Outcomes of preterm children according to type of delivery onset: a nationwide population-based study.

The objective of the study was to investigate whether spontaneous and iatrogenic preterm births are associated with different paediatric outcomes. A nationwide population-based study comprising 1 010 487 singletons used data from 1991 to 2001 from the Swedish Medical Birth Register and the Swedish Hospital Discharge Register. Intrauterine fetal deaths, unknown type of delivery onset and congenital malformations were excluded. Neonatal, perinatal and long-term neurological outcomes were studied. Spontaneous preterm births were compared with iatrogenic preterm births. Odds ratios (OR) and hazard ratios (HR) for outcome variables were obtained using the Mantel-Haenszel technique and Cox analyses respectively. Adjustments were made for gestational age at birth, maternal age, parity and smoking. The preterm population consisted of 34 215 (73.2%) spontaneous preterm infants and 12 511 (26.8%) iatrogenic preterm infants. Spontaneous preterm infants were at increased risk of cerebral palsy at gestational age 28-31 weeks (HR: 1.86 [95% CI: 1.12, 3.10]), and of sepsis at gestational age 32-33 weeks (HR: 1.58 [95% CI: 1.28, 1.96]). Other outcome variables were associated with iatrogenic preterm birth, especially respiratory and gastrointestinal diagnoses. In conclusion, spontaneous preterm birth and iatrogenic preterm birth are associated with different paediatric outcomes.