If used correctly, the contraceptive pill is 99% effective. However, due to human error and forgetting pills etc. the actual effectiveness in the general population is 91%, meaning that annually 9 in 100 women taking the pill get pregnant.

The reason women taking the pill get pregnant is usually due to incorrectly taking the pill. You should read the instructions in the patient information leaflet carefully. Don’t assume that all brands of contraceptive pill are the same. Some need to be taken every day at the same time, while some have a break during which you have your period. Other pills have placebos included to help you keep track. Take the pill exactly as advised, and your chance of getting pregnant is less than 1 in 100. If you ever miss a pill, or forget to take it at the right time, you must use alternative methods of contraception, i.e. condoms, until you start the next pack. Taking two pills at once does not compensate for missing one. If you realise that you missed a pill, after you last had unprotected sex, you could consider taking the morning after pill and taking a pregnancy test after your next period.

Taking the pill will not affect the results of a pregnancy test. Pregnancy tests detect a hormone that is uniquely produced during pregnancy, and the hormones in the pill will not interfere with this. If you test positive on a home pregnancy test, it is a good idea to speak to your GP to confirm as home tests can be less accurate than blood test methods.

The early symptoms of pregnancy include a missed period or a period that is lighter than usual, tender or swollen breasts, nausea and cravings. Taking the contraceptive pill can disguise some of these symptoms, so you may not notice them as early. Many people report nausea, cravings and tender breasts when taking the pill. Besides, some women do experience a small amount of vaginal bleeding when pregnant, so if you have lighter periods on the pill, you may not notice a difference straight away. If you use the pill to delay your periods, you may also not notice a missed period, so it is a good idea to take a pregnancy test a few weeks after you realise that you had unprotected sex or missed a pill. 

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