Figure 9. Secular trends in population attributable risk% of preterm delivery before 37, 32, and 28 weeks among multiple births.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.