The question of whether a SARS-CoV-2 infection can disrupt the menstrual cycle or lead to vaginal bleeding has been a major public health concern. Recent international studies confirm a correlation between COVID-19 illness and temporary changes in menstrual patterns. The evidence suggests the infection can cause instances of abnormal uterine bleeding in reproductive-age individuals.
COVID-19 Infection and Changes to the Menstrual Cycle
The most commonly reported observations involve alterations to the normal menstrual cycle following an acute SARS-CoV-2 infection. Individuals frequently notice a change in cycle length, which can become either shorter or longer than usual. Studies have found that individuals who contracted COVID-19 experienced an average increase in cycle length of approximately 1.45 days compared to pre-infection cycles.
Changes to the volume of menstrual flow are also commonly reported. Some individuals experience significantly lighter periods while others report heavier-than-usual bleeding. Additionally, some people have reported intermenstrual spotting, which is bleeding that occurs between expected periods. These disruptions are generally temporary, with cycles typically returning to pre-infection patterns within one to two cycles following the illness.
It is important to distinguish these effects from those associated with the COVID-19 vaccines. The observed menstrual changes are linked to the physiological stress and biological response triggered by the infection itself. For example, one large study found that approximately 35.7% of participants who had contracted COVID-19 noted some change in their menstrual pattern in the three cycles immediately following the infection.
Biological Mechanisms Behind Abnormal Bleeding
The systemic nature of the COVID-19 infection provides several pathways through which it can disrupt the balance required for a stable menstrual cycle and uterine lining.
Systemic Inflammation
One primary mechanism involves the systemic inflammation triggered by the body’s immune response. The release of inflammatory signaling molecules, known as cytokines, can interfere with the processes that regulate the growth and shedding of the uterine lining, leading to abnormal bleeding. This localized inflammation can destabilize the endometrium, the inner lining of the uterus, making it more prone to abnormal shedding. Furthermore, the SARS-CoV-2 virus has an affinity for the ACE-2 receptor, which is present in reproductive tissues, including the ovaries and endometrium.
Hormonal Stress Response
The acute stress of the illness also plays a significant role by activating the hormonal stress response. Acute illness causes the release of stress hormones, such as cortisol, which can directly impact the hypothalamic-pituitary-ovarian (HPO) axis. This axis controls the timing and regulation of the menstrual cycle. Its disruption can lead to ovulatory dysfunction, a common cause of irregular and abnormal uterine bleeding.
Vascular and Coagulation Effects
A third factor involves the virus’s known effects on the vascular system and coagulation process. COVID-19 can affect blood vessel integrity and the body’s clotting mechanisms. These are tightly controlled processes necessary for the normal cessation of menstrual flow. Disturbances in coagulation can be a non-structural cause of abnormal uterine bleeding, contributing to heavier or more prolonged bleeding episodes.
Investigating Non-Menstrual and Postmenopausal Bleeding
Vaginal bleeding that occurs outside of the normal menstrual context, such as intermenstrual bleeding or postmenopausal bleeding (PMB), warrants separate consideration.
Intermenstrual bleeding (spotting or flow occurring between expected periods) has been reported following acute COVID-19 infection and is also a common feature of long COVID symptoms. The inflammatory and hormonal disruptions caused by the infection are thought to be the underlying factors.
Postmenopausal bleeding is defined as any vaginal bleeding after 12 consecutive months without a period. While a recent COVID-19 infection could potentially trigger a transient bleeding episode, PMB is always a serious symptom requiring immediate investigation. The primary goal of a medical workup is to rule out serious underlying conditions, such as endometrial hyperplasia or uterine cancer.
Any instance of postmenopausal bleeding must be thoroughly evaluated by a healthcare provider, even if a recent SARS-CoV-2 infection is suspected. Similarly, non-menstrual bleeding in premenopausal individuals that is persistent, heavy, or significantly outside of their normal cycle pattern should not be dismissed as solely a side effect of the infection. Other potential causes must be systematically excluded to ensure patient safety.
Urgent Signs and When to Contact a Healthcare Provider
While many menstrual changes following a COVID-19 infection are temporary, certain signs indicate the need for prompt medical evaluation.
You should contact a healthcare provider if you experience excessively heavy menstrual bleeding, generally defined as soaking through one or more sanitary pads or tampons every hour for several consecutive hours. Signs of anemia, such as severe fatigue, dizziness, or shortness of breath, also necessitate urgent medical attention, as they can be a complication of blood loss.
Any vaginal bleeding that occurs during pregnancy should be immediately reported. If the abnormal bleeding (heavy flow, prolonged duration, or intermenstrual spotting) persists for more than two to three cycles after the initial infection, a full medical workup is recommended. Any instance of postmenopausal bleeding must be reported immediately, as this is a red flag for other serious conditions that need to be excluded regardless of recent illness. Your healthcare provider can determine the precise cause of the bleeding and offer appropriate management or treatment options.