Postpartum Horizontal Abdominal Hyperpigmentation
This is linea nigra, a benign physiologic hyperpigmentation of pregnancy that typically resolves spontaneously postpartum and requires only reassurance—no treatment is necessary. 1
Diagnosis and Characteristics
Linea nigra is a normal pregnancy-related skin change affecting 32-92% of pregnant women, presenting as a dark linear streak extending from the umbilicus to the pubic symphysis. 1 The hyperpigmentation:
- Develops most commonly during the second trimester (around week 24 of gestation) 1
- Results from elevated estrogen, progesterone, and melanocyte-stimulating hormone levels during pregnancy 1
- Shows histologically increased melanocytes in the basal epidermis without melanocytic atypia 2
- Can extend beyond the typical midline pattern to involve broader abdominal areas in some cases 3, 2
Expected Clinical Course
The hyperpigmentation typically resolves partially or completely within 3-12 months postpartum without intervention. 1, 2 However, some women experience persistent pigmentation beyond this timeframe. 1
Management Approach
No medical treatment is indicated for linea nigra. 3 The appropriate management consists of:
- Reassurance that this is a benign, self-limited condition with no adverse consequences to maternal or fetal health 3
- Clinical monitoring if the patient desires follow-up 3
- Counseling that resolution may take several months postpartum 1, 2
Critical Caveat
Any changing or concerning pigmented lesion on the abdomen should be evaluated to exclude melanoma, particularly if it appears raised, irregular, or develops outside the typical linea nigra pattern. 4 The American Academy of Dermatology guidelines specify that melanocytic nevi on the abdomen may appear larger due to skin stretching during pregnancy, but any lesion that is clinically or dermoscopically concerning should undergo biopsy. 4
Sun protection measures should be recommended as in non-pregnant patients. 4