I think one of the reasons our DX came as such a shock was that we didn't have any real issues with DS before he started school, so if anything we probably confound all theories that ASD children can present with symptoms in babyhood. Admittedly I don't yet have any other children of my own to compare DS to (I will be with Nyrrem in trying not to over-analyse the baby years once our second child arrives this autumn) but he seemed no different to any of the children we socialised with.
We are seeking a second opinion on our DX because the issues only manifest themselves at school and we just want to be 100% sure - but having said that I do observe my DS in school a lot and admit that he does show ASD traits there, so in many ways I am expecting the original DX to be confirmed.
So if I work on the basis that he definitely IS ASD/Aspergers he blows all theories out of the water. Breastfed easily, took bottles easily, weaned to solids and lumpy foods easily, slept through night from 9 weeks and napped well during the day, was happy and smiling, loved peep-bo type games and mirrors too, could take him anywhere, played in the same way that all the other babies his age seemed to be playing, fabulous eye contact, very sociable, went through normal developmental stages of separation anxiety. No sensory issues as a baby though developed fear of loud noises as he moved into toddlerdom; no repetitive behaviour; no developmental concerns, really. He was later to use the 'shared point' than other babies (15 months) but from that age he was always sharing interest, and his language developed normally.
The only things I could pinpoint would be some grumpier behaviour prior to crawling and walking, which we put down to frustration as DS was later to crawl (11 months) and walk (16 months) than many of his peers. And I definitely used to have to get 'out and about' with him more than some of my friends did with their children - he was always one of those babies that would get really crotchety and bored if you tried to stay at home for a whole morning, for example, and found toddler groups hard for the same reason - he'd enjoy activities for maybe 20 minutes and then ask to go.
Maybe that was a sign of discomfort in a social situation - he'd be whinging and stropping and asking to leave, but as soon as we were back in the car or buggy he'd be content again and happy and laughing. He was also very reluctant to get involved in many of the 'arty' type activities on offer at these groups, which could well have been a pre-warning of the fine motor writing/drawing/cutting issues he has now. I guess at the time I just put it all down to his being a boy and wanting to be on the go (and so many friends said 'oh well he's a boy they are often not interested in drawing etc they just want to be out and about') but perhaps it was a sign, now I look back.
But he certainly didn't present with anything that made us worry. And even now it is only school where issues arise, he is very outgoing and happy and cheerful everywhere else. Just goes to show I suppose how different they can all be.