How should we greet the news that some UK trusts have chosen to follow the lead taken by our American colleagues in screening all women for Group B Streptococcus (GBS) in late pregnancy, and then offering antibiotics in labour if they test positive? Should we celebrate the fact that we can use the might of preventative medicine to attack a bacteria that is usually harmless but can occasionally be fatal to babies, or should we lament the additional stress that this test puts on women, on top of the many other decisions that they need to make?
This is the introduction to an article that was first written in 2004 and, while some of the issues remain the same, some of the statistics have now changed. For instance, neonatal care has improved and the chance of a baby dying from early-onset GBS disease is lower than when this article was written. We also now have clearer information about which babies are at greater and lesser risk. I know that older articles are still of interest to people and some of what I wrote is still very relevant, but I have now edited and updated this article to remove the information that is no longer accurate. The latest data are included and discussed in my recently updated book on this topic and you may also like to search this site for other GBS-related resources on my website.
There are two ways we can screen women in order to try to determine which babies are at highest risk of contracting early-onset GBS disease. As is the case with all screening (as opposed to diagnostic) tests, neither provides a definitive answer. One – the “risk-based approach” – seeks to identify the babies who may be at increased risk because of clinical risk factors such as premature rupture of membranes, so that their mothers can be offered intravenous antibiotics in labour. Of course, many of the mothers of babies with clinical risk factors will not be carriers of GBS bacteria, and will therefore have unnecessary antibiotics.
The second option is called “universal” or “culture-based screening”, where women are screened for GBS in late pregnancy, and intrapartum antibiotics are offered to all women who are found to have GBS in their vagina or rectum. Although in theory (and, again, no screening test is 100% accurate) this would provide antibiotic cover for even more of the babies who are potentially at risk, with this option up to 30% of labouring women are offered antibiotics. The UK National Screening Committee consider that the risks of this approach, which means giving antibiotics to tens of thousands more labouring women, vastly outweigh the benefits.
Some of the issues which women need to consider in relation to this issue are easily overlooked in our haste to make being born as safe as we possibly can. One concerns the potential to increase the problem of antibiotic-resistant bacteria by giving antibiotics even more freely than we do already. Secondly, although routine antibiotic cover appears to reduce the number of babies who pick up GBS bacteria, the Cochrane review of this area shows that there is no evidence to support the suggestion that this reduces the number of babies who die from early-onset GBS disease (Smaill 2003). Then there are the massive implications of restricting the movement of up to a third of labouring women, and the implications this would have on their birth experiences and outcomes. Have we really thought through the effect that giving all of these antibiotics to all of these women might have on perinatal mortality and morbidity rates?
Surely women have a right to make their own decisions about these issues, and about the potentially serious implications of choosing whether or not to have GBS screening? As with a number of similar situations where women face difficult decisions around screening for rare but potentially fatal conditions, we may need to look more closely at where women can go for unbiased advice. In some cases, the advice and support available comes from companies who have technologies, screening tests or vaccines to sell, or from parents who have tragically lost a baby to the condition; both of whom may be potentially, and understandably, biased towards intervention. There are few support or information services run by people who discuss the downsides of screening or who take a more balanced approach, perhaps because the weight of opinion in our society tends to be in favour of all the tests we can find time for. Yet both sides of the picture are important facets of informed choice.
If you are interested in finding out more about this topic, you may be interested in my book, Group B Strep Explained. Or my page (also linked below) which lists all of the Group B Strep Resources available on this site.
Oddie S Embleton ND (2002). Risk factors for early onset neonatal group B streptococcal sepsis: case-control study British Medical Journal 325: 308
Smaill F (2003). Intrapartum antibiotics for Group B streptococcal colonisation (Cochrane Review). In: The Cochrane Library, Issue 4, 2003. Chichester, UK: John Wiley & Sons, Ltd. This was the version available at the time this article was originally written. An updated review of this topic was published more recently and is discussed elsewhere on this site, although the conclusions did not change: see this blog post for more details.
Wickham S (2004). The War on Group B Strep. AIMS Journal 15(4): 7-9.
A version of this article was first published as Wickham S (2004). Giant Break in Screening or Great Big Stressor? TPM 7(7):39.