Thrive Birth Center Blog


All women in the US are offered GBS testing around 36 weeks. The following information may be useful in making informed decisions regarding your Group B Beta Strep (GBS) Screening and Treatment option.


What is Group Beta Strep?

GBS is a normal bacteria that can be present in the digestive tract of 15-30% of healthy adults.  People who carry the bacteria generally do so temporarily.  If GBS is present in the lower intestines during labor and birth, it may migrate to the vagina and a small percentage of newborns may pick up the bacteria from the vagina during their birth and can become ill.  GBS infection is a very serious newborn condition, with a mortality rate of 5-20%.  Babies who develop a GBS infection and survive may have long-term neurological problems, such as hearing loss, vision loss or learning disabilities.

Rates of newborns with GBS infection

In the general population (both positive and negative mothers)   .2-.3 in 100

In mothers who test positive of GBS    .5-1 in 100

Risk factors for infection

It is not clearly understood why some babies become sick from GBS exposure while others are unaffected, however the following factors are known to increase the likelihood of infection:

Babies born before 37 weeks gestation

Prior pregnancy with a baby infected by GBS

Bladder infection caused by GBS at anytime in current pregnancy

Rupture of membranes greater than 18 hours before delivery

Sign of infection in mother during labor (i.e. fever)

Testing and treatment options

Because GBS colonization can come and go in a persons system often, it is recommended that women be tested for GBS every pregnancy between 35-37 weeks (estimated to miss only 3% of women who will be positive during labor).

The test consists of a culture swab of the vagina and rectum.

If the culture is positive

The Center for Disease Control (CDC) recommends antibiotic treatment intravenously (IV) in labor with penicillin (or an alternative antibiotic if you have an allergy) to prevent GBS infection in the newborn (by approximately 86%).

You also have the option of antibiotic treatment only in the presence of one of the previously stated risk factors (50-68% of newborn infections prevented).

In mothers who have one dose of antibiotics in labor for treatment  of a positive GBS culture, approximately  1 in 4,000 babies may acquire GBS infection.

In mothers who have 2 or more doses of antibiotics in labor that number is reduced 1 in 20,000.

Risk of antibiotic Treatment:

~  Risks of treatment include allergic or anaphylactic response to antibiotics.

~  Approximately 1 in 10 will have a minor reaction such as a skin rash to antibiotics.

~  Approximately 1 in 10,000 will have an anaphylactic response, which could include increased irritability, difficulty breathing and/or convulsion.

~   Approximately 1 in 100,000 will have a response so severe it results in  7death.

~ Risk of discomfort and/or bruising at IV site.

~Treatment of mothers for GBS during labor may mask other infections in newborns, making appropriate diagnosis more difficult.

~Increased risk of thrush in the newborn.

~Increased risk of other bacterial infections after the IV antibiotic treatment.

Talk to your Midwife or Doctor about your risk factors and options.

infomred decisions