As we approach two years since the beginning of the COVID-19 pandemic, there has been growing interest in identifying and understanding the post-infectious consequences of COVID-19, as well as the potential adverse effects associated with vaccines against the virus.
An increasing body of evidence suggests that both SARS-CoV-2 infection and vaccination against the virus, as well as the heightened psychological stress associated with the pandemic, may affect the menstrual cycle in women.
Regarding vaccines, the menstrual irregularities reported do not appear to be associated with the type of vaccine administered (whether mRNA-based or adenoviral vector-based). The most commonly reported menstrual changes include delayed menstruation and lighter menstrual bleeding, while irregular cycles and heavier bleeding are reported less frequently. In approximately 99% of cases, these menstrual disturbances resolve within 1–2 months following COVID-19 infection or vaccination.
The menstrual cycle involves a complex series of biological events and intricate interactions between various tissues, hormones, and physiological systems. Consequently, it is sensitive to both endogenous and exogenous factors, including infections and lifestyle changes. Activation of the immune system in response to viral infections appears to influence the endocrine events regulating the menstrual cycle. It is well established that certain viruses can affect the reproductive endocrine system. Menstrual disturbances are frequently observed in hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, while human immunodeficiency virus (HIV) infection has been associated with an earlier onset of menopause.
The biological mechanisms underlying the association between SARS-CoV-2 infection or vaccination and menstrual disturbances include both hormonal and immunological factors.
The proper functioning of the hypothalamic–pituitary–ovarian (HPO) axis ensures the stability and regularity of ovarian function and, consequently, of the menstrual cycle. During periods of intense physical or psychological stress, increased secretion of stress-related hormones (ACTH, cortisol, prolactin, oxytocin, epinephrine, norepinephrine, and vasopressin) occurs. These hormones can suppress the production of pituitary gonadotropins, leading to disturbances in the menstrual cycle. Furthermore, it is well established that when the body is exposed to significant stress, such as during an acute infection, ovarian function may be temporarily suppressed in order to prioritize essential physiological processes. This can result in anovulation and subsequent menstrual cycle irregularities.
The immune response to the virus also appears to play a key role in the pathogenesis of menstrual disturbances. The relationship between estrogens (which are primarily produced during the first phase of the menstrual cycle) and immune responses has been extensively studied. Cytokines—key inflammatory mediators—play an important role in regulating the menstrual cycle by influencing reproductive axis hormones, as well as by affecting the structural changes and functional activity of the uterine lining, the endometrium, throughout the menstrual cycle and during the early stages of pregnancy.
The treatment used for COVID-19 should also be considered a potential contributing factor to menstrual disturbances. COVID-19 therapy often includes corticosteroids, which may also affect menstrual cycle regularity through the mechanisms described above.
SARS-CoV-2 may potentially exert a direct effect on the ovary, as the receptor through which the virus enters cells—the angiotensin-converting enzyme 2 (ACE2)—has been shown in an animal study to be expressed in ovarian granulosa cells. High expression of this enzyme in the testes has also been documented.
It is worth noting that the menstrual cycle may have a protective role against COVID-19, as younger women of reproductive age appear to experience lower morbidity and mortality rates compared with men of the same age group. In this context, estradiol may exert a protective effect through its regulatory action on cytokines, key proteins involved in immune function.
Every medical intervention and treatment should be evaluated and studied, among other aspects, for its potential impact on the menstrual cycle. Further research will provide additional insights into the effects of COVID-19 infection or vaccination on hormonal profiles and menstrual cycle patterns in specific groups of women.
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This article is made freely available for use in accordance with BMJ’s website terms and conditions for the duration of the covid-19 pandemic or until otherwise determined by BMJ. You may use, download and print the article for any lawful, non-commercial purpose (including text and data mining) provided that all copyright notices and trademarks are retained.
How Hormones Change During Different Life Stages
If several languages coalesce, the grammar of the resulting language is more simple and regular than that of the individual languages. The new common language will be more simple and regular than the existing European languages. It will be as simple as Occidental.
To an English person, it will seem like simplified English, as a skeptical Cambridge friend of mine told me what Occidental is. The European languages are members of the same family. Their separate existence is a myth. For science, music, sport, etc, Europe uses the same vocabulary.
Women's Health Quiz
Please complete all questions. Mark the best answer from the choices given.
Their separate existence is a myth. For science, music, sport, etc, Europe uses the same vocabulary. The languages only differ in their grammar, their pronunciation and their most common words. Everyone realizes why a new common language would be desirable: one could refuse to pay expensive translators.
To achieve this, it would be necessary to have uniform grammar, pronunciation and more common words. If several languages coalesce.
Their separate existence is a myth. For science, music, sport, etc, Europe uses the same vocabulary. Everyone realizes why a new common language would be desirable: one could refuse to pay expensive translators. To achieve this, it would be necessary to have uniform grammar, pronunciation and more common words. If several languages coalesce, the grammar of the resulting language is more simple. If several languages coalesce, the grammar of the resulting language is more simple. To an English person, it will seem like simplified English, as a skeptical Cambridge friend of mine told me what Occidental is. If several languages coalesce, the grammar of the resulting language is more simple. To an English person, it will seem like simplified English.
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