Periviable Birth and the Shifting Limit of Viability.

Periviable birth carries a high risk of fetal and newborn death, and the potential for life-long complications in survivors. The family at risk for periviable birth should receive objective, accurate, and up to date information regarding fetal, newborn, and maternal risks and outcomes with delivery or with continued pregnancy. This article describes the various descriptive terms for delivery near the limit of viability, considers the evolving limit of viability over time, and highlights the importance of adjusted counseling with brief pregnancy prolongation and/or changing clinical circumstances within the periviable period.