One of my wife's pediatrics groups was looking over that article yesterday and comparing numbers. A good guess is that we're trading one sort of stress for another.
There were several studies of mental illness associated with gestation during Nazi sieges in Denmark, The Netherlands, Poland and Leningrad. Schizophrenia was way up, but it wasn't revealed until onset (usually 18 and over). I don't remember if there were any assessments about premature labor, though.