Maternal Factors, Breast Anatomy, and Milk Production During Established Lactation—An Ultrasound Investigation

Obesity is linked to suboptimal breastfeeding outcomes, yet the relationships between maternal adiposity, breast anatomy, and milk production (MP) have not been investigated. We conducted ultrasound imaging to assess the breast anatomy of 34 lactating women. The amount of glandular tissue (glandular tissue representation (GTR)) was classified as low, moderate, or high. Number and diameters of main milk ducts and mammary blood flow (resistive index) were measured. Women completed a 24 h MP measurement and an obstetric/lactation history questionnaire. Body composition was measured with bioimpedance spectroscopy. Statistical analysis employed correlation networks. Multiple relationships were revealed, with later menarche correlating with minimal pubertal and pregnancy breast growth. A minimal breast growth was further correlated with lower mammary blood flow during lactation and lower numbers and smaller diameters of main milk ducts, which in turn correlated with a lower MP. Importantly, higher adiposity also correlated with minimal breast growth during pregnancy and low GTR and MP. Several modifiable and non-modifiable maternal factors may be associated with breast development and MP. Antenatal lactation assessment and intervention in high-risk women may ensure they reach their full lactation potential and inform future interventions, such as maintaining healthy adiposity.