When can I take a pregnancy test?

It depends what test you're using. Most pregnancy tests are accurate if you take them on the day your period is due. But some tests are more sensitive, and can tell you sooner. Check the pack or ask your pharmacist about your particular test.

Some of the more sensitive tests can give you an accurate result as soon as eight days after conception. But it's important to note that conception doesn't necessarily happen on the day you have sex.

Your partner's sperm can live in your body for up to seven days, waiting for an egg to be released. So depending on when you ovulate, you could conceive up to a week after having sex. In this case, even a very sensitive pregnancy test won't be able to give you an accurate result until about two weeks after you've had sex.

If you're not sure when you ovulate, it's best to wait for three weeks after having sex, or until your period is due - whichever is sooner - before taking a test, just to be on the safe side.

How do pregnancy tests work?

Most pregnancy tests measure the amount of pregnancy hormone, human chorionic gonadotrophin (hCG), in your urine. Check the instructions on the pack carefully before using a pregnancy test. Some will ask you to wee on a stick, while others will ask you to wee in a container and dip the stick in for a particular amount of time.

The sensitivity of a pregnancy test is described on the packaging as mIU/ml (milli-international units per millilitre). In general, modern pregnancy tests range in sensitivity from 6.3mIU/ml to 50mlU/ml. The lower the number, the more sensitive the test, and the earlier it can detect pregnancy.

False positives (where the test says you're pregnant, but you aren't) are rare. So if you have a positive test, chances are you're expecting. If you want to continue your pregnancy, get off to the best start with our first trimester to-do list.

False negatives (where the test says you're not pregnant, but you are) are more common. If you test too soon, even with a sensitive test, the amount of hCG in your urine may not be high enough to detect.

If you have a negative result, but still don’t get your period, test again in three days’ time. If you are pregnant, by then the levels of hormone may be high enough to be picked up by the test.

Can a blood test detect pregnancy sooner?

It is possible for a blood test to tell you if you're pregnant or not. However, because urine tests are so accurate, blood tests for pregnancy aren't usually necessary, and you're unlikely to be offered one on the NHS.

A blood test measures the hCG in your body, just like a urine test. It's about as accurate as the most sensitive available urine tests too, meaning it can give a result about a week after you conceived. However, blood tests need to be sent to a lab for analysis, so a super-sensitive urine test can actually give you a result sooner.

Your GP will only offer you a blood test if she suspects that there may be complications with your pregnancy, such as ectopic pregnancy (where the embryo implants outside your womb). She'll explain exactly why she's offering the test, and what to expect from any results.

Talk to others who are hoping to get pregnant by joining our Actively trying group.

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