S.T.
I'm going to tell you something about my own situation, many years ago, and I don't know if it will help you or not. My first natural child was born almost 50 years ago, when we were in Germany -- my husband had a fellowship there. Of course there was no such thing as ultrasound, although the doctor had wondered why my baby seemed so small. She had a condition called D-trisome, genetic, although not inherited. The syndrome included cleft lift and palate, club feet, no retinas (blind), deaf because of missing parts of the ear, heart defects, and on and on. Everyone was amazed that she lived and got to 6 pounds so we could take her out of the hospital and then back to the US. She died at home and in my arms when she was 2 1/2, peacefully, after a smallpox vaccination which had been necessary due to other circumstances. Although I have always regretted any pain she may have suffered, she enriched the lives of our family and friends and her influence lives on today in the work I do for disabled access. Her birth made any bit of smugness I might have ever felt about my other children's abilities and talents disappear. To this day, I ask myself if we would have chosen abortion if we had known. And to this day, I don't know the answer. As I said, I'm sure she felt some pain. So that was the downside, and if she had been able to speak, I don't know if she would have preferred not to have existed at all, rather than to have the life she did. So sometimes I think it is a selfish thought that I'm glad that she was my daughter, even for that short time, and that I think of her life as a blessing to our family and friends.
After you learn more, maybe you can make your decision based on what it means for your child's life. If it's just the one condition, it seems like a minor issue. If I had known what was in store and decided to abort, I think I could have lived with the decision, although I think our family might have been different, and maybe poorer, for it.