International Scholarly Research Network ISRN Pediatrics Volume 2012, Article ID 458064, 5 pages doi:10.5402/2012/458064 Research Article Pregnancy-Related Maternal Risk Factors of Attention-Deficit Hyperactivity Disorder: A Case-Control Study Shahrokh Amiri, 1, 2 Ayyoub Malek, 3 Majid Sadegfard, 4 and Salman Abdi 4 1 Department of Psychiatry, Clinical Psychiatry Research Center (CPRC), Tabriz University of Medical Sciences, Tabriz, Iran 2 Department of Psychiatry, Razi Mental Hospital, El Goli Boulevard, P.O. Box 5456, Tabriz 5167846184, Iran 3 Department of Psychiatry, Tabriz University of Medical Sciences, Tabriz, Iran 4 Department of Psychology, Tabriz University of Medical Sciences, Tabriz, Iran Correspondence should be addressed to Shahrokh Amiri, amirish@tbzmed.ac.ir Received 21 March 2012; Accepted 9 April 2012 Academic Editors: G. J. Casimir, A. Maheshwari, and D. D. Trevisanuto Copyright © 2012 Shahrokh Amiri et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. The etiology of attention-deficit hyperactivity disorder (ADHD) is complex.This study was conducted to evaluate the pregnancy-related maternal risk factors of ADHD. Methods. 164 ADHD children attending to Child and Adolescent Psychiatric Clinics compared with 166 normal children selected in a random-cluster method from primary schools. ADHD rating scale and clinical interview based on Schedule for Affective disorders and Schizophrenia for School-Aged Children (K-SADS) were used to diagnose ADHD cases and to select the control group. Results. The mean maternal age at pregnancy, duration of pregnancy, and the mean paternal age were alike in two groups. The ADHD children’s mothers compared with those of control group had higher frequencies of somatic diseases, psychiatric disorders, and alcohol and cigarette exposure during the pregnancies (P< 0.01). Also birth by cesarean section was more common among mothers of ADHD children (P< 0.001). These factors plus trauma to the abdomen during pregnancy were significantly predictors of ADHD in children. Conclusions. Some pregnancy-related maternal factors may be considered as environmental risk factors for ADHD. Each of these factors considered in our study as a risk factor needs to be tested and confirmed through next methodologically appropriate researches in this field. 1. Introduction Attention-deficit hyperactivity disorder (ADHD) is one of the most common psychiatric disorders among school-aged children. Reports on the prevalence of ADHD in the United States have varied from 2 to 20 percent of grade-school children [1]. In a study in Brazil, the prevalence of ADHD in children of 4 primary schools was 13% with a higher rate among boys in comparison to the girls [2]. The prevalence of ADHD in primary school children in Tabriz, Iran, has been reported to be 9.7% [3]. Regarding to the high prevalence of ADHD and its psy- chosocial outcomes such as social isolation and stigma, neg- ative attributions by the peers, conduct disorder, substance- related disorders, and mood disorders, the importance of preventive and therapeutic interventions is revealed. How- ever, as the etiology of ADHD is complex and most likely includes genetic and environmental factors, preventive and therapeutic interventions may not be sufficient unless we could discover much more factors involved in developing ADHD. Hence, considering the etiological factors with different approaches is something of importance. As it is shown, genetic predisposition is a major cause in ADHD, but it does not follow the Mendelian patterns of inheritance and it is likely to be a polygenetic disorder so that genes can exert their influence only via interaction with the environment. On the other hand, the pathogenetic mechanisms for expression of various genes in interaction with various environmental factors can vary widely from one individual to another [4]. This issue emphasizes on the need to study and discovering much more environmental factors as risk factors for ADHD through appropriate research designs. A number of nongenetic environmental factors have been shown to be associated with ADHD. Some of these factors