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.
Network forest plot of results of combined oral contraceptives with 30 μg ethinylestradiol versus those with 20 μg ethinylestradiol.
Two doses of ethinylestradiol were included in network: 20 mg and 30 mg). The size of the SMD dots are proportional to the precision of the estimate (one per s.e.). SMD, standardised mean difference.
