Sexism once you have a child

I'm feeling conflicted.  Less than 2 weeks till I go back to work and there is part of me that is excited to be getting back into the workplace and using my brain but the other half is concerned that other people will be looking after my little man.

I think this is a conflict that every woman faces.  It does make me wonder with the changes to parental leave legislation whether men will start to face this conflict too.  It's made me realise that at the heart of sexism and pay differentials in the workplace, there is partly a choice; partly imposed upon women as the main carers of children.  It annoys me intensely that current flexible working legislation means it's very easy for an employer to say "no" to someone asking for flexible working simply because they manage people.  This means as women are the main child carers, that many women decide to change jobs rather than return full time.  So do women decide to get paid less?  Yes, in a way.  Does that make it right?  No.

Another thing which has been on my mind is that I found out a former job was advertised (before I took it) at between £5000 and £10,000 p.a. more than I was paid.  I'm a bad negotiator but I do wonder whether I'm not the only woman who is.