Maternal Smoking in Pregnancy, Fetal Development, and Childhood Asthma
Jouni J. K. Jaakkola, MD, DSc, PhD and
Mika Gissler, PhD
Jouni J. K. Jaakkola is with the Institute of Occupational Health, The University of Birmingham, Birmingham, United Kingdom, and the Department of Public Health, University of Helsinki, Finland. Mika Gissler is with the National Research and Development Centre for Welfare and Health, Helsinki.
FIGURE 1—The hypothesized causal model of the effect of maternal smoking in pregnancy on childhood risk of asthma. Solid arrows indicate a causal relationship; the broken arrow indicates effect modification.