AIM: To investigate whether children with autistic spectrum disorder (ASD) have 
bowel symptoms consistent with underlying enterocolitis.
METHODS: Information on children's stool patterns and gut symptoms collected by 
questionnaire at 4 weeks and at 6, 18, 30 and 42 months of age were available 
for 12,984 children from the Avon Longitudinal Study of Parents and Children 
(ALSPAC). Data on the 78 children identified by local health and/or education 
systems to have special educational provision for ASD were compared with the 
12,906 remaining children in the cohort.
RESULTS: Comparison of the ASD and control group during the first 3.5 years of 
life showed no major differences in stool colour or consistency, or in frequency 
of diarrhoea, constipation, bloody stools or abdominal pain. The ASD children 
had similar stool frequency up to 18 months, but there was a trend for ASD 
children to pass more stools at 30 months (OR 3.73, 95% CI 1.11 to 12.6; p = 
0.004) and at 42 months (OR 6.46, 95% CI 1.83 to 22.7; p<0.001), although only 
three children passed more than 4 stools/day. Repeating the analysis on only 
those cases diagnosed as having classical childhood autism resulted in very 
similar findings.
CONCLUSIONS: During the first 42 months of life, ASD children had a stool 
pattern that was very similar to that of other children, apart from a slight 
increase in stool frequency at 30 and 42 months. There were no symptoms to 
support the hypothesis that ASD children had enterocolitis.