Which inventions of the 20th century had the greatest positive impact on human lifespan?

It would be hard to argue against vaccinations or antibiotics, which have combined to limit or eliminate many life-threatening diseases throughout most of the world, such as polio, tuberculosis, and bacterial infections. Improved labor and delivery practices have significantly cut down maternal and infant morbidity rates. Electricity and synthetic fertilizers have also played key roles in establishing safe and plentiful food supply chains. There are many other examples as well.