Effects of Maternal Age and Age-Specific Preterm Birth Rates on Overall Preterm Birth Rates - United States, 2007 and 2014.

What is already known about this topic? Rates of births to teens and of preterm births declined in the United States from 2007 to 2014. Preterm births are more common among the youngest and oldest mothers. What is added by this report? Preterm birth rates declined for all age groups and overall from 10.41% to 9.54% of live births. Mean maternal age increased from 27.4 years to 28.3 years. The contribution of fewer births to teens and to women aged 20-24 years to the overall decline in preterm births was offset by increases in births to older mothers. What are the implications for public health practice The changing distribution of maternal age might indicate success of programs to prevent teen and unintended pregnancies. Effective public health strategies for further reducing preterm birth rates need to be tailored to different age groups.