Children of individuals with infertility have a slightly higher risk of developing autism, a study of almost 1.4 million children has shown.
Much of this effect can be explained by adverse pregnancy outcomes, which are more common in people with infertility and following fertility treatment, and have previously been associated with risk of autism spectrum disorders.
'The result is consistent with others and continues to provide reassurance that fertility treatments themselves do not increase the children's risk of autism,' said Ying Cheong, professor of reproductive medicine at University of Southampton, who was not involved in the study.
'This risk is more to do with the associated pregnancy and delivery complications rather than the fertility treatment techniques,' she continued.
The research team, based in Canada, used a healthcare database to study almost 1.4 million children born between 2006 and 2018 after 24 weeks or more of gestation.
Results published in Pediatrics showed an increased risk in the likelihood of autism diagnosis of 20 percent among children born to parents who had infertility but did not use fertility treatment, 21 percent among children born following ovulation induction (OI) and intrauterine insemination (IUI) and 16 percent for children born following IVF and ICSI, compared to natural conception.
'This increased likelihood was very small – a 20 percent increase on what is already a small number,' commented Professor Andrew Whitehouse from the Telethon Kids Institute and the University of Western Australia, who was not involved in the study. 'The findings of this study should not change the decision of any parent trying to conceive.'
In the example of IVF or ICSI, an increased likelihood of Caesarean birth mediated 29 percent of this increased risk, multifetal pregnancies 78 percent and preterm birth 50 percent. The corresponding figures for OI and IUI were 11 percent, 36 percent and 26 percent.
A difference in average age of parents belonging to each group may also have a hand in contributing to an autism diagnosis. The parents of those conceived naturally had an average age of 30 years, compared to 33 years for parents who experienced infertility but did not use fertility treatment, and those who used OI or IUI, and 36 years for those who used fertility treatment to conceive. The study excluded mothers over the age of 45 but did not disaggregate data based on the age of the fathers.
'We need more granular details about the baseline infertility diagnosis, paternal factors, and whether the oocyte (egg) or sperm are from the parent or a donor, among other factors,' said Dr Maria Velez, lead author of the study and associate professor of obstetrics and gynaecology at Queen's University in Ontario, Canada.