A single course of betamethasone before an elective cesarean section at term may decrease the risk of developing neonatal respiratory distress or transient tachypnea, according to the results of a randomized, controlled trial.
The 10-center trial is the first of its kind to test the use of prenatal corticosteroids in women who were delivered by elective cesarean section at term (BMJ, doi:10.1136/bmj.38547.416493.06 [2005]).
Infants whose mothers received betamethasone had a significantly lower rate of admission to the special care baby unit (11 of 467) than control infants (24 of 475). Betamethasone treatment reduced the incidence of admission to a special care baby unit by 54%, reported Peter Stutchfield, M.D., of Glan Clwyd Hospital (Wales) and his colleagues.
Still, Alex Vidaeff, M.D., of the University of Texas, Houston, questioned the significance of the study. “I don't see any clinical utility for U.S. practitioners because of a lack of external validity,” he said in an interview.
Dr. Vidaeff, who has particular interest in research on corticosteroids and fetal maturation, as well as expertise working with H-441 adenocarcinoma lung cells, said interpretation of the study results is difficult without more information on the selection of patients for the study. He also noted that the risk-benefit ratio at more than 34 weeks' gestation is not favorable because the risk level already is low in this group.
In the study, during the 48 hours before elective cesarean section, the women received either two intramuscular doses of 12 mg of betamethasone separated by 24 hours or treatment as usual without corticosteroids.
The severity and type of respiratory distress (transient tachypnea in 10 treated and 19 control babies or respiratory distress syndrome in 1 treated and 5 control babies) were similar among all babies who were admitted to a special care baby unit.
Among mothers who had a baby admitted to a special care baby unit, significantly more mothers of infants exposed to betamethasone received general anesthesia than did mothers of control infants (45% vs. 0%). Admitted babies exposed to betamethasone needed neonatal resuscitation (73% vs. 12%) or ventilation through a mask (36% vs. 0%) significantly more often than control babies.
But 2.9% of control babies received intensive care, compared with only 0.4% of babies treated with betamethasone.
The probability of admission to the special care baby unit with respiratory distress declined as the gestational age of the baby increased in the betamethasone and control groups from 37 weeks (5% vs. 11%, respectively) to 38 weeks (3% vs. 6%) to 39 weeks (0.6% vs. 1.5%), according to a logistic regression model.
There were no reports of wound infection or neonatal sepsis. Among seven women who received betamethasone, five reported generalized flushing, one had nausea, one had tenderness at the injection site, and one noted increased energy with difficulty sleeping.
“The reduced incidence of transient tachypnea in the steroid group is consistent with the hypothesis that corticosteroids, increased in mother and fetus through the stress of labor, encourage the expression of the epithelial channel gene and allow the lung to switch from fluid secretion to fluid absorption,” Dr. Stutchfield and his colleagues wrote. “Without another source of corticosteroid, elective cesarean section will disrupt this process.”