GESTATIONAL-AGE AND INTRAUTERINE GROWTH-RETARDATION AMONG WHITE AND BLACK VERY-LOW-BIRTH-WEIGHT INFANTS - A POPULATION-BASED COHORT STUDY

Very low birthweight (VLBW) is a commonly used endpoint in perinatal e pidemiology, but the population of VLBW infants comprises a wide range of gestational ages and rates of fetal growth. We used data from a po pulation-based study of all 1072 black and white VLBW liveborn infants born in 29 counties in Georgia between April 1986 and March 1988. Les s than 1% of the VLBW infants were greater-than-or-equal-to 37 weeks g estation; most were 29-32 weeks (26%) or 25 to 28 weeks (40%); 12% wer e 22 weeks or less. All infants 33 weeks gestation or greater were gro wth retarded. The population of VLBW infants seems to comprise three g roups: approximately 11% very immature infants of 22 weeks or less; th e majority of infants, born between 23 and 30 weeks, 90% of which are of normal weight for their gestational age; and a group of less premat ure, growth-retarded infants from 31 to 36 weeks. We found little or n o difference in the distribution of gestational age or the percentage of intrauterine growth rates (IUGR) between black and white infants. I n the USA the VLBW rate among black infants is over three times greate r than that among white infants and consequently the rates of the thre e types of VLBW among black infants are likely to be triple those amon g white infants.