The finding that prelabor cesarean delivery may have a correlation with acute lymphoblastic leukemia (ALL) may offer new targets for research into preventing cancer. These findings come from a pooled analysis of data from the Childhood Leukemia International Consortium (CLIC).1

The pooled analysis covered 13 studies with 33 571 participants overall, including 23 351 controls and 8655 patients with ALL. The analyses controlled for outside factors such as breastfeeding, parental education levels, and ethnicity.

No link between emergency cesareans and ALL or acute myeloid leukemia (AML) was found. In addition, AML and prelabor cesarean delivery had no link. However, the analysis showed a 23% increase in risk of ALL among children born via prelabor cesarean delivery.

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“Our goal was to determine if there was an association between cesarean deliveries and ALL, to identify potential new targets for research into cancer prevention if there is a correlation,” said Erin L. Marcotte, PhD, assistant professor at the Masonic Cancer Center at the University of Minnesota in Minneapolis, and first author of the study.

“While the link between overall cesarean delivery and childhood leukemia was not statistically significant, it was notable to find an association between prelabor cesarean delivery and ALL.”

The increased risk of ALL with prelabor cesarean delivery may be due to several mechanisms. These include the stress response in the fetus to labor and the missing colonization of microbiota that a newborn experiences during vaginal delivery.

“The most plausible explanation for the association between ALL and prelabor cesarean delivery is in the cortisol, or stress-related, mechanism,” said Marcotte. “Because ALL is not associated with all cesarean deliveries, it seems less likely the microbiota colonization is a significant factor in this phenomenon. We believe further investigation into this cortisol mechanism link is warranted due to these findings.”

Researchers noted the strength of association in these findings is comparable to other studies looking at cesarean delivery rates and other childhood outcomes, including type I diabetes and asthma. Further investigation into this study’s findings is needed, utilizing more detailed and reliable delivery information. The researchers’ working hypothesis is that cortisol exposure at birth plays a role.


1. Marcotte EL, Thomopoulos TP, Infant-Rivard C, et al. Caesarean delivery and risk of childhood leukaemia: a pooled analysis from the Childhood Leukemia International Consortium (CLIC) [published online ahead of print February 26, 2016]. Lancet Haematol. doi:10.1016/S2352-3026(16)00002-8.