Observations Medicine and the Media

Streptococcus B in pregnancy: to screen or not to screen?

BMJ 2012; 344 doi: https://doi.org/10.1136/bmj.e2803 (Published 18 April 2012) Cite this as: BMJ 2012;344:e2803
  1. Margaret McCartney, general practitioner, Glasgow
  1. margaret{at}margaretmccartney.com

The media are pushing for universal screening of pregnant women for group B streptococcus and treatment with antibiotics, but their stories often don’t mention the potential harms, says Margaret McCartney

“Why won’t Britain act to prevent biggest killer of newborns? The £10 (€12; $16) test that could save babies from death,” read the Daily Mail’s headline last month.1 The tragic story of a baby called Ewan followed. He had died from group B streptococcus (GBS) eight hours after his birth. “‘It’s hard to put into words the pain we felt at losing our first child without ever having experienced the joy of getting to know him. It was like someone ripping out our hearts.’” The article went on, “We are one of the few developed countries not to screen for the infection. A third of women carry the bacterium, which is largely harmless to adults . . . One in 300 exposed to it will develop the infection.” The bottom line from the Mail was that “Spotting it early and treatment with antibiotics during labour or in the first few hours after childbirth can be life saving and yet every year the infection kills 30 newborns.”

Screening for streptococcus B in pregnancy is not currently available on the NHS, but several companies offer pregnant women the opportunity to test themselves for streptococcus B, for about £30.2 3 The charity Group B Strep Support is campaigning for “every pregnant woman to be given accurate information on GBS as part of her antenatal care, every low risk woman to be offered a sensitive test for GBS carriage at 35-37 weeks of pregnancy without charge (until freely available, all pregnant woman should be told these tests are available privately), every higher risk pregnant woman to be offered intravenous antibiotics at the start of labour and at intervals until delivery,” and women at “highest risk should be recommended these antibiotics.”4 Another local newspaper reported, “‘My partner Eloise is now pregnant with our second child and we were both amazed to find no posters or leaflets warning about GBS. It isn’t hard or expensive to test for and once it’s been detected can be treated simply by giving the mother antibiotics as she goes into labour.’”5

Is this an accurate reflection of the evidence of benefit and lack of harm? A review is taking place by the UK National Screening Committee, which advises the government and the NHS, into whether screening during pregnancy should be recommended: the last review in 2008 concluded that screening should not be offered.6 The Royal College of Obstetricians and Gynaecologists estimates that screening would lead to about a third of women in labour receiving antibiotics. If this was 80% successful at preventing early onset group B streptococcus disease, it could reduce the number of affected UK babies from 340 to 68 a year. At least 1000 women needed to be treated with antibiotics to prevent 1.4 cases. The mortality rate from the disease is 6% for term and 18% for preterm infants. The risks of antibiotic use include anaphylaxis, which is thought to be fatal in one in 10 000 women treated.7 Broad spectrum antibiotics lead to resistant organisms, and concerns have been recently raised about the effect on gut flora of infants given antibiotics; no robust, long term data about safety or unintended effects are available. A review article from 2006 said, “The potential for long-term persistence of early-colonising bacteria suggests that much more thought should be given to the late consequences of perinatal broad-spectrum antibiotics. As a minimum, more studies are needed on the bacteriological and immunological consequences of antibiotic administration to neonates.”8

Yet many stories about streptococcus B screening fail to explain these uncertainties. The Manchester Evening News reported that each twin died at 36 weeks from streptococcus B: “Tragically their deaths might have been prevented with a simple £10 test—but Britain is one of the few developed countries not to screen for the infection.”9 ITV News Anglia did better to explain the difficulties: “Previously, the UK National Screening Committee has ruled against rolling out a national screening programme on the grounds that the test used by the NHS is unreliable and could lead to pregnant women being given antibiotics unnecessarily. The concern is that antibiotics interfere with the development of a healthy baby’s immune system, increasing the risk of asthma and other allergies. But those in favour of screening say a new test is more accurate and would only cost the NHS £10 per test.”10

Jane Plumb, chief executive of Group B Strep Support, thought that the Daily Mail article was fair. “It’s a subject which, sadly, all too many people are either uninformed or ill informed about.” However, she accepts that in several of the case studies in the media stories, the screening test for streptococcus B would not have helped: the time frame of testing at 35-37 weeks has been shown to be most effective at finding infection, and earlier gestational births are therefore unlikely to have benefited from screening. She said, “A similar story is repeated throughout the UK with term newborn babies developing group B streptococcus infections that could easily have been prevented had their mums been offered GBS screening at 35-37 weeks of pregnancy with intravenous antibiotics in labour.” These have been undoubtedly tragic deaths. But screening has limitations and potential hazards, and it may be that risk management rather than universal screening is more beneficial but will require nuanced discussion. Presenting potential benefits without the harms does mothers and children a disservice.


Cite this as: BMJ 2012;344:e2803


  • Competing interests: None declared.

  • Provenance and peer review: Commissioned; not externally peer reviewed.


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