Hi,
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The appearance of the labia depends on your genetic build-up. Sometimes you can have changes in them as a result of vaginal delivery, frequent and rough intercourse, inflammation, advancing age, weight gain, etc. The infective causes usually do not affect the size of labia. Visit your gynecologist for examination and evaluation to look for any abnormalities especially labial hypertrophy. Treatment as appropriate would be started to help you based on examination findings and investigations results. If necessary, you can discuss with your gynecologist/cosmetic surgeon about option of Labiaplasty to reduce the labial size.
Take care.