Does the Trimester of Smoking Matter in the Association between Prenatal Smoking and the Risk of Early Childhood Caries?

Abstract

Introduction: Development of the primary tooth bud commences at the end of the 5th week of gestation, with mineralization starting at about the 13th week and continuing throughout pregnancy to the end of the first year of life. During this critical period, exposure to maternal lifestyle factors, specifically, prenatal smoking can negatively affect the quality (i.e., tooth calcification and mineralization) and timing of tooth eruption. Methods: This study evaluated the association between the trimester of smoking and offspring caries experience at 3 time points (31, 43, and 61 months) by analyzing data from 1,429 mother-offspring participants in the 1991/92 Avon Longitudinal Study of Parents and Children, conducted in Bristol, England. Prenatal smoking in the first, second, and third trimesters were self-reported during pregnancy while offspring caries experience was determined by clinical oral examinations. Adjusted for confounders, log-binomial regression estimated the risk ratio (RR) and 95% confidence interval (CI) of the association between trimester of smoking and the risk of offspring caries. Results: Twenty percent smoked in the first trimester of their pregnancy, 15% in the second, and 17% in the third. Forty-six percent of children whose mothers smoked during pregnancy had caries experience (i.e., dmft ≥1) with a mean dmft count of 1.58, versus children whose mothers did not smoke during pregnancy (33% of whom had dmft ≥1 with a mean dmft count of 0.33). Smoking in the first, second, and third trimesters were independently associated with a higher adjusted RR (95% CI) of caries experience at 61 months, i.e., 1.16 (0.93–1.43), 1.11 (0.75–1.65), and 1.60 (1.09–2.32), respectively. Conclusions: Within the limitations of covariates adjusted for, with the caveat that residual confounding and bias from unmeasured covariates are likely present, our findings suggest that smoking during pregnancy may be harmful to the oral health of the offspring irrespective of the trimester during which the smoking occurred. Nevertheless, these results should be interpreted cautiously because the findings might not generalize broadly.