Elective Cesarean Section: Its Impact on Neonatal Respiratory Outcome

Abstract

The transition from a fluid filled lung to one filled with air in a very short period of time is one of the biggest challenges a newborn faces after birth. Respiratory morbidity as a result of failure to clear fetal lung fluid is not uncommon, and can be particularly problematic in some infants delivered by elective cesarean section (ECS) without being exposed to labor. The increasing rates of cesarean deliveries in the United States and worldwide, have the potential for a significant impact on public health and health care costs due to the morbidity associated with this subgroup. Whereas the occurrence of birth asphyxia, trauma, and meconium aspiration is reduced by elective cesarean delivery, the risk of respiratory distress secondary to transient tachypnea of the newborn, surfactant deficiency, and pulmonary hypertension is increased. It is clear that physiologic events in the last few weeks of pregnancy coupled with the onset of spontaneous labor are accompanied by changes in the hormonal milieu of the fetus and its mother, resulting in preparation of the fetus for neonatal transition. Rapid clearance of fetal lung fluid is a key part of these changes, and is mediated in large part by transepithelial sodium reabsorption through amiloride-sensitive sodium channels in the alveolar epithelial cells, with only a limited contribution from mechanical factors and Starling forces. In this chapter we discuss the respiratory morbidity associated with ECS, the physiologic mechanisms underlying fetal lung fluid absorption and potential strategies for facilitating neonatal transition when infants are delivered by ECS before the onset of spontaneous labor. The changing landscape for human deliveriesCesarean births rose for an tenth straight year in 2006 to a record 31.1% of all deliveries in the United States; this rate is more than 50% higher than in 1996 and is accompanied by a significant drop in the number of women attempting vaginal birth after a previous cesarean delivery (VBAC). 56 ( Fig. 1) Most of the overall increase can be attributed to the increase in the primary cesarean rates, from 14.6% in 1996 to 20.3% in 2005. This rise in the primary cesarean rate coupled with the decrease in the VBAC rate (7.9% in 2005) means that women who have a primary cesarean section have a greater than 90% chance of having a repeat cesarean section, further increasing the overall cesarean rate in the future. 90 Among the many reasons cited for this increase are older women giving birth, multiple gestations from fertility treatments, as well as the concerns of physicians and mothers about the risks of vaginal birth. Cesarean births in low risk or "no risk" mothers where no medical indication can be identified are on the rise and are often referred to as Cesarean Delivery at Maternal Request (CDMR).Address for Correspondence and Reprints: Lucky Jain, MD, MBA, Professor of Pediatrics & Executive Vice Chairman, Emory University School of Medicine, 2015 Uppergate Drive, Atlanta GA 30322, ljain@emory.edu, 404-727-1471. Coauthor...

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