The following documents would help

1. Letter from the doctor that includes at least the due date and the name of the patient -- for verification purpose

2. Your employment verification letter and copy of bank statement/letter to show your financial ability

3. A nice letter from you to the counselor saying you want them to be here for the joyous occasion (but not for help... i heard the embassy folks don't like to hear that)

4. They can also show their fincial support from Nepal (we did just bank balance and not ghar-jagga lalpurja)

Hope this helps and good luck.

you a PR and you expecting help from non-pr!!!
come on you can do better than this.

Thanks HomLal jee for information. I would prepare documents as you said.
I heard that US embassy seeks property information of visitors to make sure that they have enough in Nepal so that they would return home from the USA. Is it true? And, also a submission of bank statements only would be sufficient to show financial strength of the visitor?

Thanks in advance for your opinion.

Cyp