False Negative Pregnancy Test: 5 Reasons It May Happen

Medical review: Dr. Sheila Sedicias
Gynecologist
July 2022

Home pregnancy tests are very accurate if done according to the package instructions and if completed at the right time, i.e. the first day after the period is due and onwards after that. However, to confirm a result, the best thing to do is to repeat the test three to five days after the first test.

Even though urine tests are usually accurate, there are other unexplainable changes to your menstrual cycle that can cause concerns and doubts with the result, like when your test is negative, but your period is still late.

The best way to confirm a suspected pregnancy is with a blood test that confirms the presence of bHCG hormones in the blood. However, below are some reasons why a home pregnancy test can show a negative result when you are, in fact, pregnant: 

1. Completing a test too early 

This is one of the most common reasons for a false negative test. Many women will complete a pregnancy test as soon as they feel symptoms of early pregnancy, like sore breasts or changes to vaginal discharge.  

However, the best way to guarantee a correct result is to wait for your period to be late, and then to do the test a few days later. This allows the body enough time to produce sufficient HCG hormones to be detected in a urine test. Read more about how to correctly complete a home pregnancy test.

2. Irregular cycles

When your menstrual cycle is irregular, negative pregnancy tests are actually more likely to occur. This is because, just like above, the urine test is completed too early, before a period is actually late, resulting in a negative test. 

If you cycles are usually irregular, you should only complete a test two to three weeks after your predicted period. You should track your period symptoms to have a better understanding of when your period is due to start. 

3. Ectopic pregnancy 

An ectopic pregnancy is a rare condition. It occurs when a fertilized egg implants outside of the uterus, usually in the fallopian tubes. In these cases, the body takes longer to produce HCG hormone, and the result can appear negative even if fertilization has occurred. 

This type of pregnancy is a medical emergency that should be terminated as soon as possible, as it can cause serious damage to the woman’s reproductive system. A few signs that can indicate a possible ectopic pregnancy are intense abdominal pain, vomiting, vaginal bleeding, or feeling of abdominal heaviness. If you have these symptoms, proceed immediately to the hospital to confirm diagnosis and initiate treatment.

4. Breastfeeding

When a woman is breastfeeding, the body takes longer to return to its initial pre-pregnancy state.  Therefore, it is possible for a woman’s cycle to be irregular initially, even though she used to have a regular cycle before.

This may result in a false negative, as an expected period is not actually delayed yet, leading to an early pregnancy test. 

5. Expired or mishandled test

This may be the rarest cause, however it is possible that a pregnancy test has expired and no longer functioning properly. When a test is not used vy its valid date, the presence of HCG may not be detected, resulting a negative test.  

It is very important to check the expiration date on the package before using it. Additionally, if pregnancy tests are not stored properly, even though they are within the expiry date, they may not give an accurate result. For those reasons, if you suspect that the test is not reporting the correct result, you should complete another one. 

What can cause a delayed period

If your period is delayed and a pregnancy test confirms a negative result, you are advised to repeat the test in a few days. If the second test is still negative even when your period is still late, likelihood of pregnancy is low. There are many factors that can influence your cycle and cause a delayed period when you are not pregnant. 

Some causes of a delayed period are:

  • Excess stress and anxiety;
  • Practicing intense physical exercise for a long time;
  • Thyroid problems;
  • Very restrictive diets.

Learn about what else can cause a late period.

If your period is late and multiple home pregnancy tests confirm a negative result, you should consult your doctor to identify whether there is another factor influencing the delay. They may be able to indicate appropriate treatment based on the diagnosis. 

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Atualizado por Tua Saude editing team, em July de 2022. Medical review por Dr. Sheila Sedicias - Gynecologist, em October de 2020.

References

  • STATPEARLS. Early Pregnancy Diagnosis. 2022. Available on: <https://www.ncbi.nlm.nih.gov/books/NBK556135/>. Access in 25 Mar 2022
  • MINISTERIO DE SANIDAD, SERVICIOS SOCIALES E IGUALDAD . Guía de práctica clínica de atención en el embarazo y puerperio. 2014. Available on: <https://portal.guiasalud.es/wp-content/uploads/2018/12/GPC_533_Embarazo_AETSA_compl.pdf>. Access in 25 Mar 2022
Show more references
  • PONTIFICIA UNIVERSIDAD CATÓLICA DE CHILE. FACULTAD DE MEDICINA. Manual de Obstetricia y Ginecología. 2018. Available on: <https://medicina.uc.cl/wp-content/uploads/2018/08/Manual-Obstetricia-y-Ginecologi%CC%81a-2018.pdf>. Access in 25 Mar 2022
Medical review:
Dr. Sheila Sedicias
Gynecologist
Physician graduated in Mastology and Gynecology by UFPE in 2008 and member no. 17459 of CRM-PE, Brazil.