News | Can COVID-19 Vaccination Affect the Menstrual Cycle?
A U.S. study examined the effects of COVID-19 vaccination on women's menstrual cycles. The results showed that vaccination may cause small changes in cycle length, but these changes are usually temporary and do not persist.
Background:
As of April 2022, more than 11,000 women had reported menstrual concerns to the U.S. Vaccine Adverse Event Reporting System (VAERS), including changes in cycle length, heavier menstrual bleeding, and irregular periods. These case reports prompted researchers to investigate the potential link between vaccination and menstrual cycle changes and to provide clinicians with more information for counseling women about menstrual health after COVID-19 vaccination.
Methods:
The study used data from the Apple Women's Health Study (AWHS) to analyze the relationship between COVID-19 vaccination and menstrual cycle length. Researchers compared menstrual cycle data before and after vaccination, focusing on the effects of vaccination timing and vaccine type.
Participants were women in the United States aged 18 or older who owned an iPhone and could track their menstrual cycles with the Apple Health app. At enrollment, participants provided basic menstrual and demographic information, followed by monthly surveys about their menstrual health. The research team also asked about vaccination dates, vaccine type, and symptoms within 48 hours after vaccination.
Findings:
The analysis included 128,094 menstrual cycles from 9,652 participants, with an average of 13 cycles recorded per participant. Menstrual cycles generally became slightly longer after vaccination. The single-dose Janssen vaccine was associated with an increase of approximately 1.26 days. However, the increase was small and temporary, and cycle length gradually returned to pre-vaccination levels over time.
Interestingly, the timing of vaccination within the menstrual cycle affected cycle length differently. Vaccination during the follicular phase was associated with a slightly longer following cycle, while receiving the second dose during the luteal phase was associated with a shorter subsequent cycle. Overall, the effects on menstrual cycles were small and did not persist.
Conclusions:
The study indicates that the effects of COVID-19 vaccination on the menstrual cycle are not harmful and that vaccination does not adversely affect female fertility. Although vaccination may slightly lengthen the menstrual cycle, the change is usually temporary and does not affect long-term health. Researchers therefore advise that temporary menstrual changes should not deter women from receiving a COVID-19 vaccine.
Study Has Been Peer Reviewed:
This article was initially based on a preliminary scientific report that had not undergone peer review. Since the initial version was released, the report has been peer reviewed and accepted for publication in npj Digital Medicine. Links to the peer-reviewed version and preliminary report are provided in the source section at the end.
News | Can COVID-19 Vaccination Affect the Menstrual Cycle?
News | Can COVID-19 Vaccination Affect the Menstrual Cycle?
A U.S. study examined the effects of COVID-19 vaccination on women's menstrual cycles. The results showed that vaccination may cause small changes in cycle length, but these changes are usually temporary and do not persist.
Background:
As of April 2022, more than 11,000 women had reported menstrual concerns to the U.S. Vaccine Adverse Event Reporting System (VAERS), including changes in cycle length, heavier menstrual bleeding, and irregular periods. These case reports prompted researchers to investigate the potential link between vaccination and menstrual cycle changes and to provide clinicians with more information for counseling women about menstrual health after COVID-19 vaccination.
Methods:
The study used data from the Apple Women's Health Study (AWHS) to analyze the relationship between COVID-19 vaccination and menstrual cycle length. Researchers compared menstrual cycle data before and after vaccination, focusing on the effects of vaccination timing and vaccine type.
Participants were women in the United States aged 18 or older who owned an iPhone and could track their menstrual cycles with the Apple Health app. At enrollment, participants provided basic menstrual and demographic information, followed by monthly surveys about their menstrual health. The research team also asked about vaccination dates, vaccine type, and symptoms within 48 hours after vaccination.
Findings:
The analysis included 128,094 menstrual cycles from 9,652 participants, with an average of 13 cycles recorded per participant. Menstrual cycles generally became slightly longer after vaccination. The single-dose Janssen vaccine was associated with an increase of approximately 1.26 days. However, the increase was small and temporary, and cycle length gradually returned to pre-vaccination levels over time.
Interestingly, the timing of vaccination within the menstrual cycle affected cycle length differently. Vaccination during the follicular phase was associated with a slightly longer following cycle, while receiving the second dose during the luteal phase was associated with a shorter subsequent cycle. Overall, the effects on menstrual cycles were small and did not persist.
Conclusions:
The study indicates that the effects of COVID-19 vaccination on the menstrual cycle are not harmful and that vaccination does not adversely affect female fertility. Although vaccination may slightly lengthen the menstrual cycle, the change is usually temporary and does not affect long-term health. Researchers therefore advise that temporary menstrual changes should not deter women from receiving a COVID-19 vaccine.
Study Has Been Peer Reviewed:
This article was initially based on a preliminary scientific report that had not undergone peer review. Since the initial version was released, the report has been peer reviewed and accepted for publication in npj Digital Medicine. Links to the peer-reviewed version and preliminary report are provided in the source section at the end.
Story source:
Collected online