Nevi and pregnancy.

Changes in the moles of pregnant women are frequently attributed to pregnancy, but recent studies suggest that pregnancy does not induce significant physiologic changes in nevi. It is common for nevi on the breasts and abdomen to grow with normal skin expansion, but studies that have examined melanocytic nevi on the backs or lower extremities have found no significant changes in size during pregnancy. Several studies have also investigated the belief that moles darken during pregnancy and have found insufficient evidence to support this idea. Dermoscopically, transient changes have been identified, but none are suggestive of melanoma. Results vary in terms of histologic changes seen in samples taken from pregnant women, but all authors agree that any histopathologic features consistent with melanoma should be viewed as melanoma and not attributed to pregnancy. Biopsy specimens should be obtained promptly from any changing mole that would raise concern for malignancy in a nonpregnant patient. Such procedures can be performed safely during pregnancy.