Fertility awareness, also called natural family planning, involves paying attention to signs of fertility like body temperature and cervical secretions. There are apps these days that will help you track signs of fertility, but experts still recommend you get trained by a qualified teacher if you want to use this method.

“Some women use fertility awareness methods forever and do really well with it,” says Connolly. “But you’ve got to be very disciplined, and your partner’s got to be very disciplined.”

The idea is that by working out when you ovulate, and by knowing that sperm can survive for several days, you can work out when you’re fertile and when you’re not. On your fertile days, you have to avoid sex or use another method of contraception like condoms.

The majority of women ovulate mid-cycle. “But not everyone ovulates when we think they’re going to, some women do at any point during the cycle,” says Connolly, which can make it tricky to accurately work out your fertile window.

“It’s a method that some people will use reliably, but there’s a much higher failure rate [than other forms of contraception],” she says.