Although there are several good online query systems (e.g. NCHS and MOD), here is one site I’ve found useful for downloading programs related to formatting the NCHS birth data files.
National Bureau of Economic Research
1968-2005 U.S. birth data files from NCHS, but with some formatting done and input programs available. Many other related documents available on this page. A shorter range of years of data files are available for the territories.