There is a plethora of information regarding GBS on the internet. How do expectant parents know what is evidence based to determine what decision to make regarding testing and treatment? We have included some information below.
In Metro Vancouver, BC it is common practice for the GBS test to be done between 35-37 weeks of pregnancy. Our clients are usually informed beforehand by their care provider. Some care providers give a handout that provides information, evidence and options so that couples can decide what they want to do regarding both testing and treatment. We notice that some don’t always receive a complete explanation about the purpose of the test and/or the recommended treatment.
The Perinatal Services BC Practice Resource summarizes the SOGC (Society of Gynecologists and Obstetricians) recommendation to "Offer all women screening for colonization with group B streptococcus at 35 to 37 weeks’ gestation, including women with planned cesarean delivery."
According to The SOGC:
'It is estimated that 15 - 40% of all pregnant women are GBS colonized. Between 40 - 70% of colonized mothers pass the bacteria onto their babies during the birthing process. While most babies are not affected by the bacteria, a very small number (1-2%) of these babies will go on to develop a GBS infection. Babies who are infected with GBS may have mild to severe problems which may affect their blood, brain, lungs and spinal cord. No one method of screening (testing) and treatment will prevent all GBS infant deaths.'
In other countries, such as the UK, universal screening is not done. Here is an article from Dr. Sarah Wickham addressing potential harms from universal screening.
It's important to recognize that colonization does not mean infection, and infection does not mean death. Both mother and baby could have GBS bacteria in their systems (be colonized) and show no symptoms.
So which babies are at highest risk? Looking at the numbers is helpful.
The baby at highest risk is, in order of highest to lowest (OR means Overall Ratio):
1) gestation less than 28 weeks, (OR 21.7)
2) intrapartum fever with PROM (premature rupture of membranes) at term (OR 11.5)
3) intrapartum fever, PROM or prematurity (OR 9.74)
4) birth weight less than or equal to 2500 grams (OR 7.37)
5) prolonged rupture of membranes - more than 18 hours (OR 7.28)
6) chorioamnionitis (infection in uterus) (OR 6.43)
7) gestation less than 37 weeks (OR 4.83)8) intrapartum fever >37.5 degrees C (OR 4.05) source: webinar presentation by Gail Hart, midwife
At issue is the lack of improvement in GBS statistics after the introduction of the "screen and treat" protocol over almost 15 years ago and the widespread use of antibiotics in labour or the neonatal period.
More light is being shed on the use of antibiotics during labour and birth, which is at roughly 50% when we include those given to women having cesarean births. Currently half of all newborns are exposed to antibiotics which are associated with health risks.
'The Real Antibiotic Results: More Serious Infections
Even if early serious GBS infections are being reduced by antibiotic practices, there has been an emergence of other types of early infections from bacteria not affected by the kinds of antibiotics used—including a surge of drug-resistant E. coli infections affecting preemies.
Most importantly, the scientific review found that the use of precautionary antibiotics did not reduce the number of infant deaths—neither from GBS infection nor from all causes—and the number of later, serious infections is increased by the use of antibiotics during labor. (Late-onset infections are defined as developing after one week of age.) Serious Candida (yeast) infections are among these, as a direct result of antibiotic exposure. Later bacterial infections are also increasingly occurring from antibiotic-resistant organisms. These are making the illnesses even more challenging to treat. Today, half of late-onset infections are with the very dangerous MRSA (antibiotic-resistant strep). The conclusion of the above comprehensive review is that evidence is lacking to support preemptive antibiotic usage.'
source: Antibiotics Given to Laboring Mothers on http://pathwaystofamilywellness.org
From the Cochrane Database comes this conclusion: 'Intrapartum antibiotic prophylaxis appeared to reduce EOGBSD, but this result may well be due to bias as we found a high risk of bias for one or more key domains in the study methodology and execution. There is lack of evidence from well designed and conducted trials to recommend IAP to reduce neonatal EOGBSD.
Ideally the effectiveness of IAP to reduce neonatal GBS infections should be studied in adequately sized double‐blind controlled trials. The opportunity to conduct such trials has likely been lost, as practice guidelines (albeit without good evidence) have been introduced in many jurisdictions.'
In Antibiotic Use and Misuse during Pregnancy and Delivery: Benefits and Risks the author discusses some of the possible consequences of early exposure to antibiotics:
‘It has been suggested that exposure to antibiotics during fetal/neonatal life affects the development of allergic diseases via their adverse and possible long-term effect on gut microbiota of both the mother and child and vaginal microbiota of the mother. Antibiotic use may delay and interfere with the early colonization of the child’s gut microbiota . In turn, this delay or aberrant colonization may interfere with the development and maturation of the child’s immune system, and thus play a role in the development of allergy and disease [81,82]. It has been reported recently that antibiotic use early in life is associated with the risk of childhood asthma (with a NNTH of 87), allergy, atopic dermatitis, eosinophilic esophagitis, neonatal candidiasis, and celiac disease.’
In The infant microbiome development: mom matters the author explores the impact of antibiotics, amoung other medical interventions on the human microbiome.
‘Vaginal delivery and breastfeeding are evolutionarily adaptive for mammals and therefore are paramount to human newborn development and health. Common perinatal interventions like C-section, antibiotic use, and formula feeding alter the infant microbiome and may be major factors shaping a new microbiome landscape in human history. While mechanistic questions remain (Box 1), epidemiological evidence suggests that these impacts on the early microbiome assembly are associated with metabolic and immune pathologies. Even if antibiotic use, C-section delivery, and formula feeding are only marginally associated with disease risk at the individual level, the widespread use of these practices in the USA and other countries may contribute to considerable disease burden at the population level . Therefore, strategies to prevent perturbation of the healthy infant microbiome and restore it after alterations should be researched to help curb the epidemic trends of metabolic and immune diseases.’
Determining what course of action to take means gathering facts to make an informed decision. Some women do the test wanting to avoid risk. They receive antibiotics if their test result is positive. Some treat only if risk factors are present such as prolonged rupture of membranes, fever, or premature baby. Yet others decide to take the test, but decline antibiotics if GBS positive, while observing the baby closely in the first week post birth. Some choose to focus on nutrition and a healthy diet and decline the test. It’s important to note that in the absence of a test result if a newborn develops symptoms of infection, (for example, experiences breathing difficulties or fever with unknown cause), IV antibiotics will be administered to the baby due to not knowing if the cause is GBS.
There is no one correct choice for all. Each family weighs out the information, choosing what is best for them and their baby. It’s definitely not black and white. We hope this post is useful when determining what decision to make about GBS testing and treatment.
For more information: