The CDC recently released the final numbers on births in the US in 2012.
Almost four million babies were born in 2012. The birth rate for both teenagers and women in their early twenties declined significantly this year.
The report also found that more births occurred outside of a hospital than in over two decades.
Joyce A. Martin, MPH, and colleagues from the Center for Disease Control and Prevention (CDC) Division of Vital Statistics wrote the report.
The report examines the data on the number of births, fertility rates, and maternal and infant health characteristics in 2012. The data is based on all of the birth certificates that the 50 states and Washington, D.C. registered.
The researchers found that 3,952,841 babies were born in 2012, which is about 700 fewer than 2011.
The fertility rate for women aged 15 to 44 years old was 63 births per 1,000 women.
The teenage birth rate in 2012 was 29.4 births per 1,000 women aged 15 to 19, a six percent decrease from 2011. According to the CDC, the teenage birth rate has been declining since 1991.
The birth rates for women in their early twenties was 83.1 births per 1,000 women, down three percent from the year before. The authors of the report noted that the rate of births among this group has declined by about 5 percent each year since 2007. The 2012 figure is a record low in the US.
Since 2011, the rate of women giving birth in their thirties has increased by one percent for women 30 to 34 and two percent for women aged 35 to 39.
In 2012, the average age of mothers having their first child was 25.8 years old, up 0.2 years from 2011. In 1970, the average was 21.4 years old.
This year 98.6 percent of all US births took place in a hospital, and doctors attended 85.8 percent of births. Of the 50,000 births that occurred outside of a hospital, about two-thirds occurred in a home and most of the rest occurred at a birthing center.
According to the CDC, more births took place at home than before 1989.
32.8 percent of births were delivered by cesarean, a procedure in which incisions are made through a woman's abdomen or uterus to deliver a baby. The authors of the report noted that from 1996 to 2010, cesarean deliveries rose from 20.7 percent of births to almost one-third.
11.55 percent of babies were born pre-term, before 37 weeks. 7.99 percent were born with a low birthweight, which has been linked to health issues. 131,024 twins were born in 2012, or 33.1 per 1,000 births.
The CDC released the report on December 30.