Group B strep (streptococcus) is a common bacterium often carried in the intestines or lower genital tract. The bacterium is usually harmless in healthy adults. In newborns, however, it can cause a serious illness known as group B strep disease.

Group B strep can also cause dangerous infections in adults with certain chronic medical conditions, such as diabetes or liver disease. Older adults are at increased risk of illness due to group B strep, too.

If you're a healthy adult, there's nothing you need to do about group B strep. If you're pregnant, get a group B strep screening test during your third trimester. If you have group B strep, antibiotic treatment during labor can protect your baby.

Pregnant women get tested for group B strep in the third trimester of pregnancy. Babies suspected of being infected are diagnosed at birth by testing their blood or spinal fluid or both for group B strep bacteria.

Babies who get this infection may start to have symptoms in the first few days of life, or weeks to months later. You may notice that your little one has:

• Fever
• Fast, slow, or strained breathing
• Trouble eating
• Extreme fatigue
• Irritability
• Blue color to the skin

Group B strep bacteria live in the intestines and genital tract, including the vagina. About 1 out of every 4 pregnant women carries these bacteria.

It's normal to have these bacteria in your body. Usually you won't know you have them because they won't make you sick. In some cases, they can cause bladder and urinary tract infections (UTIs). Group strep B bacteria aren’t dangerous to you, but if you get pregnant, they are risky for your baby.

Even before lab results are in, intravenous antibiotic treatment may be started. 

Your baby might also need treatments to help with GBS symptoms, including:

• Fluids through a vein (IV)
• Oxygen
• Medicines to treat other symptoms

If you carry group B strep bacteria, your baby can become infected during a vaginal delivery. Not every baby who is exposed to GBS will get infected, but a small percentage can

• You deliver early -- before 37 weeks
• Your water breaks 18 hours or more before you deliver
• You have an infection of the amniotic fluid or placenta
• You've had a baby with GBS in the past
• You have a fever higher than 100.4 F during labor

Babies can get two types of GBS infection: Early-onset starts during a newborn's first week of life. Babies get this type during delivery. Late-onset starts a week to a few months after the baby is born. This type may be acquired in the home or in the community, and it isn't prevented by antibiotics given during delivery.