87 trials, 36,000 women: which emergency contraceptive works best
What happened
A new Cochrane review, published in September 2026, has pulled together almost every good trial ever run on emergency contraception and asked a simple question: which one actually prevents the most pregnancies? Cochrane reviews are not new studies. They gather the existing trials, check how well each one was done, and combine the results. This one was led by Dr Shaalini Ramanadhan at Oregon Health & Science University in the United States. It included 87 randomised controlled trials and around 36,000 women of reproductive age. The headline finding was about a medicine called mifepristone. At low doses (under 25mg) and middle doses (25–50mg), it prevented more pregnancies than levonorgestrel, which is the most widely used emergency contraceptive pill in the world. Compared with levonorgestrel, low-dose mifepristone cut the chance of pregnancy by about 27% in relative terms. Cochrane rated that as high-certainty evidence, which is its strongest rating. Mifepristone also caused fewer side effects overall than levonorgestrel, and far less sickness than the older combined-hormone method known as the Yuzpe regimen. Ulipristal acetate, the other pill available in the UK, also came out better than levonorgestrel.
Why this matters
In the UK, the NHS lists three kinds of emergency contraception. There is levonorgestrel (sold as Levonelle), which has to be taken within three days of unprotected sex. There is ulipristal acetate (sold as ellaOne), which can be taken up to five days afterwards. And there is the copper coil, or IUD, which can be fitted up to five days afterwards and which the NHS describes as the most effective type of emergency contraception. Mifepristone is not on that list. It is not offered as emergency contraception here. So why does the review matter to a reader in Lincolnshire? Two reasons. First, it tells you something useful about the options you can get. Ulipristal came out ahead of levonorgestrel in the same review. Many people walk into a pharmacy and simply ask for "the morning-after pill" without knowing there is more than one, or that they differ. Second, the copper coil is easy to forget in a stressful moment, even though the NHS rates it as the most effective choice. It is not the obvious thing to think of at eight o'clock on a Sunday morning, which is exactly why it is worth knowing about now rather than then.
What the evidence actually says
A 27% reduction sounds enormous. It needs unpacking, because it is a relative figure. Imagine 100 women who would have had a pregnancy after using levonorgestrel. A 27% relative reduction means roughly 73 of them would have had one with low-dose mifepristone instead. It does not mean 27 pregnancies in every 100 women were prevented. Emergency contraception failures are uncommon to begin with, so the real-world difference between the two is smaller than the percentage makes it sound. It is still a genuine difference, and with 87 trials behind it, a reliable one. The high-certainty rating is meaningful. In Cochrane's language it means further research is very unlikely to change the answer. There are limits, and the review is open about them. Of the 87 trials, 79 were carried out in China, with a handful in the UK, Cuba and across several countries. That is a lot of evidence from one place. There were only two trials comparing mifepristone with the copper coil, which is far too few to draw a conclusion. Mifepristone's main drawback was a delayed period, and the effect was bigger at higher doses. That is not dangerous, but it is unsettling — a late period after taking emergency contraception makes people worry it has not worked. One more point, because it causes real confusion. Mifepristone is used in abortion care at different doses, and that has made it politically contested in several countries. The doses in this review are much lower and the purpose is different: preventing a pregnancy from starting. The review's authors noted that legal and political restrictions, rather than the evidence, are what limit its use as an emergency contraceptive in many places. Dr Ramanadhan's own summary was measured: mifepristone in low to middle doses is "a highly effective emergency contraceptive option that clinicians should know about".
Practical advice
Speed matters more than choice. Every one of these methods works better the sooner it is used. If you are deciding between going now and going tomorrow, go now. Know the time limits. Levonorgestrel: within three days. Ulipristal acetate: within five days. Copper coil: within five days. After five days, none of them is an option, so the window is genuinely short. Ask the pharmacist which one suits you, rather than asking for a brand. They will ask a few private questions for a reason. Tell them what other medicines you take, including anything bought over the counter, and roughly when in your cycle you are. Ask about the coil if you are within five days. The NHS calls it the most effective emergency option, and it can then stay in as ongoing contraception for years if you want it to. It is free. Emergency contraception is available free from sexual health clinics, GP surgeries and NHS walk-in centres, and free or for sale at pharmacies. Cost should not be the reason anyone goes without. If your period is late afterwards, take a test. A delayed period is a known effect of some of these medicines, but the only way to be sure is to check.
What to know
A large Cochrane review of 87 trials and around 36,000 women found that low- and middle-dose mifepristone prevents more pregnancies than levonorgestrel, with fewer side effects, and rated that finding high-certainty. Ulipristal acetate also beat levonorgestrel. Mifepristone is not offered as emergency contraception in the UK, so this does not change what is on the shelf tomorrow. What it does is confirm that the different options are genuinely different, and that it is worth having a proper conversation with a pharmacist rather than reaching for the first name you recognise. It also confirms what the NHS already says: if you can get a copper coil fitted within five days, that is the most effective choice of all. Sources: Ramanadhan S and colleagues, 'Interventions for emergency contraception', Cochrane Database of Systematic Reviews, September 2026, https://www.cochrane.org/evidence/CD001324_methods-emergency-contraception; Medical Xpress, 'Mifepristone more effective than other common emergency contraception methods', 20 September 2026, https://medicalxpress.com/news/2026-09-mifepristone-effective-common-emergency-contraception.html; NHS, 'Emergency contraception', https://www.nhs.uk/contraception/emergency-contraception/ This article is for general information and does not replace advice from a doctor, pharmacist or other qualified healthcare professional.
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