Today, nearly 1 in 3 births in the United States are performed by cesarean section, and a growing number of those are planned rather than done in response to an emergency.
Planned C-sections allow doctors and expecting moms to sidestep some of the unpredictability of labor and offer an attractive amount of convenience and, for some, more peace of mind.
But a new study out of Sweden is raising some red flags about what comes later for your bundle of joy.
Researchers analyzed the data of nearly 2.5 million children born between 1982 to 1989 and 1999 to 2015 and found that that babies delivered via C-section were more likely to develop certain cancers than those delivered vaginally.
Of the nearly 376,000 children who were born using this method, 1,495 later developed leukemia — and those who were delivered by planned C-section, versus emergency, were at higher risk.
Specifically, the C-section babies had a 21% higher risk of acute lymphoblastic leukemia (ALL) — the most common type in children — and a 29% increased risk of B-cell acute lymphoblastic leukemia (B-ALL) — its most common subtype.
Experts believe the heightened risk may stem from how a planned C-section circumvents natural physiological processes triggered during labor — like the release of important hormones as well as exposure to beneficial bacteria — which may play a role in protecting against certain diseases later in life.
Crucially, the increased risk was not observed in emergency cesarean sections, which typically occur after labor has already started.
Researchers note that the overall risk of these diseases is low.
“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,” Christina-Evmorfia Kampitsi, a researcher at the Institute of Environmental Medicine, Karolinska Institutet in Stockholm, said in a press release.
“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.”
Additionally, the researchers point out that the percentage of C-section births in Sweden is only 11-15% and the overall childhood leukemia rate is roughly 4.5 per 100,000.
In the US, C-sections account for as much as 32% of all births and childhood leukemia occurs at a slightly higher rate of about 5.6 per 100,000 children.
The findings were published Friday in the International Journal of Cancer.
Kampitsi urged expecting mothers not to write off C-sections entirely — however, it might be worth discussing alternatives with your doctor, given the link between C-sections and other conditions.
“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,” Kampitsi said.
But Kampitsi points to other studies that have shown planned C-sections also increase the risk of other conditions, including asthma, allergies and Type 1 diabetes.
A 2024 meta-analysis, for one, suggests that C-section births increase the risk of food allergies by 35% and asthma by 20% in children later in life.
And a 2011 meta-analysis found that C-sections lead to a 20% increased risk of Type 1 diabetes in kids.
“There is reason to discuss C-sections that are not medically indicated,” she added.
