There's also that "personal" moment during the Destiny Rules documentary where Lindsey and Stevie work on this song together. Could be because it is a song about their (aborted? miscarried?) child.
I do not think that Stevie ever got pregnant on purpose, and if she could have had a child in the 90s I do not think she would have blamed her lack of a child on klonopin so much.
And, because I am a shipper... If Kristen and Stevie were both pregnant with Lindsey's child at the same time, I do not think that Lindsey would have chosen Kristen.
I think it's very possible that if Stevie really did terminate four pregnancies, one of them was probably Lindsey's.