Can you get a false positive pregnancy test?

It’s rare. The NHS says a positive pregnancy test is almost certainly correct. But there are a few situations where a test can show positive when there isn’t an ongoing pregnancy.

What can cause a positive without an ongoing pregnancy

A very early pregnancy loss

A test can be positive because you were pregnant, but the pregnancy ended very early. This is called a chemical pregnancy. It isn’t really a false positive, because the test was right at the time. 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.

A recent pregnancy

After a birth, miscarriage or abortion, hCG doesn’t disappear straight away. It falls gradually and can take several weeks to clear, so a test can stay positive for a while. Some NHS hospitals and abortion providers suggest a pregnancy test about 3 weeks after a miscarriage or abortion. If it’s still positive then, contact the hospital team or provider who looked after you, as you may need a check.

Fertility treatment

Some fertility medicines contain hCG, the same hormone tests look for. 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. Your clinic will tell you when to test (for IVF, this is usually around 16 days after embryo transfer).

Reading the test too late

An evaporation line can appear after the reading time and look like a faint positive. Read the result within the time it gives. See faint line or evaporation line?

A faulty test

Occasionally a test simply doesn’t work properly. Check the expiry date, and if a result doesn’t make sense, use a test from a different box.

The menopause

Around and after the menopause, small amounts of hCG can sometimes be made by the body. One test maker says that if you’re in or approaching the menopause, you may get a false pregnant result. See pregnancy or menopause?

Rare medical causes

Very occasionally, some medical conditions, including rare tumours, can produce hCG.

What a fading line can and can’t tell you

If you think a positive might be left over from a recent pregnancy, testing again over a few days and seeing the line get fainter can suggest your hCG is falling. But home tests aren’t designed to measure how much hCG there is, so a line that looks the same or darker doesn’t tell you for certain what’s happening. Only a blood test can measure your hCG level. If you’re unsure, or you’ve had bleeding or pain, get checked.

What about medicines?

The contraceptive pill won’t affect a pregnancy test. Apart from fertility medicines that contain hCG, most everyday medicines won’t cause a positive, but if you take regular medicine and aren’t sure, ask a pharmacist.

What about ectopic pregnancy?

An ectopic pregnancy, where a pregnancy grows outside the womb, will usually give a positive test because it is a pregnancy. It isn’t a false positive, but it does need medical care. An ectopic pregnancy is also possible when a test is faint or even negative, which is why pain or bleeding in early pregnancy should always be checked.

What to do if you’re not sure

Test again in a couple of days, following the instructions carefully, with your first pee of the day.
If you’ve recently been pregnant, talk to your GP, the early pregnancy unit or the provider who cared for you.
If you’re having fertility treatment, call your clinic.
If things are still unclear, a blood test can measure how much hCG there is. It’s usually arranged by an early pregnancy unit or your GP.

Questions people ask

How long does hCG stay in your body after a miscarriage?

It can take several weeks to fall to zero. Some hospitals suggest testing again about 3 weeks after a miscarriage, and getting in touch if the test is still positive.

Can a trigger shot give a positive test?

Yes. An hCG trigger injection can show up on a test for up to about 10 days. Wait for your clinic’s test date.

Can an evaporation line look like a positive?

Yes, which is why it’s important to read the test within the time it gives and ignore anything after that.

Is a positive test ever wrong if I’m not pregnant at all?

It’s rare. If you get a positive and there’s no recent pregnancy or fertility treatment, assume you’re pregnant and contact a midwife or GP, who can check if anything doesn’t add up.

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.