Determinants of bedwetting trajectories between 4 and 7 years - A birth cohort analysis

Enuresis is frequent in school-aged children and results from a complex interaction between genetics, biological and psychosocial factors. This study aims to analyze bedwetting trajectories between 4 and 7 years of age and to evaluate the impact of biological and developmental characteristics of the child and sociodemographic factors in those bedwetting trajectories.

Data from 5433 children from the Generation XXI population-based birth cohort was analyzed. Four bedwetting trajectories were defined: normative (acquired nighttime bladder control at 4 years and no enuresis at 7 years); delayed (no nighttime bladder control at 4 years and no enuresis at 7 years); enuresis (no nighttime bladder control at 4 years and enuresis at 7 years); and secondary enuresis (acquired nighttime bladder control at 4 years and enuresis at 7 years). Multinomial logistic regression models were fitted to test the association between biological and developmental characteristics of the child and sociodemographic factors with bedwetting trajectories.

At the age of 4 years, 36.5% of children had bedwetting (8.1% infrequently and 28.4% frequently) and at the age of 7 years, 11.0% had enuresis (5.8% infrequently and 5.2% frequently). Of the 4-year-old children who were infrequent bedwetters, 14.0% had enuresis at 7 years, while among frequent bedwetters, 30.2% had enuresis at 7 years. Regarding bedwetting trajectories, 26.8% of children were classified in the delayed trajectory, 9.7% in the enuresis trajectory and 1.3% were in the secondary enuresis trajectory. Children with developmental disorders presented an increased risk of being in enuresis trajectory (OR = 1.47, 95% CI 1.15-1.88) than children without developmental disorders. Living in overcrowded houses (OR = 1.60, 95% CI 1.12-2.30), growing up in families with low household income (OR = 1.27, 95% CI 1.03-1.57) and an orphan of one parent (OR = 3.19, 95% CI 1.18-8.64) presented higher odds of being in the enuresis trajectory than in the normative trajectory. Having a sibling both before the age of 4 years and between the ages of 4 and 7 years was associated with delayed trajectory (OR = 1.55, 95% CI 1.16-2.07) and with enuresis (OR = 1.53, 95% CI 1.01-2.33), when compared with children without siblings born at that time.

Both developmental disorders and sociodemographic factors seem to be important determinants of bedwetting trajectories. Further studies are needed to better characterize the impact of biological and environmental determinants, on the nighttime bladder control acquisition, to enable timely medical interventions that improve the quality of life of enuretic children.