If I am an employer in a society where, for each birth, the government mandates six month minimum paid maternity leave. I am hiring for a particular role and have two candidates of equivalent skill with the only difference being one is female and of child-bearing age. Which would you hire? The female may get pregnant and impose two costs on my company: firstly, the cost of maternity leave and, secondly, the cost of finding and training a temporary replacement for a minimum of six months. The rational thing is to hire the male to mitigate this risk since the costs will be lower and productivity assumed to be higher over term of employment.
A better solution is for governments to not force such things but allow companies to negotiate freely with employees. Some may decide to offer extended maternity leave as a differentiator and to attract and retain female talent. But if they do so, they are doing so with coercion and for rational reasons.
I may be wrong, but I think you are double counting the cost of the maternity leave. The cost to the company is the cost of finding/training/paying a temp. The cost of paying the woman her salary while she is gone would have still occurred if she wasn't gone. Or am I missreading? You would include lost productivity due to a less effective temp worker I suppose.
My general response to letting companies negotiate freely is that it seems important, but potentially destructive at it's extreme. I think there should be certain minimum labor standards applied to all employers so that no one employer is at an economic disadvantage by treating their workers humanely. Regarding such minimum requirements including six months of paid maternity leave I'm not sure how I feel.
The issue with minimum labour standards is that you have the question of what happens to people whose value is less than the standard. If you have a minimum wage of five dollars, what happens to the person who, for whatever reason, only produces two dollars of value? They are unemployable and hence never enter the labour market. It would be preferable to let them work at two dollars because, over time, we know that their value increases. One can see this on a global scale in how traditional sources of cheap labour have become more expensive and more skilled over time.
Perfectly sensible for those who have no potential of achieving more but for others who do have potential it seems rather cruel to lock them out of the labour market. Unless an employer is atruistic, they are not going to hire such a person and thereby help them realise their potential because to hire them at minimum wage would result in a net loss.
A better solution is for governments to not force such things but allow companies to negotiate freely with employees. Some may decide to offer extended maternity leave as a differentiator and to attract and retain female talent. But if they do so, they are doing so with coercion and for rational reasons.