New research suggests that babies conceived less than a year after another pregnancy are more likely to be diagnosed with autism, The Daily Mail reported on Friday.
The risk of being diagnosed with autism was one and a half times higher if a pregnancy occured within one year of their last pregnancy than if they conceived a child later, a study found.
The time to conceive for optimal health was between two to five years after the previous child. There was no extra risk of the disability found within that time period.
The risk of being diagnosed with autism increased 30 percent if the child's mother conceived after a five year gap, researchers found.
The risk of autism jumped to more than 40 percent for gaps between pregnancies of more than ten years.
The study reaffirms previous research that found a link between conceiving a child closely after giving birth and the onset of autism.
Previous studies have also shown that women with two pregnancies close together are at risk of low birth weight and premature births.
The study pulled records of 7371 children born between 1987 and 2005 in Finland, collecting data from the Finnish Prenatal Study of Autism.
Roughly a third of the children had been diagnosed with autism.
Information was then culled from national registries to compare the timing of pregnancies between the children who had been diagnosed with autism and those who had not.
The analysis took into account other factors that might explain the link, such as the parent' history of psychiatric disorders like autism, parents' age and number of children in the family.
Alan Brown, a researcher at Columbia University, said that the study proves that environmental factors affecting the prenatal period play a part in autism development.
"[Autism is] a serious and disabling condition that afflicts millions of individuals and that is increasing in prevalence," he said.
