It might not be your fondest memory, but think back to what age you were the first time you got your period. Sure, it might have been uncomfortable (cramps), scary (what is happening?!), or even embarrassing (of course you wore white pants to school that day), but a new study published in the journal BMC Medicine says there are links between major reproductive events in a woman's life and her long-term health.
From 322,972 women between the ages of 25 and 70, the team of researchers gathered data on how old the subjects were at various female biological events — first period, giving birth, breast-feeding, menopause, etc. — and other factors that would have affected these events, like taking oral contraceptives.
After 13 years, they followed up with the subjects and found that 14,383 had died. From the data, they found “childbirth, breast-feeding, oral contraceptive use, and a later age at menarche were associated with better health outcomes.”
A potential theory on why these were the findings? Estrogen. "These results highlight the possibility that hormonal mechanisms may explain the link between parity [childbearing], breast-feeding, [oral contraceptive] use, and a later age at menarche with a lower mortality risk. A shared mechanism for breast-feeding and [oral contraceptive] use is that both may reduce endogenous estradiol production."
It's important to remember that this study is absolutely not definitive. Getting your period at 11 and not breast-feeding does not mean you're unhealthy or will have a shorter life than other women.
Though having children and breast-feeding are known to lower a woman's risk of certain health issues — breast cancer is one — it doesn't mean a woman with a different reproductive history is less healthy: "Our data did not suggest that nulliparous [non-childbearing] women had poorer health as their BMI, physical activity levels, and smoking status were similar to parous women." Additionally, "Having an earlier age at menarche has been associated with elevated blood pressure and glucose intolerance, increased body fat in early adulthood, or obesity in adulthood, all of which could explain the possible link between the age at menarche and risk of mortality outcomes later in life."
Many of these factors can be controlled through lifestyle choices, so there's no need to worry. Just think of the study as a friendly reminder to stick with whatever healthy diet and exercise you prefer.