Why did the pregnancy test show a positive, but I got my period anyway?

Most at-home pregnancy tests are sticks that you pee on and look for a line or something else that indicates that you’re pregnant. You place the test into your urine and then read the results after the timeframe specified in the test instructions.

Woman questioning pregnancy test results.

It’s easy to determine if you’re pregnant early because some tests detect very low hCG levels. Make sure to schedule an appointment with your doctor soon after getting your positive result.

There are some situations where it is possible to have a positive pregnancy test, even though you aren’t technically pregnant. You may get a false-positive result for several reasons.

The most common reasons are:

Chemical Pregnancy

A chemical pregnancy occurs when a fertilized egg, known as the embryo, cannot implant or grow very early on in your pregnancy.  

What Causes a Chemical Pregnancy?

Several factors can cause a chemical pregnancy. One of these is the age of the woman. The older you are, the less able you are to get pregnant. As your body ages, it is more likely not to have enough eggs to fertilize, and the ones that do get fertilized won’t implant more often than not due to poor egg quality.

Another factor is a condition called polycystic ovary syndrome (PCOS). This condition causes your body to produce an increased amount of hormones. As a result, this causes problems with ovulation. PCOS often causes infertility issues. If you have PCOS and are trying to get pregnant, your body might not produce enough hormones, preventing the egg from implanting properly. 

Another reason a chemical pregnancy can occur is that the pregnancy was never viable because of problems with the embryo.

User Error

Home pregnancy tests aren’t foolproof. You can end up with invalid results if you don’t follow the directions precisely and check the expiration date before taking the test. 

Failure to follow the instructions correctly can lead to inaccurate results. Additionally, reading the results after the time frame outlined in the instructions can also give you incorrect results. 

Evaporation Lines

If you don’t follow the instructions precisely, an evaporation line can sometimes be mistaken for a positive. 

An evaporation line will be when a faint-colored second line appears. A faint line may represent a very early positive pregnancy test result or be an evaporation line.  

The results could be false positive since the evaporation line may show up more clearly when you read the results later than the instructions state.

Follow the test’s timing instructions precisely as written. Don’t assume that the instructions stay the same for different pregnancy test brands. Each brand has its unique instructions.

Recent Miscarriage or Abortion

 If you take a pregnancy test too soon after a miscarriage or abortion, you may end up with a false positive pregnancy test. After a miscarriage, the pregnancy hormone starts to decline around five days after the loss and can stay elevated much longer than that. A pregnancy test can still produce a positive result until all the hCG is out of your system, even though you are no longer pregnant.

Some less common causes of a false positive pregnancy test:

Ectopic Pregnancy

An ectopic pregnancy is when the embryo implants outside of the uterus. 

What Causes an Ectopic Pregnancy?

Tubal pregnancies happen when a fertilized egg gets stuck in the fallopian tube on its way to the uterus. It can occur when the tube has is damaged by inflammation or is misshapen. Hormonal imbalances and abnormal development of the fertilized egg can also play a role in an ectopic pregnancy. 

Symptoms of an Ectopic Pregnancy?

The symptoms of an ectopic pregnancy vary depending on where the egg implants. If a fertilized egg implants in the fallopian tube, it causes:

  • Pain and cramping in the lower abdomen
  • Feeling of fullness and pressure in the lower abdomen
  • Pain that radiates to the lower back
  • Heavy bleeding

An ectopic pregnancy that occurs in the ovary can cause:

  • Irregular periods
  • Unusual vaginal bleeding
  • A lump in the abdomen that may be painful

An ectopic pregnancy that occurs in the cervix can cause:

  • Aching or burning pain in the lower abdomen
  • Bleeding from the vagina 

Certain Medications

 When a woman is having a hard time getting pregnant, her doctor may prescribe fertility treatments. Some fertility medicines include hCG (human chorionic gonadotropin), which helps follicles release mature eggs within a woman’s ovary. 

A false positive can occur if you take a pregnancy test within 7-14 days after fertility treatments that utilize hCG. You should wait 1-2 weeks after the last injection or treatment before performing a pregnancy test.

Medical Conditions

Some medical conditions can cause a person’s hCG levels to rise, even when not pregnant. A few of these include:

  • Disorders affecting the pituitary gland
  • Some cancers
  • Ovarian cysts that produce hCG
  • Kidney disease or urinary tract infections