Preventative antibiotics halve the risk of infection for women who have assisted vaginal delivery using forceps or suction-cup devices. About 10% of women receiving antibiotics develop an infection within six weeks of delivery compared with 20% of women who receive a placebo.
Antibiotics are not routinely recommended for women undergoing assisted delivery as there hasn’t been enough evidence that they reduce maternal infection rates. This large NIHR-funded trial, including almost 3,500 women from across the UK, provides compelling evidence that they do.
The findings could lead to changes in UK and international recommendations. In this study, single-dose prophylaxis reduced the overall prescription of antibiotics in the first six weeks after delivery.
Why was this study needed?
There were 626,203 births in NHS hospitals in 2017-18. Just over 1 in 10 of these was assisted by forceps or suction cup device, also termed operative or instrumental deliveries.
Around 7% of maternal deaths in the UK are due to severe infection (sepsis) from delivery. Interventional deliveries are known risk factors. Infection is estimated to affect around 20-25% of women following caesarean and around 15% after assisted delivery. However, while there has been strong evidence to support the use of antibiotic prophylaxis for caesarean there has been uncertainty over the benefits for assisted delivery.
A 2017 Cochrane review identified a single trial of antibiotic prophylaxis for assisted delivery in 393 women. This suggested that antibiotics have no effect on infection rates or length of hospital stay, but the quality of this evidence was low.
With the concern over antimicrobial resistance, antibiotics cannot be recommended when there is insufficient evidence of benefit. This large trial aimed to resolve the issue.
What did this study do?
ANODE was a randomised controlled trial including 3,427 term women (36 weeks plus) from 27 maternity hospitals across the UK. Eligible women were assigned to receive a single intravenous dose of amoxicillin with clavulanic acid or placebo within six hours of forceps or vacuum delivery.
Women who were allergic to penicillin, or who had indications for antibiotics, such as evident infection or severe vaginal tear, were excluded. Antenatal antibiotics could have been given (for example, for prolonged rupture of membranes) provided there was not ongoing need.
Full outcome data was available for only 76%, though all women were included in the intention-to-treat analysis (excluding seven who withdrew consent).
The main outcome was confirmed or suspected defined as a new prescription of an antibiotic. Lack of microbiological confirmation of infection was a recognised limitation.
What did it find?
- Antibiotic prophylaxis reduced the infection rate within six weeks of assisted delivery: 11% of women were prescribed antibiotics compared with 19% who received placebo (relative risk [RR] 0.58, 95% confidence interval [CI] 0.49 to 0.69).
- Antibiotic prophylaxis reduced the number of women with perineal pain (46% vs 55%; RR 0.84, 95% CI 0.76 to 0.93), need for additional perineal care (31% vs 43%; RR 0.72, 95% CI 0.63 to 0.83) or perineal wound break down (11% vs 21%; RR 0.52, 95% CI 0.41 to 0.67). Prophylaxis also reduced the number of women reporting the perineum feeling too uncomfortable to feed the baby, or needing GP, home or outpatient visits for perineal problems.
- Antibiotic prophylaxis, however, made no difference to the length of hospital stay, need for readmission or overall quality of life.
- Adverse effects occurred in three women: two in the antibiotic group reported allergic reactions while one in the placebo group reported a rash. One of the allergic reactions was described as serious (no further detail available). Two additional serious events occurred, but these were not related to the interventions.
What does current guidance say on this issue?
WHO guidelines (2015) do not recommend routine antibiotic prophylaxis for women undergoing assisted delivery. This was a ‘conditional’ recommendation based on low-quality evidence that antibiotics do not reduce risk of maternal infection. Antibiotics were recommended for third- or fourth-degree tears, which may be associated with prolonged labour and assisted delivery.
The Royal College of Obstetricians and Gynaecologists (2011) similarly considered that there was insufficient evidence to justify the use of antibiotics for assisted delivery.
NICE guidelines do not cover this specific issue but do not recommend antibiotics during labour and birth unless there is evidence of infection.
What are the implications?
This high-quality trial provides much-needed evidence on the effectiveness of antibiotics prophylaxis for assisted delivery. Antibiotics clearly reduce post-natal infection rates and reduce the risk of common perineal problems.
Due to concerns about growing antimicrobial resistance, it is important that stewardship of the antibiotics we have is based on high-quality evidence.
Further research to confirm the optimal treatment regimen and choice of antibiotic (especially in those allergic to penicillins) will help guide practitioners.
Citation and Funding
Knight M, Chiocchia V, Partlett C et al. Prophylactic antibiotics in the prevention of infection after operative vaginal delivery (ANODE): a multicentre randomised controlled trial.
This project was funded by the NIHR Health Technology Assessment Programme (project number 13/96/07)
NHS Digital. NHS Maternity Statistics, England 2017-18. London: NHS Digital; 2018.
NICE. Intrapartum care for healthy women and babies. CG190. London: National Institute for Health and Care Excellence; 2014 (updated 2017).
NICE. Intrapartum care for women with existing medical conditions or obstetric complications and their babies. NG121. London: National Institute for Health and Care Excellence; 2019.
RCOG. Operative vaginal delivery. Green-top guideline 26. London: Royal College of Obstetricians and Gynaecologists; 2011.
Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre