American Journal of Epidemiology Advance Access originally published online on July 16, 2007
American Journal of Epidemiology 2007 166(4):490-491; doi:10.1093/aje/kwm199
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LETTERS TO THE EDITOR |
THE AUTHORS REPLY
1 Longitudinal Studies Unit, School of Population Health, University of Queensland, Brisbane, QLD 4006, Australia
2 Department of Social Medicine, University of Bristol, Bristol BS8 2PR, United Kingdom
3 Child Development and Rehabilitation Services, Mater Children's Hospital, Brisbane, QLD 4101, Australia
4 School of Social Science, University of Queensland, Brisbane, QLD 4006, Australia
(e-mail: mamun{at}sph.uq.edu.au)
We appreciate Dr. Ansari's observations (1). Dr. Ansari appears to question whether we demonstrated in our study (2) that smoking during pregnancy is causally related to later adiposity in offspring. We tried to examine this issue in a more detailed way than previous investigators by using the repeated measurements of maternal smoking that we had from before pregnancy to later in the offspring's childhood. However, we agree that it is impossible to prove causality in observational epidemiology. In a recent study which compared the effect of maternal smoking on offspring fat mass (assessed by dual-energy x-ray absorptiometry) with the effect of paternal smoking on fat mass, Leary et al. (3) questioned whether intrauterine exposure to tobacco is causally related to later adiposity, since paternal smoking (which is unlikely to have a strong intrauterine effect) was associated with offspring fat mass with a magnitude similar to that of maternal smoking.
Ansari's main critique of our paper is that our conclusion, with respect to how our findings might provide an incentive for young women to not take up smoking or to quit smoking, goes beyond what our data can support. What we actually concluded in our paper was, "Our findings suggest a direct effect of maternal smoking in pregnancy on adolescent overweight and obesity. They provide yet another incentive for pregnant women to be persuaded not to smoke and for young women to be encouraged to never take up smoking" (2, p. 324). We believe that disseminating information on adverse health consequences has been essential in persuading women and men of all ages to avoid or quit smoking. Clearly, had the point about the adverse health effects of smoking not been so robustly made, the population prevalence of smoking would not have declined from very high levels prevalent early in the last century to the now-low levels seen in most developed countries. However, we agree with Ansari that the methods needed to persuade young women not to take up smoking require full understanding of the many factors (including home and school environment, self-esteem, beliefs, and understanding) that are likely to be related to the decision. This is particularly important because young women are now a group in which smoking rates are increasing in several developed and developing countries.
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ACKNOWLEDGMENTS |
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Conflict of interest: none declared.
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References |
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 TOP References |
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- Ansari R. Re: "Does maternal smoking during pregnancy have a direct effect on future offspring obesity? Evidence from a prospective birth cohort study." (Letter). Am J Epidemiol (2007) 166:490.
[Free Full Text] - Al Mamun A, Lawlor DA, Alati R, et al. Does maternal smoking during pregnancy have a direct effect on future offspring obesity? Evidence from a prospective birth cohort study. Am J Epidemiol (2006) 164:317–25.
[Abstract/Free Full Text] - Leary SD, Smith GD, Rogers IS, et al. Smoking during pregnancy and offspring fat and lean mass in childhood. Obesity (Silver Spring) (2006) 14:2284–93.[Medline]
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