Skin Disease and Pregnancy

Pigmentary Changes

Mild forms of localized or generalized hyperpigmentation occur to some extent in up to 90% of pregnant women and are most noticeable in the areolae, nipples, genital skin, axillae, and inner thighs. Familiar examples include the darkening of the linea alba (linea nigra) and periareolar skin. Melasma, also termed chloasma or mask of pregnancy, refers to the facial hyperpigmentation reported in up to 70% of pregnant women. Hyperpigmented, symmetric, poorly demarcated patches are commonly seen on the malar areas (malar pattern) and are often distributed over the entire central face ( centrofacial pattern ; Fig. 56.1 ). In 16% of cases, hyperpigmentation occurs on the ramus of the mandible (mandibular pattern). Melasma results from melanin deposition in the epidermis (70%), dermal macrophages (10% to 15%), or both (20%). It is likely secondary to the hormonal changes of gestation with increased expression of α-melanocyte–stimulating hormone. Melasma is typically exacerbated by exposure to ultraviolet and visible light. Hyperpigmentation is often more pronounced in brunettes and women with more melanocytes than in women with lighter baseline skin tone; the use of a broad-spectrum sunscreen with a high sun protection factor during pregnancy may decrease the severity of hyperpigmentation.

Melasma usually resolves postpartum but may recur in subsequent pregnancies or with the use of oral contraceptives. Troublesome, persistent melasma can be treated postpartum with topical hydroquinone, with or without a topical retinoid, and a mild topical steroid. Strict sun protection with mineral sunblock containing zinc or titanium dioxide must be used during and after treatment. Despite treatment postpartum, melasma persists in approximately 30% of patients, especially in women with the dermal or mixed subtypes in which the deeper level of pigmentation results in decreased efficacy of topical agents. Combination therapies including laser treatment and chemical peels may be effective in resistant cases. There have been no reports of adverse fetal effects from laser skin treatment during pregnancy. Most laser experts agree that laser radiation does not penetrate through the skin into deeper soft tissues, therefore it should not affect the fetus or the placenta. Still, because of potential liability issues, most dermatologists and plastic surgeons prefer not to perform laser procedures during gestation.

Uncommon pigmentary patterns such as pseudoacanthosis nigricans, dermal melanocytosis, vulvar melanosis, and verrucous areolar hyperpigmentation can also be seen in pregnancy (see Box 56.1 ). Postinflammatory hyperpigmentation secondary to specific dermatoses of pregnancy (see the section “ Specific Dermatoses of Pregnancy ”) is also common in women with more highly pigmented skin types.