Potential harms of GBS screening “outweigh benefits”

A review published in the British Medical Journal has considered the harms of GBS screening as well as the benefits. And the authors have concluded that, based on current evidence, routine screening for group B streptococcus colonisation in late pregnancy should not be introduced in the UK, as the potential harms of unnecessary treatment with antibiotics may outweigh the benefits.

Farah Seedat et al (2019) explain the background to their review:

“The media and politicians regularly call for universal antenatal screening for GBS as an alternative means of selecting women for prophylaxis. Advocates point to countries across Europe and North America where screening is recommended and where reductions in early onset GBS infection have been observed. But the evidence shows that the effectiveness of screening, using established screening criteria, is uncertain and that screening has potential harms. Here, we explain why the UK National Screening Committee decided not to introduce routine screening in the UK—namely, high levels of overtreatment, unknown potential hazards from screening and intrapartum antibiotic prophylaxis treatment, and uncertain benefit.” (Seedat et al 2019).

There is particular concern about overtreatment and this is something of deep concern to many women and those who care for them during pregnancy and childbirth. I have recently updated my book on this topic and, as always, sought input from women, midwives, doctors and other birth workers. Although I heard from a few people who feel strongly in favour of increased screening and treatment (often based on their own experiences of having a baby with GBS disease), the overwhelming majority of comments received were from people who feel that taking the universal screening approach is “too much”. Some women who are offered antibiotics because they have risk factors do not want them in those circumstances either, because they are concerned about side effects and the impact of this treatment on a number of aspects of the woman’s and baby’s health and experience.

Group B Strep Explained

Group B Strep Explained; the updated second edition of a popular book which helps parents, professionals and others to understand the issues and the evidence relating to the screening and prophylactic measures offered in the hope of preventing early-onset group B strep (EOGBS) disease.

Many of those who contacted me about this topic are also aware that the chance of a baby getting GBS disease is very small, which means the chance of overtreatment is extremely high. The new analysis shows that, “in 2014-15, under risk based prevention, 138 933 term pregnant women were colonised with GBS, but only 350 term neonates developed early onset infection, meaning screening would have led to overtreatment of 138 583 (99.75%) women in labour.” (Seedat et al 2019).

This is of particular concern given what we know about the importance of a baby’s microbiome. Giving antibiotics to women in labour can interfere with the development of a baby’s microbiome and, as I note in the new book, Recent research shows that not only are bacteria beneficial, but they need to be passed on to the baby during birth via its mother’s vagina and have an important part to play in future health, especially relating to the gut and digestion, but in many other areas of wellbeing as well.” (Wickham 2019).

The BMJ review also contains a couple of useful infographics which illustrate the problem of overtreatment.

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Seedat F, Geppert J, Stinton C et al (2019). Universal antenatal screening for group B streptococcus may cause more harm than good. BMJ 2019; 364 :l463

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