An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
van der Poel N, Farquhar C, Abou-Setta AM, Benschop L, Heineman MJ.van der Poel N, et al.Cochrane Database Syst Rev. 2010 Nov 10;(11):CD006225. doi: 10.1002/14651858.CD006225.pub2.Cochrane Database Syst Rev. 2010.PMID: 21069687Review.