Maternal Characteristics Associated With Child Growth and Adiposity. Search for Nutrigenomic Biomarkers in Peripheral Blood

The goal of this observational study is to investigate the concentrations of leptin, insulin, liver expressed antimicrobial peptide 2 (LEAP2), and cortisol in plasma and breast milk and their relationship with eating behavior, growth, adiposity and with the levels of these hormones in infants, comparing mothers with normal weight and with pre-pregnancy overweight/obesity. The main question\[s\] it aims to answer are: * Are maternal hormones associated with child growth and adiposity * Are maternal hormone receptors associated with child growth and adiposity * Are infant hormones and their receptors associated with child growth and adiposity * Are maternal and infant hormones and their receptors associated with child eating behavior Participants will provide milk and blood samples. Researchers will compare mothers with normal weight and with pre-pregnancy overweight/obesity to see if there are differences in child growth and adiposity .