Nine months after the declaration of a national emergency due to the emergence of the Covid-19 pandemic, U.S. births fell by 8% in a month.

The December drop marked an acceleration in declines in the second part of the year. For the full year, the number of babies born in the country fell 4% to about 3.6 million, the largest decline since 1973, according to a Wednesday report from the Centers for Disease Control and Prevention.

The latest data are early evidence of the drastic impact from the health crisis on birth rates, with the full effect expected to show in 2021 data.

Births have generally been on the decline in the years since the Great Depression, as Americans have been getting married later and putting off having kids. That’s only grown more pronounced during the pandemic, as people feared going to hospitals and lacked nearby family support because of lockdown restrictions.

The cost of child care is also rising, squeezing already-tight budgets with millions of Americans still out of work.

The December declines were led by states like California, which experienced a 19% drop that month. In the second half of the year, New Mexico, New York, Hawaii and West Virginia also posted substantial decreases, ranging from 8% to 11%.

Coupled with the more than half a million Americans who have died from Covid-19, the drop in births will have long-term consequences for the population growth.

By race, the drop in births in December was most evident among Asian mothers, falling 19% from the same period in 2019. Black and Hispanic births dropped at roughly half that rate, while those among White mothers fell 6%.