No. Feminism does not "encourage" being child-free unless with "encourage" you mean merely "accept".
Feminism does want the freedom for both genders to live their lives according to their own wishes, without being constrained unduly by strongly gendered norms that say that if you're a woman you "SHOULD" want certain things (for example marriage and children) and if you're a man you SHOULD want other things (for example a "career")
But giving people more freedom to live their lives as they see fit, is not the same thing as encouraging them to live their lives in one particular way. @mexbit