Fertility Rates Drop to Lowest Level Measured in the US, Says the CDC Population data shows women are having children later in their lives.

 -- Fertility rates in America — the number of babies born per 1,000 women ages 15 to 44 — are at the lowest levels ever recorded, according to researchers in a new report from the U.S. Centers for Disease Control and Prevention.

The findings are based on population data from the CDC that track birth and fertility statistics dating back to 1909. This does not indicate there are more infertile women; rather it means that fewer babies are being born to women of likely childbearing age in the U.S. Measuring the fertility rate is viewed as a more accurate measure than overall birthrate, which compares babies born with the total U.S. population.

The fertility rate decreased from 60 births per 1,000 women in the first quarter of 2015 to 59.8 per 1,000 in the first quarter of 2016. This means there are on average fewer than six babies born for every 100 women in this age group. In 2010 there were 6.4 births for every 100 women in the group. This follows a trend in recent years of declining birthrates in the U.S., with general fertility rates declining more than 10 percent since 2007.

This is the first time the CDC is releasing the fertility rate data quarterly instead of annually, in an effort to understand more trends from this data and provide better information to public health and other medical officials.

The "report is trying to give us a picture of what is happening to fertility among U.S. women by specific characteristics, in particular by age," said Donna Strobino, a professor of population, family and reproductive health at Johns Hopkins University.

The report also found a continued decline in birthrates for women ages 15 to 29 and a drop in teen birthrates. The birthrate for those 15 to 19 declined from 22.7 per births per 1,000 women in the first quarter of 2015 to 20.8 births per 1,000 in the first quarter of 2016.

While teen pregnancy is decreasing, the birthrate among women 30 to 44 is increasing, from 95.6 per 1,000 women in the first quarter of 2015 to 97.9 per 1,000 for the same period this year — part of an ongoing trend.

Strobino pointed out that the findings reflect demographic changes in general.

"The good news is that infertility treatment has allowed women to extend the age of childbirthing, going along with a lot of trends we are seeing in increasing age of marriage, increasing education levels and increasing labor force participation," she said. "The bad news is the complications associated with aging that have to do with an increase in chronic diseases as women age, increase in pregnancy-induced complications and increase in complications for the fetus and newborn."

Lauren Rossen, a senior service fellow at the CDC's National Center for Health Statistics and the lead statistician for this report, said the center hoped releasing the information quarterly will help with surveillance.

"We have focused on indicators that are important for public health surveillance and to public health practitioners, public health researchers and the broader community," she said.

ABC News' Gillian Mohney contributed to this report.