Macrosomia is one of risk factors for dental caries in 3-year-old infants in Japan

INTRODUCTION: The relationship between birth weight and the presence of dental caries in early childhood has often been reported in low-birth weight infants; however, no conclusion has yet been reached about how these two conditions are associated. In addition, no studies have assessed the correlation of these conditions with macrosomia. Further, few longitudinal studies have evaluated the risk for development of dental caries in early childhood starting from fetal life.The purpose of this study was to elucidate the association between birth weight and dental caries at 3 years of age, by a longitudinal study of more than 100,000 participants, evaluated since pregnancy and followed-up to 3 years of age.

METHODS: The study included data from infant health checkups conducted in Okinawa prefecture from 1999 to 2010. Dental caries were diagnosed by dentists, and lifestyle habits were surveyed by a self-administered questionnaire. In 18-month-old infants with no dental caries, the presence of dental caries at the time of a medical checkup at the age of 3 years was considered as the outcome. The following were used as explanatory variables: birth weight, mother’s age at the 3-month medical checkup, order of birth of siblings, number of teeth at the time of the 18-month medical checkup, parents’ employment status and smoking status at the time of the child’s medical checkup at the age of 3 years, the child’s experience in undergoing fluoride treatment, the parents’ habit in assisting the child in the final stages of tooth brushing at the age of 18 months to 3 years, drink milk, whether meals and snacks were provided on fixed schedule, and whether the child was allowed to watch TV every day at the age of 3 years. The statistical analysis consisted of the relative risk calculation using the Poisson regression.

RESULTS: The analysis was conducted on 127,609 participants. Based on the results of the Poisson multivariate analysis, the risk factors included, among others, birth weight of 4000 g or greater (1388 infants, accounting for 1.1% of births) (RR: 1.18, CI: 1.10–1.27), mother’s age of 25 years or less (RR: 1.18, CI: 1.15–1.20), whether the child was the first or second among siblings (RR: 1.27, CI: 1.25–1.30), whether at the age of 18 months, the child brushed his/her teeth without parental assistance at the final stages of the tooth brushing process (RR: 1.19, CI: 1.17–1.21), whether the mother or father was a smoker when the child was 3 years old (RR: 1.15, CI: 1.13–1.17), and whether the child’s meals and snacks were provided at a fixed schedule at 18 months of age (RR: 1.16, CI: 1.14–1.18). To the best of our knowledge, this study has shown for the first time that macrosomia was associated with the risk of dental caries in 3-year-old infants. The findings of this study were consistent with the results of previous analyses conducted on data collected in other regions in Japan regarding the relationship between macrosomia and dental caries in 3-year-old infants. All the other factors we identified as risk factors had already been previously indicated as risk-associated. Although the underlying mechanism by which macrosomia increases the risk for dental caries remains unknown, we consider that it might be related to fetal environment.

CONCLUSIONS: This study using Poisson longitudinal multivariate analysis has shown that macrosomia was associated with the risk of dental caries in 3-year-old infants.