Breastfeeding has long been considered the preferred diet for infants, both with regard to nutritional value and the protection provided against infection and allergies. Breastfeeding rates have increased fairly steadily over the last 40 years. The Ross Mothers Survey cites national breastfeeding rates at 6 months increasing from 18.9% in 1992 to 33% in 2002. Kentucky is among the states with the lowest overall rates of breastfeeding with approximately 14% of babies being breastfed at 6 months in 2002.
The few studies which have looked at breastfeeding and autism suggest either lower or similar rates of breastfeeding in children with autism as compared to controls. A 1989 study by Tanoue noted earlier weaning rates in children with autism compared to typically developing children. A 1988 study by Burd et al yielded similar rates of breastfeeding for 50 children with Pervasive Developmental Disorders and controls. Schultz et al (2006) used data from the Autism Research Internet Study to conclude that no breastfeeding was associated with increased odds of having autism when compared to breastfeeding for more than 6 months. However, a recent study by Kenet et al (2007) identified significant differences in the brain development of rat pups which were exposed to polychlorinated biphenyls (PCB's) through nursing and in utero. The authors theorized that PCB's in breast milk might act as an environmental risk factor for autism.
Our objective was the investigation of rates of breastfeeding among children diagnosed with autism.
Our study was an interview study which looked at medical issues associated with autism. Of those interviewed, information on breastfeeding was available for 45 children with autism as compared to 68 age and gender matched controls with other developmental disabilities. Chi square tests were performed to compare data between the two groups.
The percent of ASD patients who were breastfed at 6 months was 37% as compared to 13% of controls (p of 0.003).
In contrast to previous studies, our interview study yielded significantly higher rates of breastfeeding in subjects with autism as compared to controls with other developmental disabilities. The control rate of breastfeeding at 6 months was similar to the general rate for Kentucky, but the rate of breastfeeding in children with autism was nearly 3 times higher. The Kenet study pointed to possible concerns associated with substances in breast milk. While PCB's were banned in the late 1970's, these substances are very slowly degraded and maintain a significant presence in breast milk. Infants breastfed for more than 3 months have as much as a 6.6 fold increase of plasma PCB concentrations compared to those who were not breastfed. The authors hypothesized that exposure to PCB's in breast milk might act as an environmental trigger, disrupting brain development and resulting in autism for those already genetically predisposed. While the known breastfeeding benefits still outweigh risks, our study points to the need to further investigate rates of breastfeeding in autism and evaluate potentially harmful substances in breast milk.