Mothers of “hyperkinetic” children were found to smoke an average of 14 cigarettes during pregnancy compared to only 6 cigarettes smoked on average for mothers of “normal” children. The study, conducted by the Department of Psychology at the University of Saskatoon, Canada, studied 20 children (18 boys, 2 girls) who were currently being treated with Ritalin for their hyperactivity. Although cigarette smoke contains many highly poisonous compounds, the researchers speculate that the accumulation of carbon monoxide in the fetal blood stream could lead to serious reductions in oxygen to the developing infant. It was found that the carboxyhemoglobin levels (hemoglobin that is carrying carbon monoxide instead of oxygen) was concentrating in the developing fetus reaching twice the levels of that in the mother. The potential for second hand smoke effects could also be a problem as it was found that after birth, mothers of hyperactive children consumed an average of 23 cigarettes per day compared to 8 cigarettes daily for the normal control mothers.
SOURCE: Canadian Psychiatric Association Journal, Vol. 20:183-187, 1975
In summary the researchers stated,
“The hyperkinetic syndrome is the result of several causes and the effect of any single agent is difficult to discern. Although the apparent association with heavy maternal smoking, in methylphenidate (Ritalin)-sensitive cases, does not predicate a causal connection, it does justify a careful assessment of the possible role of tobacco addiction in the etiology of this common disorder.”
Child Test Scores Lower When Mothers Smoke
A Study of 2nd and 5th Grade Students
SOURCE: British Medical Journal, 4:573-575, 1973
This study of a very large sample of children gives insights into the real dangers of smoking during pregnancy. Known as the National Child Development Study, in Britain, there were over 9,000 children measured to determine the effects of their mother’s smoking either 0, 10, or more than 10 cigarettes per day during pregnancy. When each child reached 7 and 11 years, there were a number of tests given to evaluate math ability, reading ability and general physical measurements. Results showed children of mothers who smoked 10 or more cigarettes a day are on average 1.0 centimeters shorter and between three and five months behind in reading, mathematics, and general ability when compared to the offspring of non-smokers, after allowing for associated social and biological factors.
Auditory Processing Reduced in School Age Children Exposed to Cigarette Smoke
SOURCE: Neurotoxicology and Teratology, Vol. 16(3), 1994
The ability to process auditory information in a child relates to his ability to listen to what a teacher is saying, to follow directions or to remember what the teacher has said. Obviously, all of these skills are important for effective academic performance in school. This present study, carried out by Dr. Joel S. McCartney, Department of Psychology, Carleton University, Ottawa, Canada, found overall poorer performance on central auditory processing tasks (SCAN) among 110, six to eleven year old children exposed to prenatal cigarette smoke. Maternal smoking during pregnancy was linearly associated with the poorer performance on the overall SCAN tests which assessed listening skills in a noisy background and the dichotic task, which required the child to attend to simultaneous information in both ears and is thought to be a measure of the child’s auditory maturation or developmental level. This task involves a greater degree of auditory processing, aspects of memory, and word discrimination. Also of interest, it was found that children exposed to passive cigarette smoke performed more poorly than children of non-smokers and equal to that found in children exposed to “light” prenatal smoking.
Math, Language, & Behavior Problems Elevated in Children of Smoking Parents
SOURCE: Neurotoxicology and Teratology, Vol. 13, 1991
Ninety-one children between the ages of six and nine years were tested for a wide range of developmental, academic and behavioral skills by researchers at the Department of Psychology, Carleton University, Ottawa, Canada. This is one of the most thorough studies to date looking for harmful effects from cigarette smoke.
Children of nonsmoking mothers generally were found to perform better than the two smoking groups (active and passive) on tests of math ability, speech and language skills, intelligence, visual/spatial abilities and on the mother’s rating of behavior. The performance of children of passive smokers was found, in most areas, to be between that of the active smoking and nonsmoking groups. Some of the tests given included the Wechsler Intelligence Scale for Children-Revised (WISC-R), the Wide Range Achievement Test -Revised (WRAT-R) for measuring general reading, spelling and math ability and the Test of Language Development-Primary (TOLD), which measures grammatical understanding, the ability to imitate sentences and correctly produce speech sounds. The behavioral assessment was done by the Conners Parent Questionnaire, a behavioral symptom checklist, completed by the child’s mother. On the academic achievement tests, the mathematics score was the most lowered by active and passive cigarette smoking. The three main areas appearing more often in the Connors behavior rating scale were Hyperactivity, Conduct Problems and Impulsivity. Of significant interest, twice as many children in the active smoking group compared to the nonsmoking group were perceived by the mother as having problems in school. This is in agreement with five other studies showing children of active smokers have a higher incidence of misbehavior, poorer adjustment at school and increased activity levels. The nonsmoking group was rated as showing the best attention and cooperation.
Severe Child Behavior Problems Linked to Mother’s Smoking
SOURCE: Associated Press – Florida Today Newspaper, September 4, 1992
The more cigarettes a mother smoked during pregnancy, the greater the likelihood her child would demonstrate severe behavior problems as the child became older. Women who smoked at least a pack a day had children with twice the rate of extreme behavior problems – such as anxiety, conflict with others, or disobedience, when compared with children of non-smokers.
