Behavior of melanocytic nevi during pregnancy.

Three hundred eighty-nine pregnant women were interviewed and examined for the purpose of determining the incidence and quality of changes that may have occurred in their pigmented cutaneous lesions during their pregnancies. Somewhat more than 10% of them reported changes had occurred in their pigmented lesions, most in the first trimester of pregnancy. However, in 26 lesions that had been biopsied, no significant histologic changes were found when compared with comparable pigmented lesions from age-matched women who were not pregnant.