Elective Cesarean = Higher Risk for Infant Respiratory Morbidity

Working in L&D as an RN, this did not come as a surprise. However, I am glad to see that studies are being undertaken in this topic, as the rate of elective cesareans are rising -- especially primary elective cesareans. One can only hope that this will help change how physicians practice in the future regarding elective cesareans.

The article was found on www.Medscape.com


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Elective Cesarean Delivery Linked to Higher Risk for Infant Respiratory Morbidity

News Author: Laurie Barclay, MD
CME Author: Penny Murata, MD

Complete author affiliations and disclosures, and other CME information, are available at the end of this activity.

December 14, 2007 — Infants delivered by elective cesarean delivery had a higher risk for respiratory morbidity vs infants delivered vaginally or by emergency cesarean delivery, according to the results of a cohort study reported in the December 12 Online First issue of the BMJ.

"Previous studies have shown elective caesarean section to be associated with an increased risk of respiratory morbidity in neonates, although methodological shortcomings and differences between studies make it difficult to evaluate properly the causality and magnitude of the association," write Anne Kirkeby Hansen, MD, from Aarhus University Hospital in Denmark, and colleagues. "It is plausible that hormonal and physiological changes associated with labour are necessary for lung maturation in neonates and that these changes may not occur in infants delivered by elective caesarean sections. Gestational age at the time of elective caesarean section may also be important for respiratory morbidity in neonates."

The goal of this study was to determine the association between elective cesarean deliveries and neonatal respiratory morbidity, as well as the role of timing of elective cesarean deliveries. The investigators prospectively collected data from the Aarhus birth cohort enrolled from the neonatal department of a university hospital in Denmark. This cohort consisted of all liveborn infants without malformations, with gestational ages between 37 and 41 weeks, who were delivered between January 1, 1998, and December 31, 2006 (n = 34,458).

The primary endpoints were respiratory morbidity, defined as transitory tachypnea of the newborn, respiratory distress syndrome, or persistent pulmonary hypertension of the newborn; and serious respiratory morbidity, defined as the use of oxygen treatment for more than 2 days, use of nasal continuous positive airway pressure, or need for mechanical ventilation.

Of the 34,458 infants in the cohort, 2687 were delivered by elective cesarean delivery; these infants had an increased risk for respiratory morbidity vs newborns intended for vaginal delivery. Odds ratio (OR) for increased risk for respiratory morbidity was 3.9 for infants delivered by elective cesarean delivery at 37 weeks' gestation (95% confidence interval [CI], 2.4 - 6.5), 3.0 at 38 weeks' gestation (95% CI, 2.1 - 4.3), and 1.9 at 39 weeks' gestation (95% CI, 1.2 - 3.0).

For serious respiratory morbidity, the increased risks followed the same pattern, but with higher ORs: at 37 weeks, OR was 5.0 (95% CI, 1.6 - 16.0). Exclusion of pregnancies complicated by diabetes, preeclampsia, intrauterine growth retardation, or breech presentation did not significantly affect these findings.

"This study suggests that elective caesarean section compared with intended vaginal delivery leads to a twofold to fourfold increased risk of overall neonatal respiratory morbidity and even higher relative risks of serious respiratory morbidity in term newborns," the study authors write. "Our results also suggest that a significant reduction in neonatal respiratory morbidity may be obtained if elective caesarean section is postponed to 39 weeks' gestation. This information should be taken into consideration by women contemplating an elective caesarean section and by the obstetricians counseling them."

The Clinical Institute, Aarhus University, the Research Initiative, Aarhus University Hospital, and the Aase and Einer Danielsens Fund supported this study. The study authors have disclosed no relevant financial relationships.

BMJ. Published online December 12, 2007.

Learning Objectives for This Educational Activity

Upon completion of this activity, participants will be able to:

1. Report whether elective cesarean delivery is associated with neonatal respiratory morbidity.
2. Identify the effect of gestational age on the association between elective cesarean delivery and neonatal respiratory morbidity.

Clinical Context

The rate of cesarean delivery has been increasing. Reasons for cesarean delivery include obstetric complications, maternal illness, breech presentation, and previous cesarean delivery. As reported by Hansen and colleagues in the 2007 issue of the Acta obstetricia et gynecologica Scandinavica, previous studies showed an apparent association between elective cesarean delivery and the increased risk for neonatal respiratory morbidity.

