Children born from embryos placed in frozen storage are at increased risk of developing cancer, according to an alarming new study.
Researchers at the University of Gothenburg in Sweden have found that children born from frozen embryos in particular suffer from an increased risk of developing leukemias and cancers related to the central nervous system. Interestingly, the same risk was not found for children born by other means of assisted fertilization.
Frozen embryo births are relatively rare and represent a tiny fraction of all babies born using assisted reproductive technology (ART), and therefore there is little large-scale demographic data available for them.
There are over one million embryos currently frozen in the United States, although the vast majority will never be used. Penn Medicine reports that approximately one million babies were born through in vitro fertilization from 1987 to 2015 – although nearly all were born using a fresh embryo.
A Centers for Disease Control and Prevention report published in 2017 found that there were approximately 29,000 frozen embryos that resulted in a live birth in 2015, the most recent data available, in the United States.
Children born from embryos that have been stored by freezing them are more likely to develop cancer, a new study has found. People born from fresh embryos did not run the same risk. Researchers don’t know why this is the case (file photo)
The researchers, who published their findings last week in PLOS, collected data from 7.9 million children in four Scandinavian countries – Denmark, Finland, Norway and Sweden – for the study.
IVF: the technology allowing thousands of people to start a family
In vitro fertilization, known as IVF, is a medical procedure in which a woman has an already fertilized egg inserted into her womb to become pregnant.
It is used when couples are unable to conceive naturally, and a sperm and egg are removed from their bodies and combined in a laboratory before the embryo is inserted into the woman.
Once the embryo is in the uterus, the pregnancy should continue as normal.
The intervention can be done using eggs and sperm from a couple or from donors.
National Institute for Health and Care Excellence (NICE) guidelines recommend that IVF should be offered on the NHS to women under 43 who have been trying to conceive through regular unprotected sex for two years.
People can also pay for IVF privately, which costs an average of £3,348 for a single cycle, according to figures released in January 2018, and there are no guarantees of success.
The NHS says success rates for women under 35 are around 29%, with the chances of a successful cycle decreasing as they get older.
Around eight million babies are thought to have been born through IVF since the very first case, Britain’s Louise Brown, was born in 1978.
Chances of success
The success rate of IVF depends on the age of the woman undergoing treatment, as well as the cause of infertility (if known).
Young women are more likely to have a successful pregnancy.
IVF is generally not recommended for women over 42, as the chances of a successful pregnancy are considered too low.
Of this population, 172,000 were born using ART of some kind, and 22,630 were from a frozen embryo.
Researchers found that children born after an embryo was thawed were more likely to develop cancer at a younger age, with leukemia and cancers of the central nervous system – usually affecting the brain or spinal cord – being the most currents.
On average, 2.07 out of 1,000 children born by spontaneous conception developed cancer.
Children born from a fresh embryo – which accounts for the majority of IVF pregnancies – were slightly less likely to develop cancer. The researchers found that 1.97 out of 1,000 developed the disease.
People born from a frozen embryo were most at risk, with 2.12 out of 1,000 being diagnosed.
Children born from frozen embryos also often suffered from their diagnosis earlier in life. The study found 30.08 cases per 100,000 years of life – nearly double the figures for the fresh embryo and spontaneous birth groups.
Overall case levels were low, however, and the researchers don’t think it should scare off a future family from freezing their embryos.
“The individual risk was low, whereas at the population level it may have an impact due to the huge increase in frozen cycles after assisted reproduction,” said Ulla-Britt Wennerholm, co-author of the study that serves as OBGYN. reported by UPI.
“No increase in the number of cancers was found in children born after assisted reproductive technologies overall.”
Researchers aren’t sure why children born from frozen embryos might be most at risk, though they have a few theories.
“The reason for a possible higher risk of cancer in children born after [embryo freezing] is not known,” they wrote.
“Each type of childhood cancer has its own profile of risk factors, but many childhood cancers are believed to derive from embryonic accidents and originate in utero.
High birth weight has been associated with a higher risk of childhood cancer, and [changes to the DNA based on environment] have been offered as a possible explanation.
The number of women freezing their eggs has skyrocketed in recent years as many people in the Western world have chosen to put off building a family in order to pursue their career goals.
In 2018, 13,000 women chose to freeze embryos, down from less than 500 nearly a decade earlier in 2009.
Children born from frozen embryos are more likely to develop cancer later in life