672: Is there a critical threshold? Preterm delivery and long term infectious morbidity of the offspring

Abstract

Infectious disease is a well-established cause of preterm birth (PTB), but the significance of PTB as a risk factor for subsequent long-term infectious morbidity of the offspring is more elusive. We sought to ascertain a relationhip between the gestational age at delivery and long-term pediatric infectious morbidity. A population-based cohort analysis comparing the long-term incidence of infectious morbidity in infants born preterm according to gestational age at birth. Cases were divided into groups according to the extremity of prematurity (extreme PTB 24+0-27+6, very PTB 28+0-31+6, moderate to late PTB 32+0-36+6 weeks of gestation and term deliveries). infectious morbidity included hospitalizations involving a predefined set of ICD9 codes, as recorded in hospital records. Deliveries occured between 1991-2014 in a tertiary medical center. A Kaplan Meier survival curve was constructed to compare cumulative incidence of infectious-related morbidity. A Cox proportional hazards model controlled for confounders. 220,594 patients met the inclusion criteria of which 125 (0.1%) were extreme PTB, 784 (0.4%) were very PTB, 13,323 (6.0%) were moderate to late PTB and 206,362 were term deliveries. Offspring born preterm had significantly more hospitalizations due to infectious morbidity compared to term offspring (18.4%, 19.8%, 14.9% and 11.0% for offspring born in extreme PTB, very PTB, moderate to late PTB and term respectively p< 0.001, Table). Using a Cox proportional hazards model, controlling for confounders including maternal age, birth weight, diabetes, hypertensive disease and mode of delivery, delivery at very, and late to moderate PTB was independently associated with long-term infectious morbidity (aHR 1.5 95% CI 1.27-1.77 and aHR 1.23 95% CI 1.17-1.3 respectively, p< 0.001, Figure). An increased risk was also found with extreme PTB (aHR 1.24 95% CI 0.83-1.89 p=0.34) but this association did not achieve statistical significance. Preterm delivery is an independent risk factor for long-term infectious morbidity of the offspting, starting from 28 weeks.View Large Image Figure ViewerDownload Hi-res image Download (PPT)