Just birth date

Yep, set this with the wcbcf_billing_fields filter.
Good luck.

Thank you, Claudio, very much, I was looking for something like this.

Ok, I will try, thank you.
Is it possible to add more options in this field?

Yep, with this: https://docs.woothemes.com/document/tutorial-customising-checkout-fields-using-actions-and-filters/