Scheduled cesarean sections increase the risk of certain childhood cancers

Children born by planned cesarean section have an increased risk of developing acute lymphoblastic leukemia (ALL) later in life. This is demonstrated by a study conducted by researchers at the Karolinska Institute. The researchers emphasize that the risk remains low.

The study, published in The International Journal of Cancer , covers nearly 2.5 million children born in Sweden during two periods: from 1982 to 1989 and from 1999 to 2015. Of these, 15.5 percent were born by caesarean section, or nearly 376,000 children. In total, 1,495 children later developed leukaemia .

Using the Medical Birth Registry, the authors of the publication were able to divide cesarean sections into planned and emergency cesarean sections. Children who later developed leukemia were overrepresented in the group born by planned cesarean section . In particular, the risk of acute lymphoblastic leukemia (ALL), the most common form of childhood leukemia , was increased. The risk of ALL was 21% higher in children born by planned cesarean section than in those born vaginally.

The risk of developing the most common form of ALL, B-cell acute lymphoblastic leukemia (B-ALL), was 29% higher in those born by planned cesarean section . This increased risk remained even when researchers adjusted for other relevant maternal and infant factors. The increased risk was more pronounced in boys than in girls and among younger children.

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The researchers emphasize that the risk remains low, regardless of the type of delivery . Between 50 and 70 Swedish children are diagnosed with B-ALL each year. The additional risk associated with planned cesarean sections corresponds to approximately one case of B-ALL per year , according to the researchers responsible for the study.

Caesarean sections are an important and often life-saving part of obstetric care . We don't want mothers to feel anxious about medically indicated caesarean sections. However, when you combine this result with other studies showing that the risk of asthma, allergies, or type 1 diabetes increases later in children born by planned caesarean section, there is reason to talk about caesarean sections without medical indication," explains Christina-Evmorfia Kampitsi , a researcher at the Institute of Environmental Medicine at Karolinska Institutet and lead author of the study.

Researchers are examining possible mechanisms that could explain why elective, but not emergency, cesarean sections carry a higher risk of certain diseases, all of which are related to immunological factors . The reasoning is that emergency cesarean sections often begin as vaginal births. This causes stress to the baby and exposes it to vaginal bacteria if the amniotic sac ruptures.

However, in planned cesarean sections, which are usually performed before the natural onset of labor, the baby doesn't experience this stress or exposure to vaginal bacteria . Researchers suggest this difference could explain the increased risk of ALL and believe the study could contribute to a better understanding of the causes of ALL in children.

Some of the results did not meet the threshold for statistical significance , meaning that "chance cannot be completely ruled out." "Fortunately, acute lymphoblastic leukemia (ALL) is rare," they explain. This means that many cesarean 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 "significant," consistent with those shown in previous studies and remain relevant when adjusted for other relevant factors, making them relevant, Kampitsi concludes.