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Reassurance from Sweden about autism and IVF

JAMA 2013;310:75-84 Two and a half million infants were born in Sweden between 1982 and 2007, and close to 31 000 were conceived by in vitro fertilisation (IVF). A series of large scale analyses found no association between IVF and risk of autism in children and a weak association between IVF and mental retardation, which disappeared when researchers excluded multiple births. Further exploration of different types of IVF suggested that intracytoplasmic sperm injection (ICSI) was associated with a higher risk of mental retardation than IVFwithout ICSI (adjusted relative risk 1.47, 95% CI 1.03 to 2.09; 90.6 v 60.8/100 000 person years). This association was weaker in singletons and stronger in infants born preterm. In Sweden, ICSI is generally reserved for couples with male factor infertility. The standard procedure, and reference for all comparative analyses, was IVF without ICSI combined with fresh embryo transfer. All children in Sweden have a neurodevelopmental assessment at 4 years of age. The authors defined mental retardation as an IQ below 70 combined with limitations in adaptive behaviour. In autism analyses, they counted only children with a narrow definition of infantile or childhood autism, not wider autistic spectrum disorders. These new findings underline once again the importance of avoiding multiple pregnancies and preterm deliveries after IVF, says a linked editorial (p 42). But they don’t rule out small independent risks associated with ICSI, so long term surveillance should continue.