There are an estimated 1.2 million unused frozen embryos in the U.S. and millions more sitting in cryopreservation tanks across the world. The majority of these test tube babies will never be implanted in a womb. Instead, they will stay indefinitely preserved — literally frozen in time — until they are discarded or dissected. The small percentage of cryopreserved embryos that do escape the liquid nitrogen tanks, according to a new study out of Denmark, will experience a higher rate of childhood cancer than children who were conceived without ART.
Denmark has one of the highest rates of ART in the world — approximately 10 to 12 percent of the Danish babies born are the product of fertility help like in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), a process that involves isolating and injecting a single live sperm cell into a mature egg with hopes of fertilization.
According to researchers who examined 1,086,136 of the Land of Danes’ live births from 1996 to 2012, 3,736 cancers “occurred.” The study was careful to note that “absolute risks were low,” but indicated that the “modestly increased childhood cancer” rate is “procedure-related, rather than infertility-related.”
Babies born after they were conceived using ART had a higher rate of cancer incidence, 23.6 per 100,000 person-years, than their naturally conceived peers, 18.3 per 100,000. Those rates doubled in children born of frozen embryos, which yielded a 41.1 per 100,000 cancer rate, and also increased in children born after ICSI, 27.9 per 100,000.
Children born of IVF with fresh embryos — embryos that were created in a petri dish and implanted within three to five days after egg retrieval — did not show any specific cancer associations. Dane babies born of frozen embryos, however, suffered an 11.1 pediatric leukemia incidence rate, a 3.03 lymphoma rate, and a 7.63 soft tissue sarcomas rate.
ICSI also saw significant associations with lymphomas, soft tissue sarcomas, and an 8.2 per 100,000 incidence rate for central nervous system neoplasms.
This particular study is significant because it’s one of the longest and largest scientific examinations of children born using ART. Most IVF transfers in the U.S. and around the world involve frozen embryos. Yet the risks of those transfers are not always apparent or publicized.
“Nobody yet has long-term data on IVF as it is done today. Children conceived with today’s methods won’t have 20 years of data until the 2040s, so today’s IVF children are, in effect, the trial,” Josh Wood, executive director at Them Before Us, noted.
ART is more popular and profitable now than ever, but conceiving children outside of the human body doesn’t come without risks for mothers or their babies. In addition to the cancer incidence findings of this latest study, children who are conceived via IVF are at higher risk for preterm delivery, low birth weight, congenital heart problems, “neurodevelopmental disorders as well as potentially long-term metabolic outcomes,” and myriad birth defects.
Mothers who carry babies conceived by IVF also face risks such as ovarian hyperstimulation syndrome after egg retrievals, reactions to fertility drugs, infection, bleeding, bowel perforation, ectopic pregnancy, and an increased risk of major postpartum hemorrhage. Women who undergo fertility interventions also see a “transient increase” in the risk of certain cancers.
ART, like IVF, is often pitched to people struggling with infertility as a quick fix. Yet scientific data detailing the risks of outsourcing reproduction can be limited. In some ART, like surrogacy, data is more established but downplayed. That’s because detailing the imminent and measurable harm renting wombs has on women, babies, and intended parents puts the industry at risk of regulation and profit loss.
The cancer risk detailed in the recent Denmark study should raise concerns among reproductive technology specialists. Yet little to no legal or financial incentives exist for the global fertility industry to act on those concerns.
