My feelings do not differ from those on general abortion.
Any woman who wants an abortion is a woman who should not be then made to have that child.
The act of NOT wanting to carry, birth or raise a child, is all that qualifies someone to abort.
Because being a child raised by someone who does not want to do that, or does not feel able to do that, is not something any child should have to live with.
Specifically on aborting a fetus late, because you've discovered late on they may be affected by a disability - still yes, because does anyone SERIOUSLY believe a disabled child needs to live their life either in care because the parent cannot cope or does not want to cope, or with a parent who cannot cope, or does not want to cope?
Heidi is an amazing young woman, she clearly copes with her Down Syndrome very well and isn't as severely affected as some, she also very evidently has an incredibly capable and supportive mother.
Not everyone is that lucky, and not every parent is able to face the prospect of being a child, and then an adults, full time carer, until they or the child, die -and that IS the reality for some parents of disabled children.
And note, I say all this as a disabled person with an inherited condition.