No, I have gone back full time. I worked 12 hour days up to my 38th week of pregnancy. On the back of that I don't think I could convince myself - let alone boss that the role could be done part time.
Thing is I do love my job and I couldn't give it up, and for me personally going part time would feel like too much of a compromise. Although if I have no.2 I think my views may change.
On the support thing, well I think there may be a few things, but I was genuinely interested in others views - hence the thread. 
I think line managers can chose to have a bigger part in this. Although I accept that everyone is different and the maternity laws are tricky. You can feel as a line manager constrained into doing nothing.
Basics, the line manager and direct report need to have a good, postive intent relationship or it won't work.
(Some of the threads on the mumsnet seem to be individuals who have got themselves into a negative pattern 
, they lost contact with work/people and think that the situation is worse than it is. They then tar all of work with the same thought and do not want to contact anyone, they assume negative intent.
So another would be as an indiviudal assume positive intent.
There could be a parents return to work net group in companies, or in nct groups.
I think for certain groups companies could invest in coaches for women returners.
Other women in the company who do have children could talk about thier experiences more openly, the tough decisions they have personally had to make. Role Model
The ex CEO of Coca Cola was a young female with 2 children who resigned saying you can't have it all. Although she is now a non exec of other companies and paid a wedge to present and talk. So it seems maybe you can but just not in the same way!