Risk factors for developmental delay in early childhood: An umbrella review as a basis for a population based clinical study

PD Dr. Michael von Rhein (University Children's Hospital Zurich) 
Prof. Boris Quednow (Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich)
Dr. Holger Dressel (Department of Epidemiology, Epidemiology, Biostatistics and Prevention Institute)
Corina S. Rüegg (Department of Epidemiology, Epidemiology, Biostatistics and Prevention Institute)
Prof. Oskar Jenni (University Children's Hospital Zurich)

In recent years, the number of children with special educational needs has increased significantly - both in elementary school and in early childhood. Obviously, more children than before have a global developmental delay, a language development disorder, an autism spectrum disorder, ADHD or other behavioral problems. This can be partly explained by medical advances: Thanks to improved medical care, many more children with significant risk factors (such as children with congenital heart defects or former premature babies) survive today than 20 years ago. These children are more likely to have developmental disorders or disabilities than children without such risks. However, these factors cannot fully explain the increase in numbers. Other possible explanations include changes in biological and environmental risk factors. Recently, a number of environmental toxins and pollutants have been suspected of having negative effects on health and development. An increase in parental consumption of medication and psychoactive substances could also be considered as a possible cause. Negative influences on early childhood development have also been described through experiences of social deprivation, psychosocial trauma or social isolation. However, systematic studies on the etiology of developmental disorders are rare, particularly regarding modifiable or even avoidable causes. We therefore plan to perform an umbrella review on environmental factors, drugs and toxins as risk factors for developmental delay in children, which will lay the grounds for clinical studies targeting specific factors potentially causing developmental disorders in early childhood.