What Causes Baby Acne (Neonatal Acne)?
Baby acne (neonatal acne) is caused by stimulation of the infant's sebaceous glands by maternal and neonatal androgens that cross the placenta or are produced by the baby's adrenal glands and testes (in boys), leading to increased sebum production and subsequent development of acne lesions. 1, 2
Pathophysiologic Mechanism
The underlying cause involves hormonal stimulation of immature skin structures:
- Androgen exposure from maternal hormones that cross the placenta during late pregnancy stimulates the baby's sebaceous glands 1, 3
- In male infants, androgens are produced by both the adrenal glands and testes, while female infants produce androgens primarily from adrenal sources 1, 3
- These androgens cause hyperactivity and hyperplasia of sebaceous glands, which are well-developed at birth 2, 4
- The result is increased sebum production in the first weeks to months of life 2
Clinical Presentation Pattern
The typical presentation reflects this hormonal mechanism:
- Mean age of onset is 3 weeks after birth, with lesions persisting for an average of 4 months 2
- Male predominance (approximately 82% of cases are boys), consistent with additional testicular androgen production 2
- Lesions appear most commonly on the cheeks (82% of cases), followed by forehead and chin 2
- Papules and pustules are the most frequent lesion types (73%), though comedones can occur alone in about 23% of cases 2
Important Clinical Distinctions
While neonatal acne is typically benign and self-limited, certain presentations warrant further evaluation:
- Recalcitrant or severe cases may indicate underlying androgen excess and require endocrinologic investigation 2
- Infantile acne (occurring after 6 weeks of age) tends to be more inflammatory and pleomorphic than neonatal acne, requiring more aggressive therapy 5
- Early-onset acne with signs of virilization (early body odor, pubic/axillary hair, accelerated growth) necessitates hormonal evaluation 6
Key Clinical Pitfall
Do not confuse neonatal acne with other neonatal skin conditions such as milia, erythema toxicum neonatorum, or seborrheic dermatitis, which have different pathophysiology and management 5. Histologic examination, when performed, shows hyperplastic sebaceous glands with keratin-plugged orifices, confirming the diagnosis 2.
The condition is self-limited in most cases, resolving spontaneously within several months as neonatal androgen levels decline 2. Topical treatment can hasten resolution but is not always necessary 2.