Planned C-Sections Linked to Higher Leukemia Risk in Children

A recent study reveals a potential connection between planned Cesarean sections and an elevated risk of childhood leukemia. Although the overall risk remains low, the findings suggest a possible association that warrants further investigation.

Planned C-Sections and Leukemia Risk

The study, featured in The International Journal of Cancer, examined data from nearly 2.5 million children born in Sweden between 1982 and 2015. Researchers found that children born via planned C-section had a 21% higher risk of developing acute lymphoblastic leukemia (ALL), the most common type of childhood leukemia. According to the American Cancer Society, leukemia accounts for about 25% of all childhood cancers.

Boys Face Greater Risk

Specifically, the risk of B-cell acute lymphoblastic leukemia (B-ALL) was 29% higher in children delivered by planned C-section. The increased risk was more evident in boys and younger children, even after adjusting for various maternal and child factors.

According to Christina-Evmorfia Kampitsi, researcher at the Institute of Environmental Medicine, Karolinska Institutet, and lead author of the study: “C-sections are an important and often life-saving part of obstetric care. We don’t want mothers to feel anxious about medically indicated C-sections. But when this result is combined with other study results showing that the risk of later asthma, allergies or type 1 diabetes increases in children born by planned C-section, there is reason to discuss C-sections that are not medically indicated.”

Vaginal Bacteria and Stress as Possible Factors

Researchers propose that the difference in risk between planned and emergency C-sections may be related to the baby’s exposure to vaginal bacteria and the stress experienced during vaginal delivery. Emergency C-sections often begin as vaginal deliveries, exposing the baby to vaginal bacteria and stress if the amniotic sac ruptures. Planned C-sections, typically performed before labor, prevent this exposure and stress.

Study Limitations

It is important to note that some of the study’s results did not reach the threshold for statistical significance, meaning chance could not be entirely excluded.

Kampitsi stated, “Fortunately, ALL is rare. This means that many C-deliveries are needed to obtain a statistically significant result, and it is difficult to obtain such a large sample in a Swedish registry study. However, the results are close to significant, are in line with what previous studies have shown, and remain when we adjust for other relevant factors, which still makes them relevant.”

Small Increase in Cases

Researchers emphasize that the overall risk remains low, regardless of the delivery method. In Sweden, between 50 and 70 children are diagnosed with B-ALL annually. The increased risk associated with planned C-sections corresponds to approximately one additional case of B-ALL per year, according to the research team.

Looking Ahead

The scientists believe this study can improve understanding of what causes ALL in children. The research was funded by the Swedish Research Council and the Swedish Cancer Society, and the authors declare no conflicts of interest.

Reference: Kampitsi CE, Mogensen H, Heyman M, Feychting M, Tettamanti G. Mode of delivery and the risk of lymphoblastic leukemia during childhood—A Swedish population-based cohort study. Int J Cancer. 2025. doi: 10.1002/ijc.70027