By Karen Kaplan, Los Angeles Times (TNS)

The nation’s birth rate rose 1 percent last year as parents in the U.S. welcomed nearly 4 million babies into the world, according to a new report from the Centers for Disease Control and Prevention.

That increase may not sound like much, but it’s the first time the birth rate has gone up in seven years.

The bump in births was courtesy of women in their 30s and 40s, the CDC data show. The birth rate jumped 3 percent for women between the ages of 30 and 39 and 2 percent for women ages 40 to 44.

Women between the ages of 25 and 29 and ages 45 and older had babies at the same rate in 2014 as they did in 2013.

The birth rate fell 2 percent for younger women in their 20s, and it plunged 9 percent for teenagers. In fact, the teen pregnancy rate hit another all-time low of 24.2 births per 1,000 young women between the ages of 15 and 19. That represents a 61 percent decline since 1991, the most recent peak for teen births, according to the report.

Overall, the birth rate — also known as the general fertility rate — was 62.9 births per 1,000 women, according to data compiled by the CDC’s National Center for Health Statistics. That added up to 3,985,924 live births in 2014.

But that wasn’t enough babies to keep the U.S. population steady, the report authors noted. Their calculations showed that a hypothetical group of 1,000 women would give birth to 1,861.5 babies over their entire lives. But in order for a generation to replace itself, those 1,000 women would need to have 2,100 babies. That hasn’t been the case since 2007, the researchers wrote.

Women in nearly all racial and ethnic groups gave birth to more babies in 2014, the CDC noted. The birth rates for whites, African-Americans and Latinas all rose by 1 percent in 2014, and it rose 6 percent for Asian-Americans. The only exceptions were Native American and Alaska Native women, whose birth rate declined 2 percent.

The birth rate for new mothers was slightly lower in 2014 than in 2013, declining by less than 1 percent. However, the rate of second births rose 1 perccent, third births increased 2 percent and the birth rate for additional children grew by 3 percent.

The total number of babies born to unmarried women rose by nearly 9,000 in 2014, up 1 percent compared with the previous year. However, the birth rate for these women actually declined by 1 percent.

The rate of preterm births — those that occurred before 37 weeks of pregnancy — also fell slightly from 9.62 percent in 2013 to 9.57 percent in 2014. In addition, 8 percent of babies born in 2014 weighed less than 5 pounds, 8 ounces and were considered to have a low birth weight, the same as in 2013.

The data in the study came from birth records in all 50 states and the District of Columbia. Ten states contributed incomplete data, and the study authors estimate that their nationwide figures account for 99.7 percent of the births that actually occurred last year.

Photo: Cuties. Aimee Ray via Flickr