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Story highlights

CDC releases quarterly data from 2016

US fertility rate has been in a steady decline since post-World War II baby boom

(CNN) —  

The US fertility rate fell to the lowest point since record keeping started more than a century ago, according to statistics released by the Centers for Disease Control and Prevention.

In 1909, the government began keeping track of what’s called the fertility rate. The general fertility rate is the number of births out of 1,000 women between the ages of 15 to 44.

In the first three months of 2016, the fertility rate in the US fell to the lowest level. The rate was 59.8 births per 1,000 women.

The first quarter of 2015 had seen similarly low rates at 60 births per 1,000 women.

The US fertility rate has been in a steady decline since the post-World War II baby boom. Back at its height in 1957, the fertility rate was 122.9 births per 1,000 women.

The latest quarterly CDC data also indicate the larger pattern of women having babies later in life.

As birth rates increased among women in their 30s and 40s, the rate among teenagers and women in their 20s dropped.

Another report by the CDC in January found that the age of mothers rose in the United States. The average age when women had their first child increased from 24.9 in 2000 to 26.3 in 2014.

What this means for US population

Although the fertility rate is decreasing, that doesn’t necessarily mean the US population is going to shrink. The rate of growth may be slower, but the population is still expected to increase.

The U.S. Census Bureau took the falling fertility rate into account and still projected that the population would go from 319 million in 2014 to reach 400 million by 2051.