American women are having fewer and fewer babies, according to a report released Thursday by the Centers for Disease Control and Prevention (CDC).

The national total fertility rate — an estimate of how many babies the average woman in the U.S. will have — was 1.765 (1,765 births per 1,000 women) in 2017, the report says. That’s a drop from 1.820 in 2016, and continues a 10-year downward trend. It’s also the lowest rate since 1978.

The U.S. fertility rate is now 16 percent below the rate — 2.100 — that experts say is needed for the country’s population to replace itself over time without immigration. Only two states, South Dakota and Utah, had fertility rates above that replacement level in 2017, according to the CDC report.

South Dakota had the highest fertility rate (2.227) in 2017, and the District of Columbia had the lowest (1.421) — a difference of 57 percent.

Minnesota’s fertility rate in 2017 was 1.872 — above the national rate, but below the replacement one.

Racial and ethnic trends

For the report, CDC researchers looked at 2017 birth certificate data from all 50 states and the District of Columbia. The certificates included self-reported information on the mother’s race and Hispanic origin.

In addition to the fertility-rate differences among states, the data revealed differences among racial and ethnic groups.

The overall fertility rate among non-Hispanic white women in 2017 was 1.666. The rate for this group did not rise above the replacement level in any of the states, although it almost reached that level in Utah (2.099). The lowest fertility rate among non-Hispanic white women was in the District of Columbia (1.012).

By contrast, the fertility rate was above the replacement level in 12 states for non-Hispanic black women and in 29 states for Hispanic women. Across the entire U.S., however, neither of these groups is having children at replacement levels.

In 2017, the overall fertility rate among non-Hispanic black women was 1.824. It was highest in Maine (4.003) and lowest in Wyoming (1.146).

Among Hispanic women, the overall fertility rate was 2.006. It was highest in Alabama (3.085) and lowest in Vermont (1.200).

In Minnesota, the fertility rate in 2017 was 1.727 among non-Hispanic white women, 2.900 among non-Hispanic black women and 2.168 among Hispanic women. Those rates were all higher than the national ones.

Not necessarily a negative thing

The CDC report does not speculate on why the U.S. fertility rate is declining, but other experts have pointed to several possible reasons, including greater access to contraceptives, a decline in teen pregnancy and women starting their families at later ages.

In addition, attitudes regarding the ideal family size appear to be changing. In a 2013 survey, almost half of Americans said that two is the best number of children for a family.

The CDC report also doesn’t comment on whether a shrinking population is a good or a bad thing for the country. Some economists have argued that decreasing populations lead to increasing standards of living.

FMI: The CDC report can be read in full online.