Perhaps the existential anxiety was already there and has kept them from working towards a family? Look at a history of births and you see a major drop-off in W

Perhaps the existential anxiety was already there and has kept them from working towards a family? Look at a history of births and you see a major drop-off in WW2, a period where it really felt like the world could end, literally people anxious over their continued existence. Take away the War, and you get a baby boom.