Elective Cesarean Section: Its Impact on Neonatal Respiratory Outcome
Section snippets
The changing landscape for human deliveries
Cesarean births rose for a 10th 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) (Fig. 1) [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
Maternal choice: “too posh to push”
Although difficult to quantify, it has been estimated that nearly 4% to 18% of all cesarean deliveries worldwide are done upon maternal request [17]. In the United States, cesarean delivery on maternal request is estimated to be between 2.6% and 5.5% [18]. A recent NIH state-of-the-science consensus seminar, Cesarean Delivery on Maternal Request, reiterates the assertion that maternal request is playing an increasingly important role in obstetricians' decisions to perform cesarean sections [19].
Respiratory morbidity in infants born by cesarean delivery
Several studies have documented the high incidence of respiratory distress and neonatal intensive care unit (NICU) admissions in infants born by cesarean delivery before the onset of spontaneous labor [12], [16], [21], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49]. However, the incidence of birth asphyxia, trauma, and meconium aspiration is lower with cesarean delivery, and these advantages of elective
Role of retained fetal lung fluid in neonatal respiratory morbidity
The fetus has an interesting challenge presented to it at birth [64]. Often at short notice, sometimes with no notice at all, it is asked to rapidly clear its air spaces of the fluid that it has been secreting through much of the pregnancy. The ability of a neonate to self-resuscitate at birth after remaining “submerged” in fluid for much of its life is truly remarkable, considering that victims of near-drowning faced with similar amounts of fluid in the lungs do so poorly [64], [71], [72]. A
How is the fetal lung fluid cleared?
It is now clear that active sodium transport across the pulmonary epithelium drives liquid from lung lumen to the interstitium, with subsequent absorption into the vasculature [64], [81]. In the lung, sodium reabsorption is a two-step process [104]. The first step is passive movement of sodium from the lumen across the apical membrane into the cell through sodium-permeable ion channels. The second step is active extrusion of sodium from the cell across the basolateral membrane into the serosal
What causes the neonatal lung epithelium to switch to an absorptive mode?
Our basic science investigations have focused on physiologic changes that trigger the change in lung epithelia from a chloride-secretory to a sodium-reabsorption mode [64], [71], [81], [87], [113], [114]. Although several endogenous mediators, including catecholamines, vasopressin, and prolactin, have been proposed to increase lung fluid absorption, none explains this switch convincingly [111], [115]. Mechanical factors, such as stretch and exposure of the epithelial cells to air interface, are
Can rescue strategies work once an infant has become symptomatic?
Considerable evidence shows that high levels of endogenous catecholamines at birth may be important for accelerating alveolar fluid clearance [82], [85], [119]. We [115] have shown that β-agonists increase the activity of sodium channels in the lung through a cAMP-PKA–mediated mechanism. It is logical to conclude that, in the absence of an endogenous surge in fetal catecholamines, exogenous catecholamines should be effective in initiating fetal lung fluid clearance. However, recent studies show
If cesarean sections are here to stay, can we make them safer?
As mentioned earlier, delaying elective cesarean birth until 39 weeks seems to be the first logical step in reducing iatrogenic prematurity and excess risk of respiratory distress. Risk of respiratory distress and NICU admissions is inversely proportional to the gestational age. Recent analysis of the MFMU network cesarean section registry by Tito and colleagues confirms this. We believe that antenatal glucocorticoids, after having been introduced in 1972 to enhance fetal lung maturity, now
Summary
In the United States, a significant number of babies each year are delivered by cesarean delivery before onset of spontaneous labor. Although the occurrence of such complications as birth asphyxia, meconium aspiration, and hypoxic-ischemic encephalopathy is reduced, a significant number of these infants develop respiratory distress due to failed transition and may require additional treatments, such as ventilation, surfactant, inhaled nitric oxide, and ECMO. The need is urgent for preventive
References (135)
- et al.
Caesarean section: the paradox
Lancet
(2006) - et al.
Caesarean delivery rates and pregnancy outcomes: the 2005 WHO global survey on maternal and perinatal health in Latin America
Lancet
(2006) - et al.
Cesarean delivery: background, trends, and epidemiology
Semin Perinatol
(2006) - et al.
Cesarean delivery and respiratory distress syndrome: does labor make a difference?
Am J Obstet Gynecol
(2005) - et al.
Neonatal respiratory distress following elective delivery. A preventable disease?
Am J Obstet Gynecol
(1976) - et al.
Association of elective repeat cesarean delivery and persistent pulmonary hypertension of the newborn
Am J Obstet Gynecol
(1985) - et al.
