Hey mama,
Am wondering if it’s because the veins are enlarged somewhat….
Thought these articles were pretty good tho:
https://www.google.com.sg/amp/s/amp.flo.health/menstrual-cycle/health/symptoms-and-diseases/vaginal-bumps-main-causes
https://www.acog.org/womens-health/faqs/skin-conditions-during-pregnancy
But if you’re worried, do ask your gynae at your next visit :)