Sheryl Sandberg, the COO of Facebook, misses a key factor in becoming a parent when she suggests that employers should be able to ask female employees about their family plans.
Employees who add a child to their household have a greater burden to provide for their family than employees who do not have to take care of someone else. Many young women I have hired are more focused than ever upon returning to work -- they have another mouth to feed and a child to educate. I've even seen older employees who begin to care for aging parents become much more committed to their job with the additional healthcare expenses they take on.
I do think it is sensible for all employees, both male and female, to inform their employer in a reasonable amount of time of an impending pregnancy leave. Employees should also announce their intended time frame for returning from maternity or paternity leave so that the management can plan accordingly.
However, truth be told, we have seen so much more production loss from divorce rather than new babies. Babies are a finite amount of loss and a renewed sense of need to support. Divorce for both males and females is at least a year adjustment period where depression and denial inevitably result in a loss of focus. Understanding that, should we ask potential employees whether or not their relationship is stable?