Antenatal Betamethasone and Incidence of Neonatal Respiratory Distress After Elective Cesarean Section
Antenatal Betamethasone and Incidence of Neonatal Respiratory Distress After Elective Cesarean Section
Abstract & Commentary
By John C. Hobbins, MD, Professor and Chief of Obstetrics, University of Colorado Health Sciences Center, Denver, is Associate Editor for OB/GYN Clinical Alert.
Synopsis: Antenatal betamethasone and delaying delivery until 39 weeks both reduce admissions to special care baby units with respiratory distress after elective caesarean section at term.
Source: Stutchfield P, et al. Antenatal betamethasone and incidence of neonatal respiratory distress after elective caesarean section: pragmatic randomised trial. BMJ. 2005;331:662.
A surprising study recently surfaced in the British Medical Journal. A randomized trial was designed to determine if giving a standard maternal dose of steroids (two injections of 12 mg of betamethasone separated by 24 hours) would decrease the incidence of respiratory distress syndrome (RDS) in infants whose mothers were to have elective Cesarean sections.
In this study, 998 women having elective sections between 36 and 39 weeks were recruited from 11 collaborating centers. Half were given betamethasone and half were not. Of the 503 women receiving steroids, 10 of their babies had transient tachypnea of the newborn (TTN), compared with 19 in the 495 controls (2.1% vs 4%). There were 5 babies with X-ray diagnosis of RDS in the control group and one in the "treated group" (1.1% vs 0.2%). There also was a decrease in admissions to the newborn special care unit in the treated group. Stutchfield and colleagues concluded that giving steroids to mothers having elective Cesarean sections decreased the incidence of RDS and TTN enough to warrant its use.
Commentary
What is going on? The latest US statistics indicate the Cesarean section rate to be 34%. An increasingly large percentage of these are elective repeat Cesareans sections, which are now sharing the spotlight with the emergence of Cesarean section by maternal choice. Our neonatologists tell me that TTN is not a big deal while, obviously, RDS can be. This study, which Stutchfield et al indicate is powered to show a statistical difference between groups, shows that giving steroids to 100 women may prevent one infant from developing RDS. It is important to note that the severity of the RDS in this study did not differ between groups. Interestingly, Stutchfield et al suggest that the reason the steroids could work in elective Cesareans is that the infants, deprived of endogenous corticosteroid release during "the stress of labor," might need some exogenous help in inducing surfactant release.
Other RCT’s have failed to show a benefit of steroids in preterm delivery after 34 weeks or when membranes are ruptured after 32 weeks.1-4 Moreover, there is now some evidence that "if some is good, more is not necessarily better," with regard to repeated dosage of steroids and its affect on the fetal brain.
Call me old fashioned, but it seems weird that the aim of today’s designer births is to interrupt pregnancy before labor ensues. Then, to compound the meddling, steroids are doled out to everyone because 1 in every 100 might have needed labor to discourage the development of RDS or, perhaps, because he/she really could be a preterm baby.
References
- Morrison JJ, et al. Neonatal respiratory morbidity and mode of delivery at term: influence of timing of elective cesarean section. Br J Obstet Gynaecol. 1995;102:101-106.
- Walters DV, Olver RE. The role of catecholamines in lung fluid absorption at birth. Pediatr Res. 1978;12:239-242.
- ACOG committee opinion. ACOG committee opinion. Antenatal corticosteroid therapy for fetal maturation. American College of Obstetricians and Gynecologists. Int J Gynaecol Obstet. 2002;78:95-97.
- Guinn DA, et al. Single vs weekly courses of antenatal corticosteroids for women at risk of preterm delivery: A randomized controlled trial. JAMA. 2001;286:1581-1587.
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