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 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," 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.
But the higher fertility rate isn't all good. Last month, the CDC reported that America's teen birth rate rose for the first time in 15 years.
The same report also showed births becoming more common in nearly every age and racial or ethnic group. Birth rates increased for women in their 20s, 30s and early 40s, not just teens. They rose for whites, blacks, Hispanics, American Indians and Alaska Natives. The rate for Asian women stayed about the same.
Total births jumped 3 percent in 2006, the largest single-year increase since 1989, according to the CDC's preliminary data.
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 several children, Astone said.
Demographers say there has been at least one boomlet before, around 1990, when annual U.S. births broke 4.1 million for two straight years before dropping to about 3.9 million in the mid-1990s. Adolescent childbearing was up at the time, but so were births among other groups, and experts aren't sure what explained that bump.
The 2006 fertility rate of 2.1 children is the highest level since 1971. To be sure, the fertility rate among Hispanics -- 3 children per woman -- has been a major contributor. That's the highest rate for any group. In 2006, for the first time, Hispanics accounted for more than 1 million births.
The high rate probably reflects cultural attitudes toward childbirth developed in other countries, experts said. Fertility rates average 2.7 in Central America and 2.4 in South America.
Fertility rates often rise among immigrants who leave their homelands for a better life. For example, the rate among Mexican-born women in the U.S. is 3.2, but the overall rate for Mexico is just 2.4, according to the Pew Hispanic Center, a Washington-based research organization.
"They're more optimistic about their future here," said Jeff Passel, a Pew Center demographer.
Some complain that many illegal immigrants come here purposely to have children.
"The child is an automatic American citizen, thus entitled to all benefits of American citizens. This gives a certain financial incentive for people coming from other countries illegally to have children here," said John Vinson, president of the Virginia-based American Immigration Control Foundation.
Fertility rates were also relatively high for other racial and ethnic groups. The rate rose to 2.1 for blacks and nearly 1.9 for non-Hispanic whites in 2006, according to the CDC.
Fertility levels tend to decline as women become better educated and gain career opportunities, and as they postpone childbirth until they are older. Experts say those factors, along with the legalization of abortion and the expansion of contraception options, explain why the U.S. fertility rate dropped to its lowest point -- about 1.7 -- in 1976.
But while fertility declines persisted in many other developed nations, the United States saw the reverse: The fertility rate climbed to 2 in 1989 and has hovered around that mark since then, according to federal birth data.
Hans-Peter Kohler, a University of Pennsylvania sociology professor, and others say the difference has more to do with culture than race. For example, white American women have more children than white European -- even though many nations in Europe have more family-friendly government policies on parental leave and child care.
But such policies are just one factor in creating a society that produces lots of babies, said Duke University's S. Philip Morgan, a leading fertility researcher.
Other factors include recent declines in contraceptive use here; limited access to abortion in some states; and a 24/7 economy that provides opportunities for mothers to return to work, he said.
Also, it is more common for American women to have babies out of wedlock and more common for couples here to go forward with unwanted pregnancies. And, compared with nations like Italy and Japan, it's more common for American husbands to help out with chores and child care.
There are regional variations in the United States. New England's fertility rates are more like Northern Europe's. American women in the Midwest, South and certain mountain states tend to have more children.
The influence of certain religions in those latter regions is an important factor, said Ron Lesthaeghe, a Belgian demographer who is a visiting professor at the University of Michigan. "Evangelical Protestantism and Mormons," he said.
