Changes in Neurodevelopmental Outcomes at 18 to 22 Months Corrected Age Among Infants of Less Than 25 Weeks?? Gestational Age Born in 1993???1999

Abstract

Advances in perinatal/neonatal medicine in recent years, including surfactant in particular, have increased the chances of survival for extremely preterm, extremely low-birth-weight infants. Comparatively little, however, is known about neurosensory and developmental impairments in survivors. This study examined outcomes at corrected ages of 18 to 22 months for infants born in the 1990s whose estimated gestational age was less than 25 weeks and who weighed 501 to 1000 g at birth. The multicenter, retrospective, comparative analysis compared 366 infants born in 1993 to 1996 (epoch I) with 473 born in 1996 to 1999 (epoch II). Logistic regression analysis was used to determine the independent risk of cerebral palsy, a Mental Development Index (MDI) less than 70, a Psychomotor Development Index (PDI) less than 70, and neurodevelopmental impairment. Prenatal antibiotic treatment, steroid treatment, and cesarean section all were more frequent in epoch II, and 5-minute Apgar scores below 5 were significantly less frequent for these infants. Both surfactant and prophylactic indomethacin were used significantly more often in epoch II. Bronchopulmonary dysplasia, defined as a need for supplemental oxygen at 36 weeks of postconceptional age, was more frequent in epoch II, as was retinopathy of prematurity. Diagnoses more frequent in epoch I included patent ductus arteriosis, necrotizing enterocolitis, and grade III or grade IV intraventricular hemorrhage (IVH). There were no substantial differences between epochs in major neurosensory outcomes (Table 1). Cerebral palsy (CP) developed in just over half of infants in each epoch. In both periods, 21% of infants were considered not to be impaired because of no CP, deafness, or blindness and MDI and PDI scores of 85 or higher. On regression analysis, epoch was not an independent risk factor for CP or low PDI scores, but the risk of an MDI score below 70 was lower in the earlier epoch. Epoch was not an independent risk factor for being unimpaired. Significant factors included male gender, grade III or IV IVH, and postnatal steroid treatment.TABLE 1: CP, deafness, and blindness at 18 to 22 months' corrected age in epochs I and IIEarly childhood neurodevelopmental outcomes for infants of less than 25 weeks estimated gestational age are not improving despite more aggressive treatment. Studies of later childhood status are needed to learn whether these infants are at risk of severe cognitive impairment.