Pregnancy doesn't really affect your ability to work (except for complications that require bedrest, and even then you work from home). A newborn does require care from the mother, but many women are able to return to work full time after 6 weeks (and some as early as 3 weeks). She'll probably be on leave for a few weeks after baby arrives, but I'm sure she'll be able to keep an eye on things even while she's gone (this is why the night nurse was invented).

A baby and a career are not mutually exclusive, I just wish people would stop assuming that they are.