A womanazier rich man dies, and in heaven he claims everybody loves him and he died by mistake, he gets another chance and comes back on earth as a woman, he has to find one woman who loves him truly in order to stay. He is having great trouble wt exgirlfriends who did not love him... but finally after a drunk-onenight stand he(she) gets pregnant...
What is the title? I think it's a 80-90's movie.

Sounds a bit like Heaven Can Wait?

The Heaven can wait something similar. But this movie is newer, much newer. And I forget to say that the caracter has to find a woman who loves him (her) truly.. and at the end of the movie when her baby born, she has a daughter so that will be the woman who loves her truly and he can stay on earth in the second (woman) body, that's how the movie ends.

Maybe this?:
Switch (1991) - IMDb