Earlier quoted context omitted.
A sabbatical can be long (and is not "vacation time" or "sick leave") because by default it's unpaid. So it's in the developer's interest as well for the manager to figure out a way to reshape his/her job to make it sustainable (and thus keep the paychecks coming) rather than just saying "uh, sure, go deal with your problems, take as long as you need; when you run out of money we'll still have your job here for you."…
> Plus -- "first newborn in the house" is something that causes upheaval for maybe 6 months or so, and then life settles down again. Ha! That's fine until they get to 8 months and stop sleeping through the night again (which apparently is a common thing). A few weeks of chronic sleep deprivation can absolutely destroy your ability to do anything vaguely brain-work-related.
I have two kids, 3 and 6. The second was hard, but we knew what were getting into, largely, and how to survive it. The first was... rough.
I'm not sure about sleeping through the night stuff -- we did the co-sleeping thing, which helps a lot! But still, by 8 months I'll bet the parents would have some strategy in place -- maybe "hey, tonight's your night to wear earplugs" coupled with strategic naps.