Association of long-duration breastfeeding and dental caries estimated with marginal structural models

PurposeTo estimate the association between breastfeeding 24 months or beyond and severe early childhood caries (S-ECC).MethodsWithin a birth cohort (n = 715) from low-income families in Porto Alegre, Brazil, the age 38-month prevalence of S-ECC (≥4 affected tooth surfaces or ≥1 affected maxillary anterior teeth) was compared over breastfeeding duration categories using marginal structural models to account for time-dependent confounding by other feeding habits and child growth. Additional analyses assessed whether daily breastfeeding frequency modified the association of breastfeeding duration and S-ECC. Multiple imputation and censoring weights were used to address incomplete covariate information and missing outcomes, respectively. Confidence intervals (CIs) were estimated using bootstrap resampling.ResultsBreastfeeding 24 months or beyond was associated with the highest adjusted population-average S-ECC prevalence (0.45; 95% CI, 0.36 to 0.54) compared with breastfeeding less than 6 months (0.22; 95% CI, 0.15 to 0.28), 6–11 months (0.38; 95% CI, 0.25 to 0.53), or 12–23 months (0.39; 95% CI, 0.20 to 0.56). High-frequency breastfeeding enhanced the association between long-duration breastfeeding and caries (excess prevalence due to interaction: 0.13; 80% CI, −0.03 to 0.30).ConclusionsIn this population, breastfeeding 24 months or beyond, particularly if frequent, was associated with S-ECC. Dental health should be one consideration, among many, in evaluating health outcomes associated with breastfeeding 24 months or beyond.