the economy is a big factor.

However, “you get to the point where the biological clock starts ticking and people realize they have to do it,” said Trussell, who was not involved in the research.

The new report on births was issued Tuesday by the Centers for Disease Control and Prevention. It’s based on a review of more than 99 percent of birth certificates for the year 2008 – the first full year of the recession.

Overall, the number of births declined 2 percent from 2007. It’s the first annual decline in births since the start of the decade.

Experts say the most likely explanations are the recession and a decline in immigration to the United States, which has been blamed on the weak job market.

Some early birth information for the firstsix months of 2009 indicates a continuing decline of about 3 percent in total births, CDC officials said.

Last summer, the agency gave a first glimpse of the 2008 numbers. The new report confirms the birth rate decline, and also gives a breakdown of births by age group.

The new report found that birth rates fell by 3 percent for women in their early 20s, 2 percent for women in their late 20s, and 1 percent for women in their 30s.

The trend in those numbers indicates that the older women got, the less willing they were to postpone a birth, said the new report’s lead author, Brady Hamilton of the CDC’s National Center for Health Statistics.

The teen birth rate dropped 2 percent – and the rate for Hispanic teenagers was