Monica is right: PRENATAL vitamins do NOT make your hair grow faster anymore than taking regular vitamins would. The hormonal changes during pregnancy sometimes make a woman's hair grow faster. It has nothing to do with taking vitamins, which are simply taken to ensure a healthy mother and child.
Here is a link to a site debunking this myth:
http://www.hair-news.com/hair-grow-faster.shtml ANY vitamin supplements (even Flintstone chewables) will help you overcome deficiencies, which is in turn can lead to healthier hair (and more importantly, a healthier YOU.) There is nothing special about PRE-NATAL supplements.
Hope this helps! :-)