Parents who use reproductive technologies like in vitro fertilization (IVF) may be more likely to have children with intellectual disabilities than those who conceive without help, an Australian study suggests.
Researchers examined data on 2,876 children conceived with assistive reproductive technology (ART) and 207,751 kids born without ART in Western Australia from 1994 to 2002. Just 3,551 of these children were diagnosed with intellectual disabilities after being followed for at least eight years.
Children born with the help of ART were 58 percent more likely to have intellectual disabilities by age 8 or older. With ART, kids were also more likely to have severe deficits.
Overall, rates of intellectual disability were still low, however. Among all children born during the study period, the 3,551 diagnosed with intellectual disability represent about 17 kids in every 1,000 live births. Among kids conceived with ART, the rate was 20 per 1,000.
“The vast majority of children conceived using ART are born healthy and will not be diagnosed with an intellectual disability,” said lead study author Michele Hansen of the Telethon Kids Institute and the University of Western Australia in Perth.
One type of IVF known as intracytoplasmic sperm injection (ICSI) was responsible for most of the increased risk of intellectual disabilities seen with ART. Unlike traditional IVF, when the sperm and egg mix together “naturally” in a dish, ICSI involves injecting sperm into the egg, and is often used in cases of male infertility or low sperm count.
Kids born with ICSI had more than twice the risk of intellectual disabilities of children conceived without ART, the researchers report in Pediatrics.
“Until we know more about whether there are risks associated with the ICSI technique itself versus the underlying male-factor subfertility and older age of fathers using the technique, clinics may consider restricting the use of ICSI to those couples that are unlikely to be able to conceive without it – that is, those with severe male factor subfertility,” Hansen said.
Children born after ICSI were more likely to have a known genetic condition than kids born after IVF or without ART, the study found. While 28 percent of ICSI kids had a genetic disorder, only 12 to 13 percent of other children did.
Down syndrome was the most common cause of intellectual disabilities, accounting for 10 percent of ART cases of intellectual disabilities and 5 percent of non-ART cases.
The cause of the majority of intellectual deficits wasn’t known for 72 percent of cases in the ART group and 82 percent of cases in the non-ART group.
Among kids without an identified cause for intellectual disabilities, children conceived by ART were more likely to be underweight, multiples, to have been exposed to pregnancy complications or diagnosed with cerebral palsy.
The study wasn’t designed to prove whether or how ART might contribute to intellectual disabilities in children. Another limitation is that reproductive technology has changed in the years since the children in the study were born, with doctors increasingly encouraging singleton rather than multiple births to minimise complications.
It’s also still not clear whether ART or underlying fertility issues that lead couples to conceive this way might be ultimately responsible for intellectual disabilities, said Judy Stern, a professor of obstetrics and gynecology at Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire.
“Parents who pursue ART do so because they have exhausted other options for having a family,” Stern, who wasn’t involved in the study, said. “Patients should remember that the magnitude of the abnormalities demonstrated in this paper is low.”
Women considering ICSI still may want to ask their physician whether this is the only option in case they can do traditional IVF instead, said Logan Spector, a researcher at the University of Minnesota in Minneapolis who wasn’t involved in the study.
“Physicians should limit the use of ICSI when possible,” Spector said.