Using data from the National Vital Statistics System, the agency closely examined births among white, black and Hispanic women, and found the country's overall fertility rate fell to 59.1 per 1,000 women aged 15 to 44 — a 2% drop from the previous year.
Fertility rates declined 2% for white and black women, and 3% for Hispanic women.
Teen birth rates also hit record lows. According to the report, teen birth rates fell from 18.8 per 1,000 teens aged 15 to 19 to 17.4.
Researchers further noted teen births dropped by 4% for black teens, and 8% for white and Hispanic teens.
Fewer babies were delivered to full-term, or under 39 weeks, as well. And the percentage of preterm births climbed from 9.93% in 2017 to 10.02% in 2018, according to the report.
That increase in preterm births, according to March of Dimes chief medical and health officer Dr. Rahul Gupta, may be linked to a rise in women in their late 30s and 40s giving birth. Gupta told CNN in May that "the continuing shift toward increased maternal age at first birth is something that does increase the risk, [but] does not fully explain the increase in the preterm birth rate. ... There is a lot more work that needs to be done as the preterm birth rate continues to rise."
The National Center for Health Statistics in January reported the U.S. rate had already dipped below what's necessary for the human population to replace itself.
Read the full report at CDC.gov.