One is born with it.
It can be from irritation and friction from clothes or even a STI. If you think you might be at risk for a STI see a doctor.
if the swelling occurs after intercourse or sexual arousal of any kind it may be caused by the increased blood flow to your labia
Every female's vagina is different. Having a larger labia majora is NOT uncommon. Some men find it attractive, and some females get a labiaplasty surgery to reduce the size. But you should be...