Hi Eponine,
My husband and I are both thal minor and knew this prior to getting pregnant. I know your question is directed at majors, but I think I fit in this category.
I knew our odds of having a thal (We went to a genetic counselor,we researched etc...). To be honest, it's not that I thought "it couldnt happen to me", but I wanted a child with my husband so badly, that we decided what ever GOD had in store for us, we would accept it.(Easy for me to say now,.....I was devestated when i first found out.) I still have my moments.
My OBGYN offered us a cvs test when I was 12 weeks pregnant, to see if Lauryn was thal, and I declined. I declined, b/c I knew if she was thal, I wouldnt get an abortion anyway, so why did I need to know during my pregnancy? So I can stress out and risk harm to her and myself? ( I already had extremely high blood pressure, and pre-term contractions.)
Anyway, to answer your question, we did plan Lauryn and wanted her so badly regarless. She was concieved out of pure LOVE, and she will always be reminded of that.
I would do it all over again.(with Lauryn I mean)
LOL No more kids for me!!!!!!!!!