A story of two miracles: the impact of the discovery of insulin on pregnancy in women with diabetes mellitus.

Before the discovery of insulin in 1921, pregnancies in women with diabetes mellitus were a rarity because most reproductive-age patients died soon after diagnosis of this illness. In the limited number of pregnancies reported in the pre-insulin era, both perinatal and maternal mortality were approximately 50%, with stillbirths being the primary cause of perinatal deaths. Insulin treatment restored the fertility of women with diabetes and was associated with a marked reduction in maternal mortality. Women with more severe disease had the opportunity to become pregnant; however, their pregnancies frequently resulted in neonatal death due to prematurity. Therefore, perinatal mortality was not substantially reduced.