Dental caries incidence in infants with abnormal birth weight for gestational age: a longitudinal study in the Japan Environment and Children's Study.

backgroundEarly childhood caries (ECC) remains a major global public health concern, influenced by complex socioeconomic and biological factors. Although deviations in fetal growth, including being small for gestational age (SGA) or large for gestational age (LGA), have been linked to various long-term health outcomes, evidence regarding their association with ECC remains inconsistent. This study examined the influence of SGA and LGA on the cumulative experience of ECC and severe ECC (S-ECC) using a large-scale nationwide birth cohort.

methodsThis prospective cohort study utilized data from the Japan Environment and Children's Study, a nationwide investigation of approximately 100,000 mother-child dyads. After applying exclusion criteria, 79,006 children were included in the final analysis. SGA and LGA were defined according to Japanese reference standards. Information on ECC experience was obtained from caregiver-reported questionnaires administered at 4 and 5 years postpartum. Based on established criteria, S-ECC was defined as any caries experience by 3 years of age, and ECC as any experience by 5 years of age. A generalized linear mixed model (GLMM) was used to estimate risk ratios (RRs) and 95% confidence intervals (CIs) for longitudinal ECC trajectories. Sensitivity analyses using Poisson regression with multiple imputation were conducted to assess the robustness of findings.

resultsLongitudinal trajectories demonstrated distinct differences in ECC risk across the birth weight spectrum. In fully adjusted GLMMs, children born LGA had significantly higher risks of both S-ECC and ECC than those born appropriate for gestational age (S-ECC: RR = 1.13, 95% CI: 1.08-1.18; ECC: RR = 1.13, 95% CI: 1.10-1.15). In contrast, children born SGA exhibited significantly lower risks (S-ECC: RR = 0.91, 95% CI: 0.86-0.96; ECC: RR = 0.94, 95% CI: 0.92-0.97). These associations remained consistent in sensitivity analyses addressing missing data.

conclusionsChildren born LGA demonstrated a relatively higher prevalence of ECC, consistent with findings from previous studies. Conversely, the lower prevalence observed among children born SGA may reflect greater parental vigilance or enhanced medical monitoring. Birth weight for gestational age may therefore serve as a useful indicator for identifying children who could benefit from targeted oral health interventions.