著急:請教明白人關於withdraw H-1B petition

I submitted H-1B petition early Sept this year VSC. It is not approved yet. due to personal reason, I am thinking to withdraw that. I was H-4 before I submitted H-1B. Will I resume to H-4 visa automatically after INS receive my withdraw H-1 letter?

Also, if I am not lucky, the INS approved my H-1 just a day before they receive my withdraw letter, what will happen?

thanks a lot!