Skin conditions during pregnancy fall into three categories: benign hormone-related changes, preexisting skin conditions, and pregnancy-specific disorders. Classification of these conditions has evolved over time and varies in the literature. This article summarizes the most common terminology and groupings of these conditions.

Hormonal Skin Changes in Pregnancy

Benign changes to the skin, hair, and nails often occur during pregnancy due to hormone fluctuations and changes in body composition.

HYPERPIGMENTATION

Hyperpigmentation is the most common skin change during pregnancy and is caused by increased levels of progesterone, estrogen, and melanocyte-stimulating hormone.^1,2 Darkening of the skin around the nipples, areolae, and genital region can occur as early as the first trimester. Scars, nevi, and freckles on the breasts and abdomen may enlarge as the pregnancy progresses.² Any changes to nevi that are concerning for malignancy should be biopsied during pregnancy.³

Generalized hyperpigmentation may develop in pregnant patients with lighter skin tones.¹ Linea nigra (Figure 1), a vertical, hyperpigmented line on the abdomen, can develop in the second trimester. Patients should be reassured that this is a benign, self-limited change that resolves within a few months of delivery.¹

Melasma (Figure 2), or mask of pregnancy, is an irregular darkening of the central face that occurs in up to 75% of patients.² Because it can worsen with sun exposure, patients should use broad-spectrum sunscreen and avoid prolonged periods in the sun. Melasma resolves postpartum in 90% of cases but can recur with future pregnancies and use of oral contraceptives. Postpartum treatment options include topical tretinoin, hydroquinone, and corticosteroids.² A 2010 Cochrane review showed that products containing all three drugs are most effective.⁴

STRIAE GRAVIDARUM

Striae gravidarum (Figure 3⁵), also known as striae distensae or stretch marks, occur in 55% to 90% of pregnancies.⁶ These red or purple marks appear on the abdomen (most common), breasts, buttocks, and extremities.⁵ Underlying causes include mechanical stretching, genetic factors, and hormonal changes (e.g., estrogen, relaxin).⁶

Striae gravidarum are more common in women with younger age, higher prepregnancy body mass index, excessive weight gain during pregnancy, or a family history of the condition and in those who have newborns with a higher birth weight.⁶ They usually develop in the third trimester of singleton pregnancies and can be self-limited, fading postpartum.⁶ Over-the-counter topical treatments to prevent or reduce stretch marks have limited evidence of effectiveness. Common treatments include cocoa butter, vitamin E, olive oil, almond oil, and aloe vera.^5,6 Topical products containing Centella asiatica or hyaluronic acid combined with daily massage may offer a modest preventive benefit.⁶ Postpartum treatment options include topical tretinoin, laser therapy, microdermabrasion, radiofrequency, and microneedling.⁶

HAIR AND NAIL CHANGES

Most pregnant people experience a thickening of scalp hair due to an increased anagen phase, and some develop mild to moderate hirsutism on the face, limbs, and back.^1,2 Most pregnant people experience some degree of telogen effluvium postpartum that lasts up to 12 to 18 months. Rare changes such as male pattern baldness and hypertrichosis can occur in the antepartum or postpartum period due to increases in androgenic hormones.¹

Nails tend to grow more quickly during pregnancy and may become more brittle; however, this resolves after delivery. Some pregnant patients are more susceptible to onychomycosis; patients should be encouraged to maintain good nail hygiene.¹