I had a recent experience where I transfered a woman during labour to hospital and she was going to be treated with intravenous antibiotics for unknown GBS as she did not have the GBS screening done as part of her routine pregnancy care. I was shocked about this aggressive approach to an unknown GBS status and thought this is a great opportunity to have a look at the evidence.
What is GBS and why are women screened for GBS?
Group B Streptococci or GBS is a common organism that lives in the gut, bladder and vagina. 10 to 30% of women are colonised with GBS. Carrying GBS is benign in adults and not a cause of concern but it can potentially be very problematic for the newborn baby due to the risk of GBS transmission to the baby in labour. There is a 40-50% chance of the baby becoming colonised with GBS during labour and birth however it does not necessarily cause GBS disease. Once the baby is colonized the risk of GBS disease is 1-2%, so overall 15-30 babies per 100.000 births will have a serious outcome. GBS causes Sepsis, Pneumonia and Meningitis in the newborn and does have a 5-10% mortality rate. Babies diagnosed with GBS disease are treated with antibiotics and will be admitted to the special care unit. Because of this GBS screening is done to prevent GBS disease in the newborn. Screening for GBS involves collecting a vaginal swab. As the GBS organism ‘comes and goes’ it is recommended for the swab to be obtained around the time of birth (35 to 37 weeks of pregnancy) to get an accurate estimate of GBS presence in the vaginal flora.
How do the Melbourne Hospitals approach GBS screening?
Some hospitals take the universal approach, which involves taking a vaginal swab on every pregnant woman around 35-37 weeks of pregnancy. Other hospitals have decided to work with a risk-based approach, meaning that the swab is only taken after identifying certain risk factors that increase the risk of GBS disease in the newborn:
- Preterm labour (before 37 weeks of pregnancy)
- Women whose waters have been broken for more than 18 hours
- A fever in labour (greater than 38C)
- A previous GBS affected baby
- GBS urinary tract infection in pregnancy.
The Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) have recommended either a risk-based or screening approach to identify pregnant woman for antibiotic prophylaxis during labour. In the UK The Royal College of Obstetricians and Gynaecologists (RCOG) do not recommend universal screening for GBS.
In my own practice I adapted the risk-based approach. I do not routinely screen for GBS during pregnancy unless the pregnant woman presents with risk factors.
What interventions during labour can increase the rates of GBS infection in the newborn?
- Membrane Sweeping ‘Stretch & Sweep’
- Vaginal Exams
- Breaking waters artificially, having intact waters is protective!
- Applying an electrode to the baby’s head to monitor the baby’s heart rate in labour
What is the consequence of a positive GBS result?
If the vaginal swab returns positive for GBS or if the woman has risk factors then the hospital protocols state that the woman will be given 4 hourly intravenous antibiotics once in labour. In Melbourne the hospitals have different guidelines on the prophylactic antibiotic cover and doses.
To prevent 1 neonatal death from GBS disease, 24.000 women would need to get screened for GBS and 7000 women would need treatment with antibiotics in labour. If a woman that is GBS positive has no risk factors and no treatment the chance that her baby is being affected by GBS is 1 in 500, which is a low risk.
What does it mean to give 7000 women antibiotics to prevent 1 baby from dying?
Babies are born sterile and during the first contact the baby gets all the bacterial flora from the mother. The baby swallows the mother’s healthy bowel flora during a vaginal birth and the baby’s gut gets coated with healthy bacteria.
The antibiotics given to the woman in labour will have an impact on the woman’s own flora that she passes on to her baby at the time of birth. If antibiotics are given to the woman in labour there is a delay in newborn gut colonisation. The antibiotics that the woman receives in labour will partially pass to the baby at the first moment of gut colonisation, interfere with the baby’s development of a healthy gut flora and potentially allow dangerous penicillin-resistant bacteria to become established.
This first opportunity of developing or not developing a healthy gut flora does have life long consequences. According to Bedford Russell (2006) “There is rapidly increasing evidence from experimental studies that the initial colonisation of the intestine is a moment of pivotal importance in long-term health, playing a profound role in imprinting of immune and systemic homeostasis.” The gut flora is the largest part of the immune system and an abnormal gut flora has been implicated in asthma, autoimmune diseases, diabetes, cancers and obesity.
Women who receive antibiotics in labour have a 10% chance of getting nipple thrush within 1 month after birth. Nipple thrush is very painful and can be a reason for women to stop breastfeeding, which is a significant public health concern.
There is also a possibility of allergic reactions and anaphylaxis that can potentially lead to death. Another big concern is antibiotic resistances. Penicillin is currently effective for treating GBS disease in newborns. One of the serious ramifications of the mass antibiotic cover for women whose babies were at risk of GBS disease is that ever since antibiotics have been introduced to treat large amounts of women, the rate of E.coli infections in premature babies has more than doubled. In one study 85% of the E.coli infections showed resistance to the antibiotics prescribed to treat GBS.
Does giving antibiotics actually make a difference?
A Cochrane review looked at trials comparing women who had received antibiotics with women who had no antibiotics. Antibiotics did reduce the incidence of GBS infection in newborns but there was no significant difference in the number of babies that died. Cochrane concluded that “Very few of the women in labour who are GBS positive give birth to babies who are infected with GBS and antibiotics can have harmful effects such as severe maternal allergic reaction, increase in drug-resistant organisms and exposure of newborn infants to resistant bacteria, and postnatal maternal and neonatal yeast infections. Giving antibiotics is not supported by conclusive evidence” (2009).