Number of teeth at the age of one year in relation to maternal smoking.

The mean number of deciduous teeth at the age of 1 year was investigated in the 10 499 children comprising a birth cohort from 1966 in Northern Finland. The 1563 children whose mothers smoked during pregnancy had on average 0.3 tooth more than the children of the control mothers. Highly significant explanatory variables in a regression analysis on the number of teeth at the age of one were weight at one year, maternal smoking, height at one year and birthweight, whereas gestational age and place of residence on a north-south axis were significant. Differences in cumulative percentages of eruption of the first tooth between the children of smokers and their controls were seen from the age of 4 months, with a maximal difference at 5 months: 30.0% versus 25.6%. The discrepancy was less that 1% by the age of 12 months.