Why would breast milk smell rotten or like spoiled eggs?

Breast milk can develop a rotten or spoiled egg-like smell due to the presence of certain bacteria, particularly if it has been improperly stored or is past its expiration date. This odor may also arise from the breakdown of fats in the milk, leading to the production of volatile compounds. Additionally, maternal diet and health can influence the smell of breast milk. If there are concerns about the smell or quality of breast milk, it is best to consult a healthcare professional.