There's something in all that, Xenia. One of my colleagues made so much fuss recently about having a baby you would think she was the first person ever to have done it, frankly, and she clocked off mentally before even going on leave, leaving me and a colleague (me being a brand new person on the team and her boss for 50% of her job) to do half her job for her on top of our own because she was 'so tired' (nothing out of the normal for pg I hasten to add - no major health issues as far as I could tell). I let this go, partly to err on the safe side from a H&S point of view, and partly because because actually it simplified things for me a bit in a roundabout micromanagement sort of way, but I personally think she was a bit daft to lay herself so open professionally.
She then had a big childcare flap and made a big (unnecessary) fuss about flexible working (it's quite routine in my industry), and eventually came back three days a week. She then wanted to have lunch with me, and was angling for a more senior role.
I then gave her a bit of a talking to about professional image, pointed out I have three kids, was pg myself with nobody doing half my workload, and on the whole manage to stay relatively unruffled and on top of my job. I basically explained to her that by going part time, choosing days that suited her and not the demands of the business, without discussing it with colleagues first, she had successfully timetabled herself at short notice out of all the available work that would help her career move onwards and upwards.
I said that if she wanted higher status, she had to sort herself out and decide what she wanted her priorities to be, otherwise she would need to stop moaning about equal opps because it was the (part and full time) people with good time management, team instincts and real commitment and graft who were getting promoted, who were committed to seeing projects through and so on, not just blokes or non-parents.
She took this OK because I am an incredibly family friendly on many levels (eg making arrangements for her to bring her baby to our annual awayday for one of her keeping in touch days, so she was in the loop, but on her own terms) and I think she knew full well she had taken advantage during pg, but there are few employers who can afford to be so frank with female employees without fear of censure.