Planned cesarean versus planned vaginal delivery at term: comparison of newborn infant outcomes
Am J Obstet Gynecol
(2006) - et al.
Neonatal respiratory morbidity following elective caesarean section in term infants. A 5-year retrospective study and a review of the literature
Eur J Obstet Gynecol Reprod Biol
(2001) - et al.
The influence of timing of elective cesarean section on risk of neonatal pneumothorax
J Pediatr
(2007) - et al.
Influence of labor and route of delivery on the frequency of respiratory morbidity in term neonates
Int J Gynaecol Obstet
(1993)
Mode of delivery and risk of respiratory diseases in newborns
Obstet Gynecol
The impact of labor at term on measures of neonatal outcome
Am J Obstet Gynecol
Changes in the gestational age distribution among U.S. singleton births: impact on rates of late preterm birth, 1992 to 2002
Semin Perinatol
Iatrogenic respiratory distress syndrome. An analysis of obstetric events preceding delivery of infants who develop respiratory distress syndrome
Am J Obstet Gynecol
The role of stillbirth prevention and late preterm (near-term) births
Semin Perinatol
Physiology of fetal lung fluid clearance and the effect of labor
Semin Perinatol
Alveolar fluid clearance in developing lungs and its role in neonatal transition
Clin Perinatol
Labor decreases the lung water content of newborn rabbits
Am J Obstet Gynecol
Massive decline in lung liquid before vaginal delivery at term in the fetal lamb
Am J Obstet Gynecol
Electrical potential difference and ion transport across nasal epithelium of term neonates: correlation with mode of delivery, transient tachypnea of the newborn, and respiratory rate
J Pediatr
Decreased sodium ion absorption across nasal epithelium of very premature infants with respiratory distress syndrome
J Pediatr
Births: preliminary data for 2006
Natl Vital Stat Rep
Births: final data for 2005
Natl Vital Stat Rep
Rates and implications of caesarean sections in Latin America: ecological study
BMJ
Health consequences of the increasing caesarean section rates
Epidemiology
Effect of modern obstetrics on mothers from third-world countries
J Matern Fetal Med
Centers for Disease Control and Prevention. Rates of cesarean delivery—United States, 1991
MMWR Morb Mortal Wkly Rep
Comparison of a trial of labor with an elective second cesarean section
N Engl J Med
US Department of Health and Human Services. Repeat cesarean birth
Indications for cesarean section: final statement of the panel of the National Consensus Conference on aspects of cesarean birth
CMAJ
Risk of perinatal death associated with labor after previous cesarean delivery in uncomplicated term pregnancies
J Am Med Assoc
Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery
N Engl J Med
Risk of uterine rupture and adverse perinatal outcome at term after cesarean delivery
Obstet Gynecol
Maternal and neonatal individual risks and benefits associated with caesarean delivery: multicentre prospective study
BMJ
Patient choice cesarean: an evidence-based review
Obstet Gynecol Surv
Rise in “no indicated risk” primary caesareans in the United States, 1991–2001: cross sectional analysis
BMJ
National Institutes of Health state-of-the-science conference statement: cesarean delivery on maternal request
Obstet Gynecol
Elective cesarean section and decision making: a critical review of the literature
Birth
Maternal risk profiles and the primary cesarean rate in the United States, 1991–2002
Am J Public Health
Listening to mothers II: the second national U.S. survey of women's childbearing experiences
Grand rounds: when mom requests a cesarean
Contemporary ob/gyn
Could a randomised trial answer the controversy relating to elective caesarean section? National survey of consultant obstetricians and heads of midwifery
BMJ
Admission to neonatal intensive care with respiratory morbidity following ‘term’ elective caesarean section
Ir Med J
Comparative neonatal morbidity of abdominal and vaginal deliveries after uncomplicated pregnancies
Arch Pediatr Adolesc Med
The epidemiology of respiratory failure in neonates born at an estimated gestational age of 34 weeks or more
J Perinatol
Laeknabladid
Increasing incidence of respiratory distress in neonates
Acta Paediatr
Severe respiratory disorders in term neonates
Paediatr Perinat Epidemiol
Cited by (137)
Are children born by cesarean delivery at higher risk for respiratory sequelae?
2022, American Journal of Obstetrics and GynecologyDoes structured obstetric management play a role in the delivery mode and neonatal outcome of twin pregnancies?
2024, Archives of Gynecology and ObstetricsFrequent Apnea Attacks in a 1-Month-old Infant with Influenza C Virus Infection
2023, Pediatric Infectious Disease Journal