / 100.4 °F);
  • If GBS was found in your urine during pregnancy.

Antibiotics: well-assessed risks

Like any medication, antibiotics can have side effects. These may include diarrhea, with or without a yeast infection, both for the mother and the baby. However, in this context, the benefits far outweigh the risks.

Marie Fortier
The baby expert

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