Your contraception guideWill a pregnancy test work if I'm on the pill?
No contraceptive method is 100% effective, so it's always advisable to take a pregnancy test if you think you might be pregnant, regardless of the type of contraception you're currently using or have used in the past.
Hormonal methods of contraception – such as the contraceptive pill, contraceptive implants and injections – contain the hormones oestrogen and progestogen. They work by changing a woman's hormone balance.
However, these hormones will not affect the result of a pregnancy test because they are not used to measure whether or not you are pregnant.
How pregnancy tests work
A pregnancy test only reacts to the pregnancy hormone human chorionic gonadotrophin (HCG).
However, if you're pregnant, this hormone will not be present in your urine or blood until 13 to 16 days after the release of an egg (ovulation), which is around the time you would normally get your period.
Until this time has passed it will not be possible to see a positive result in a pregnancy test.
Urine tests require a certain level of HCG to be present in order to indicate a positive pregnancy result. Blood tests are more sensitive because they can detect a smaller amount of HCG, which means that pregnancies can be picked up earlier, usually between 6 to 8 days after ovulation.
You can have a blood test at your GP surgery, but it's recommended you take a home urine test before booking an appointment.
HCG is sometimes used in fertility treatment, which could cause a false-positive result (where the result shows as positive but is actually negative). You should wait 14 days after having fertility treatment before taking a pregnancy test.
A negative result
If you get a negative result after taking your pregnancy test, it can mean several different things.
Firstly, it can mean you are not pregnant, or that you have taken the test too early. Taking a test early is easily done because it can be difficult to work out the exact day you began ovulating.
If you think you may have taken the test too early, wait a few days before taking a second test, or see your GP for advice and possibly a blood test.
Negative results may also be because you have timed the test incorrectly. For instance, if you collect a sample of your urine for testing and have not conducted the test within 15 minutes, it may affect the result. Home pregnancy tests can vary, so always read the instructions carefully before you do the test.
Drinking too much fluid before a test can also lead to your urine being diluted, which can affect the levels of HCG in your sample.
If you are in any doubt about your pregnancy test result, you should make an appointment with your GP.
Page last reviewed: 29/01/2018
Next review due: 29/01/2021