Smoking less than a pack a day also was shown to increase behavior problems, but the rates were not as high as for heavier smokers, the researchers found. The study was conducted by the Labor Department in which parents of 2,256 youngsters ages 4 to 11 were interviewed. The fathers smoking was not assessed in this study.
In a following September 4, 1992 Associated Press article describing the study, Dr. Michael Weitzman, the lead author stated,
“We are aware of no other study to date that has investigated the relationship between maternal smoking and behavior problems in children.”
Nicotine Damages Brain Cell Quality
SOURCE: Neurotoxicology and Teratology, 16(4) 1994
Human reports as well as animal studies have recorded accelerated motor activity, learning and memory deficits in offsprings of mothers exposed to nicotine during pregnancy. This study, conducted by Dr. T. S. Roy, Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India, is the first to investigate actual physiological changes of the cerebral cortex of rats after prenatal nicotine exposure. Several groups of experimental rats were exposed to varying levels of nicotine reaching up to that experienced by a heavy smoker. Animals were examined at different periods after birth. Observable effects included significantly reduced thickness of the cerebral cortex, smaller cerebral cortex neurons, and reduced brain weight. Also noted was an overall decrease in “dendritic branching” (connections to other brain cells), as seen in the camera lucida drawings at right. The present study also shows that the greater the dose of nicotine, the greater the biological effects upon the offspring. This research provides an excellent biological model to support the many other studies linking increased hyperactivity, attention deficits, lower IQ, and learning disabilities in children with parents who smoked during pregnancy.
Smoking During Pregnancy Increases Conduct Disorders
SOURCE: Archives General Psychiatry, 54:670-676, July, 1997
More evidence on the connection between a mother’s smoking during pregnancy and increased risk of having a child with behavior disorders. Below is a direct quote of the summary of the 1997 journal article report in the Archives of General Psychiatry, 54:670, 1997.
Background: Previous animal and human studies have indicated that prenatal exposure to nicotine isassociated with adverse reproductive outcomes, including altered neural structure and functioning,cognitive deficits, and behavior problems in the offspring. Our study extends previous research onhumans by controlling a broad range of correlates of maternal smoking during pregnancy todetermine if smoking is associated with behavior problems in the offspring severe enough to qualifyfor DSM-III-R diagnoses.
Method: Subjects were 177 clinic-referred boys, ages 7 to 12 years at the time of the first assessment, who underwent longitudinal assessment for 6 years using annual structured diagnostic interviews. Correlates of maternal smoking during pregnancy and previously identified demographic, parental, perinatal, and family risk factors for the disruptive behavior disorders were controlled in logistic regression analyses.
Results: Mothers who smoked more than half a pack of cigarettes daily during pregnancy were significantly more likely to have a child with conduct disorder (odds ratio, 4.4; P=.001) than mothers who did not smoke during pregnancy. This association was statistically significant when controlling for socioeconomic status, maternal age, parental antisocial personality, substance abuse during pregnancy, and maladaptive parenting.
Conclusions: Maternal smoking during pregnancy appears to be a robust independent risk factor for conduct disorder in male offspring. Maternal smoking during pregnancy may have direct adverse effects on the developing fetus or be a marker for a heretofore unmeasured characteristic of mothers that is of etiologic significance for conduct disorder.
Children Age 14 Still Show Harmful Effects if Mothers Smoked During Pregnancy
SOURCE: Department of Public Health, University of Oulu, Oulu, Finland
Several thousand 14 year old children were included in a follow up study which found more health and academic problems among the children whose mothers smoked during pregnancy. This large study was conducted by the Department of Public Health, University of Oulu, Finland.
The study began with an assessment of 12,068 pregnant mothers in two northern provinces in Finland. A questionnaire given to the 12,000+ women showed 19.7% of the mothers smoked at the beginning of pregnancy. However, by the second month of pregnancy, 15.5% of the mothers were smoking for a total of 1,819 women. It was of these 1,819 women that the study of health and academic performance was conducted.
At the end of 1980 and early 1981, 11,780 of the original children (now age 14) were located for the follow up study. The questionnaire inquired on the children’s health, growth, school performance, various habits (smoking, drinking, participation in sports) and family conditions including father’s smoking history.
On the positive side, there were no significant differences between the groups in respect to “severe” mental retardation, diabetes, rheumatic diseases or other long term diseases, according to the questionnaire sent to the families or from information received from the school or national registers.
Asthma proportion was similar in both groups, about 2.1% of cases, however, the children of smokers did have over a 50% higher chance of being administered to the hospital for severe asthma reactions, 1.30% compared to .80% for the non-smokers.
In conclusion the researchers stated,
“School performance of the smokers’ children was poorer than that of their controls when measured in terms of their mean ability on theoretical subjects and scored from 4 to 10 on the child’s school report, this trend being seen among both the boys and the girls and in all social classes The children of the smokers were more prone to respiratory diseases than the others. They were also shorter in length by nearly 1 centimeter (a little less than a half an inch) and their mean ability at school was poorer than among the controls for mothers who smoked 10 cigarettes and 20 cigarettes per day. The differences remained significant after adjusting for the mother’s height and age, social class as determined by the father’s occupation, number of older and younger children in the family and the sex of the child.”