March 23 (UPI) -- The birth rate in the United States dropped 1% between 2018 and 2019, continuing a six-year downward trend, according to figures released Tuesday by the Centers for Disease Control and Prevention.
Just under 3.75 million births were registered nationally in 2019, down from 3.79 million the year before, the data showed.
The birth rate among women ages 15 to 19 years fell by 4% from 2018 to 2019, while births among women ages 20 to 29 dropped by 2% over the same period.
Only women ages 40 to 44 years saw an increase in birth rate over the two-year period, with births increasing by 2%.
"The mean age of mothers at first birth was 27, and increase from 26.9 in 2018, and another record high for the nation," CDC researchers wrote in the new report.
"The increase in the mean age in 2019 reflects, in part, the decline in the number of first births to females in their teens and 20s," they wrote.
The birth rate in the United States has declined every year since 2014, the agency reported.
"Our prediction is that the birth rates will continue to decline for several years in high-income countries such as the United States, further accelerating population aging," child health expert Dr. David Gozal told UPI in an interview.
"In general, longevity has increased while fertility has declined resulting in an increase in the proportion of the older people," said Gozal, pediatrician-in-chief at University of Missouri Women's and Children's Hospital in Columbia, who was not part of the CDC analysis.
Data on the birth rate in the United States in 2020 is not yet available. However, Gozal and others expect that it declined further last year because of the COVID-19 pandemic.
"The unique circumstances imposed by the pandemic are likely to affect the total fertility rate, particularly in developed economies, where the population susceptibility to economic changes appears to exert increased impact on reproductive decisions," Gozal said.
"The inaccessibility to childcare outsourcing services during COVID-19 pandemic could also impact the birth rates to some extent," he said.
The CDC report is based on 100% of the birth certificates registered in all 50 states and Washington, D.C. More than 99% of births across the country are registered, according to the agency.
The percentage of babies born preterm, or less than 37 weeks into pregnancy, rose 2% from 2018 to 10.2% in 2019, the agency reported.
As in 2018, just over 8% of babies born in the United States had low birth weight, placing them at high risk for health complications.
That figure is among the highest in the world, according to data from the World Health Organization.
"The rate of prematurity increasing and the unchanged rate of low birth weight are indicative of the poor social healthcare measures available for preventive care in the United States," Gozal said.
"We definitely need to institute a healthcare coverage system that will universally provide care to all pregnant women at no cost to them," he said.