(RxWiki News) The cause of autism is unknown. It's possible that it might be associated with environmental factors. One such factor that recently interested researchers was the way a baby is conceived.
A team of researchers recently studied the relationship between assisted reproductive technology (ART) — artificial methods used to help women get pregnant when natural fertility is difficult or not possible — and autism.
These researchers found that ART did not increase the risk of autism, and said that more research is needed.
"Learn about the risks of assisted reproductive technology."
This study was conducted by Andrea Guzzetta, MD, from the Department of Developmental Neuroscience of IRCCS Stella Maris in Pisa, Italy, and colleagues.
The researchers reviewed a total of seven previously published studies, all of which were published after 2000. Four of the studies were from Scandinavian countries, two were from Israel, and one was from Japan.
There were a total of 9,216 study participants who had been diagnosed with infantile autism or autism spectrum disorder (ASD), and were born between 1970 and 2006. All cases were officially diagnosed in hospital records.
The researchers found that four of the previous studies reported no evidence of a link between ART and ASD.
Two of the studies did report an increased risk of ASD in children born using ART; however, the authors of this review argued that these studies were very limited in study design and method, and also ranked as the lowest quality studies used in this review.
The review also found that one study reported that ART was associated with a decreased risk of ASD. The authors of the review explained that this study had the smallest patient population out of any of the studies in this review.
Overall, the review's findings showed no evidence linking ART to ASD.
The researchers suggested a need for further research that focuses on the association between ASD and different types of ART, as well as on whether or not children with ASD who were born using ART differ from those who were not born using ART in terms of gender, severity of symptoms, IQ level and co-occurring psychiatric conditions.
The researchers also suggested that future research should use larger study populations that are followed for a longer period of time.
The authors noted a few limitations and explanations of the differences in study findings.
First, the reviewed studies did not all use the same definition of ART, with some including technical procedures, hormone therapy and fertility drugs, and some excluding hormone therapy and/or fertility drugs.
Second, all the studies considered different outside factors and considered the significance of them differently.
Third, the studies did not get ASD diagnoses of participants in the same manner. Although all cases had diagnoses in their medical records, some studies interviewed participants, while other studies used information from medical databases.
Fourth, some of the studies were cohort studies (comparisons of a particular outcome in a group of people), and some were case-controlled studies (comparisons of two groups of people, usually using past data).
Lastly, the studies included people born from 1970 to 2006, and the techniques and success of ART might have changed over the years.
This review was published online on October 15 in Human Reproduction.
The Italian Ministry of Health and Tuscany Region provided funding.