Question on H1B visa extension

Dear Sir,

I am from India. I am working in Arkansas with H1 B visa. It is getting expired on Jan 31, 2013. Now i am planning to go on Maternity leave on Dec 5th. My employer told me to apply for my extension from India. My questions are,

Is it possible to start the extension process from US, before i go for my vacation? Will it cause issue in the visa processing?

As my employer told, is it good to start the visa extension process from India?

Please provide me the best possible solution for my visa processing.

Best Regards,