That means we are more likely to be expected to make career and life sacrifices in order to have a family.
Career sacrifices fair enough, but life sacrifices? To many people being a wage slave is not necessarily a good life, and it has been shown repeatedly that a lot of women prefer having a healthier work-life balance than men do.
Managers will expect women with children to take off more time for things like doctor's appointments and will (perhaps unwittingly) take that into consideration when doling out promotions etc.
A majority of women tend to put their children as a higher priority than work (there is more to life than work). If managers notice this tendency in an employee, how is it a problem putting the person more dedicated towards work first?
Raising kids is hard work, sacrifice, expensive and life-long. If you can't even hack the process of finding the person who wants to try to do it with you, what does that say?
A lot of guys are willing to take the time and effort. But the risks and lop-sidedness if the woman decides to leave at a whim can be too high. A growing number of men are becoming aware of the increasing risks involved in partnering with a woman, and after a certain point the risks are not worth the reward.
Quite a few men are willing to try regardless of the risks of course, but in the cases where it doesn't pan out they are often left destitute to the point of suicide. To some people that risk is worth the reward, to others, it's not worth their life.