Fertility techniques linked to intellectual disability
New research has revealed a link between intellectual disability and some forms of Assisted Reproductive Technology (ART), highlighting an urgent need for the long-term monitoring of children conceived via these techniques.
The study by the Telethon Kids Institute, published in Pediatrics, linked intellectual disability and ART data from population-based registers in Western Australia. The cohort included 210 627 live births from 1994 to 2002, with at least 8 years of follow-up.
The researchers found that 1 in 48 ART children were diagnosed with intellectual disability, compared to 1 in 59 for non-ART children. Children conceived through intracytoplasmic sperm injection (ICSI) showed a higher risk of intellectual disability at 1 in 32.
The risk of intellectual disability in very preterm births was much greater regardless of the method of conception – but within preterm singleton births, the risk was doubled for those that were ART-conceived. The researchers showed that 1 in 8 ART singletons vs 1 in 14 non-ART singletons born before 32 weeks were diagnosed with intellectual disability.
The findings are significant – but practices have changed since the study period
Lead researcher Dr Michele Hansen from the Telethon Kids Institute said that while the results are significant, it is important to note these findings relate to births from 1994 to 2002 and there have been major shifts in ART clinical practice in Australia since that time.
“During the study period, the transfer of multiple embryos in a single treatment cycle was the norm in Australia. This practice led to high rates of multiple pregnancies and preterm birth – which are both known to increase the risk of intellectual disability,” Dr Hansen said.
“However, this practice has changed dramatically in Australia over time. As of 2016, 88 per cent of treatment cycles saw only a single embryo transferred, resulting in much lower proportions of multiple and preterm births.”
Concerns over intracytoplasmic sperm injection technique
Dr Hansen said the research reinforces concerns about ICSI, which is now being used more broadly.
“Genetic abnormalities occur more frequently in men who are infertile, so ICSI – which bypasses natural selection barriers by injecting a sperm directly into an egg – may allow for the transmission of anomalies to the offspring,” Dr Hansen said.
ICSI use has increased over time in Australia since the study period and is currently used in 63 per cent of treatment cycles.
An urgent need for long-term monitoring of outcomes in ART children
Dr Hansen said that “our findings show an urgent need for more recent data to establish whether the increased risks of intellectual disability seen in children conceived using ICSI are solely related to severe male subfertility and older paternal age, or if there are other risks associated with the technique itself.”
Dr Genia Rozen, obstetrician and gynaecologist from Melbourne IVF, said this latest research was in agreement with similar studies showing a higher rate (though absolute risk is still low) of intellectual disability in the ART population, even when comparing similar groups such as singleton births.
“As fertility specialists this is something we must be counselling our patients about.”
Dr Rozen said that given the much higher rates of ICSI now observed in parts of the world, “to uphold ‘primum non nocere’ – first do no harm – studies, such as this one, are imperative.”