From what I understand, you need to send the following:
1. Invitation letter from you and your husband, citing the reason why you want your relative to come over.
2. Letter from your OBGYN confirming the impending birth of your child.
3. Proof of source of income. Your husband's graduate scholarship/stipend verification letter from his dept.
4. Your bank balance.
5. Photocopies of both of your passports and visa stamps.
6. Photocopies of I-20 and all other related documents.
All this will merely be secondary support materials. The main thing is that your relative will have to show his/her tie to Nepal and prove to the consul that s/he will return without overstaying. Chances are better for your parents, especially new mom's mother.
Good Luck!!!
Nails, you are joking, right? It is alright for
uttaulo Neprican teenager (or wannabe) to be oblivious of the ordeals that new parents have to go through, especially when they are alone, thousands of miles away from home and trying to make do with graduate student stipend. But please try not to be oafishly insensitive about it just to score some points with your equally sophomoric compadres!