Unless you want to get pregnant, you should always use regular contraception – period.
Even if your menstrual cycle is as regular as clockwork, ovulation is very tricky to pinpoint. Combine that with the fact that sperm can live in the female reproductive system for up to five days, and you can see how hard it is to confidently track the ‘fertile window’.
Even if you could accurately predict the fertile window and avoid having sex on the day you ovulate… we all know that sometimes things don’t go to plan or you get caught up in the moment. There’s a reason that we don’t prescribe abstinence as a method of contraception!