Childhood obesity is a significant global health issue with complex and multifactorial origins, often beginning before conception and influenced by both maternal and paternal health. The increased prevalence of pre-pregnancy obesity and gestational diabetes mellitus in women of reproductive age contributes to a heightened risk of metabolic dysfunction in offspring. Current clinical practices often implement lifestyle interventions after the first trimester, and have limited success, implying that they miss a critical window for effective metabolic adjustments. This review examines the limitations of lifestyle interventions during pregnancy in improving perinatal outcomes and highlights the importance of initiating such interventions before conception to positively impact parental health and fetal development. A re-evaluation of strategies is needed to enhance the metabolic health of prospective parents as a preventive measure against childhood obesity.