The teen birthrate in the U.S. reached another record low last year, with signs that there may not be much room left for improvement, the Centers for Disease Control and Prevention said in a report published Thursday.

Teen birthrates fell 3% in 2022, the report found — a smaller decrease than in previous years. Since 2007, the teen birthrate has decreased about 8% per year. The smaller decline last year could indicate the nation is reaching a plateau thanks to years of progress, experts say.

“If there are a lot of states where the rates are already low, they bottom out. They can’t get any lower,” said the report’s lead author, Brady Hamilton, a statistician and demographer at the CDC’s National Center for Health Statistics. Hamilton noted that the data in the new report are provisional and will be updated once the final numbers for 2022 are available.

Access to both contraception and comprehensive sex education has driven the sharp decrease in teen births, which are down nearly 80% from what they were in the early 1990s.

“Declining birthrates, especially among those in their teens and early 20s, is a good thing, because a lot of these pregnancies are unplanned,” said Karen Guzzo, the director of the Carolina Population Center at the University of North Carolina, Chapel Hill. “This means people are having babies when they want to.”

For many people, that means having children later in life.

Birthrates in women ages 35 to 39 rose 2% in 2022, the report found. For women ages 40 to 44 — who have had near-continuous increases since 1985 — the birthrate rose 4%. Women ages 45 and up had an even greater increase in birthrate, at 12%, though the overall number of births to women that age remained low.

Waiting to have kids is a trend across all nations with low or moderate fertility rates, such as most of Europe, said Joshua Goldstein, the director of the Berkeley Population Center at the University of California, Berkeley.

That’s usually a good thing, but researchers are left with questions about why it is happening.

“It probably means that more women are having children when they want to have children.  They’ve had chances to get better education, better chances to find the right partner, more chances to excel in their career,” Goldstein said.

The CDC report included data from more than 99% of birth records for babies born in the U.S. last year. It found that overall, the birthrate declined by a marginal amount, less than 1%, in 2022.

Aside from a small uptick in 2021, the number of babies born in the U.S. has been falling steadily since 2007. Since that year, birthrates have consistently been below the rate needed for a generation to replace itself.

Goldstein said he isn’t concerned that not enough people in the U.S. are becoming parents.