451: Perinatal Risk Factors for Long-Term Respiratory Morbidity among Neonates with Preterm Birth And/or Growth Retardation

Many obstetrical interventions are performed to improve long-term neonatal outcome. However, long term neonatal outcome is usually not a primary outcome since it is time-consuming, expensive, not in the awareness of obstetricians, and falls outside the funding-period of most obstetric studies. Respiratory distress syndrome (RDS) is often used as primary end-point for unripeness of the fetal lungs, but the relation between RDS and long-term respiratory morbidity is not clear. The aim of this project was to identify different perinatal risk factors for long-term respiratory morbidity. In the Dutch POPS cohort 1338 live born infants delivered in The Netherlands in 1983, either before 32 completed weeks gestation and/or with a birth weight below 1500 g were followed prospectively till the age of 19. We used multivariable logistic regression analyses to construct three prediction models for respiratory morbidity at 2, 5 and 19 years of age respectively. In total, 30% of infants had respiratory problems at 2 years of age and 15% at 5 and 19 years of age. Maternal smoking (OR 1.5), prolonged rupture of membranes (OR 2.3), pre-eclampsia (OR 1.9), male gender (OR 1.5) and BPD (OR 1.9) were significantly associated with respiratory morbidity at 2 years of age. Prolonged rupture of membranes (OR 3.7), family history of asthma (OR 5.9) and BPD (OR 1.8) were significantly associated with respiratory morbidity at 5 years of age. At 19 years of age only higher social class was associated with respiratory morbidity (OR 0.64). RDS was not associated with respiratory morbidity at any age. The area under the curve (AUC) was 0.65, 0.71 and 0.61 respectively. The prediction models for respiratory morbidity at 2 and 5 years of age show a good calibration, while the calibration plot for respiratory morbidity at 19 year is less optimal. Future obstetric studies interested in the effect of a specific perinatal intervention on long-term respiratory morbidity, should consider taking BPD as primary outcome instead of RDS.