Pigmentation and Pregnancy: Knowing What Is Normal.

Changes in melanocytic nevi during pregnancy are frequently attributed to the new hormonal milieu and are dismissed without concern for malignancy. Recent studies suggest that pregnancy itself does not induce significant change in nevi, and delays in the assessment of changing moles may contribute to the often more advanced nature of melanomas diagnosed during or soon after pregnancy. Nevi on the breasts and abdomen can grow as a result of skin expansion, but studies have found no significant changes in nevi located in more stable areas such as the back or lower extremities. There is also insufficient evidence to support the notion that nevi darken during pregnancy. As such, any changing nevus that would raise concern for malignancy in a nonpregnant patient should do so in a pregnant patient as well. Pregnancy can, however, induce physiologic pigmentary changes that are often worrisome to both patients and physicians. These benign changes include melasma, pigmentary demarcation lines, secondary areola, and linea nigra as well as other less common findings. It is important for physicians to recognize these changes as physiologic to provide adequate reassurance to their patients and avoid unnecessary stress.