Group B Streptococcus (GBS) in Pregnancy: What Every Mom-to-Be Should Know
GBS in pregnancy explained: what it is, how it's tested, and how it's safely managed to protect your baby.
In short: Group B streptococcus (GBS) is a common bacterium carried in the vagina and rectum by 2–4 in 10 women without symptoms, but it can pass to the baby during birth and cause infection of the blood, lungs or meninges. It is found by a vaginal and rectal swab and treated with intravenous penicillin once labour starts; the baby benefits most when the antibiotic is given at least 4 hours before birth.
Group B streptococcus (GBS) is one of many types of bacteria that naturally live in our bodies and usually do not cause any harm.
If you’re a carrier of this bacterium, please don’t worry — most babies are born healthy and uninfected even when the mother carries GBS. Understanding the facts can help ease any concerns as you prepare for your baby’s arrival.
What is Group B Streptococcus Bacteria (GBS)?
It is a common bacterium found in the vagina and rectum in 2-4 out of every 10 women.
It is not transmitted through sexual contact.
Most women who carry it do not show any symptoms at all.
It can affect babies during childbirth and, in some cases, cause a serious infection in the newborn.
How is it detected?
It is detected with a simple swab taken from the lower vagina and the rectum, ideally at 35–37 weeks of pregnancy and sent for a special (enriched culture) test. Sometimes it is found by chance in a urine test or a vaginal swab taken for another reason.
What are its effects on the child?
GBS infection in newborns is uncommon (about 1 in 1,750 babies in the UK), but it is the most common cause of severe infection in the first week of life and can lead to bloodstream infections, pneumonia, and meningitis, and in rare cases may be fatal.
The reassuring news is that with prompt treatment, most affected children recover completely.
The risk of infection increases in the following cases:
- Delivery before 37 weeks
- A previous child affected by group B streptococcal infection
- Fever during labor
- Rupture of membranes 18 hours or more before delivery
- A positive urine test result during this pregnancy
GBS found in a previous pregnancy (about half of these women carry it again; they are offered either antibiotics in labour or a swab test at 35–37 weeks)
When do we start antibiotics (penicillin)?
If GBS is detected through a vaginal or rectal swab, you won’t need antibiotics until labor begins — at that point, they are given intravenously. If it’s detected through a urine test, an antibiotic is given immediately upon diagnosis, in addition to the intravenous antibiotic at the start of labor.
- If the amniotic fluid ruptures before week 37 but labor doesn’t begin, antibiotics may be given.
- If a cesarean section is planned, antibiotics for GBS are not necessary, as long as labor has not started and your waters have not broken before the operation.
- If you’ve had a previous child with group B streptococcal infection, antibiotics should be given at the onset of labor in this pregnancy too.
- Your baby benefits most if antibiotics are given at least 4 hours before delivery.
What symptoms might a child infected with this bacteria experience?
- Grunting, noisy breathing, or signs of difficulty breathing
- Excessive drowsiness
- Unresponsiveness
- Incessant crying
- Poor feeding
- Fever
- Rapid or slow breathing rate
- Low blood sugar
- Low blood pressure
Why aren’t all pregnant women tested for these bacteria?
Because there is no completely accurate test, and a negative result doesn’t necessarily mean a woman is not carrying the bacteria.
Most women who carry GBS give birth to perfectly healthy babies, and giving antibiotics to every pregnant woman who carries it would mean a large number of women undergoing unnecessary treatment.
This is the approach followed in the UK. In other countries, including the United States, all pregnant women are offered a GBS swab at 36–37 weeks, and those who test positive receive antibiotics during labour. Your doctor will advise which approach is right for you.
If you have questions about GBS testing or how it may affect your pregnancy plan, Dr. Najeeb Layyous and his team are here to guide you through every step of your prenatal care, from routine screening to a safe, well-supported delivery.
Dr Najeeb Layyous F.R.C.O.G
Consultant Obstetrician, Gynecologist and Infertility Specialist
The finest doctor in Jordan — may God bless him and his whole medical team. A doctor in every sense of the word. I advise anyone planning a pregnancy to visit Dr. Najeeb Layyous. His manner is wonderful, always smiling, with the highest ethics; he gives every patient her due, and the patient’s comfort matters most to him. We had been to many doctors and none understood and treated my case except him. Special thanks to him and the whole team, and to Dina in particular — a lovely person. I recommend anyone considering IVF or pregnancy to visit his clinic.