Abstract 1196 Poster Session IV, Tuesday, 5/4 (poster 263)

An increasing number of extremely low birth weight infants (ELBW) are surviving in the 90's with improved perinatal and neonatal care. Fetal and early postnatal growth of ELBW infants are usually evaluated using Lubchanco's growth curves, which were developed before more accurate assessment of GA was available for these ELBW infants. Moreover, Lubchenco's growth curves have no birth weight or occipital-frontal circumference (OFC) data for infants <26 weeks GA. The purpose of this study was to develop fetal growth standards for ELBW infants born during the 1990's. (Figure)

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All infants with gestational age <29 weeks born between 1992 and 1996 and admitted to three different Michigan NICUs were studied. Subjects with major congenital anomalies, uncertain last menstrual period (LMP) dates, or who were outborn (maternal chart unavailable) were excluded. In addition, in order to minimize the error in GA assignment, infants were excluded if the GA estimated by Ballad exam differed by >one week from obstetric estimate. Data of 838 premature infants ≤29 weeks were elevated. 56% were male and 70% were white infants. The birth weights and OFCs of 604 (72%)infants whose GA were documented in the OB chart (defined as LMP and first trimester exam or first trimester IS) and which agreed within 1wk of the Ballard estimates were plotted as a function of GA.

Our 10th percentile curve for birth weight was similar to that of Lubchenco's curves. However, the 90th percentile for our data was significantly lower than that of Lubchenco's. Our OFC data (not shown) compared similarly to Lubchenco's curves. Lubchenco's growth curves are not appropriate for ELBW infants in the 90's.