I agree with alle01 and secretme.
The assumption that if the baby had defects and you could not do anything about it anyway is False. Read secretme's post.
Dd1 had multiple anomalies picked up at 13 weeks. She was scanned every 2 weeks until she was term (she is right handed BTW). I was offered a termination, I was offered CVS - I took it. My pregnancy was entirely easy physically but the emotional stress and rollercoaster of repeated scans and uncertain diagnoses and treatments would test anyone.
She was born with a major heart defect in a medically managed way that ended up with my having a crash cs.
BUT she had a bed in NICU and was monitored from birth, stressful too in terms of feeding, weight gain obsession etc.
Medical advancements are such that she had surgery at 4 months and I have a beautiful healthy daughter with no damage to her heart, just a zipper scar on her chest.
If I did not know her condition, she would have in all likelihood gone into irreparable congestive heart failure before doctors picked it up. She was asymptomatic right up till her surgery, but when they opened up her chest, her heart was already very strained.
Did I think the worry was unnecessary. Some of it, yes. Would I go through it again? Definitely. Did I refuse tests/scans for ds - absolutely not.
I have a phobia for needles too. I had all my bloods, I just looked away. Since when is it a right for women to have a worry-free pregnancy - it is not an 'experience' you book. I wonder how many men take the same attitude to screening tests with their wife's pregnancy?
If something was wrong, wouldn't you want to know and be prepared, if not for yourself at least for the sake of the baby. Granted there are false diagnoses, but the downside is just unnecessary worry and perhaps a more medically managed birth than necessary. The downside could equally have been much much worse, particularly if something could have been done earlier.