We've all heard that women are supposed to have 28-day cycles between periods...but we also know that no two women are alike when it comes to matters like these. Case in point: Some of us got our first periods at age 9 while others went into the teen years having never menstruated. But did you know that a woman who has a 26-day cycle might have a different level of fertility than someone who gets her period every 30 days? And that the age at which you had your first period could have an effect on your baby-making odds as well?
According to a 2016 study from Boston University, both length of menstrual cycles and onset of menstruation can affect fertility.
These findings appear in Annals of Epidemiology and are based on the study of more than 2,100 women who were trying to conceive. The women responded to questionnaires detailing characteristics of their menstrual cycles, and after taking a good look at the data, researchers determined that women with short cycles (26 days or fewer) had lower odds of getting pregnant. Similarly, women who started menstruated before age 12 had reduced fertility when compared to women who started menstruating between 12 and 13 years old.
According to the study's authors, a short menstrual cycle could signal a narrow fertile window or ovarian aging, and may also reflect a lack of ovulation (we don't have to tell you how important ovulation is when you're trying to get pregnant!).
“In agreement with previous studies, we found that short menstrual cycles were associated with reduced fecundability among North American pregnancy planners, independent of age, irregular cycles, and history of reproductive illness,” the research team said, according to Futurity. “These results indicate that menstrual cycle characteristics may serve as markers of fertility potential among pregnancy planners.”
While the link between early onset of menstruation and fertility isn't quite explained, it's an interesting one to consider—and Boston University's Pregnancy Study Online initiative is ongoing, so hopefully we'll have a clear picture of how this works soon.
Does this mean that women who have short cycles or got their periods early in life can't get pregnant? No! Like most other studies, this one represents one slice of the population and these results definitely shouldn't get you down if you're trying to conceive.