paid leave (
congé maternité) : The standard rule is 16 weeks (6 before and 10 after) for the first kid.
more here - I assume you have some basic knowledge of French, otherwise you'd better get some before you move
unpaid leave (
congé parental d'éducation) is maximum 3 years
here
Generally speaking lots of support for working mothers (creche and nanny expenses are tax-deductible)
It's not unusual that mothers work part time 4 days a week, Wednesday off.