Key messages

• Giving antibiotics to women in labour (whose pregnancies were at least 28 weeks along) probably reduces their risk of developing sepsis – a life-threatening condition that happens when the body overreacts to an infection.

• Giving antibiotics in this way makes little or no difference to the number of babies who develop sepsis or die, and probably makes little or no difference to the number of women who die.

• The evidence about the adverse (i.e. harmful, unwanted) effects of preventative antibiotics is very uncertain, so we do not know if this treatment contributes to the problem of antimicrobial resistance – when antibiotics stop being effective at fighting bacterial infections.

What is antibiotic prophylaxis, and its benefits and risks?

'Antibiotic prophylaxis' means giving antibiotics to prevent infection before any signs appear. This approach has shown some benefit in reducing infections in new mothers and newborn babies. However, routinely giving women preventative antibiotics during labour is controversial due to concerns about unnecessary antibiotic use and antimicrobial resistance.

What did we want to find out?

We wanted to assess the effects of giving preventative (i.e. 'prophylactic') antibiotics to women during labour, whose pregnancies were at least 28 weeks along (i.e. 28 weeks' gestation). We looked at how many women and babies got infections, particularly sepsis, and how many died.

What did we do?

We searched for studies that compared prophylactic antibiotics with a placebo in pregnant women in labour after 28 weeks’ gestation. A placebo is an inactive substance that looks identical to the antibiotic but has no therapeutic effect. This allows researchers to measure the true impact of the intervention.

The studies included women planning a vaginal birth, as long as they did not have a specific medical reason to receive antibiotics (such as a planned caesarean section or a known infection).

We compared and summarised the study results, and rated our confidence in the evidence, based on factors such as study methods and sizes.

What did we find?

We identified four studies involving a total of 42,846 pregnant women. The studies were conducted in 10 countries: Bangladesh, Burkina Faso, Cameroon, the Democratic Republic of Congo, The Gambia, Guatemala, India, Kenya, Zambia, and Pakistan, all low- and middle-income countries.

Roughly half of the women received prophylactic antibiotics (a single dose by mouth), and half received a placebo.

Compared to placebo, prophylactic antibiotics:

• probably reduce the number of women who develop sepsis;

• probably make little or no difference to the number of women who die;

• make little or no difference to the number of newborns who develop sepsis or die;

• make little or no difference to the number of women who develop a perineal wound infection (an infection of the tissue between the vagina and anus);

• make little or no difference to the number of babies admitted to the neonatal intensive care unit (NICU).

Only one study looked at antimicrobial resistance, and we are not confident in its evidence. The study reported short-term increases in antibiotic-resistant bacteria found in some samples (e.g. of breast milk, nasal or vaginal swabs) from women given antibiotics compared to those given placebo, but these differences disappeared by 13 months. In newborns, antimicrobial resistance was rare.

What are the limitations of the evidence?

We had moderate or high confidence in the evidence about the number of women and babies who developed infections (including sepsis) or died. As noted above, we are not confident in the evidence about antimicrobial resistance. Antimicrobial resistance patterns and antibiotic use practices vary widely, and the studies focused primarily on azithromycin, a broad-spectrum antibiotic, without evaluating other options. The long-term impact on antibiotic resistance remains very uncertain and requires further research.

How current is this evidence?

The evidence is current to July 2024.