Preterm birth is the most common cause of death among infants worldwide.[1] About 15 million babies are preterm each year (5% to 18% of all deliveries).[2] Approximately 0.5% of births are extremely early periviable births, and these account for most of the deaths.[13] In many countries, rates of premature births have increased between the 1990s and 2010s.[2] Complications from preterm births resulted in 0.81 million deaths in 2015 down from 1.57 million in 1990.[7][14] The chance of survival at 22 weeks is about 6%, while at 23 weeks it is 26%, 24 weeks 55% and 25 weeks about 72%.[15] The chances of survival without any long-term difficulties are lower.[16]