New numbers out from the Centers for Disease Control and Prevention reveal that fewer women in the United States are having children.

Between 2000 and 2009, pregnancy rates for U.S. women fell by 12%, or nearly 6.4 million pregnancies. The pregnancy rate is the lowest it has been in 12 years.

In fact, the rates for teenage pregnancy reached historic lows in 2009, for all three major race groups: non-Hispanic whites, non-Hispanic blacks and Hispanic teenagers. In 2009, there were 39% fewer teen pregnancies than the 1991 peak rate of 61.8 teen pregnancies for every 1,000 teens.

"Research suggests that more teens are delaying initiating sex, waiting longer to have sex," said Rachel Jones, a senior research associate with the Guttmacher Institute, who was not associated with the study.



"More teens are using more contraceptives and using more effective methods of contraception," Jones said.

But while pregnancy rates for women younger than 30 fell, rates for women older than 30 have increased steadily since 1990. In fact, the number of women between the ages of 35 to 39 becoming pregnant has jumped by 30% since 1990.

"The expectation is that women in their 30s have considered career and education, delaying childbirth till their 30s, so they're making a conscientious decision to become pregnant and have a baby," Jones said.

Abortion rates overall have also dropped since 1990. There were 32% fewer abortions in 2009 than in 1990. The biggest drop was seen in the number of teen abortions. The rate of teen abortions in 2009 was less than one-half the rate it was in 1990.

"A lot of effort and lot of money have been spent on reducing teen pregnancy, and it shows that you can make a change... that when you put the effort in," said Jones.

The CDC also came out with birth rates for the past year. Between June 2012 and June 2013, nearly 4 million children were born. While the number of births has been dropping steadily since 2007, the number of children born this year remained steady since the previous year.