Cause of Preterm Birth as a Prognostic Factor for Mortality.

OBJECTIVE

To investigate the association of the cause of preterm birth on in-hospital mortality of preterm neonates born from 24 to 34 weeks of gestation.

METHODS

L'Etude épidémiologique sur les petits âges gestationnels (EPIPAGE)-2 is a prospective, nationwide, population-based cohort of very preterm births. After dividing causes of preterm birth into six mutually exclusive groups, we analyzed the association of each cause with in-hospital deaths of preterm neonates born alive with adjustment for organizational, maternal, and obstetric factors.

RESULTS

The analysis included 3,138 singleton live births from 24 to 34 weeks of gestation with a newborn in-hospital mortality rate of 5.0% (95% confidence interval 4.5-5.7). Preterm labor was the most frequent cause of preterm birth (n=1,293 [43.5%]) followed by preterm premature rupture of membranes (n=765 [23.9%]), hypertensive disorders without suspected fetal growth restriction (n=397 [12.7%]), hypertensive disorders with suspected fetal growth restriction (n=408 [10.9%]), placental abruption after an uncomplicated pregnancy (n=92 [3.0%]), and suspected fetal growth restriction without hypertensive disorders (n=183 [5.9%]). Neonates born because of suspected fetal growth restriction with or without hypertensive disorders (adjusted odds ratio [OR] 3.0 [1.9-4.7] and adjusted OR 2.3 [1.1-4.6], respectively) had higher adjusted risks of in-hospital death than those born after preterm labor. Risks of in-hospital mortality for preterm births caused by preterm premature rupture of membranes (adjusted OR 1.3 [0.9-1.9]), hypertensive disorders without fetal growth restriction (adjusted OR 0.7 [0.4-1.4]), or placental abruption (adjusted OR 1.6 [0.7-3.7]) were similar to those born after preterm labor.

CONCLUSION

Among neonates born alive before 34 weeks of gestation, only those born because of suspected fetal growth restriction have a higher mortality risk than those born after preterm labor.