The most common time to develop menstrual migraines is during the first three days of your period and the two days before it begins. This is thought to be due to falling oestrogen levels in the body. And around this time, chemicals associated with pain (called prostaglandins) also increase.
This is a companion discussion topic for the original article at https://patient.info/news-and-features/is-your-period-causing-your-migraines