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Ask the Doc: How effective is the pull-out method?

Question

How effective is the pull-out method?

Answer

The pull-out method of contraception is also known as the withdrawal method or coitus interruptus. The idea is, the male partner withdraws his penis from his partner before he ejaculates, so sperm do not enter the vagina and therefore the female won’t become pregnant.

That’s how it’s supposed to go but, in practice, the pull-out method is far from perfect when it comes to preventing pregnancy, and it offers no protection against sexually transmitted diseases.

If a couple doesn’t use contraception at all, we’d expect about 85% of them to get pregnant after one year. If they use the pull-out method, we’d expect 20% of them (one in every five couples) to get pregnant within a year1. In comparison, around one in eight couples who use condoms, and one in 14 couples who rely on the pill, would be expected to get pregnant in a year.

Part of the reason why the withdrawal method is unreliable is that sperm may be present in pre-ejaculate fluid. Another part of the reason is, it’s difficult to do the withdrawal method perfectly. Most forms of contraception suffer from ‘user error,’ meaning they don’t work as well in the real world as theoretically possible. That goes for withdrawal, condoms and the pill. So, when you find a contraception method that suits you and your partner, you need to make sure you use it properly every time you have sex.

A/Prof Tim Moss
A/Prof Tim Moss

Associate Professor Tim Moss has PhD in physiology and more than 20 years’ experience as a biomedical research scientist. Tim stepped away from his successful academic career at the end of 2019, to apply his skills in turning complicated scientific and medical knowledge into information that all people can use to improve their health and wellbeing. Tim has written for crikey.com and Scientific American’s Observations blog, which is far more interesting than his authorship of over 150 academic publications. He has studied science communication at the Alan Alda Centre for Communicating Science in New York, and at the Department of Biological Engineering Communication Lab at MIT in Boston.

References
  1. Woodhams & Gilliam, 2019. Contraception. Annals of Internal Medicine. https://doi.org/10.7326/AITC201902050

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