The causes of post-partum pimples (medically known as acne) mainly include large amounts of sebum secretion, keratinization of follicular sebaceous gland ducts, and propagation of Propionibacterium acnes. 1. Massive sebum secretion: Generally speaking, estrogen levels in a woman’s body will drop rapidly after giving birth, resulting in an imbalance of androgen levels, which can easily cause sebaceous gland hypertrophy and sebaceous glands to function exuberantly, leading to an increase in sebum secretion and clogging of pores, thus triggering the emergence of acne. 2. Keratinization of follicular sebaceous gland ducts: Excessive keratinization of cells around the hair follicle makes the follicle opening smaller, narrower, and blocked, preventing normal sebum secretion and discharge, resulting in sebum as well as keratin plugs blocking the follicle opening and forming acne pimples. 3. Propionibacterium acnes reproduction: After the skin is infected with Propionibacterium acnes, Propionibacterium acnes breaks down the triglycerides in sebum into free fatty acids, which stimulates the keratinocytes at the follicle ducts to proliferate and over-keratinize, leading to the formation of acne. Patients are advised to keep the skin clean and hygienic, pay more attention to rest, and follow the doctor’s instructions for treatment if necessary.