Maternal Prenatal Smoking and Early Childhood Physical Aggression and Hyperactivity-Impulsivity
Huijbregts S, Seguin JR, Zoccolillo M, Boivin M, Tremblay RE.
The Issue
Discovering which risk factors have the greatest negative effect on children with mental health or behavioural problems helps in the development of interventions to reduce their harmful effects. Some children who behave badly or are hyperactive when very young are more likely than other children to become delinquent as adolescents or to engage in criminal activity as adults Some risk factors, such as harsh parenting practices and physically aggressive friends are known to be related. Another risk factor is maternal smoking, particularly during pregnancy. How and why it affects child behavior are not well understood.
The Research
This study was part of a long-term study of children in Montreal, Canada. Mothers first reported on how much they smoked during pregnancy, and if their child was physically aggressive or hyperactive-impulsive at 17, 30 and 42 months of age. The mothers and fathers were asked about the presence of other risk factors known to be related to childhood aggression: their age at child’s birth, how long they remained in their relationship, whether there were other children in the family, their family income, and maternal education, family functioning, parenting strategies, parental history of antisocial behavior or maternal depression. Mothers provided most of the information when the child was 5 months and again at 17 months. Parenting behavior was assessed with the Home Observation for Measurement of the Environment (HOME) - Infant version when the child was 5 and 17 months.
The Outcome
The study found that most of the children showed an increase in aggression as they got older. Some of the children were on a path of persistent and worsening levels of aggression. Maternal prenatal smoking predicted that her child would be physically aggressive, as did being male, having siblings, and hostile parenting by the mother. Hyperactivity-impulsivity was predicted by maternal smoking, as well as by hostile parenting, maternal depression, and the age of mother when she had her first child.
Conclusions
Both physical aggression and hyperactivity were more likely in children whose mothers smoked during pregnancy. Even when considering the effects of parenting skill, gender, family size and other factors, smoking during pregnancy by itself still predicted that young children born under these circumstances develop behaviour problems.
The preceding is a summary of:
Huijbregts S, Seguin JR, Zoccolillo M, Boivin M, Tremblay RE. Associations of Maternal Prenatal Smoking with Early Childhood Physical Aggression, Hyperactivity-Impulsivity, and Their Co-Occurrence. Journal of Abnormal Child Psychology. 2007; 35:203-215.
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