Does the Covid Vaccine Really Affect Menstrual Cycles? - Kamm McKenzie OBGYN

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Does the Covid Vaccine Really Affect Menstrual Cycles?

I know at this point in the Covid-19 pandemic, I am unlikely to change anyone’s mind on their vaccine beliefs.  It doesn’t matter if almost all the hospitalizations, ICU stays, and deaths are in the unvaccinated population, or if unvaccinated pregnant moms who get Covid have worse outcomes including increases in stillbirth.  I still like to present interesting data as it comes out to help prove or disprove some of the vaccine rumors.  

When Covid vaccines first came out some hesitancy existed in women planning to get pregnant, despite all the major obstetrical, gynecology, and fertility organizations advocating for it. People would hear about their friend whose period was never the same after a Covid vaccine and freaked out.

A recent study in Obstetrics and Gynecology looked into this so we could get a real answer (as opposed to a Facebook one).  It looked at nearly 4000 women (2500 vaccinated and 1500 unvaccinated) who reported regular predictable menstrual cycles.  For the vaccinated group, it tracked 3 cycles before and 3 cycles after vaccination. It compared this to 6 consecutive cycles in the unvaccinated group.

Are you ready for the dramatic results?  Those in the vaccine group experienced a 1-day difference in cycle length! (Cycle length refers to the number of days from the first day of one period to the first day of the next period.  It does NOT refer to how many days one would bleed during a single period.)  For those who got 2 doses of the vaccine during 1 cycle they had a 2 days difference for that cycle.  These alterations were gone after 2 post-vaccine cycles.  There was no difference in the groups with regards to menstrual length (the number of days bleeding).

In conclusion, there may be a very small and temporary change of 1 day in menstrual cycle length that can be attributed to Covid vaccination.  I think everyone can agree this is not overly significant.

There we go. We all learned something new today! Stay safe everyone.

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