It seems to be the acting profession in particular that contains many of the women who have children after forty. There could be reasons for that; not many female characters on film or television are written as pregnant, and therefore becoming pregnant rules you out of a lot of parts. Add to that the fact that you don't make money when you're not working, and it's easy to see why a lot of people wait.
Mary Stuart Masterson can be added to that list of names from the acting world; she already had one child with her first husband before she was forty, but when she married fellow actor Jeremy Davidson in 2006, she went on to have no less than three children with him, with the first arriving when she was 43. A year later, at 44, she became pregnant again; this time with twins! Now in her early 50s, she has three children under 10 years old.