Caesarean Delivery and Risk of Childhood Leukemia
Results from case-control studies have shown an increased risk of acute lymphoblastic leukemia (ALL) in young children born by caesarean delivery, and prelabor caesarean delivery in particular. However, an association of method of delivery with childhood leukemia subtypes has yet to be established. Therefore, a study, published online in Lancet Haematology (26 February 2016), performed a pooled analysis of data to investigate the association between childhood leukemia and caesarean delivery.
For the study, data were pooled from 13 case-control studies from the Childhood Leukemia International Consortium (CLIC) done in nine countries (Canada, Costa Rica, Egypt, France, Germany, Greece, Italy, New Zealand, and the USA) for births between 1970-2013. The authors analyzed caesarean delivery overall and by indications that probably resulted in prelabor caesarean delivery or emergency caesarean delivery. Multivariable logistic regression models, adjusted for child’s birthweight, gender, age, ethnic origin, parental education, maternal age, and study, were used to estimate odds ratios (ORs) and 95% CIs for the risk of ALL and acute myeloid leukemia (AML) in children aged 0-14 years at diagnosis.
Overall, the studies provided data for 8,780 ALL cases, 1,332 AML cases, and 23,459 controls, of which the birth delivery method was known for 8,655 (99%) ALL cases, 1,292 (97%) AML cases, and 23,351 (>99%) controls. Indications for caesarean delivery were available in four studies (1,061 ALL, 138 AML, and 1,401 controls). Results showed that the OR for all indications of caesarean delivery and ALL was 1.06, and was significant for prelabor caesarean delivery and ALL (1.23; p=0.018). Emergency caesarean delivery was not associated with ALL (OR 1.02). AML was also not associated with caesarean delivery, prelabour caesarean delivery and emergency caesarean delivery.
According to the authors, the results suggest an increased risk of childhood ALL after prelabor caesarean delivery. The authors then added that if this association is causal, maladaptive immune activation due to an absence of stress response before birth in children born by prelabor caesarean delivery could be considered as a potential mechanism.