Why do girls have to deal with pms?

NOT SURE WHAT U ASK?: Women have to deal with the possible symptoms of pms because our bodies experience cyclical hormonal changes that allow for the lining of the uterus to receive a fertilized egg. When this does not happen then the lining sheds. This hormonal shift can lead to mood changes to varying degrees of severity. The greek word for uterus is hystera. So you know where this is going right! : > ).

Hormone changes: Changes in hormones are likely a causative agent. Progesterone & Estrogen levels change throughout the menstrual cycle. This affects neurochemicals like serotonin, GABA & dopamine.