Fig. 1.
Flow chart of the clinic study and follow-up of the study participants.
a, 878 singletons and 182 twins. b, 138 singletons and 18 twins.
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.