This report presents 2000 data on U.S. births, highlighting maternal demographics (e.g., age, race, Hispanic origin, marital status, and educational attainment); maternal characteristics (medical risk factors, weight gain, and tobacco and alcohol use); medical care utilization during pregnancy women (e.g., prenatal care, labor and/or delivery complications, and delivery method); and infant characteristics (e.g., gestation period, birthweight, Apgar score, and congenital anomalies). Birth and fertility rates by age, live-birth order, race, Hispanic origin, and marital status are presented, as are data by mother's state of residence, birth date, sex ratio, and father's age. Fertility patterns and maternal and infant characteristics are described. Information comes from the birth certificates of 4,059 million births. The number of births rose 3 percent in 2000. Birth and fertility rates rose 1-2 percent. Teenage birth rates fell, while birth rates for all other age groups rose. The number of births to unmarried women, birth rate, and percent of births to unmarried women rose, while birth rates for unmarried adolescents declined. Smoking by pregnant women declined. Cesarean delivery rates rose by 4 percent. For the first time in a decade, the preterm birth rate declined. (Contains 25 tables and 50 references.) (SM)