U.S. births declined 1% in 2016 to 3.94 million, according to a new report by the Centers for Disease Control and Prevention. Birth rates for women under age 30 fell to record lows while rates for women in their 30s and 40s rose. The Cesarean delivery rate fell for the fourth year in a row, to 31.9%, the lowest rate since 2006. The percentage of infants born before 37 weeks of gestation rose for the second year in a row, to 9.8%, after falling since 2007. The low birthweight rate also rose for the second straight year.