The U.S. fertility rate has dropped for the seventh year in a row—and Americans are now having so few babies that the population will be sent into decline without immigration, according to new government numbers. The new figures from the Centers for Disease Control and Prevention, released early Thursday, show that the annual rate of births per 1,000 women of childbearing age was 1,765.5, or 16 percent below the number needed to keep the population stable without immigrants. The total fertility rate has been declining year on year since 2010, but the numbers for 2017 represent the biggest drop in recent history, NBC News reports. Experts say the decline is due to changing economics, delays in childbirth by women pursuing jobs and education, the greater availability of contraception, and a decline in teen pregnancies. “It may not be all doom and gloom,” said Donna Strobino, a professor at the Johns Hopkins Bloomberg School of Public Health. “I think it may stabilize once women who have been postponing pregnancy have the births they are planning to have.”