Do the COVID-19 Vaccines Cause Menstrual Irregularities?

This new corona virus causes various health problems like pneumonia, acute respiratory distress syndrome (ARDS), kidney injury, myocardial dysfunction, and gastrointestinal diseases (1). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects the immune system and causes an increase in interleukin (IL)-6, IL-8, tumor necrosis factor-α (TNF-α) and other cytokines. In addition to COVID-19 itself, impaired immune system may cause alteration on hypothalamic– pituitary–gonadal axis (2). Some studies showed a change in menstrual cycle, worsening of premenstrual symptoms and menorrhagia in women with COVID-19 compared to before the pandemic (3, 4). On the other hand, World Health Organization (WHO) suggests safe and effective vaccines to end COVID-19, besides wearing masks, cleaning hands, ensuring good ventilation indoors, physically distancing and avoiding crowds (5). After vaccination, some women complained of menstrual irregularities such as heavy menstrual bleeding (menorrhagia), frequent bleeding (metrorrhagia/ polymenorrhea), or postmenopausal bleeding. One of the underlying causes may be a vaccine-induced thrombocytopenia (6). The female human menstrual cycles could be affected by many situations such as stress, weight gain, hormones etc. During pandemic, studies show that women have significantly higher stress, anxiety, and depression compared to men (7, 8). Hypothalamic– pituitary–gonadal axis is sensitive to inadequate sleep, physical and psychological stress. Pulsatile mechanism of hormones is essential for regular menstrual cycle. Therefore, disruption of regularity in hormone release may cause to menstrual disorders (9). In addition, the vaccines activate the immune system and activated immune system might attack immune cells and inflammatory molecules in the uterus. This event may be associated with changes in menstrual cycles. To clarify these hypotheses, controlled studies are needed. Until now; pain, redness, swelling, tiredness, headache, muscle pain, chills, fever, Do the COVID-19 Vaccines Cause Menstrual Irregularities?