born following IVF have no increased risk of autism but may be at a very small increased risk of intellectual disability, a Swedish study suggests. However,
the researchers stress that the overall likelihood of children conceived via
IVF having an intellectual impairment remains extremely low.
published in the Journal of
the American Medical Association, found that the occurrence of intellectual
disability was 46.3 per 100,000 births in children born after IVF, compared with
39.8 per 100,000 in those conceived spontaneously - a difference of just 6.5
cases per 100,000 births.
Dr Karl-GÓ§sta Nygren from the Karolinska Institutet,
a co-author of the paper, said that it confirmed that 'the majority of children
are born perfectly healthy following IVF'.
In the study,
the largest of its kind, the researchers analysed 2.5 million Swedish birth
records from between 1982 and 2007. Of the 2.5 million children, 1.2 percent were
born following IVF procedures.
researchers recorded whether the children had a clinical diagnosis of autism or
intellectual disability (defined by an IQ of less than 70, the general
population average being 100) at the age of four. For children conceived via IVF the
authors also noted whether fresh or frozen embryos were used, whether sperm was
ejaculated or surgically extracted, and if intracytoplasmic sperm injection
(ICSI) was used. ICSI is an IVF technique that is used in cases of male
infertility, and involves injecting a single sperm directly into the egg. (In
standard IVF, the egg is fertilised by sperm in a laboratory dish.)
Sandin, a study co-author from King's
College London's Institute of Psychiatry, noted that 'when we separated the
different IVF treatments, we found that traditional IVF is safe, but that IVF
involving ICSI, which is specifically recommended for paternal infertility, is
associated with an increased risk of both intellectual disability and autism in
the analysis was restricted to singleton births, this small risk increase disappeared.
The authors considered possible explanations for the increased risk of developmental
disorders following ICSI, such as parental age and hormonal treatments, but
found that these factors could not explain the results. The precise
mechanism therefore remains unclear.
Dr Allan Pacey, chair of the
British Fertility Society, who was not involved in the study, said that the
main message of the research 'is a positive one, suggesting that any risk of
these disorders is very low, or absent, in comparison to children conceived