Timing of indicated late-preterm and early-term birth

Abstract

The growing public health awareness of prematurity and its complications has prompted careful evaluation of the timing of deliveries by clinicians and hospitals. Preterm birth is associated with significant morbidity and mortality, and affects more than half a million births in the United States each year. In some situations, however, a late-preterm or early-term birth is the optimal outcome for the mother, child, or both owing to conditions that can result in worse outcomes if pregnancy is allowed to continue. These conditions may be categorized as placental, maternal, or fetal, including conditions such as placenta previa, preeclampsia, and multiple gestations. Some risks associated with early delivery are common to all conditions, including prematurity-related morbidities (eg, respiratory distress syndrome and intraventricular hemorrhage) as well as maternal intrapartum morbidities such as failed induction and cesarean delivery. However, when continuation of the pregnancy is associated with more risks such as hemorrhage, uterine rupture, and stillbirth, preterm delivery maybe indicated. In February 2011, the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the Society for Maternal-Fetal Medicine held a workshop titled "Timing of Indicated Late Preterm and Early Term Births." The goal of the workshop was to synthesize the available information regarding conditions that may result in medically indicated late-preterm and early-term births to determine the potential risks and benefits of delivery compared with continued pregnancy, determine the optimal gestational age for delivery of affected pregnancies when possible, and inform future research regarding these issues. Based on available data and expert opinion, optimal timing for delivery for specific conditions was determined by consensus.

Figure 1

Conceptual diagram representing the competing risks and benefits of indicated late preterm or early term birth vs. pregnancy continuation. The figure does not represent specific magnitudes or rates of changes in risks as these will vary according to the specific pregnancy complication and individual circumstances. Neonatal morbidity and mortality decreases with advancing gestation, these are typically related to prematurity. For these deliveries in the late preterm or early term period, maternal morbidity and mortality generally are higher as a result of prolonged or failed induction and resultant cesarean deliveries. Potential maternal consequences of continued pregnancy in the setting of complicated conditions, maternal morbidity and mortality are related to hemorrhage, hypertensive crises and uterine rupture. Continued pregnancy in these settings also can result in fetal morbidity and mortality due to stillbirth and uteroplacental insufficiency.