Can a pregnancy test be wrong?

Yes, but not equally often both ways. The NHS says a positive result is almost certainly correct, while a negative result is less reliable, especially if you test early. Here’s which result you can trust, and what to do next.

Can I trust a positive result?

Almost always. A test can only show positive if it finds hCG, the pregnancy hormone, and outside pregnancy your body doesn’t normally make enough for a home test to find.

The rare exceptions are a recent pregnancy (hCG takes several weeks to clear), fertility medicines that contain hCG, a test read after its reading time, a faulty test, and, very occasionally, the menopause or a medical condition. Read can you get a false positive?

A positive followed by a period may be a very early miscarriage, sometimes called a chemical pregnancy. If you’ve had a positive test and then start bleeding, contact your maternity unit, an early pregnancy unit or NHS 111 so you can be checked, even if you think it’s a chemical pregnancy. Nobody can tell the cause of bleeding at home.

Can I trust a negative result?

Less so. A negative only means the test hasn’t found enough hCG yet. That’s often because it was taken too early, or because you ovulated later than you thought. Even on the day your period is due, some pregnancies can’t be picked up yet.

Read false negative pregnancy tests for why it happens and when to test again, and how accurate are pregnancy tests? for what “99% accurate” really means.

What to do next

If your test is positive

You can refer yourself straight to a midwife. See tested positive? What to do now

If your test is negative and your period hasn’t come

Wait a few days and test again, with your first pee of the day. If you get a second negative and your period still hasn’t arrived, speak to your GP.

If your test is negative and your period has come

You’re very likely not pregnant this cycle. If you were hoping for a positive, read coping with a negative result.

If you got a faint line

It usually means you’re pregnant, very early. Test again in a couple of days. See what does a faint line mean?

If two tests disagree

Go by a newer test, read within its reading time. hCG rises over a few days, and tests vary in how little hCG they can pick up, so an earlier or less sensitive test can be negative when a later one is positive.

If you’re having fertility treatment

If you’re having fertility treatment, test on the date your clinic gives you (for IVF, this is usually around 16 days after embryo transfer). Testing earlier may give a false result. If you had a ‘trigger’ injection containing hCG, it can stay in your body for up to about 10 days and give a positive that isn’t a pregnancy.

What about ectopic pregnancy?

An ectopic pregnancy usually gives a positive test. But the NHS says to get advice if you have symptoms of one, such as pain low down on one side or pain in the tip of your shoulder, even if you haven’t had a positive test.

Questions people ask

Which is more likely, a false positive or a false negative?

A false negative, by a long way. It usually just means you tested too early.

Can a pregnancy test be wrong at 6 weeks?

It’s unusual, as hCG has usually risen a lot by then. If you have symptoms and a negative test, or the result doesn’t make sense, see your GP.

When to get help

Mild cramps that ease with rest are usually nothing to worry about. But if you’re pregnant, or think you could be, get urgent advice from your maternity unit, an early pregnancy unit or NHS 111 if you have:

any bleeding or spotting, even if it’s light
tummy pain that’s severe, on one side, or hasn’t eased after resting for 30 to 60 minutes
pain in the tip of your shoulder

Call 999 if you have bleeding along with severe tummy pain, pain in your shoulder, or feeling sick, faint or dizzy, or if the bleeding is heavy (soaking a pad soon after putting it on). Also call 999 if you have sudden, sharp and intense tummy pain and you feel very dizzy or faint, feel sick or look very pale. These can be signs of an ectopic pregnancy or a miscarriage that need treating straight away.