The first major milestone is 24 weeks: the threshold of viability. Babies born this early will…

The first major milestone is 24 weeks: the threshold of viability. Babies born this early will likely spend at least three months in the neonatal intensive care unit (NICU), and a third of them will survive with no long-term problems.

The second milestone is 28 weeks, when viability skyrockets. Ninety percent of babies who make it to this stage of gestation survive. Long-term complications — including cerebral palsy, vision and breathing problems — are still a possibility, however.

The next milestone is 32 weeks to 34 weeks. Babies born now generally have an excellent chance of survival, without any major long-term complications, though they might not have full lung maturity and will need to spend time in the NICU. Some babies born at this stage may require oxygen to help them breathe, while others may need to be fed through a nasogastric tube (which runs through the nose into the stomach). “Super-twins” (triplets or more) almost always spend time in a NICU, but if you can get past that 32-week mark, chances are excellent that the babies will be healthy.

The following milestone is 37 weeks, when your babies will have full lung maturity and should be able to leave the hospital within a few days of delivery.The final milestone is 39 weeks, when your babies will be considered full-term at delivery