Objectives: To determine the sociodemographic and clinical characteristics of mothers of infants at the limit of viability and to know the perinatal factors associated to infants' survival.
Method: Single-center cohort study of mothers and newborns assisted in our tertiary care center (2004-2010). Demographic and perinatal variables were compared between mothers who gave birth ≤26 weeks GA and the general population. The association between perinatal factors and neonatal survival was studied by Cox regression analysis.
Results: Mothers of newborns ≤26 weeks (n = 136) had less education and pregnancy control. They had more frequently assisted reproductive technologies (ART) (5.2% versus 2.3%; p< 0.05), multiple gestations (16.6% versus 2.1%; p < 0.05), pregnancy complications and C-section (39.7% versus 13.4%; p < 0.001). After correcting for confounders, the perinatal factors independently associated with a variation in the risk of mortality were the administration of antenatal steroid [aHR (95%CI): 0.465 (0.254-0.853), p = 0.013], singleton pregnancy [aHR (95%CI): 0.482 (0.279-0.834), p = 0.009], infant's temperature on admission [aHR (95%CI): 0.642 (0.426-0.968), p = 0.035] and CRIB score [aHR (95%CI): 1.151 (1.058-1.251), p = 0.001].
Conclusions: Mothers of preterm infants at the limit of viability had more ART, multiple pregnancies, obstetrical complications and C-section. Infants' survival was independently associated to antenatal steroids, singleton pregnancy, temperature on admission and CRIB score.
Keywords: Extremely preterm newborn; cesarean section; limits of viability; risk factors; survival.