Birthweight percentiles by gestational age in Kuwait.

Our aim is develop a curve for singleton birthweight based on accurately calculated gestational age. A retrospective analysis of all singleton live births from 22-44 completed weeks of gestation during the period from September 1998 to December 2000 in the two largest birth birth centers in Kuwait was conducted. Neonates with major congenital anomalies and those with unrecorded gestational age were excluded from the study population. Total population and gender-specific birthweight percentiles according to gestational age were developed after smoothening of growth curves. A total of 35768 births were included in the development of the birthweight curve. Percentiles of birthweight for all population and by gender are presented. There was significant difference in birthweight among different ethnic groups in this population. At term, 9.8% of births are smaller than the 10th percentile and 10.0% are larger than the 90th percentile. Plotting birthweight in our population on percentile curves derived from the United States or United Kingdom would generally overestimate small for gestational age newborns and underestimate large for gestational age newborns. We conclude that the diagnosis of clinically significant birthweight abnormalities depends on the fetal growth curve used. A population specific curve of fetal growth dated by ultrasonography would provide a reliable reference for birthweight distribution.