Risk of Autism in Children with Large Head Circumference during the First Year of Life

Abstract

Risk of Autism in Children with Large Head Circumference during the First Year of Life

Pongsak Noipayak MD, MSc (Epidemiology)

Department of Pediatrics, BMA Medical College and Vajira Hospital

Objective: To determine risks of autism in children who has head circumferences more than 97 and 75 percentile.

Study design: Case-control study.

Subjects: Autistic children and non-autistic children from the division of developmental and behavioral pediatrics, Department of Pediatrics, BMA Medical College and Vajira Hospital from March 2007 to July 2008.

Methods: Records of head circumferences were obtained from child health books. Data were recorded and analysed.

Main outcome measures: Head circumferences at birth, 2, 4, 6, 9 and 12 months.

Results: Of 92 subjects, 46 were autism and 46 were control. There were 39 males (84.8%) and 7 females (15.2%) in each group. Means of head circumferences of males in all age group were statistically different between the autistic group and the control group while those of females were not. The odds ratio of autism of all age groups of males who had head circumferences larger than 97 percentile were between 2.78 and 11.00 which were statistically significant difference, but not in females. In respect of head circumferences larger than 75 percentile at 6, 9, 12 months, the risks of autism in males remained statistically significant higher than those who had head circumferences smaller than 75 percentile with the odds ratio from 1.53 to 3.67 but there was no significance in female.

Conclusion: Head circumferences of males larger than 75 and 97 percentile were able to predict risks of autism with statistical significance. However, the ability to predict autism varied across age groups.

Vajira Med J 2009 ; 53 : 161-170