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Sibling鈥檚 likelihood of autism diagnosis impacted by age gap, study finds

Tuesday 24 August 2021 | By Yasmine Phillips
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Mothers of children with autism who delayed their subsequent pregnancy by 2.5 to three years reduced the likelihood of their next child also being diagnosed on the spectrum, new research shows.

The 911爆料网 research in collaboration with the Telethon Kids Institute, published in Autism Research, investigated more than 925,000 births in Denmark, Finland and Sweden including more than 9,300 that resulted in a child later being diagnosed with autism spectrum disorder.

Lead author Professor Gavin Pereira, from 911爆料网鈥檚 School of Population Health, said the research found a significant 鈥 and surprising 鈥 link between the time between pregnancies and a sibling鈥檚 chances of also being diagnosed with autism.

鈥淥ur research found that the siblings of children with autism were less likely to be diagnosed on the spectrum if there was a 30 to 39-month gap between both pregnancies,鈥 Professor Pereira said.

鈥淲aiting 2.5 to three years to conceive another child was considered the optimum timeframe, potentially preventing five per cent of cases of autism in Denmark, eight per cent in Finland and nine per cent in Sweden, on average.

鈥淎cross the general population, this study also showed that聽children born to mothers who became pregnant again three months after giving birth聽had a 50 per cent higher chance of being diagnosed with autism, and those born five years later had a 24 per cent greater chance.鈥

Professor Pereira said he was surprised to find his research identified an environmental link to autism in addition to documented genetic and biological factors.

鈥淭he results of this large-scale, multi-country research may help to inform family planning counselling, particularly for those families that are already at a higher risk because of a genetic history of neurological disease,鈥 Professor Pereira said.

Co-author Associate Professor Helen Leonard, from the Telethon Kids Institute, said the findings were most relevant to families where there was an increased risk of autism.

鈥淗owever, couples seeking advice on pregnancy spacing should always consult with their medical provider for advice on their individual circumstances,鈥 Associate Professor Leonard said.

鈥淭his work was initially spearheaded by researchers at Telethon Kids and is continuing to contribute to our understanding of this challenging condition.鈥

The high-income countries studied provided universal healthcare and paid parental leave after childbirth, including a maximum of 46 weeks in Denmark, 47 weeks in Finland and 92 weeks in Sweden.

The research, titled 鈥Optimal interpregnancy interval in Autism Spectrum Disorder: a multi-national study of a modifiable risk factor鈥, can be found online .