This large, prospective cohort study uses data from the Aarhus birth cohort study, described by Wisborg and colleagues in the February 22, 2003, issue of the BMJ, to evaluate whether delivery by elective cesarean delivery is associated with neonatal respiratory morbidity in neonates born near term and the effect of gestational age.

Study Highlights

• 34,458 liveborn babies with gestational ages between 37 and 41 weeks, without malformations, were delivered during a 9-year period.
• 2687 (7.8%) neonates were delivered by elective cesarean delivery.
• 31,771 (92.2%) neonates were delivered by intended vaginal delivery, including 2877 neonates delivered by emergency cesarean delivery (performed after onset of labor or rupture of membranes).
• Subgroup analysis of 32,580 low-risk pregnancies with no intrauterine growth retardation, maternal diabetes, or maternal preeclampsia or hypertension was conducted.
• 604 (1.8%) neonates had respiratory morbidity, defined as any respiratory distress, transient tachypnea of the newborn, or persistent pulmonary hypertension of the newborn reported by neonatologists.
• 64 (0.2%) had serious respiratory morbidity, defined by need for continuous oxygen supplementation for 3 or more days, nasal continuous positive airway pressure, or any mechanical ventilation.
• In the low-risk pregnancy group, respiratory morbidity occurred in 1.7% and serious respiratory morbidity occurred in 0.2%.
• Comparison of respiratory morbidity risk for elective cesarean vs intended vaginal delivery at each gestational age showed a higher risk for elective cesarean delivery group at any gestational age of less than 40 weeks:
  • 37 weeks: OR, 3.9 (95% CI, 2.4 - 6.5)
  • 38 weeks: OR, 3.0 (95% CI, 2.1 - 4.3)
  • 39 weeks: OR, 1.9 (95% CI, 1.2 - 3.0)
  • Adjustment for potential confounders of smoking, alcohol intake, parity, body mass index, marital status, maternal age, and educational level did not affect risk at 37 weeks (adjusted OR, 3.7), 38 weeks (adjusted OR, 3.0), and 39 weeks (adjusted OR, 1.9).
• Analysis excluding neonates with meconium aspiration syndrome, sepsis, or pneumonia showed higher risk for respiratory morbidity in elective cesarean delivery vs intended vaginal delivery group at any gestational age.
• The low-risk pregnancy group who underwent elective cesarean delivery had slightly higher respiratory morbidity risk vs intended vaginal delivery group at 37 weeks (OR, 4.2) and 38 weeks (OR, 3.3) and similar risk at 39 weeks (OR, 1.8).
• Comparison of respiratory morbidity risk for elective cesarean delivery at each gestational age vs intended vaginal delivery at 40 weeks showed higher risk for elective cesarean delivery at 37 weeks (OR, 6.8; 95% CI, 4.4 - 10) and 38 weeks (OR, 3.3; 95% CI, 2.4 - 4.4).
• Serious respiratory morbidity was significantly higher for elective cesarean vs intended vaginal delivery at 37 weeks (OR, 5.0; 95% CI, 1.6 - 16) and 38 weeks (OR, 4.2; 95% CI, 1.6 - 11).
• Serious respiratory morbidity in low-risk pregnancy group who underwent elective cesarean delivery was slightly lower at 37 weeks (OR, 3.2; 95% CI, 0.8 - 13) and similar at 38 weeks (OR, 4.2; 95% CI, 1.6 - 11) and 39 weeks (OR, 2.7; 95% CI, 0.5 - 14) vs intended vaginal delivery group at corresponding gestational ages.
• Analysis excluding neonates with meconium aspiration syndrome, sepsis, or pneumonia showed a higher risk for serious respiratory morbidity in the elective cesarean delivery vs intended vaginal delivery group at 37 and 38 weeks.
• Serious respiratory morbidity risk was higher for elective cesarean delivery at 37 weeks (OR, 13.6; 95% CI, 5.1 - 36) and 38 weeks (OR, 6.0; 95% CI, 2.8 - 13) vs intended vaginal delivery at 40 weeks.

Pearls for Practice

• The risk for neonatal respiratory morbidity is higher in neonates delivered by elective cesarean delivery vs neonates delivered vaginally or by emergency cesarean delivery at gestational ages 37 to 39 weeks.
• The risk for neonatal respiratory morbidity in neonates delivered by elective cesarean delivery increases as gestational age decreases from 39 to 37 weeks.