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[Importance of pre- and perinatal risk factors in respiratory distress syndrome of premature infants. A logical regression analysis of 1100 cases].

BACKGROUND
Respiratory distress syndrome (RDS) due to surfactant deficiency remains a cause of considerable mortality in the neonatal period.


METHODS
In a retrospective study we analysed the records of 1109 premature newborns with a birth weight below 1500 g that were treated on our unit. RDS was assumed if the infants needed mechanical ventilation with oxygen supplementation and the typical radiological signs were present on chest x-ray.


RESULTS
No changes in the incidence of RDS were found during the period of observation. Below 29 weeks gestational age 90% of infants suffered from RDS (55% severe RDS grade III or IV). The incidence was 75% (grade III or IV: 32%) for infants born at 29 and 30 weeks, 48% (grade III or IV: 15%) at 31 and 32 weeks and 33% (grade III or IV: 6%) for neonates born at 33 weeks of gestation. Using a logistic regression analysis model the following parameters were found to increase the risk for RDS significantly (p < 0.05): no prenatal steroid treatment, Cesarean section, male gender, APGAR at 5 min < 7, metabolic acidosis (base excess < or = -6 mval) and rectal temperature < 36 degrees C on admission. Following gestosis, insufficiency of the placenta and premature rupture of membranes a decrease in the incidence of RDS was observed.


CONCLUSION
We conclude that although some risk factors for RDS will be difficult to exclude (e.g. maternal disease, gender) the incidence and severity of RDS can be reduced by measures like maternal antenatal steroid treatment. Perinatal asphyxia (low APGAR values and/or acidosis) and hypothermia should be avoided, as these conditions increase the relative risk for developing RDS.