# Group B Streptococci in Pregnancy ## What are Group B Streptococci? **Group B Streptococci (GBS)
Pregnancy brings with it a whole range of examinations that can be confusing or worrying for expectant mothers. One of the tests performed towards the end of pregnancy is the Group B streptococcus screening. Although this bacterium is not particularly dangerous in everyday life, it deserves attention in the context of childbirth and the neonatal period. Why do doctors place such emphasis on detecting it, and what does the test result actually mean for the mother and child?
Group B streptococci, formally known as Streptococcus agalactiae or abbreviated as GBS (from the English Group B Streptococcus), are bacteria that naturally inhabit the digestive and urogenital tract of many adults. Their presence does not in itself indicate illness – in the vast majority of cases they are completely asymptomatic and the person is entirely unaware of them. It is estimated that approximately 10 to 30% of pregnant women are carriers of these bacteria without experiencing any symptoms whatsoever. The problem arises at the moment of birth, when the newborn may encounter the bacteria while passing through the birth canal.
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Why are GBS bacteria a risk during pregnancy?
Newborns have an immature immune system and are unable to deal with GBS bacteria in the way an adult organism would. Transmission from mother to child during birth can in some cases lead to serious neonatal illnesses – most commonly pneumonia, meningitis, or generalised bloodstream infection, i.e. sepsis. The World Health Organization and professional gynaecological societies note that neonatal GBS infections are among the most common causes of serious bacterial illness in the first weeks of life. Although modern medicine can treat these conditions, prevention is always the better option.
It is important to distinguish between the so-called early and late forms of neonatal GBS infection. The early form manifests within the first 7 days of the child's life and is associated specifically with transmission during birth. The late form can appear up to three months of age and has more varied origins – it may involve transmission through breastfeeding, contact with the environment, or even the hospital setting. This is precisely why screening focuses primarily on preventing the early form, which is directly influenced by the preventive administration of antibiotics to the mother during labour.
It is understandable that the word "antibiotics" may cause concern in pregnant women. However, the administration of antibiotics directly during labour – most commonly intravenous penicillin – is considered safe for both mother and child, and its benefits far outweigh any potential risks. According to data published by the US Centers for Disease Control and Prevention (CDC), universal screening and preventive antibiotic administration have succeeded in reducing the incidence of early neonatal GBS infections by more than 80% compared to the period before this measure was introduced.
But how do doctors determine whether a particular pregnant woman is carrying the bacteria? The answer lies in a simple yet very important examination.
How Group B streptococcus testing works
The GBS test is performed between weeks 35 and 37 of pregnancy. It involves a swab from the vagina and rectum, carried out on an outpatient basis at the gynaecologist's office and taking only a few seconds. The woman experiences no pain whatsoever – it is a completely non-invasive procedure comparable to a routine gynaecological examination. The collected sample is then sent to a laboratory, where the presence of GBS bacteria is determined by culture. Results are typically available within a few days.
Why is the test performed during this particular period and not earlier? The presence of GBS bacteria in the body can change over time – a woman who tested negative at week 20 may be positive at week 36, and vice versa. A test performed too early might therefore not reflect the actual situation at the time of delivery. Testing between weeks 35 and 37 provides the most reliable information about the situation immediately before birth.
Consider a specific example: Jana is in week 36 of her pregnancy and comes in for a regular check-up with her gynaecologist. The doctor explains that it is time for a GBS swab, collects the samples, and four days later Jana receives the result – a positive finding. This means that the bacteria is present in the vaginal and rectal environment. Jana is naturally concerned, but her doctor reassures her: a positive result does not mean the baby will be ill, only that antibiotics need to be administered during labour as a preventive measure. Jana gives birth to a healthy boy and the entire delivery proceeds without complications.
This scenario is entirely common and reflects the everyday reality of maternity wards around the world. The key to success lies precisely in the timely identification of the situation and the appropriate response from the healthcare team.
There are, however, situations in which antibiotic prophylaxis is administered even without a prior test. These include, for example, premature labour before the completion of week 37 when the test has not yet been performed, or situations where a woman arrives for delivery without screening results. In such cases, doctors base their decisions on risk factors – such as fever in the mother during labour, premature rupture of membranes, or a previous child with a GBS infection. The approach to prevention is therefore individualised and always tailored to the specific situation.
As noted by leading American paediatrician and neonatal infection specialist Dr. Richard Polin: "Prevention of GBS infection in newborns is one of the greatest achievements of perinatal medicine in recent decades." This statement precisely captures how far medicine has advanced in the field of neonatal protection – and the important role played by what appears to be an unremarkable swab taken a few weeks before delivery.
What to do after a positive test result
Learning that a test has come back positive can be stressful news for a pregnant woman. However, it is absolutely essential to understand that a positive result does not require any treatment during pregnancy. GBS bacteria are not treated with antibiotics before delivery – and for good reason. Even if the bacteria were suppressed, they would in all likelihood reappear by the time of delivery. It is therefore most effective to administer antibiotics during labour itself, when they have the greatest protective effect for the child.
Women with a positive result should inform the maternity ward staff as soon as they are admitted for delivery, so that antibiotic prophylaxis can be initiated in good time – ideally at least four hours before delivery. This information should be included in the birth plan or medical documentation that the woman brings to the maternity ward.
Regarding breastfeeding, a positive GBS finding during pregnancy is not a reason to limit it. Breast milk contains antibodies and substances that actually help the newborn build immunity. If GBS bacteria were to appear directly in breast milk – which is a rare but possible occurrence – the situation would need to be addressed individually with a doctor.
Pregnant women also sometimes ask whether they can influence the presence of GBS bacteria through their lifestyle or diet. The scientific evidence in this regard is not convincing. Probiotics, dietary changes, and other natural methods have not been sufficiently proven as a way to reliably eliminate GBS or prevent it. The best protection remains reliable screening and, where necessary, antibiotic prophylaxis during labour.
For those who wish to learn more about the topic, a valuable source of information is the NHS website, which covers the issue of GBS in a clear and accessible manner, as well as Czech professional gynaecological and perinatological societies, whose recommendations form the basis of procedures at maternity wards throughout the country.
It is natural for every pregnant woman to want the best for her child, and every new piece of information may raise questions or concerns. GBS screening is, however, an example of how modern medicine can significantly reduce the risk of serious illness in newborns through a simple and safe procedure. A swab taking seconds, results within a few days, and if necessary antibiotics during labour – that is the entire process, which can be of fundamental importance for a newborn child. Awareness of this examination, its purpose, and how it is carried out is therefore one of the most valuable gifts an expectant mother can give to herself and her child, long before that child enters the world.
