I am Indian, my girlfriend is Chinese and she is pregnant. Delivery due is in 1 month. I will go to China, however I got only a 1-month visa.
Is there any way I can extend to 6 months or more? I know that it is very difficult for me to apply and get a Chinese visa every month.
The only real possibility is to enlist for a language course. There should be a university (and probably several), where you girlfriend lives, that teaches Chinese.
You would need to hurry though, as registration in universities will be around February 28, and Chinese consulates might close for a few days.
Failing that, you have zero chance of extending your visa in-situ, unless you have business connections that can help you get a 6-month or 12-month business visa (good luck with that). And that will be costly too.
