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Contraceptive effectiveness explained

by The Lowdown · Nov 20, 2021

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What does 'typical use' vs 'perfect use' even mean? Get the lowdown on contraceptive effectiveness.
The table below shows the % of women experiencing an unintended pregnancy during the first year of typical and perfect use of that method of contraception. 
So if you followed 100 women who used the combined pill typically for a year, 7 of them would get pregnant. 
‘Typical use’ is the measure we should care about most. This is how contraceptives perform in the real world, with us sometimes forgetting to take a pill or having our injection a bit later than we should do.
‘Perfect use’ is when the method is always used completely correctly and consistently, for example taken at the right time every day.
This table contains estimates based on available data. These may differ between studies or change slightly as studies are repeated or updated.

Statistics on each contraception typical use and perfect use percentages

* = Tubal occlusion

** = Symptothermal method

A note on Fertility Awareness Methods:

  • Typical use with a single fertility indicator such as the ovulation method at 1 year is around 24%
  • Typical use of the symptothermal method at 1 year is 2% and with perfect use is 0.4%.
  • The Symptothermal method is a double-check method based on evaluation of cervical mucus to determine the first fertile day and evaluation of cervical mucus and temperature to determine the last fertile day.

  • The effectiveness for the Natural Cycles app is self-reported from their website
Tags
  1. Trussell J. Contraceptive failure in the United States. Contraception. 2011;83(5):397-404. doi:10.1016/j.contraception.2011.01.021. Contraceptive failure rates table available here
  2. Ballerine IUB patient information leaflet
  3. Natural Cycles website
  4. Faculty of Sexual and Reproductive Health 
  5. NHS