A recent study published in the BMJ found that there is no strong association between COVID-19 vaccines and changes in menstruation. Researchers at the Swedish Medical Products Agency looked at medical records from nearly 3 million Swedish women between the ages of 12 and 74, particularly those who visited healthcare professionals because of menstrual changes between December 2020 and February 2022. The study found that it is a weak and inconsistent association between vaccination and contact with healthcare for postmenopausal bleeding and even less consistent for menstrual disturbance and bleeding in those who were premenopausal.
The study authors looked at millions of women both pre and postmenopausal to see if the COVID-19 vaccine could affect menstruation or bleeding risk. Weak and inconsistent associations were observed, and especially in premenopausal women, there was no association of increased risk of irregular periods. The highest risks for bleeding in postmenopausal women were seen after the third dose in the 1-7 days risk window and in the 8-90 days risk window.
Earlier research had suggested that there was a link between the COVID-19 vaccine and changes in menstrual cycles. However, those studies had certain limitations including a limited pool of participants and not controlling for other factors such as COVID-19 hospitalization that could impact menstrual irregularities. Other factors like stress and depression have an effect on the menstrual cycles, and many people during the pandemic were experiencing new symptoms of both stress and depression.
Premenopausal women may experience period irregularities for various reasons, and it is not uncommon. While the latest study did find weak and inconsistent associations between vaccination and menstrual disturbance or bleeding, the study authors concluded that people should not be discouraged from getting vaccinated because of menstrual irregularities. The new research from Sweden is considered to be amazing in that it’s a national registry and the data is very clean, without bias.