The risk of autism is higher in babies having a higher weight at birth according to the latest and largest study conducted in Sweden. It is the first time that a clear link has been identified in babies with bigger weight in comparison to average and the risk of autism spectrum disorder (ASD).
This study was conducted on 40,000 children by The University of Manchester. The findings of this research has also confirmed the previous studies in which it was found that low weight and poor growth could also raise the risk of autism.
Professor Abel said: “The processes that leads to ASD probably begin during fetal life; signs of the disorder can occur as early as three years of age. Fetal growth is influenced by genetic and non-genetic factors. A detailed understanding of how fetal growth is controlled and the ways in which it is associated with ASD are therefore important if we are to advance the search for cures.
“To our knowledge, this is the first large prospective population-based study to describe the association between the degree of deviance in fetal growth from the normal average in a population of children and risk of ASD with and without intellectual disability.
“We have shown for the first time categorically that abnormal fetal growth in both directions increases risk of autism spectrum disorder.”
Researcher during this study found that babies with weight over 4.5kg (or 9lb 14) were at a greater risk of developing autism in comparison to infants having weight less than 2.5kg (5.5lb).
If a baby has poor fetal growth then he has 63% more chances to have autism in comparison to normal infants and the baby having higher weight at birth would have 60% more risk.
Professor Abel added: “We think that this increase in risk associated with extreme abnormal growth of the fetus shows that something is going wrong during development, possibly with the function of the placenta.
“Anything which encourages abnormalities of development and growth is likely to also affect development of the baby’s brain. Risk appeared particularly high in those babies where they were growing poorly and continued in utero until after 40 weeks. This may be because these infants were exposed the longest to unhealthy conditions within the mother’s womb.
“We now need more research into fetal growth, how it is controlled by the placenta and how this affects how the brain develops. One of the key areas to research is maternal condition and healthy growth.”
Reference: Catherine Lord, Ph.D. Fetal and Sociocultural Environments and Autism Am J Psychiatry 2013;170:355 358. 10.1176/appi.ajp.2013.13010078