Approximately 40% of women start pregnancy with overweight or obesity, and around 70% retain weight in the postpartum period (PP). Obesity is related to low-grade systemic inflammation, primarily driven by the secretome of white adipose tissue (WAT), which includes dysfunctional adipocytes and immune cells that infiltrate WAT, releasing pro-inflammatory signals into the circulation. In women with obesity, the mammary gland undergoes structural and endocrine changes, such as reduced prolactin secretion, fewer mammary gland branches, and a higher abundance of adipocytes in mammary fat pad, which have not been studied under this condition. Maternal obesity during lactation also alters the composition of breast milk, promoting pro-inflammatory characteristics. The endocannabinoid system (ECS) is hyperactive in obesity, contributing to metabolic inflammation. Its primary receptors, cannabinoids 1 and 2, are expressed in the mammary gland and implicated in inflammation and weight gain. Endocannabinoids (ECs), the main ECS ligands, are typically not released into the bloodstream; however, their increased levels in obesity suggest upregulation in peripheral tissues. ECs are also present in breast milk, where their higher concentrations in women with obesity may influence infant food intake.
Elgueta et al. (Wed,) studied this question.