Association between small-for-gestational age and neurocognitive impairment at two years of corrected age among infants born at preterm gestational ages: a cohort study.

OBJECTIVE: To investigate the association between small-for-gestational age (SGA) and neurocognitive impairment at 2 years of corrected age among infants born at preterm gestational ages.

STUDY DESIGN: A secondary analysis of a prospectively conducted NICHD/Maternal-Fetal Medicine Units BEAM trial. Non-anomalous pregnancies delivered before 37 weeks of gestation were included in the analysis. Neurocognitive outcomes at 2 years of corrected age were compared between infants who were SGA (<10% for gestational age) and those appropriately grown (AGA). The primary outcome was a severe or moderate neurocognitive impairment at 2 years of corrected age among survivors, defined as either mental (MDI) or psychomotor (PDI) developmental index score <70 for severe and <85 for moderate impairment.

RESULTS: Of 2299 preterm neonates 67 (3%) were SGA. SGA infants were more often twin pregnancies (31% vs 17%, P=0.003) and delivered more often by cesarean section (63% vs 40%, P<0.001) at similar gestational ages (30.0±2.6 vs 29.5±2.8 weeks, P=0.11). At 2 years of corrected age, SGA and AGA survivors had similar rates of neurocognitive impairment (MDI <70: 18% vs 18%, P=1.0; MDI <85: 44% vs 46%, P=0.96; PDI <70: 20% vs 15%, P=0.51; PDI <85: 40% vs 34%, P=0.48).

CONCLUSION: In this cohort, SGA at preterm gestational ages was associated with similar rates of neurocognitive impairment at two years of corrected age among surviving infants.