Over half of premature babies born between 23 and 24 weeks of pregnancy will survive delivery and live to see life outside of the NICU. Babies born before 23 weeks may survive - the youngest preemie ever to survive was Amillia Taylor, born at only 21 weeks and 6 days gestation - but 23 to 24 weeks is often considered the age of viability for premature babies.
Premature babies born at 23 to 24 weeks are called micro preemies. They weigh just over a pound and measure about 8 inches long from their head to their bottoms. Babies born at this time will be covered by fine hair called lanugo. Although their eyes will most likely be fused shut, they'll have fully developed eyelashes and brows. They will even have tiny fingernails!
Most of the body's systems are underdeveloped at 23 to 24 weeks gestation. The lower airways are only beginning to develop, so 23-weekers and 24-weekers will need respiratory support for long periods of time.