NIDA
Notes
Research Findings
Volume 16, Number 1
(March, 2001)
Maternal Smoking During Pregnancy
Associated With Negative Toddler Behavior and Early Smoking
Experimentation
By Josephine Thomas, NIDA NOTES Contributing
Writer
<Read
This article On The NIDA Website>
NIDA-funded researchers have added to the accumulating scientific
evidence that women's smoking during pregnancy adversely affects their
children's health and development. Two new studies have linked prenatal
tobacco exposure to negative behavior in toddlers and smoking
experimentation by pre-adolescents. In a study conducted by Dr. Judith
Brook, Dr. David Brook, and Dr. Martin Whiteman of the Mount Sinai
School of Medicine in New York City, mothers who smoked during pregnancy
indicated that their toddlers exhibited more negative behaviors -
impulsiveness, risk-taking, and rebelliousness - than mothers who did
not smoke during pregnancy reported among their children.
A study conducted by NIDA-funded researchers Dr. Marie Cornelius and
Dr. Nancy Day demonstrates that, even more than growing up in a home
where the mother smokes, prenatal exposure to smoke may predispose
children to early smoking experimentation. Dr. Cornelius, Dr. Day, and
their colleagues at the University of Pittsburgh School of Medicine
found that not only does such exposure to maternal smoking predict early
experimentation, it also appears linked to child anxiety, depression,
and behaviors such as hitting and biting others.
Previous studies have supported a link between prenatal smoking
exposure and behavioral problems in later childhood and adolescence (see
"Drug
Abuse and Conduct Disorder Linked to Maternal Smoking During Pregnancy,").
Combined with earlier results, the new studies suggest that prenatal
smoking contributes to a train of developmental difficulties and health
risks that begin at an early age.
Toddler Negativity
The Mount Sinai study included 99 mothers who smoked and their
2-year-old children. The mothers are participants in a large community
study that Dr. Judith Brook has been conducting with Dr. Patricia Cohen
of Columbia University in New York City for the past 25 years. In the
new study, the mothers answered a questionnaire that elicited
information about their children's behaviors and their own smoking
histories, alcohol and drug use, personalities and attitudes, styles of
child-rearing, and socioeconomic characteristics.
Fifty-two of the women reported that they had smoked while pregnant,
and 47 said they either stopped smoking during pregnancy or did not
begin to smoke until after they had given birth. The mothers who smoked
during pregnancy scored their children higher on the questions that
measured toddler negativity. The mother's disciplinary style also was
strongly linked to a toddler's negative behavior. However, when the
researchers adjusted for this factor in the analysis, they determined
that a mother's smoking during pregnancy independently increased the
estimated risk of negativity at age 2 by fourfold.
"We found three major maternal risk factors related to toddler
negativity," says Dr. Brook. "They are maternal smoking during
pregnancy, conflicts between the mother and child, and the mother's use
of power-assertive discipline, such as hitting the child. We can
speculate that maternal smoking during pregnancy causes disturbances in
the neurophysiological functioning of the fetus," says Dr. Brook.
"This, in turn, could precipitate the toddler's negative
behavior."
The potential implications of these findings reach beyond early
childhood. Previous studies have demonstrated that toddlers who display
negative behaviors are more likely to use drugs, exhibit delinquent
behaviors, and achieve less as adolescents and to develop severe mental
health problems later in life.
Early Experimentation With Tobacco
Although the effects of maternal smoking on childhood behaviors have
been studied, few studies have investigated the connection between
maternal smoking and childhood experimentation with tobacco. The
connection is important because the earlier a person starts smoking, the
more likely he or she is to become a regular smoker, become addicted,
and suffer the long-term adverse health effects of smoking.
Dr. Cornelius and her colleagues interviewed 589 10-year-olds. Six
percent of the children said they had tried cigarettes, smokeless
tobacco, or both. Most of the reported tobacco use was experimental;
only a few children had used tobacco more than a few times.
In this prospective study, begun by Dr. Day in 1982, the children's
mothers have been providing researchers with information about
themselves, and they reported on their smoking at the time they were
pregnant with the children who are now 10. Putting data from the
children together with those reports, the researchers estimated that
maternal smoking of at least a half-pack of cigarettes per day during
pregnancy increased by fivefold the likelihood that a child would have
tried tobacco by age 10. The only factor that produced a greater risk of
early experimentation was exposure to smoking within the child's peer
group.
It is not yet clear exactly why these factors are related to early
experimentation. "Perhaps the nervous system damage caused by
maternal smoking may later be expressed as impulsivity, inattention,
aggression, depression, and/or anxiety and may create a vulnerability in
the child that could contribute to poorer adjustment and an increased
likelihood of early initiation of tobacco use," Dr. Cornelius says.
Dr. Cornelius notes that in her study, the 10-year-olds who were
exposed prenatally to tobacco were more likely to have experimented than
those whose mothers were current smokers. This finding reinforces the
hypothesis that a physiological effect of prenatal exposure to smoking,
rather than a genetic vulnerability affecting both mother and child, may
be an important link between mothers' smoking during pregnancy and early
childhood experimentation.
Sources
Brook, J.S.; Brook, D.W.; and Whiteman, M. The influence of maternal
smoking during pregnancy on the toddler's negativity. Archives of
Pediatric and Adolescent Medicine 154(4):381-385, 2000.
Cornelius, M.D.; Leech, S.L.; Goldschmidt, L.; and Day, N.L. Prenatal
tobacco exposure: Is it a risk factor for early tobacco experimentation?
Nicotine & Tobacco Research 2:45-52, 2000.
NIDA Notes - Volume 16, Number 1
