Preterm delivery trends by maternal race/ethnicity in the United States, 2006-2012.

PURPOSE: To estimate changes in preterm delivery (PTD) in the United States from 2006 to 2012 by clinical circumstance, timing of delivery, and race/ethnicity.

METHODS: We used vital statistics natality data on all singleton live births from the 18 U.S. states continuously using the 2003 birth certificate from 2006 to 2012. We estimated change in PTD overall and by clinical circumstance (spontaneous vs. medically indicated) and delivery timing among all women and by race/ethnicity, using descriptive and multivariable regression methods.

RESULTS: Overall, indicated, and spontaneous PTD declined by 10.31%, 8.40%, and 11.52%, respectively. Late-preterm, early-term, and post-term deliveries decreased substantially (12.13%, 18.37%, and 32.20%, respectively), with simultaneous increase (13.57%) in full-term deliveries. Non-Hispanic white, non-Hispanic black, and Asian/Pacific Islander women experienced larger declines in PTD compared with Hispanic and American Indian/Alaska Native women. Non-Hispanic white women experienced larger declines in late and medically indicated PTD, while non-Hispanic black women experienced larger declines in early and moderate and spontaneous PTD.

CONCLUSIONS: Overall, spontaneous, and indicated PTD declined from 2006 to 2012. Declines were lower than previously reported and differed substantially by race/ethnicity.