The article discusses the study that determined the association of cesarean section (CS) delivery with the risk of childhood leukemia, specifically acute lymphoblastic leukemia (ALL), using data from California Childhood Leukemia Study (CCLS) case-control study. Findings discussed include no association between CS and acute myelogenous leukemia, suggested association for ALL and CS, and strong association of common ALL (cALL) with CS in Hispanics.