DS1 had a ventouse delivery. I was warned to be gentle with him, as he may have a headache (as though I wasn't going to be gentle with my first newborn, lol!)
DS reached his milestones early...smiled at three weeks, proper laughing at 5 weeks, rolling over just before he was 4 months, walking at 11 months, started recognising numbers at 18 months, and recognised numbers to 20 by his second birthday, rhyming before he was 2, and reading familiar words such as Next and Gap, etc by 2.5.
When he was 4yo, we discovered he had poor eyesight, and the sight in one eye was so poor, it just hadn't developed. His eye was patched for two years, and he's now a +6 in that eye. Yes, I did wonder if the ventouse delivery had caused this. His optometrist told me that was absolutely not the case, though.
DS is also on autistic spectrum (Aspergers), Before he was diagnosed, I did attribute his behaviour to his difficult birth.
And it was a difficult birth, but without the ventouse DS1 and I would probably both have died.
I think there was a link recently between ventouse and autism, which I personally took no notice of. Just another stick for mothers to beat themselves with, if you ask me.