On your period, hormonal shifts, namely an increase in prostaglandins, can lead to muscle contractions in the uterus, putting pressure on the bladder and causing the urge to urinate more frequently. Additionally, water retention and bloating can further contribute to the need to urinate more often.
Knowing the causes of increased urine throughout the menstrual cycle helps allay worries and reassure that it’s a typical aspect of the menstrual cycle.