This is also a continuum, not a step function as writers of law might wish. As of 2016, the chance of survival for a premature birth in the following weeks was cited as:
| Week | Survival |
|---|---|
| 22 | 6% |
| 23 | 26% |
| 24 | 55% |
| 25 | 72% |
This assumes first-world neonatal care. A 2019 reference cited a survival rate of 30% for births at 22 weeks with intensive care, although 33% of those born at 22 weeks who survive have severe disabilities.
In 2014, a baby was born in San Antonio, Texas at 21 weeks 4 days weighing 410 grams. As of 2018, she was attending preschool and other than delay in speech, exhibited no known medical problems or disabilities.