If you’ve had unprotected sex and are experiencing symptoms of pregnancy, you may be confused when you see a negative pregnancy test result. There could be many reasons for a late/missed period or symptoms that can resemble a pregnancy.

Testing Too Early

Taking a urine pregnancy test too early may result in a “false negative.” Your body needs time for the pregnancy hormone (hCG) to rise to a level high enough to be detected in your urine. Alpha Center’s lab-quality, urine-based pregnancy tests are 97-99% effective in determining pregnancy as soon as 10 days after your most recent sexual encounter or one day after a first missed period. A blood pregnancy test usually ordered by a physician, may be able to detect hCG earlier.

Sexually Transmitted Diseases (STDs)

Some STDs, such as Gonorrhea and Chlamydia, can cause changes in a woman’s menstrual cycle. Any untreated STDs can cause bleeding between periods or a delayed/missed period. Gonorrhea and Chlamydia can also remain asymptomatic, yet transmissible, for several years.


Stress can cause an imbalance in your body’s hormones, which could disrupt your cycle. Stress is one of the most common causes of irregular periods. When you are stressed, the body produces the hormone cortisol. Cortisol interferes with your body’s ability to produce the other hormones necessary to have and maintain regular menstrual cycles.

Birth Control

Birth control pills and other forms of hormonal contraceptives can cause a change in your period or bleeding/spotting between periods. These changes can occur if you have recently started a new form of birth control or have not taken the medication as prescribed.


Breastfeeding can disrupt your menstrual cycle. This is because the hormone prolactin, which causes your body to produce milk, can suppress ovulation. However, it is still possible to become pregnant while breastfeeding, even if you haven’t had a period.

Weight Loss/Strenuous Activity or Exercise

Weight loss and strenuous activity can cause your menstrual cycle to become irregular, lighter or stop altogether. It is important to contact your doctor if this occurs or if you have concerns about significant changes in your overall health.  

It is important to remember that you can still become pregnant even if you are not having regular periods. If you have missed your period or have experienced changes in your fertility cycle, schedule a lab-quality pregnancy test and consultation at Alpha Center. A trained staff member will meet with you in a confidential and caring environment to discuss any concerns you have. You don’t have to face uncertainty alone.


Why has my period changed? American Pregnancy Association. https://americanpregnancy.org/unplanned-pregnancy/birth-control-pills-patches-and-devices/why-has-my-period-changed/. Published February 8, 2022.

Menstruation. La Leche League International. https://llli.org/breastfeeding-info/menstruation/. Published March 17, 2021.

Pregnancy tests. American Pregnancy Association. https://americanpregnancy.org/healthy-pregnancy/are-you-pregnant/pregnancy-tests/. Published June 20, 2022.

Sexually transmitted diseases – information from CDC. Centers for Disease Control and Prevention. https://www.cdc.gov/std/default.htm. Published January 31, 2023. https://health.clevelandclinic.org/can-stress-cause-you-to-skip-a-period/

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