In the course of a generation, the information available to families regarding the health and future of their unborn children has been transformed. In the era of our parents and grandparents, even the number of babies to be born was a mystery. Following delivery of the first baby, careful checking for the appearance of another head or foot was routine. The arrival of the second twin made for a crowded bassinet in the back seat of the car on the way home, as well as hasty modifications to the cot, sleeping arrangements and siblings’ expectations