Fertility rates have fallen significantly in the United States over the past 10 years, with the biggest declines occurring in large metropolitan areas, according to a data brief released Wednesday by the Centers for Disease Control and Prevention (CDC).

The average age of first-time mothers has increased during that period as well, and the rise has been greatest in large metro areas, the CDC report also shows.

The report doesn’t discuss why American women are having fewer babies and at older ages, but other research has pointed to several possible factors. These include women declining or delaying marriage, often to finish their education and establish their careers.

Teen pregnancies have also been at historic lows in recent years, including in Minnesota.

A recent New York Times survey of a nationally representative group adults aged 20 to 45 found that the top reasons for why people aren’t having as many children as previous generations have to do with wanting more leisure time and personal freedom, not having found a partner yet, and — leading the list — not being able to afford child-care costs.

In fact, four out of the five top reasons cited in the survey for having fewer children had to do with financial worries.

Across all areas

The total fertility rate — the estimated number of births expected from a group of 1,000 women during their lifetime — reached its most recent peak in the U.S. in 2007, the CDC report points out.

The rate has been dropping ever since — and in all areas of the country.

During 2007 and 2017, the total fertility rate fell 12 percent in rural areas (to 1,950 per 1,000 women), 16 percent in small or medium metro areas (to 1,778 per 1,000 women), and 18 percent in large metro areas (to 1,712 per 1,000 women).

The CDC data also shows that as the decade progressed, the difference between the fertility rates of rural and metro areas widened.

In 2007, the total fertility rate for rural areas was 5 percent higher than that of both small/medium and large metro areas. By 2017, that gap had widened to 10 percent with small/medium metro areas and to 14 percent with large metro areas.

“The differences in total fertility rates between rural and metro areas are consistent with previous research describing differences in childbearing behaviors and a higher average number of children in rural areas compared with metro areas,” the CDC researchers write.

The decline in total fertility rates occurred among all races, but the largest drops occurred among Hispanic women. Their rates decreased 26 percent in rural areas, 29 percent in small/medium metro areas and 30 percent in large metro areas.

Older new moms

The average age at which women are having their first child has also increased in all areas of the country during the past decade. New moms in rural areas, however, still tend to be younger (by an average of about three years) then their counterparts in metro areas.

First-time mothers in rural counties were, on average, 23.2 years old in 2007 and 24.5 years old in 2017 — an increase of 1.3 years, according to the CDC report. By comparison, the average age of new moms in small/medium metro areas rose 1.5 years, from 24.3 years to 25.8 years. And in large metro areas, the increase was 1.8 years, from 25.9 years to 27.7 years.

That trend  — having a first baby at a later age — occurred across all races. Black women experienced the greatest increase in average age for a first birth, however, with rises of 1.7 years in rural areas, 1.9 years in small/medium metro areas, and 2.4 years in large metro areas.

FMI: You can read the CDC data brief in full on the agency’s website.