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.


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 (10th-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.
Sharma
Puneet
P
Department of Pediatrics, Division of Neonatology, University of Connecticut Health Center, Farmington, CT 06030-2948, USA. punsharma@hotmail.com
McKay
Kathleen
K
Rosenkrantz
Ted S
TS
Hussain
Naveed
N
D002908:Chronic Disease; D003237:Connecticut / Q000453:epidemiology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000401:mortality*; D007236:Infant, Small for Gestational Age; D007902:Length of Stay / Q000706:statistics & numerical data; D008171:Lung Diseases / Q000453:epidemiology*; D008297:Male; D015999:Multivariate Analysis; D015995:Prevalence; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012127:Respiratory Distress Syndrome, Newborn / Q000453:epidemiology; D012189:Retrospective Studies; D018570:Risk Assessment; D015996:Survival Rate; D016896:Treatment Outcome