Does leaving US with H1B pending jeopardize my processing

Hi, I am on H4 and have applied for H1B with COS and it is under initial processing. I have planned a vacation to India for 3 weeks and plan to return by 28th August 2013. I also have to appear for H4 stamping in India. Does leaving US with H1B pending affects my H1B processing and also What affects will my H4 stamping have on my H1.

Your COS from H-4 to H-1 will be abandoned, but your H-1 petition will continue to be processed. You can return on H-4 visa and will have to file for separate COS from H-4 to H-1 in order to work on H-1. The other option is to enter US on stamped H-1 visa.