Space & Innovation

Median Age of First-Time US Moms Rises to 26

First births to mothers in their 30s are also rising, as women increasingly pursue careers before having children.

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.

There are fewer teen pregnancies and more women are seeking to establish careers before having children.

Dads often get a bad rap in the animal kingdom, but many animal moms engage in behavior that would never be celebrated in a Mother’s Day card. Here, we highlight just a few, beginning with this mustachioed mom. Female mustached tamarins sometimes kill their babies. “Genetic analysis enabled us to show that the mothers themselves take the lives of their own offspring,” said Yvan Lledo-Ferrer, an Autonomous University of Madrid researcher who co-authored a study on the primates. Lledo-Ferrer, however, explained that mothers perpetrate infanticide that have poor prospects for survival due to the social make-up of particular groups. Nevertheless, it's pretty horrific. The moms sometimes just pick up an infant and toss it to the ground from a tree branch high above the forest floor.

Like a chimp mom version of Bonnie and Clyde, sometimes chimpanzee mothers cooperate with their daughters to kill other chimps. In the 1970s, noted primatologist Jane Goodall documented this behavior in Passion and Pom, a deadly mother/daughter murdering duo. She and her team observed them killing and cannibalizing at least two infant offspring of other females. Simon Townsend and colleagues of the University of St. Andrews, Scotland, believe that the killings result when females are under pressure to compete for foraging areas. Not all female chimpanzee mothers and daughters do this, as the peaceful-looking pair in this image shows.

Some zebra finch mothers like to fool around. There is some equality here, as male zebra finch dads can do this too. “This means a male and a female will hang out together as a couple; they will build nests together and share other forms of bonding,” Wolfgang Forstmeier, a researcher in the Department of Behavioral Ecology and Evolutionary Genetics at the Max Planck Institute for Ornithology, told Discovery News. “They may also, however, engage in extra-pair mating behavior.” As if that isn’t bad enough for the offspring, Forstmeier’s investigations found that promiscuous behavior can be inherited. “The study provides a good explanation for what we see in humans,” Forstmeier said. “Statistics have shown that promiscuous parents are more likely to sire sons and daughters with a greater tendency to cheat.”

Mothers sometimes risk their own lives for the sake of their children. When times are tough for female kangaroos, however, they may sacrifice their offspring. This can happen when kangaroo mothers have three or so young at different stages of development: one in the body, one in the pouch, and one that lives mostly outside of the pouch. A starving or otherwise physically stressed female kangaroo may leave the older infant to his own devices and ditch the pouch, leading to the possible death of multiple offspring at a time.

In the case of lions, it is not so much what they do that’s bad, but what they don’t do. When a dominant male takes over a pride, he may kill numerous cubs less than 2 years old to rid himself of competition. The lioness allows this to happen, and even may go into heat, permitting the takeover male to start his own family with her.

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Giant panda moms don’t mean to be bad, but sometime they cannot help it. Weighing up to 280 pounds, these large mammals have incredibly tiny offspring. At birth, most cubs typically weigh just 3.5 to 7 ounces. Giant panda mothers have been known to squash their infants by stepping on them or rolling over them in their sleep.

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The pregnant seahorse shown here is actually a male. Seahorses are another example of animal mothers being bad not for what they do, but what they don’t do. In this case, males take care of nearly everything, with pregnancies being exceptionally physically challenging, as this photo suggests. “The most advanced form of male parental care is found in the seahorses, where a brood pouch has evolved that resembles a placenta, and male seahorses even go into labor,” Peter Teske, a postdoctoral researcher in Macquarie University’s Molecular Ecology Lab, told Discovery News.

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Queens and workers of the appropriately named Dracula ant chew holes into the colony’s own larvae, feeding on the insect’s “blood.” The behavior is technically called larval hemolymph feeding. It surprisingly does not kill the larvae, but it doesn't help them much either.

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Many sharks consume members of their own species, and Galapagos sharks are no exception. Hungry shark mothers are not too picky. If one finds a small shark to eat, it’s usually dinner time before any further investigation takes place to see if the small shark is a relative.

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Humans seem to include some of the best and worst mothers in the animal kingdom. Joan Crawford, for example, was the subject of "Mommie Dearest," a book that alleges she emotionally and physically abused at least two of her children. The book was made into a popular movie of the same name starring Faye Dunaway. Crawford, however, appeared to suffer from her own personal problems, despite her movie fame. Another daughter of hers expressed sadness about her mother’s difficult life. The good news is that most mothers -- be they human or not -- treat their offspring tenderly, ensuring successful future generations.