Atlanta ? Bucking the trend in many other wealthy industrialized nations, the United States 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 U.S. 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 U.S. births was the highest since 1961, near the end of the baby boom. An examination of global data also shows that the United States 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 U.S. 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 percent higher than the U.S. 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,”‘ said Nan Marie Astone, associate professor of population, family and reproductive health at Johns Hopkins University.

Demographers say it is too soon to know whether 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,” said Brady Hamilton, a statistician with the Centers for Disease Control and Prevention.

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 U.S. 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.

Clearly, U.S. birth rates are not what they were in the 1950s and early 1960s, when they were nearly twice as high and large families were much more common. The recent birth numbers are more a result of many women having a couple of kids each, rather than a smaller number of mothers each bearing a higher number of children, Astone said.