Perhaps not a contradiction in itself, but I'm not sure how a feminist woman defines her own gender as 'woman' in those cases where she adamantly supports the idea that it's people who get pregnant and menstruate and so on.

Once your gender (woman) has nothing to do with your biological sex (female), which must be the case in the above example, how is that gender defined? You are a woman, because you like pink and sparkles? Makeup and high-heeled shoes? Feel feminine and submissive and passive? Or what?

The contradiction here is that once you relinquish the connection between biological sex and the gender 'woman' then the bottom of much of feminist activism falls away. That's because the oppression women experience is sex-based, not gender-based, on the whole.