3 sentences

1. 我来月经了。

   wǒ lái yuè​jīng le.

   I have my period.

   Source: OpenSubtitles

2. 什么是月经？

   shén​me shì yuè​jīng?

   What is menstruation?

   Source: OpenSubtitles

3. 由于压力过大，她的月经周期变得不规律。

   yóu​yú yā​lì guò dà, tā de yuè​jīng zhōu​qī biàn de bù guī​lǜ.

   Her menstrual cycle has become irregular due to excessive stress.

   Source: Dong Chinese Dictionary