My guess is that paid maternity leave has a very big influence on that stat, but you'll never see it written anywhere that it is an influence.
No employer will ever admit to it because they'd be sued to oblivion, but I can tell you as an ex-employer that if I had to choose between a man and a women of equal quals to fill a position, I'd take the man every time because he's gunna cost me less. Sad, but it's reality.
Unfortunately not all businesses have that option.
Whilst we don't know the proposed details of the new laws, my fiancée is against them. She's a realist and can see the reality that she's reaching her child bearing years, and given the choice between her and a guy - why would an employer choose her, all other things being equal? It's actually going to prove to be a huge disadvantage to a lot of women. Unless of course it's government funded, which again is not what this country needs - more people relying on govt. hand outs.
As far as small business is concerned - if they were made to pay for it, it would be crippling in many cases. I haven't had to face this sort of issue yet, but could imagine what it would be like. Not only would the small business need to pay the mother for a proposed 3 months (or more is it?) maternity leave, but at the same time pay someone else to do her job. Then what happens when she decides to come back at some point? The new girl gets the axe? That opens up another whole can of worms.
No wonder small business is hard! Yeah, keep piling on more crap/issues for us to deal with!