Comparisons of mortality and pre-discharge respiratory outcomes in small-for-gestational-age and appropriate-for-gestational-age premature infants

BACKGROUND: There are differences in the literature regarding outcomes of premature small-for-gestational-age (SGA) and appropriate-for gestational-age (AGA) infants, possibly due to failure to take into account gestational age at birth. OBJECTIVE: To compare mortality and respiratory morbidity of SGA and AGA premature newborn infants. DESIGN/METHODS: A retrospective study was done of the 2,487 infants born without congenital anomalies at ≤36 weeks of gestation and admitted to the neonatal intensive care unit (NICU) at John Dempsey Hospital, between Jan. 1992 and Dec. 1999. Recent (1994–96) U.S. birth weight percentiles for gestational age (GA), race and gender were used to classify neonates as SGA (<10th percentile for GA) or AGA (10(th)–90th percentile for GA). Using multivariate logistic regression and survival analyses to control for GA, SGA and AGA infants were compared for mortality and respiratory morbidity. RESULTS: Controlling for GA, premature SGA infants were at a higher risk for mortality (Odds ratio 3.1, P = 0.001) and at lower risk of respiratory distress syndrome (OR = 0.71, p = 0.02) than AGA infants. However multivariate logistic regression modeling found that the odds of having respiratory distress syndrome (RDS) varied between SGA and AGA infants by GA. There was no change in RDS risk in SGA infants at GA ≤ 32 wk (OR = 1.27, 95% CI 0.32 – 1.98) but significantly decreased risk for RDS at GA > 32 wk (OR = 0.41, 95% CI 0.27 – 0.63; p < 0.01). After controlling for GA, SGA infants were observed to be at a significantly higher risk for developing chronic lung disease as compared to AGA infants (OR = 2.2, 95% CI = 1.2 – 3.9, P = 0.01). There was no significant difference between SGA and AGA infants in total days on ventilator. Among infants who survived, mean length of hospital stay was significantly higher in SGA infants born between 26–36 wks GA than AGA infants. CONCLUSIONS: Premature SGA infants have significantly higher mortality, significantly higher risk of developing chronic lung disease and longer hospital stay as compared to premature AGA infants. Even the reduced risk of RDS in infants born at ≥32 wk GA, (conferred possibly by intra-uterine stress leading to accelerated lung maturation) appears to be of transient effect and is counterbalanced by adverse effects of poor intrauterine growth on long term pulmonary outcomes such as chronic lung disease

Respiratory morbidity at follow up of small for gestational age infants born very prematurely

Background: To determine whether small for gestational age (SGA) infants, born very prematurely had increased respiratory morbidity in the neonatal period and at follow up.Methods: Data were examined from infants entered into the United Kingdom Oscillation Study (UKOS). 174 of 797 infants who were born at less than 29 weeks of gestational age, were SGA. Overall, 92% were exposed to antenatal corticosteroids and 97% received surfactant and follow up data at 22-28 months were available for 367 infants.Results: After adjustment for gestational age and sex, SGA infants had higher rates of supplementary oxygen dependency at 36 weeks postmenstrual age (OR: 3.23; 95% CI 2.03, 5.13), pulmonary haemorrhage (3.07; 1.82, 5.18), death (3.32; 2.13, 5.17) and postnatal corticosteroid requirement (2.09;1.35,3.23). After adjustment for infant and respiratory morbidity risk factors, a lower mean birth weight z- score was associated with a higher prevalence of respiratory admissions (OR 1.40; 1.03, 1.88 for one standard deviation change in z score), cough (1.28; 1.00, 1.65) and use of chest medicines (1.32; 1.01, 1.73).Conclusion: Small for gestational age, very prematurely born infants, despite routine use of antenatal corticosteroids and postnatal surfactant, had increased respiratory morbidity at follow up, which was not due to poor neonatal outcome