Simmer_89 a RAR is a type of compressed archive like a ZIP file, it requires software to extract and use the files. There is a comprehensive list of RAR software in this thread: http://www.insimenator.org/index.php/topic,27964.0.html
There are some rather dry and technical reasons why there is no pregnancy morph in the bodybuilder family of meshes. Not the least of which is that there is no easy way to make pregnany morphs for custom meshes, the tools just don't exist for that.