My cousin is a U.S. citizen. He is male. I’m female. I live outside of the U.S. My cousin and his wife have fertility problems, and they asked me if I could be a surrogate for them. I agreed. Now the plan is: I come to the U.S., get IVF in a fertility clinic, and go back to my country. For the next 9 months I will carry their biological child, and then when the child is born, my cousin and his wife will come to my country to take the child back with them to the U.S. 

Question: what visa should I apply to go to the U.S. for IVF fertilization procedure. I will probably need 1-2 months.