Group B Streptococcal Infection

During the last trimester of pregnancy, around 36 weeks, we will do a vaginal culture to screen for a bacteria called group B streptococcus (GBS). GBS is one of the many bacteria that exist in the body without causing serious illness. Although it can be found in the digestive and urinary tracts, in women it is most often found in the vagina and rectum. Although the name is similar, GBS is not the bacteria that causes Strep Throat (that is group A streptococcus). It is also not a sexually transmitted disease.

When a woman has GBS in her vagina, but has no symptoms of an infection - we say she is "colonized". Being colonized with GBS causes no health problems in the woman and would normally not require treatment. When she is pregnant, though, she can pass the bacteria to her baby. This happens in 1 to 2 of every 100 babies born to mothers colonized with GBS. BGS can pose a threat to her baby.

Could My Baby Be Affected?

Early infections occur within the first 7 days of birth, most within the first 6 hours. In most of these babies, the infection was passed to them during labor and delivery. Late infections occur after the first 7 days of life. About half of these infections are passed during labor and delivery, the other half come from other sources, such as other carriers.

Both early and late infections with GBS can be serious and are fatal to about 5% of infected babies. The infection causes inflammation of the baby's blood, lungs, brain or spinal cord.

How Can I Be Tested?

A swab is taken from the vagina, perineum and rectum during pregnancy, usually between 35 and 37 weeks of pregnancy. This swab is sent to the lab to be cultured and your provider will receive a report telling if GBS is present or not. If GBS is present, you will receive antibiotics through an IV during labor and delivery. Sometimes GBS is detected earlier in pregnancy during a urine culture or a vaginal culture for symptoms of an infection.

Decreasing The Risk

The risk of GBS infection to newborns is decreased by 1) treating all women who test positive for the bacteria during their pregnancy and 2) treating all women with risk factors for GBS. Those risk factors include: 1) preterm labor, 2) premature rupture of membranes, 3) more than 18 hours since the amniotic sac broke (prolonged rupture of membranes), 4) prior baby with GBS infection, and 5) fever during labor.

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