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.
Trentham-Dietz A, Nichols HB, Egan KM, Titus-Ernstoff L, Hampton JM, Newcomb PA.Trentham-Dietz A, et al. Among authors: nichols hb.Epidemiology. 2007 Sep;18(5):629-38. doi: 10.1097/EDE.0b013e318127183a.Epidemiology. 2007.PMID: 17700252