COVID-19 is most often associated with respiratory symptoms, such as cough and shortness of breath, though it can also impact other body systems, resulting in digestive, neurological, and cardiovascular symptoms. Some new evidence suggests that it may also affect your reproductive system, including your period.

COVID-19 and Your Menstrual Cycle

Throughout the pandemic, various women have reported lighter, heavier, irregular, or missed periods. A 2020 study concluded that the endometrium (uterus lining) is probably safe from direct infection by the virus due to the fact that, during your menstrual cycle, the endometrium contains lower levels of ACE2, the receptor to which the virus binds:

In a 2021 study involving 177 participants:

• 45 (25%) experienced changes in menstrual volume
• 36 had lighter periods 
• Nine had dramatically heavier periods
• 50 (28%) experienced changes in their menstrual cycle, with most having cycles that were longer than normal 
• 34% of people with severe illness had long cycles vs. 19% of people with mild illness
• 84% of participants had returned to their normal menstrual volume and 99% had returned to their normal cycle length between one and two months after having COVID-19

No difference was found in sex hormone levels between people who had COVID-19 and people who didn’t.

COVID-19 Vaccines and Your Period

While anecdotal reports have linked COVID-19 vaccination with changes in menstruation, the scant research that exists does not support that link at this time. Most of the anecdotal reports describe either irregular or heavier periods immediately after vaccination, with a return to normal menstrual patterns within a few weeks. 

According to the UK’s Medicines and Healthcare Products Regulatory Agency (MHRA), out of 47.8 million vaccine doses (mostly Pfizer-BioNTech or AstraZeneca) given to women between December 8, 2020 and September 8, 2021, there were only 34,633 reported menstruation-related incidents thought to be reactions to vaccination. Incidents included:

• Heavier than usual periods
• Delayed periods
• Bleeding between periods
• Vaginal bleeding after menopause

Though it’s possible that a link exists between menstrual cycle changes and COVID-19 vaccines, a September 2021 editorial in the BMJ suggests that those changes may be related to the body’s general immune response to receiving vaccination. Many other factors can affect your period, as well.

What Other Factors Can Affect My Period?

Menstrual irregularities affect between 5% and 35.6% of the menstruating population. These irregularities can be caused or at least influenced by a wide variety of factors that include:

• Stress
• Age
• Where you live (e.g., environmental pollution)
• Lifestyle habits (e.g., smoking, diet, exercise, hydration, breastfeeding)
• Medications (e.g., hormonal birth control, antidepressants, blood pressure meds)
• Underlying physical or mental health conditions or illnesses

Which Health Conditions and Illnesses Can Affect My Period?

There is definitely some overlap regarding how various factors can influence your period, whether individually or in combination. Certain health conditions, however, are more likely to impact menstruation in specific ways.

• Heavy periods. Heavy periods can be caused by such conditions as:
  • Uterine fibroids or polyps
  • Endometriosis or adenomyosis
  • Endometrial or cervical cancer
  • Thyroid disease
  • Obesity
  • Stress
• Irregular periods. Irregular periods may result from:
  • Polycystic ovary syndrome (PCOS)
  • Pelvic inflammatory disease (PID)
  • Diabetes 
  • Thyroid disease
  • Obesity 
  • Stress
• Missing periods. Missing periods (also called amenorrhea) can be caused by:
  • Polycystic ovary syndrome (PCOS)
  • Pregnancy
  • Menopause
  • Thyroid disease
  • Rapid weight loss or gain from eating disorders or other reasons
  • Stress 

What about Pandemic Stress? 

For most Americans alive today, the global impact of the pandemic–and our awareness of that impact–is unprecedented. Stress levels have been at an all-time high, so if you’ve recently noticed changes in your period, pandemic stress could be the reason. You may be worried about:

• Your health and the health of your loved ones
• Social and physical isolation 
• Finding childcare or managing your child’s remote learning
• Finding or keeping a job, or returning to an insecure workplace
• Maintaining your weight and fitness level
• Unhealthy habits you may have picked up as coping mechanisms

What Can I Do If My Period Has Changed?

If you are experiencing ongoing period changes that don’t seem to be resolving themselves, speak with your gynecologist, primary care physician, or other healthcare provider to explore potential physical and psychological causes.

Dr. Kathryn Clancy, a researcher at the University of Illinois at Urbana-Champaign, launched a survey earlier this year to measure the impact of the COVID-19 vaccine on menstruation. The survey is in the process of receiving IRB approval before the results are processed for scientific publication.

Additional research is planned, as well. The U.S. National Institutes of Health recently awarded a total of $1.67 million to five institutions to investigate possible links between COVID-19 vaccination and menstrual changes.

*Seladi-Schulman, J. (2021, May 25). Can COVID-19 or the COVID-19 Vaccine Affect Your Period? Healthline. https://www.healthline.com/health/menstruation/can-covid-affect-your-period 

Much about the novel coronavirus, i.e., COVID-19, is still not fully understood. As research progresses and our knowledge of the virus increases, information can change rapidly. We strive to update all of our articles as quickly as possible, but there may occasionally be some lag between scientific developments and our revisions.