Background: Low birth weight (LBW) continues to increase and is a major public health problem in Japan. In the present cross-sectional study, we examined the associations between LBW, preterm birth and small-for-gestational-age (SGA) and the prevalence of dental caries in young Japanese children.
Methods: Study subjects were 2,055 children aged 3 years. Data on birth conditions were obtained through the transcription by parents or guardians of the information from their maternal and child health handbook, in which the data were recorded by staff at the birth hospital or clinic, to our self-administered questionnaire. Children were classified as having caries if one or more deciduous teeth were decayed, missing, or had been filled at the time of examination. Adjustments were made for sex, toothbrushing frequency, use of fluoride, regular dental check-ups, between-meal snack frequency, breastfeeding duration, paternal and maternal educational levels, maternal smoking during pregnancy, and secondhand smoke exposure at home.
Results: The prevalence of dental caries was 20.7%. The mean birth weight was 3018.3 g, and 8.3% were classified as LBW (< 2,500 g), 4.5% as preterm birth (< 37 weeks), and 7.1% as SGA (< 10th percentile). Preterm birth was associated with a 40% decreased prevalence of dental caries (adjusted prevalence ratio = 0.60, 95% confidence interval: 0.36-1.02, p = 0.06). There were no associations between LBW or SGA and the prevalence of dental caries.
Conclusions: The results of the study failed to detect significant associations between LBW, preterm birth or SGA and the prevalence of dental caries in Japan. Further study is needed in other populations to confirm the generalizability of these findings.