I can only assume she meant if a woman miscarries, then God did not mean for that child to be born, and it would not be our place to question that. She clearly stated that only God can decide that.
From the article:
“... and what Lisa meant by saying she was pro-choice was that she was for God’s choice, at least that is what she said in clarification on her Facebook page. “
That’s kind of the way I understood it as well.