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.
Taylor RN, Casal DC, Jones LA, Varma M, Martin JN Jr, Roberts JM.Taylor RN, et al. Among authors: casal dc.Am J Obstet Gynecol. 1991 Dec;165(6 Pt 1):1705-10. doi: 10.1016/0002-9378(91)90019-n.Am J Obstet Gynecol. 1991.PMID: 1750464