THURSDAY, Jan. 14, 2016 (HealthDay News) -- The average age that American women have their first baby continues to rise, U.S. health officials reported Thursday.
From 2000 to 2014, the age of first-time mothers increased 1.4 years -- from 24.9 years old on average to 26.3 years, according to a new report from the U.S. Centers for Disease Control and Prevention.
While age at first birth has been inching up for some time, "we have seen sharper increases since 2009," said lead author T.J. Mathews, a demographer at the CDC's National Center for Health Statistics (NCHS).
Two key trends lie behind these significant statistics. "The largest impact has been the decline in first births to women under 20," Mathews said. "There has also been an impact of older women having births."
Economic factors, more interest in higher education and greater career choices may play a role both in reducing teen births and prompting some women to put off motherhood until after 30, he suggested.
All states and the District of Columbia reported delays in motherhood since 2000. Washington, D.C., saw the highest increase -- 3.4 years -- followed by Oregon where the average age rose 2.1 years, the researchers found.
Delaying parenthood can have broad implications for maternal and child health as well as population growth, Mathews said.
"The average is going up for mothers, which is likely to delay childbearing, and if you delay you are more likely to have fewer births, and that has ramifications for our overall population," Mathews said.
"You need 2.1 births per couple to replace the population over the long term," he added. "The U.S. is right on the cusp of replacement."
Also, the mix is changing, Mathews explained. "There is a higher fertility rate among Hispanics than among whites," he said.
The fertility rate among whites in 2013 was 1.7 -- below the 2.1 births needed to replace that group, Mathews said. Among Hispanics the fertility rate is 2.1, he said.
According to the report, first births among teens fell 42 percent since 2000 -- from about one in four to one in seven. Also, first births to women aged 30 to 34 rose 28 percent, while first births among women 35 and older increased 23 percent.
In 2014, Asian or Pacific Islander women had the oldest average age for their first birth (29.5), while American Indian and Alaska Native women had the youngest (23.1).
Differences were seen among blacks, whites and Hispanics, too. For white women in 2014, average age at first birth was 27; for Central and South Americans it was 26.5, and for women of Cuban descent it was 27.
Also, the average age was lower for Puerto Ricans (24.1 years), blacks (24.2) and Mexican Americans (23.7), Mathews said.
Dr. Jennifer Wu, an obstetrician/gynecologist at Lenox Hill Hospital in New York City, said the drop in teen pregnancies is a positive trend.
"For the most part teen pregnancies are unplanned," she said. "And teen pregnancies can have poor outcomes, and most teenagers aren't ready to have a baby," Wu added.
Wu is concerned, however, about older women having babies. "As they delay pregnancy, women are incurring other risks," she said. "An older mother has a higher risk of gestational diabetes, pre-eclampsia and other complications, including passing on genetic defects."
The full report is published in the CDC's January NCHS Data Brief.
For more on birth statistics, visit the U.S. Centers for Disease Control and Prevention.