Change of status H4 to H1B

[nikv]

My wife has h1b approved but not stamped on passport yet. Currently she is india and got her H4 visa stamped on passport. She is planning to enter US on H4 and then apply for change of status to go back to H1B. What are the chances of getting approval ? . She took a break from a job for 6 months to take care of baby , that is the reason we are hesitant to go for h1b stamping in India.

please advice.