Gestational age and the long-term impact on children's infectious urinary morbidity.

Purpose: Given the negative impact of prematurity on offspring's health, we sought to determine whether different gestational ages at birth impact differently on the prevalence of childhood infectious urinary morbidity in the offspring.
Methods: In this population-based cohort analysis, all singleton deliveries occurring between 1991 and 2014 at a single regional tertiary medical center were included. Gestational age upon delivery was sub-divided into early preterm (< 34 weeks), late preterm (34-36 6/7 weeks), early term (37-38 6/7 weeks), full term (39-40 6/7 weeks), late term (41-41 6/7 weeks) and post-term (> 42 weeks). Congenital malformations were excluded. Rates of infectious urinary morbidity-related hospitalizations of offspring up to age 18 years were assessed using a survival curve and a Cox multivariable model.
Results: During the study period, 238,620 deliveries met the inclusion criteria. Urinary-related hospitalization (n = 1395) rates decreased as gestational age increased, from 1.7% in the early preterm group, 0.9% in the late preterm group, 0.6% in the early-term group and only 0.5% in the full, late and post-term groups (p > 0.001; chi-square test for trends). In the Cox model, controlled for maternal age, preterm as well as early-term deliveries exhibited an independent association with pediatric urinary morbidity as compared with full term (early preterm: aHR-3.305, 95% CI 2.4-4.54; late preterm: aHR-1.63, 95% CI 1.33-1.99; early term: aHR-1.26, 95% CI 1.1-1.43, p = 0.01).
Conclusions: Deliveries occurring at preterm and at early term are independently associated with pediatric urinary morbidity in the offspring. This risk decreases as gestational age advances.