Have you heard of the phenomenon that girl friends' periods get synchronized when they are in each other's company (for a certain period of time)? [Details inside].
To make it more clear: Say, Ellen used to have her period at around the fifteenth of the month and Gina around the twentyfifth of the month, but after a while, when they are in close company for a period of time (months?) their start dates will be the same (about).
My girlfriend has experienced this, with multiple girl friends.
Have you heard of this?
Is it a known phenomenon?
If so, what causes it?
Can males (partners or friends of the female) also get similar symptoms (belly ache) when her period is there?
This question is in the General Section. Responses must be helpful and on-topic.