As recently as 50 years ago, babies born before 37 weeks had a slim chance of survival. Now, some preterm babies have survived as early as 21 weeks of age. Each week in the womb boosts a baby's chances of survival, but the fight is still a major challenge to these newborns and their families.
A preterm baby's odds of survival will depend upon several factors, including his weight, rate of development, labor complications and any other risks.
Survival Rate for Late-Preterm Birth
In general, a baby who is born late-preterm, between the 34th and 36th week of pregnancy, has a good chance of survival. According to the March of Dimes, babies born in this stage account for 70% of preterm births, and their odds of survival are excellent. In the United States, these early babies have had excellent survival rates exceeding 90%. Babies born less than two months early usually survive if they receive good medical care, and most do not have any lasting medical problems.
Survival Rate for Mid-Preterm Birth
Babies who are born moderately premature, between 27 and 32 weeks' gestation, have a good chance of survival but usually require intensive care in a neonatal intensive care unit (NICU). These babies are usually very small and have under-developed organs. Survival rates among babies born in this stage rage from 80-95% depending on the week of gestation and the quality of medical care received. However, long-term complications are common and recovery is painful.
Survival Rate for Early Preterm Birth
Babies born between 23 and 26 weeks' gestation have relatively low survival rates, although it has increased tremendously in recent years. The Quint Boeker Premie Survival Organization notes that more than half of babies born at 26 weeks' gestation will survive, but 80% will have a disability. At 25 weeks, the survival rate drops to 50%, while babies born at 24 weeks have a 39% chance. Newborns born at 23 weeks' gestation currently have a 17% chance of surviving. In all these cases, survival is virtually impossible without intensive care.
Survival Rates for Extremely Premature Babies
Before the advent of modern medicine, no babies survived before 23 weeks' gestation. Now, very rarely, some babies can survive and thrive when born this early in gestation, although the road toward recovery is long and painful. Babies born at 22 weeks have a less than 10% chance of survival, while there are only two recorded cases of babies surviving at 21 weeks' gestation. Although survival at 20 weeks is theoretically possible and may occur some time in the future, a 20-week-old preterm baby effectively has a 0% chance of surviving.
If you are pregnant and have any questions about the viability of your unborn baby, or your risk of preterm labor, discuss your concerns with your obstetrician or midwife.