(CNN) -- The birth rate for women over 40 in the United States rose between 2007 and 2009. Among every other age group, however, the birth rate fell during the same period, according to a report released by the Centers Disease for Control and Prevention.
According to the study, women between 40 and 44 experienced a 6% increase in birth rate during the time period. There were 9.5 births for every thousand women in that age group in 2007, 10.1 births per thousand in 2009.
Younger mothers had more babies per thousand women during the time period, however, birth rates declined for every age group under 40, according to the study released Thursday.
The study also found that after reaching an all-time high of 4.3 million births in 2007, the number of babies born in the United States dropped 4% to 4.1 million in 2009. A provisional count taken between 2009 and June 2010 indicated a continued fall in births, the CDC said.
Fertility rates also dropped for all major racial groups in the United States during the study period. The largest decline was among Hispanic women, for whom birth rates declined 9 percent between 2007 and 2009.
The decline in births from 2007 to 2009, the report stated, "is relatively small in a historical context compared with the declines in the early 20th century and in the 1960s and early 1970s."
The report was prepared by researchers in the CDC's National Center for Health Statistics, Division of Vital Statistics, Reproductive Statistics Branch.