Oral glucose tolerance tests were performed during late pregnancy, on the second and fifth days of the puerperium and finally six weeks after delivery in a group of 12 healthy women. The glucose response showed no significant change from the pregnancy values on the second and fifth days of the puerperium but each woman had returned to 'normal' by the sixth week post partum. In contrast, the insulin response had returned to the non-pregnant value by the second day of the puerperium.