Do very sick neonates born at term have antenatal risks? 2. Infants ventilated primarily for lung disease.

AIMS: 1. Ascertain antenatal and intrapartum risk factors for term neonates ventilated primarily for respiratory problems. 2. Describe the neonatal morbidity and mortality.

METHODS: Population-based case control cohort study.

SETTING: Sydney and four large rural/urban Health Areas in New South Wales, 1996.

SUBJECTS: Singleton term infants, no major congenital anomaly: subset of 99 infants ventilated primarily for respiratory problems from 182 cases admitted to a tertiary neonatal intensive care unit (NICU) for mechanical ventilation, and 550 randomly selected controls.

OUTCOME: Risk factors for case status by maternal, antenatal, labor, delivery, and combined epochs, adjusted Odds Ratios (OR), 95 per cent Confidence Intervals (CI), p<0.05.

RESULTS: Predictors of case status by multivariate epochs: mother's age > or =35 years (1.9 (1.1, 3.2) p=0.03), primigravida (1.8 (1.1, 2.8) p=0.01), any antenatal complication (3.8 (2.4, 5.9) p=0.0001), birth weight < 3rd percentile (3.7 (1.5, 9.1) p=0.006), gestational diabetes (2.9 (1.3, 6.9) p=0.01), maternal pyrexia (6.5 (1.6, 27.2) p=0.01), birth weight >90th percentile (1.8 (1.01, 3.2) p=0.047), gestation 37-38 weeks (2.3 (1.5, 3.6) p=0.0004), forceps (4.4 (2.1, 9.1) p=0.0001), elective cesarean section (3.7 (2.0, 6.5) p=0.0001), emergency cesarean section (4.5 (2.4, 8.4) p=0.0001). Case mortality rate was 5 per cent.

CONCLUSION: The pathways to neonatal respiratory morbidity in term infants are multifactorial. Several areas which warrant more in-depth study are: elective cesarean section at 37-38 weeks gestation, fetal growth restriction, macrosomia and the pattern of in-utero growth, maternal weight gain during pregnancy, gestational diabetes, pyrexia in labor and the role of chorioamnionitis.