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(CNN) - Children born through the transfer of frozen embryos have a higher risk of developing childhood cancer, although the danger would be low, according to the finding of new research.
The study, published in the medical journal JAMA on Tuesday, analyzed babies born in Denmark, a country that has one of the highest rates of assisted reproduction technology. In 2018, almost 10% of all children were born through some type of fertility treatment.
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Scientists already knew that children conceived with the help of fertility treatments face greater risks to their health. Previous studies have shown that these babies are more likely to be born prematurely, have a low birth weight and have some birth defects. However, part of the long-term health consequences of fertility procedures are still unknown, the authors noted.
This research analyzed data from the Danish Birth Medical Registry, the Cancer Registry and the Infertility Cohort, which included 1,085,172 children born in the country between January 1996 and December 31, 2012. Of that total minors, 2,217 were diagnosed with cancer.
When the scientists compared the number of children born to fertile parents versus those born with some assistance, they noticed a high risk of childhood cancers in cases where frozen embryos were used.
Specifically, the childhood cancer rate was 17.5 per 100,000 children born to fertile women and 44.4 per 100,000 for children using frozen embryos.
There were no statistically significant links between cancer and the other types of fertility treatments that the scientists in this study have identified. The risk of cancer was not greater for children with parents who used fertility drugs, in vitro fertilization or intracytoplasmic sperm injection, among other methods.
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"I think this is interesting and potentially worrying, but you have to look at this study in perspective," said Dr. Jeffrey Goldberg, a gynecologist and reproductive endocrinologist at the Cleveland Clinic who was not involved in the study. "Fortunately, childhood cancers are quite unusual," he added.
And he said that "it is something that deserves further evaluation, but there are a couple of explanations." Goldberg said it is important to note that the study began in 1996 and since then there have been many changes in technology and in laboratory and stimulation protocols, which could have an impact if the study is conducted again with more recent data. .
Women who undergo this procedure using frozen embryos may also have a higher risk if they are older and their partners are of similar age, as the possibility of cancer increases. If the mother is obese, the weight may also present an increased risk of a child developing cancer, Goldberg said.
"In a way, (the investigation) raises more questions than it answers," Goldberg said. "I think it was reasonable to ask the question first in this study."
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Most previous studies did not find an association between cancer and frozen embryos. Although a previous investigation did observe a link, all analyzes were based on much smaller patient populations.
This study had a large number of patients, but it is not clear if the results would change if scientists looked at patients from other countries with different racial and ethnic characteristics.
The research also focuses on retrospective data, so researchers could not ask why there could be a high risk of cancer with this procedure.
Now, Goldberg points out that parents shouldn't worry.
"A 2.4-fold increase is clinically significant, but these are very small numbers, and this is based on older data dating back to 1996 and some of the things at that time may not be applicable now," Goldberg said. "I don't want this to trigger alarms."
CancerChildhood CancerEmbryosFertilityFertilization