Written by Sabrina Tavernise

The birthrate declined for the sixth straight year in 2020, the federal government reported Wednesday, early evidence that the coronavirus pandemic accelerated a trend among American women of delaying pregnancy.

Early in the pandemic, there was speculation that the major changes in the life of American families could lead to a recovery in the birthrate, as couples hunkered down together. In fact, they appeared to have had the opposite effect: Births were down most sharply at the end of the year, when babies conceived at the start of the pandemic would have been born.

Births declined by about 8% in December, compared with the same month the year before, a monthly breakdown of government data showed. December had the largest decline of any month. Over the entire year, births declined by 4%, the data showed. There were 3,605,201 births in the United States last year, the lowest number since 1979. The birthrate — measured as the number of babies per 1,000 women ages 15 to 44 — has fallen by about 19% since its recent peak in 2007.

The declining birthrate is just one piece of America’s shifting demographic picture. Combined with a substantial leveling-off of immigration, and rising deaths, the country’s population over the past decade expanded at the second-slowest rate since the government started counting in the 18th century. The pandemic, which pushed the death rate higher and the birthrate even lower, appears to have deepened that trend.

Kenneth Johnson, a demographer at the University of New Hampshire, has calculated that together with the rise in deaths — up by about 18% from 2019 — the drop in births is contributing to the aging of the American population: A total of 25 states had more deaths than births last year, Johnson said, up from five at the end of 2019.

“The birthrate is the lowest it’s ever been,” he said. “At some point the question is going to be: the women who delayed having babies, are they ever going to have them? If they don’t, that’s a permanent notch in the American births structure.”

Births tend to dip after economic crises, as women put off having babies because of uncertainty with jobs and income. The birthrate dropped sharply in the early 1930s after a stock market crash precipitated the Great Depression. But it picked up a few years later, once the economy started to bounce back. However, the recent decline, which began after the Great Recession in 2008, has continued, despite improvements in the economy. This unusual pattern has led demographers to wonder whether something else is going on.

A woman awaits the arrival of guests to her baby shower in Orange, N.J., on Nov. 15, 2020. (Alice Proujansky/The New York Times)

“It’s a big social change in the US,” said Alison Gemmill, a demographer at Johns Hopkins Bloomberg School of Public Health who studies fertility. “A gradual shift of family formation to later ages.”

Births declined across all age groups in 2020, except among women in their late 40s and girls in their early teens, groups that were tiny fractions of total births. The birthrate was down by 8% among teenagers, compared with 2019, and by 6% among women ages 20 to 24. The rate among women in their early 20s is down by 40% since 2007, the government said. Teenagers have had the sharpest decline, down by 63% since 2007, the data showed.

That is a dramatic change from several decades ago, when rates of unintended pregnancy were high, particularly among teenagers, and American women tended to have babies earlier and more frequently than women in much of Europe. Today the average age at first birth is 27, up substantially from 23 in 2010.

“I’m far too young to be responsible for a child,” said Molly Sharp, 25, who works for a women’s health research group at East Tennessee State University in Johnson City. “I’m still learning about myself and being an adult. There’s just no way I could take on that responsibility of having a kid right now.”

Sharp, who got engaged in December, has been with her fiancé, now a medical student, for about seven years. She said she had also been deterred by the rising costs of having a child — from day care to college — and the knowledge that she and her fiancé would have a large amount of debt from his medical school to pay off. She said that her ideal age to have a child would be in her early 30s and that she could not imagine having a baby before the age of 30.

“None of my close friends are having kids,” said Sharp, who was just accepted into graduate school. “We are working jobs and figuring out what we are doing but don’t have plans much past five years.”

It is only recently that parenthood has been considered a choice at all. Caroline Sten Hartnett, a sociologist at the University of South Carolina, pointed out that before the advent of birth control pills on a national scale, in the late 1960s, women had much less control over their fertility. In 1950, they had, on average, three children. At today’s rates, women have around 1.6, a level that demographers call “below replacement” because it signals that today’s generation of parents may be producing a generation of children smaller than itself.

That the rate has gone down is not necessarily bad, Hartnett said. One factor driving the decline is a drop in unintended pregnancies, and some people may simply be delaying childbearing to older ages. In other words, some share of American women may eventually have the number of children they want but simply at later ages.

“It could be good news if women feel like they have more control over their fertility,” she said. “But it is not good news if having a child is just becoming harder than it was because jobs are more precarious and families just can’t make it work in a minimally functional way.”

Tess Jackson, 28, an English teacher from Hurricane, West Virginia, has experienced both. She has a 10-year-old, the result of an unplanned pregnancy in high school. But birth control got better, she said, and for years, she did not have another. Recently, she and her partner decided that they did not want another child, and she got sterilized.

“My mom and my grandmother could not imagine having an adult life without having children,” she said. “Now there is less of a social requirement to have them. There are other options on the table.”

The generational change has been profound. Angie Willis, 57, a retired schoolteacher from West Virginia, said she had her first child when she was 20 in 1983. She went to college — driving nearly two hours each way from rural West Virginia to a university in a different part of the state — but said she did not get to experience college life because she had to care for an infant.

“I was a baby,” she said, remembering her years as a young mother.

Her daughters are different. Her youngest, who is 29, went away to college and now has a master’s degree and works in information technology at a large hospital in Charleston, West Virginia. She got married last summer and does not have children.

“I am glad that they have waited and gotten their careers going first,” Willis said of her daughters. “It’s a good change.”

She said that her youngest, Cortney Jones, “is getting to live her life.” “And being more mature, being sound financially,” she added. “That’s a big deal.”

Jones got married last summer and said she wanted to enjoy time with her husband before shifting her attention to a child. She loves going for runs, traveling to see friends on weekends and working without feeling frantic to get to a day care pickup.

“I’m feeling a little bit selfish,” Jones said. She said only one of her friends had a child.

“Everybody in my friend group is saying, ‘When is the right time to let go of that selfishness?’” she said. “We are all putting it off.”