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Prenatal Smoking and the Cause of Autism

Prenatal smoking and autism

Unquestionably one of the most debated cause topics surrounding Autism is maternal smoking. For years now, the credibility of the theory of maternal smoking and Autism has been questioned. There have been studies done for countless years on whether smoking while you are pregnant can cause Autism. The number one question needing answered is if there really is a tangible correlation between mothers who smoked during pregnancy and children who are diagnosed with Autism. The answer to this question seems to be held in studies linked out of the U.S. and Sweden.


A collaboration between Harvard School for Public Health, Department of Environmental Health; Ziber School of Public Health, University of Wisconsin-Milwaukee; The department of population Health Sciences, Wisconsin School of Medicine and Public Health; The Weisman Center, University of Wisconsin; The Department of Pediatrics, University of Arizona; The Department of Epidemiology, John Hopkins Bloomberg School of Public Health; The College of Public Health, University of Arizona; The Department of Medicine, Division of Biostatistics and Epidemiology, Medical University of South Carolina; and The Department of Epidemiology, University of North Carolina at Chapel Hill looked into these claims.

Researchers Involved:
-Dr. Amy Kalkbrenner
-Dr. Joe Braun
-Dr. Maureen Durkin
-Dr. Matthew Maenner
-Dr. Christopher Cunniff
-Dr. Li-Chung Lee
-Dr. Sydney Pettygrove
-Dr. Joyce Nicholas
-Dr. Julie Daniels

To do their research these doctors used the ADDM Network, or the Autism and Developmental Disabilities Monitoring Network and birth certificate databases to look into any links of maternal prenatal smoking and Autism. They started with the information of 633,989 children around the age of 8 whom lived in a state that participates in ADDM.

Areas used that Participate in ADDM:
-5 Northern Counties in Alabama
-All of Arkansas
-All of Miami-Dade County in Florida
-5 Counties in the Metropolitan of Atlanta, Georgia
-Baltimore County and the 5 surrounding counties in Maryland
-6 Counties in the Metropolitan area of St. Louis in Missouri and Illinois
-Union County South of Newark, New Jersey
-10 Counties surrounding Durham and Greensboro in North Carolina
-Philadelphia County in Pennsylvania
-5 Counties in Southern Wisconsin, including Milwaukee
-All of West Virginia

The children used at the time of this study were all born in the years 1992, 1994, 1996 and 1998. The years that the prevalence rates all seemed to have been on the rise significantly. Of these 633,989 children, 3,315 were found to have Autism.

In that group of Autistic children, it was found that 13 percent of the mothers smoked while pregnant. Of this 13 percent it was found that a majority of these mothers were from backgrounds of lower education, being unmarried, and being young at the time of childbirth. So, basically the findings were not high enough for researchers to say that smoking is a cause of Autism. In the end, only 11 percent of the source population diagnosed with Autism had a mother that smoked while pregnant.

Interestingly, studies into the correlation between smoking and Asperger’s disorder had the same results as the classic autism study did, as far as maternal smoking goes. PDD-NOS, however, did have a correlation present. Given this correlation researchers do believe more studies need to be done into this topic.

International Study

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A Swedish based study took on the results in the U.S. study to see if there were calculations errors. This collaboration included researchers from Drexel University's School of Public Health; Sweden's Karolinska Institute; and England's University of Bristol.

Researchers involved:
-Dr. Brian Lee
-Dr. Renee Gardner
-Dr. Henril Dal
-Dr. Anna Svensson
-Dr. Maria Rosaria Galanti
-Dr. Dheeraj Rai
-Dr. Christina Dalman
-Dr. Cecilia Magnusson

Their point being that the U.S.A. study must have had the wrong results because not enough factors were compensated for in the calculations. They wanted more factors considered.

Factors they wanted considered as well:
-Parental Income

To complete this study researchers took the information of 3,958 Autistic children and 38,983 non-Autistic children, as a control group. The results were that the United States was right. The U.S. numbers were inaccurate to an extent however, according to what research we have. It was right none-the-less though.

The Swedish study showed that 19.8 percent of Autistic children had a correlation between maternal smoking and them being Autistic; however, when looking at the control group, there was found to be near the same percentage of non-Autistic children with mothers whom smoked during pregnancy. With this number dangling at 18.4 percent and a much larger control group, it initially led them to believe that there was a correlation and that the U.S. was wrong; however, when you figure for the extra factors of Parental Income, Parental Jobs and Education the link virtually disappears. Showing no link between maternal smoking and the diagnosis of Autism.

Whether there is a correlation between the diagnosis of Autism and prenatal smoking the truth is that you shouldn’t smoke when you are pregnant. It is not good for the baby, as well as it not being good for you. Smoking when pregnant does cause a laundry list of complications for a baby.

Per Webmd, The Complications for a Baby from prenatal smoking are:
-Lowered amount of oxygen available to you and your growing baby
-Increase in your baby's heart rate
-Increase in the chances of miscarriage and stillbirth
-Increase in the risk that your baby is born prematurely and/or born with low birth weight
-Increase in your baby's risk of developing respiratory (lung) problems
-Increases in the risks of birth defects
-Increases in the risk of Sudden Infant Death Syndrome

It is important to also know that the more cigarettes you smoke per day, the greater your baby's chances of developing these and other health problems. As Webmd said, there is no "safe" level of smoking while pregnant, whether or not it causes Autism.