The average age of first-time mothers is rising in the United States, and reached 26.3 years of age in 2014, according to US government data out Thursday.
In 2000, women on average became mothers at the age of 24.9, said the National Center for Health Statistics.
The report updates a previous version which tracked ages of mothers back to 1970, when the average age of a US woman's first birth was 22.
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Researchers say changes in the age of motherhood are important because having children later in life can affect overall family size and population growth.
Women's ages at childbirth are also "associated with a range of birth outcomes, such as multiple births and birth defects," it said.
The main reason for the rise in average age at first birth is a sharp decline in teen pregnancies. First births to mothers under 20 dropped 42 percent from 2000 to 2014.
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Today, about one in seven of these first births is to teenagers. In 2000, the figure was one in four. First births to mothers in their 30s are also rising, as women increasingly pursue careers before having children.
"From 2000 to 2014, the proportion of first births to women aged 30?34 rose 28 percent (from 16.5 percent to 21.1 percent)," said the report.
Meanwhile, first births to women 35 and over rose 23 percent in those 15 years.
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Still, it is relatively rare for women to have their first child when they are older than 35, making up just nine percent of all first births in the country.
When the numbers were crunched according to ethnicity, Asian or Pacific Islander mothers "had the oldest average age at first birth in 2000 (27.8 years) and 2014 (29.5 years)."
The youngest mothers tended to be American Indian or Alaskan native, at 21.6 years in 2000 and 23.1 years in 2014.