ATLANTA — Bucking the trend in many other wealthy industrialized nations, America seems to be experiencing a baby boomlet, reporting the largest number of children born in 45 years.

The nearly 4.3 million births in 2006 were mostly due to a bigger population, especially a growing number of Hispanics. That group accounted for nearly one-quarter of all American births. But non-Hispanic white women and other racial and ethnic groups were having more babies, too.

An Associated Press review of birth numbers dating to 1909 found the total number of American births was the highest since 1961, near the end of the baby boom. An examination of global data also shows that America has a higher fertility rate than every country in continental Europe, as well as Australia, Canada, and Japan. Fertility levels in those countries have been lower than the American rate for several years, although some are on the rise, most notably in France.

Experts believe there is a mix of reasons: a decline in contraceptive use, a drop in access to abortion, poor education, and poverty. There are cultural reasons as well. Hispanics as a group have higher fertility rates — about 40% higher than America overall. And experts say Americans, especially those in middle America, view children more favorably than people in many other Westernized countries.

“Americans like children. We are the only people who respond to prosperity by saying, ‘Let’s have another kid,'” an associate professor of population, family, and reproductive health at Johns Hopkins University, Nan Marie Astone, said.

Demographers say it is too soon to know if the sudden increase in births is the start of a trend.

“We have to wait and see. For now, I would call it a noticeable blip,” a statistician with the Centers for Disease Control and Prevention, Brady Hamilton, said. Demographers often use the word boomlet for a small and brief baby boom.

To many economists and policymakers, the increase in births is good news. The American fertility rate — the number of children a woman is expected to have in her lifetime — reached 2.1. That’s the “magic number” required for a population to replace itself.

Countries with much lower rates — such as Japan and Italy, both with a rate of 1.3 — face future labor shortages and eroding tax bases as they fail to reproduce enough to take care of their aging elders.

But the higher fertility rate isn’t all good. Last month, the CDC reported that America’s teenage birth rate rose for the first time in 15 years.