ABSTRACT
Clinical observation suggested an association between an increased cardiothoracic
ratio (CT) and growth retardation (IUGR) in the premature neonate. To investigate
this hypothesis, a case-control study was performed. Study subjects included 23 cases
(IUGR) and 55 control (appropriate for gestational age [AGA]) premature infants with
birth-weights 2000 gm or less; Apgar scores greater than 5 at 5 minutes; no congenital
heart disease; no polycythemia; no toxoplasmosis, rubella, cytomegalovirus, or herpes
infection. In random order, the first chest radiograph of each infant (less than 24
hours) was reviewed by a single radiologist, unaware of the infant's growth status.
The CT ratio was computed after measuring the widest internal width of the bony thorax
and the cardiac diameter. Mean birthweight (±1 SD) of the IUGR infants was 1161 ±
289 g and of AGA infants was 1401 ±401 g (p < 0.002); the mean gestational ages (±1
SD) were 33.2 ±2.8 and 30.8 ± 2.5 weeks (p < 0.001). Mean CT for IUGR infants was
0.57 ± 0.07 (±1 SD) versus AGA infants, 0.51 ± 0.04 (±1 SD), p < 0.001. When the infants
were stratified by growth status and CT ratio, 11 of 23 IUGR and 1 of 55 AGA infants
had an increased CT ratio p < 0.0001. When birthweight and gestational age were covaried,
growth status remained the best predictor of CT, p = 0.005. There is a strong association
of increased CT and growth retardation in premature infants with birthweights 2000
gm or less.
