While living into your 90s or even to 100 isn’t as rare a phenomenon as it once was (especially for women), no one quite knows what biological components or behavioral “secrets” make someone predisposed for such a long life span.

For the study, published in the journal Menopause, researchers looked at data from the Women’s Health Initiative, a long-term analysis of 16,000 postmenopausal U.S. women. The research showed that starting menstruation at the age of 12 was the best indicator of a longer life. Same goes for hitting menopause after age 50.

The woman who has got their period later are prone to live longer. Among them were those who did not smoke and does and who have never received diabetes. Healthy habits and healthy menstruation mean equally healthy life.

In terms of other health issues tied to the timing of period, Aladdin Shadyab, one of the lead authors of the study, also said:

OUR TEAM FOUND THAT WOMEN WHO STARTED MENSTRUATION AT A LATER AGE WERE LESS LIKELY TO HAVE CERTAIN HEALTH ISSUES, LIKE CORONARY HEART DISEASE, AND THOSE WHO EXPERIENCED MENOPAUSE LATER IN LIFE WERE MORE LIKELY TO BE IN EXCELLENT HEALTH OVERALL, WHICH MAY BE A POSSIBLE EXPLANATION FOR OUR FINDINGS.

In any case, researchers say, the calculation is clear: healthy habits = healthy menstruation = healthy life.