A fetus is considered previable if it is younger than how many weeks of gestation?

A fetus is classified as previable if it is younger than 24 weeks of gestation. This classification is based on the general medical consensus that survival outside the womb is highly unlikely before this gestational age due to the immature development of the lungs and other organ systems.

At 24 weeks, although there are significant risks and the chances of survival are still not guaranteed, advancements in neonatal care have led to a growing number of infants surviving delivery at this age. Thus, the threshold of 24 weeks serves as an important marker in discussions about viability and medical intervention during pregnancy complications.

In contrast, earlier gestational ages, such as younger than 20 weeks or even 22 weeks, are considered too early for the fetus to have a realistic chance of survival outside the womb, and therefore, those ages do not meet the standard criteria for viability.