Abstract Because of the physiological changes that occur during pregnancy and lactation, diagnostic ultrasound of the breast during these periods is a challenge for physicians. Therefore, a comprehensive understanding of imaging, anatomy, and physiology of the breast is important to effectively diagnosing diseases that can arise in women who are pregnancy or lactating. The aim of this article was to review the physiological changes that occur in the breasts during pregnancy and lactation, as well as to describe the main features of the breast diseases that occur most frequently during these periods.