I have never in my life had a "normal" menstrual period.

我一生中经期就没正常过。

youdao

In particular, a good period of time to control the seizures of epilepsy, if not well controlled epilepsy, menstrual onset of the harm caused to patients is greater.

这段时间尤其要控制好癫痫病的发作，如果不能良好的控制癫痫，经期发病对患者所造成的危害是更加巨大的。

youdao

Those who have good competitive conditions or feel little effect of training on their health during the menstrual period have a lower MBL.

经期机能状态良好的运动员和认为经期运动对身体影响不大的运动员MBL较少。

youdao

Endometrial tissue builds up during the menstrual cycle, and then breaks down and sheds off during a period.

BBC: NEWS | Health | A life plagued by painful periods