Overview

• Researchers reviewed nearly 2.5 million Swedish births from 1982–1989 and 1999–2015 and found a 21 percent higher risk of acute lymphoblastic leukemia (ALL) among children born by planned C-section compared to vaginal births.
• The most common ALL subtype, B-cell ALL, showed a 29 percent increase in risk for elective C-section deliveries, though the absolute excess amounts to about one additional case per year in Sweden.
• No elevated leukemia risk was observed in emergency C-sections, suggesting that exposure to labor stress hormones and maternal vaginal bacteria may play a protective role.
• Investigators propose that bypassing labor-associated immune exposures in planned C-sections could influence early immune development and contribute to leukemia susceptibility.
• Authors emphasize that medically indicated C-sections remain essential but recommend careful discussion of non-medically indicated procedures in light of potential long-term child health trade-offs.