For how we live.
A meta-analysis of 78 studies found the menstrual cycle has at most a trivial effect on performance. A randomised trial found timing strength training to cycle phase built no more muscle than training consistently.
Cochrane reviews rate anti-inflammatory painkillers a very effective treatment for menstrual cramps, roughly doubling the odds of good pain relief. Exercise helps too, but on lower-quality evidence.
Most breast pain is self-limited, and cancer is rarely the cause — though it should be ruled out. A 2025 meta-analysis found no clear benefit from vitamin B6, a widely recommended remedy.
In a study of 543,167 cycles, calendar-based apps misclassified a fertile day as safe in two-thirds of cycles. Apps that track a real biological signal do better, but plain calendar apps remain the most common kind.
In one study of 62,685 women, iron deficiency prevalence ranged from 3% to 15% depending on the ferritin threshold. On treatment, a recent trial found alternate-day iron caused fewer side effects than daily dosing.
A systematic review of 43 studies judged cups a safe option, with leakage similar to or lower than pads and tampons. For the newer reusable products, published research is mostly about acceptability, not safety.
PMDD is the severe, mostly psychological form of premenstrual illness, affecting about 3.6% of women in one study. For it, SSRIs are the best-evidenced treatment, with side effects that are common and dose-related.
Pooling five studies that confirmed cycle phase by hormone testing, researchers found no significant VO2 max difference between phases, though the base is too thin to rule an effect out.