Men with fertility issues leading their partners to conceive via vitro fertilization (IVF) due place their offspring at a higher risk of developing mental retardation or intellectual disability, according to a new study published Wednesday.

The Swedish study, published in the Journal of the American Medical Association, is the first of its kind to compare a wide range of IVF treatments and their impact on autism and intellectual disability. Intra-cytoplasmic sperm injection (ICSI), a fertility method used where the men are deemed to be almost completely infertile, involves injecting the sperm directly into their partner's egg.

While the study initially found that IVF treatment carried a small but statistically significant risk of intellectual disability, when the results were restricted to single births (as opposed to implanting multiple embryos) the risk disappeared.

The study also found that in the most severe cases of male infertility, where men require surgery as part of the treatment, children were more than four times more likely to develop autism.

"The reasons (for an increased risk) could be the underlying infertility," says Abraham Reichenberg, one of the study authors and a professor at Mt. Sinai School of Medicine in New York and King's College London.

"It could be something happening in the many steps that are involved in each of the treatments, or something that's happening later in the pregnancies, or all of them combined together. It could be any one of those steps. In any one of them it could go wrong." The increased risk was seen even in singleton births utilizing ICSI. However, the overall risk remains low.

The study found a 51 per cent increased risk of intellectual impairment, an IQ below 70, in children conceived by IVF treatments in which sperm cells are injected directly into eggs.

This amounted to a rise from 62 per 100,000 children (0.062 per cent) to 92 per 100,000 (0.092 percent).