text: An OB/GYN is a doctor specializing in preganancy and women's reproductive health. It's short for Obstetrics-Gynecology.\n\nIf your cycle isn't regular, your OB-Gyn will do a transvaginal ultrasound to see whats going on with your uterus and ovaries. Then she/he will recommend treatment.\n\nI went to one when I have irregular periods. MY OB-Gyn prescribed birth control pills to regularize me period. It's no big deal.