Objectives: Postnatal growth in children exposed in utero to tobacco smoke is not well understood. This study investigated growth during the first 6 years in children whose mothers smoked during pregnancy.
Materials and methods: Weight, length, and head circumference were measured annually for 6 years in 100 children in each group of smoking (study) and nonsmoking (control) mothers.
Results: Weight and head circumference were significantly smaller in the neonates whose mothers smoked >or=15 cigarettes/day, but the difference disappeared by 3 years of life. Length was significantly smaller in the study neonates at birth, followed by increasing divergence from normality up to 2 years, when the mean difference of children whose mothers smoked >or=15 cigarettes/day from control children was -3.4 cm (p <or= 0.0001). Subsequently, they manifested catch-up growth ,and the difference from the controls at 3, 4, 5, and 6 years was -2.5 cm (p <or= 0.0001), -2.2 cm (p = 0.005), -2.1 cm (p = 0.013), and -1.9 cm (p = 0.055), respectively.
Discussion: The delayed growth was related to smoking per se and appeared to be independent of several confounding factors. At birth, there was a significant negative correlation between the number of cigarettes smoked per day and the growth parameters studied; it remained significant up to the 6 year only for length.
Conclusion: Length exhibits the most persistent growth delay of the parameters studied, but catch-up growth occurs after the second year of life, and thus, intrauterine exposure to tobacco smoke seems to have no permanent effect on children's growth.