Ultrasonography linked to Autism?

       Social communication is one of the pearls of the child’s development. Impairment in the ability to engage in social interaction with restricted, repetitive patterns of behavior encompass the hallmark of Autism Spectrum Disorder (ASD). Children with ASD have dilemmas in sharing their thoughts and feelings with others. Delayed language with lack of interest and play are mostly the initial symptoms that are mostly recognized during their second year of life. Autism specific screening are considered to be done at 18 and 24 months of age. During the past few several decades, prevalence of ASD increased rapidly with estimates of 1 in 68 individuals affected. It may be due to heightened awareness and screening and may be in part from historical shifts of diagnostic categories. Currently, ASD is thought to be brought about by set of environmental and genetic contributions. . Advanced maternal and paternal age, closer spacing at pregnancies, premature birth and family members with learning problems, psychiatric disorders and social disability have been identified as risk factors. Genetic causes are to be unveiled. Exposure to toxic environmental factors to the developing fetus is also considered as a risk in ASD and prenatal ultrasonography was proposed.
As the incidence of ASD increased during the past several decades, the use of ultrasonography has increased substantially. Ultrasonography which is mostly started at first trimester of pregnancy is routinely done during prenatal check-ups. Viability, gestational age, number of fetuses and most importantly, the gross fetal abnormalities are being detected by ultrasound. However, despite its benefits, a study by Mcclintic and Webb suggested that ultrasonography  causes alterations in behaviors and disrupts cortical migration during the fetus’ brain development based on animal studies. Ultrasonography consists of pulses of high frequency sound whose backscatter from tissue yields details of the structure of the tissues and movements of blood. It also has the ability to create local increases in temperature which is detrimental in the developing brain at the first trimester.Thus, the brighter the ultrasonography, the higher the ultrasound exposure and the shallower the tissue, the more harm to the fetus.
A case control study of 420 children  was done by Rosman et.al. The study included 107 children with ASD, 104 control individuals with developmental delay and 209 controls with typical development. They were identified from prenatal care medical records and delivery at Boston Medical Center from July 1, 2006 through December 2014 with a gestational age of at least 37 weeks. Data were analyzed from May 1,2015 through November 30,2017. However, authors found out that children with ASD compared with typically developed children had fewer first trimester scans, a later-first trimester scan, lower mean total time of exposure in the first and second trimester, increased mean depth of  ultrasound exposure.
Increased depth of prenatal ultrasonographic presentation may be associated with disturbances in fetal cortical migration and later autism spectrum disorder. However, this correlation deserves yet a further study. Further research is needed to determine whether other variables of ultrasound exposure also have adverse effects to the developing fetus.
However, ultrasonography has the potential to act as an environmental stressor in a genetically vulnerable system. The goal of searching mechanistically valid environmental modifiers of child outcomes remains important especially if the environmental insult deserves to be limited or regulated.  There remains an consistent call for further studies on the safety of diagnostic ultrasonography.

For more information check on this page:  https://jamanetwork.com/journals/jamapediatrics/fullarticle/2672728


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