(HealthDay News) – Generally there is no association between maternal smoking during pregnancy and risk of the child developing autism spectrum disorders (ASDs), although there may be a link between smoking and development of high-functioning autism.

Amy E. Kalkbrenner, PhD, MPH, from the University of Wisconsin at Milwaukee, and colleagues used publicly available birth certificate data to identify 633,989 children born in 1992, 1994, 1996, and 1998 from parts of 11 US states subsequently under ASD surveillance. Using active, records-based surveillance from the Autism and Developmental Disabilities Monitoring Network, 3,315 of these children were identified as having an ASD. The association between maternal smoking during pregnancy and ASDs was estimated among 8 year old children.

The researchers found that, of the source population, 13% reported maternal smoking in pregnancy, compared to 11% in the ASD cohort (adjusted prevalence ratio [aPR], 0.90; 95% confidence interval [CI], 0.80–1.01). Similar associations were found for the case subgroup Autistic Disorder (1,310 cases; aPR, 0.88; 95% CI, 0.72–1.08). For ASD Not Otherwise Specified (ASD-NOS; 375 cases) the association was positive but not statistically significant (aPR, 1.26; 95% CI, 0.91–1.75). After correcting for assumed under-ascertainment, the associations were 1.06 (95% CI, 0.98–1.14) for all ASDs, 1.12 (95% CI, 0.97–1.30) for Autistic Disorder, and 1.63 (95% CI, 1.30–2.04) for ASD-NOS.

“After accounting for the potential of under-ascertainment bias, we found a null association between maternal smoking in pregnancy and ASDs, generally,” the authors write.

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