Injection interference
Question
Can the contraceptive injection affect the results of a pregnancy test?
Answer
Pregnancy tests work by looking for a particular hormone, HCG, which is only produced by the body if you're pregnant. The contraceptive injection contains the hormone progestogen, which won't affect the outcome of a pregnancy test.
It's worth bearing in mind that the contraceptive injection is over 99% effective in preventing pregnancy, which means it's very unlikely that a woman on the injection would become pregnant.
If you think you might be pregnant, you can buy a home-testing kit from a chemist, or get one done by your local doctor (GP). Pregnancy tests can work as soon as a period is late (one day overdue). If you don't have a regular cycle it can be difficult to know when a period is due. It's best to take the test three weeks after having unprotected sex, as this is roughly how long it takes for the hormone levels to show up fully on the test.
If you're under 25, you can get a free test carried out at a Brook clinic. Here, you'll also be able to talk through how you feel and what your options are. This will be done in confidence, which means nobody will be told about your visit unless you want them to.
If you are pregnant, it's important to get advice as soon as possible to decide what you want to do next. If you're not pregnant, you may want to get further advice about the right contraception for you, especially if you want to avoid unwanted pregnancy in future. To do this, you could call Brook's free helpline on 0808 802 1234.
Updated: 07/06/2011
Question answered by Brook
