Gestational age and long term pediatric urinary morbidity of the offspring

Objective
We sought to determine whether the different subgroups of ‘preterm’ and ‘term’ delivery impact differently on the prevalence of childhood urinary morbidity in the offspring.

Study Design
In this population-based cohort analysis all preterm and term singleton deliveries occurring between 1991-2014 at a single regional tertiary medical center were included. Gestational age upon delivery was sub- divided into: early preterm (<34 weeks), late preterm (34-36.9 weeks), early term (37-38+6 weeks), full term (39-40+6 weeks), late term (41-41+6 weeks) and post term (>42 weeks). Fetuses with congenital malformations were excluded. Rates of urinary morbidity related hospitalizations of the offspring up to the age of 18 years were assessed in the different categories of gestational age, and cumulative rates were compared using a Kaplan-Meier survival analysis. A Cox proportional hazard model was used to study the association between gestational age at birth and the risk for pediatric urinary morbidity in the offspring.

Results
During the study period 238,620 preterm and term deliveries met the inclusion criteria. Urinary morbidity up to the age of 18 years (n=1395) was more common in the early preterm term group (1.7%), and decreased to 0.9% in the late preterm group and to 0.6% in the early term group, as comparted with full (0.5%), late (0.5%), and post term (0.5%) group rates (p=0.001; using the chi-square test for trends). The survival curve demonstrated higher cumulative incidence of urinary morbidity in the preterm and early term groups as compared with other gestational age groups (Figure, log rank p<0.001). In the Cox model (controlled for maternal age) early preterm delivery and early term delivery exhibited an independent association with pediatric urinary morbidity as compared to full term deliveries (early preterm adjusted HR- 3.305 95%CI 2.4-4.54, late preterm adjusted HR-1.63 95%CI 1.33-1.99, early term adjusted HR-1.26 95%CI 1.1-1.43, p=0.01).

Conclusion
Deliveries occurring at preterm and early term are independently associated with higher risk of pediatric urinary morbidity in the offspring which decrease as gestational age advances.