COMPARISON OF BIRTH-WEIGHT BY GESTATIONAL-AGE BETWEEN CHINA AND THE UNITED-STATES

Objective To probe into the similarities and differences of birth weig ht by gestational age between China and the United States by a compara tive study. Methods For China, we used the records of 2 4150single liv ebirth neonates. These records were collected between February 1986 an d May 1987 from 43 hospitals and health care units in 15 large and mid dle cities in the South and North of China. For the United States, we used the natal records of National Center for Health Statistics from 1 980 to 1987, selecting infants whose parents were coded as white and w ith higher socioeconomic back grounds in the birth records. A total of 6 295 102 singleton livebirth neonates were selected. We used a metho d based on probability plots to define birth weight distributions. Res ults The 50th and 95th percentiles of birth weights by gestational age of American newborns with white parents were more than those of Chine se newborns. The 50th percentile values of birth weights of American m ale and female newborns were 357 g and 277 g (about 10% and 8% respect ively of the birth weight of a term newborn) more than those of Chines e male and female newborns respectively at 40 weeks of GA. Conclusions American white newborns were heavier than Chinese newborns. The diffe rences were mainly due to race-specific influences, and were related t o the differences in socioeconomic and educational background. We sugg est that the references of birth weight by gestational age should be f ormulated separately in China and in the U.S..