About 11% of women develop depression and anxiety after giving birth. These symptoms can reduce a mother's quality of life and daily functioning and may negatively affect her child's growth and development. Blue light therapy, based on chronobiology principles, has shown promising results for treating postpartum depression. It is relatively low-cost and has no known side effects. However, it is still unclear whether treating mothers with blue light therapy improves their children's growth and development. This study will investigate whether infants of mothers treated with blue light therapy for postpartum depression show better growth and developmental outcomes during their first year of life. Mothers diagnosed with postpartum depression within the first six weeks after childbirth will be assigned to one of two light exposure groups: a therapeutic blue light group or a control light exposure group (from another research study NCT06246214). A third group will include mothers without postpartum depression, and a fourth with previous depression. Children will be followed until 12 months of age. At that time, researchers will assess their growth, nutrition, and developmental milestones. The main goal is to compare child growth and development across these groups using statistical analyses.