Ruari, what country are you referring to that has government mandated maternity leave rights? In the US we have parental leave (not limited to women) in all but the smaller businesses (I think small may be 50 employees or less but I could be wrong about that).
Responding to your other comments, 'who knows why' less women in IT, this has been well documented for decades with the 'hard stats' you are looking for. Statistically speaking (and again not true of any given individual), females do not perform as well as a group on mathematical-spatial relationship thinking as males. This increases dramatically around puberty. It is known that this ability is directly related to and developed by physical movement. From infantcy, parents tend to restrict movement of female children to a greater extent than males, so at this point it's impossible to tell how much of the initial difference is genetic. Normally brains do not vary dramatically in development in later years (except in rare cases like recovery from brain damage), so the dramatic difference at puberty is related directly to socialization, when females tend to take over the role of telling themselves it's inappropriate for a female to appear smart, competitive, or math-&-science-inclined. This self-censorship is much more effective in retarding interest that censorship by others. The only places where females continue to improve in those skill areas are all-female schools.
Also I won't go into the details but the fact that females often can and do give birth does not (statistically) increase the amount of time they are away from work at a given job nor increase the number of job changes. It was true in the 50's when the stay-at-home-Mom became the new symbol of middle-class-American wealth. (Incidentally, the number of prescriptions written for tranquilizers and mood-enhancers increased during that period, i.e. the Beatles reference to "a little yellow pill" as "Mother's little helper"

. But it has gradually decreased and by the 80's or 90's there was actually a greater percentage of females than males in the workforce in total.
BeckahC, if you do not want to give up your career when you have children, and you can't afford good daycare, you might want to talk to your husband about him staying home with the kids for awhile. The very few men who have told me they did this were absolutely blown away by the new perspective it gave them on life, and their relationship with their children, and found they had no repercussions with employers later.