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.
Age-specific reproductive rates declined over time. Dark shades (warm) indicate high reproductive rates, and light shades (cool) indicate low reproductive rates. Reductions in age-specific reproduction with time (a fertility transition) are visualized as isoclines that decrease on the y axis (age) with increased birth year x.
