Q: My Thai girl friend ask me to do the love contract. Is that normal in Thai ?

I am in short-term relationship with my Thai girl friend. In short , she told me that she is pregnant with no prove at all. So , she wants me to do the contract which I have to pay her 35,000 THB per month for 10 years. I mean should I do it . Is this usually happen in Thailand ? Can I refuse to do so ? Is this can be affecting my VISA ?