Is prolonged breastfeeding a risk factor for dental caries at 2 years of age?

A birth cohort study.

Children born at Womens and Childrens Hospital of Juruá in the Western Brazilian Amazon from July 2015 to June 2016 were invited to join the study. 1246 children were invited and accepted into the study. Follow-up included visits at 6, 12 and 24 months of age, and a dental caries examination between 21 and 27 months of age (n = 800). Data collected included baseline co-variables and sugar consumption.

Data was collected at 6, 12 and 24 months. At 24 months, a 24-hour diet recall was obtained from the mother to obtain information on sugar consumption. A dental examination was carried out by two research paediatric dentists and caries was scored in accordance with the WHO criteria: decayed, missing and filled primary teeth (dmft).^.Children were then categorised into absence of caries (dmft = 0) or presence of caries (dmft = >1). Follow-up interviews were carried out in 10% of cases to ensure accuracy and quality of the results. Statistical analysis was carried out using the G-formula. It was assumed breastfeeding had a direct effect on caries at 2 years and is indirectly mediated by sugar consumption. This was modified to include the presence of intermediate confounders (bottle-feeding) and time-varying confounders. Total causal effect of these confounders was calculated by the addition of natural direct effect and natural indirect effect. The odds ratio (OR) for total causal effect was estimated.

In total, 800 children were followed up throughout the study; of these, the prevalence of caries was 22.8% (95% CI, 19.8%-25.8%). 14.9% (n = 114) of children were breastfed at 2 years of age and 60% of children (n = 480) were bottle-fed. Bottle-fed children were found to have an inverse relationship with caries. Children breastfed for 12-23 months (n = 439) were found to have an OR 1.13 for having caries at 2 years compared to those breastfed <12-months (n = 247), equating to a 13% higher risk. Children breastfed for ≥24-months had an even higher risk (27%) of caries at 2 years of age compared to those breast-fed to 12-months (TCE: OR = 1.27, 95% BC-CI 1.14:1.40).

There is a weak association with prolonged breastfeeding and increased caries rate in children. Decreasing sugar consumption alongside prolonged breastfeeding marginally reduces the effect of breastfeeding on dental caries.