Vaccine trials include tens of thousands of people in phase 3 to ensure that even rare side effects are more likely to be detected. But once the vaccine is authorized and millions of people have begun receiving it, sometimes researchers learn about other even rarer side effects not captured in the trials. But scientists could also miss a side effect if they simply don’t ask about it — or don’t record it when participants report it.
It happens monthly, for two up to seven days at a time. A woman will menstruate for about seven years during her lifetime, on average. And yet there are still plenty of unknowns and misunderstandings around the effect menstruation has on women’s health.
“There is tremendous variation in how girls and women think about menstruation and what they define as healthy and normal,” says Dr. Geri Hewitt, a professor of obstetrics/gynecology at Ohio State University, and a chair of the American College of Obstetrics and Gynecology (ACOG) adolescent health committee. “There is also tremendous cultural variation regarding expectations around menses.”