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.
Stulberg DB, Zhang JX, Lindau ST.Stulberg DB, et al. Among authors: zhang jx.Matern Child Health J. 2011 Feb;15(2):234-41. doi: 10.1007/s10995-010-0579-6.Matern Child Health J. 2011.PMID: 20177756Free PMC article.