Customized birth weight percentiles for identification of SGA short statue

OBJECTIVES: About 10-15 % of small for gestational age (SGA) children have persistent short stature (SGA-SS) and may benefit from growth hormone therapy. Customized percentiles that consider maternal height and weight, among other factors, appear to more accurately identify pathologically small newborns at higher risk of perinatal morbidity. We aim to determine whether the consideration of maternal height and weight in definition of SGA has an impact on the frequency of SGA-SS diagnosis and potential therapy. METHODS: Birth data of 1321 infants with a gestational age of ≥30 weeks of gestation were analyzed using both conventional percentiles and customized birth weight percentiles, the latter incorporating maternal height and weight. Growth data at 2 and 4 years of age were analyzed for the presence of persistent short stature (SGA-SS) in infants born SGA. RESULTS: Using the conventional birth weight percentiles, 129 (9.8 %) newborns are classified as SGA compared to 158 (11.9 %) using the customized percentiles. Forty-one infants of high-weight mothers were identified using only the customized classification. Twelve infants born to low-weight mothers were identified by conventional classification only. At 2 and 4 years of age, seven children had persistent short stature. The diagnosis of SGA-SS differed in only one case between the conventional and customized birth weight percentiles. CONCLUSIONS: Customized percentiles classify more children as SGA based on their birth weight but do not appear to identify more children with postnatal growth failure than do conventional percentiles.