What Causes Baby Acne?
Neonatal acne is caused by elevated production of placental and neonatal androgens (from the adrenal glands in both sexes and from the testes in males), which stimulate enlargement of the sebaceous glands and increase sebum production. 1
Primary Pathophysiology
The hormonal mechanism underlying neonatal acne involves:
- Androgen surge from multiple sources: Placental androgens transferred to the infant and the baby's own adrenal production (plus testicular production in male infants) drive the development of acne lesions 1
- Sebaceous gland stimulation: These androgens cause the sebaceous glands to enlarge and produce excess sebum, creating the environment for acne development 1
- Timing of onset: This hormonal activity explains why neonatal acne typically appears between the second and fourth weeks of life, affecting approximately 20% of newborns 1
Clinical Presentation Pattern
The distribution and characteristics provide additional clues to the hormonal etiology:
- Male predominance: Boys develop neonatal acne 4.5 times more frequently than girls, reflecting the additional testicular androgen contribution 1
- Characteristic locations: Lesions appear on the forehead, cheeks, chin, and eyelids—areas with high sebaceous gland density—and occasionally spread to the scalp, neck, and trunk 1
- Lesion types: Open and closed comedones develop first, which can progress to papules, pustules, and rarely nodules or cysts 1
Important Clinical Caveat
If neonatal acne is severe, persistent, or long-lasting, investigation for underlying endocrine pathology is necessary, including congenital adrenal hyperplasia or virilizing tumors of adrenal or gonadal origin 1. However, the vast majority of cases are mild, transient, and resolve spontaneously without indicating systemic disease 1.
The sebaceous glands themselves are well-developed at birth (having formed after the fourth month of gestation), and sebum production is relatively high in newborns, which may serve evolutionary purposes related to birth lubrication 2. These glands then become pathologically activated by the postnatal hormonal environment to produce acne 1.