Dexamethasone dosage in preterm births: Efficacy found from 5-mg dose

A 5-mg dexamethasone dose and a 6-mg dose are equally effective in preventing neonatal respiratory distress syndrome (RDS) in preterm births, according to a recent study published in the American Journal of Obstetrics & Gynecology.

Approximately 15 million preterm births occur annually and are responsible for approximately 0.88 million neonatal deaths. RDS is one source of neonatal death in preterm birth, caused by underdeveloped lungs and poor surfactant production.

The risk of RDS is often reduced using corticosteroids, with the World Health Organization recommending dexamethasone and betamethasone. However, while administration of antenatal corticosteroids (ACS) is recommended in patients at 34+0 to 36+6 weeks’ gestation, caution is recommended in patients at 34+0 to 35+6 weeks’ gestation because of unclear risks and benefits.

ACS administration has been linked to decreased birth weight and anthropometric measurements among preterm infants, as well as adverse neurocognitive and psychological outcomes. Adverse outcomes are more likely from higher doses, indicating a lower dose may be safer. Animal studies have indicated efficacy from a decreased dose of ACS.

To evaluate the outcomes of a 5-mg dexamethasone dose vs a 6-mg dose among preterm newborns, investigators conducted an open-label, randomized, controlled, noninferiority study. Participants included women with a singleton pregnancy at 32 to 36 6/7 weeks’ gestation and spontaneous preterm labor from December 2020 to April 2022.

Women with regular uterine contractions and cervical changes and an estimated gestational age were eligible for the analysis. Transvaginal ultrasound was performed to determine gestational age.

Patients with a contraindication to corticosteroids, evidence of active infection, prolonged steroid use, or corticosteroids administration before 32 weeks’ gestation were excluded from the analysis. Participants were randomly assigned 1:1 to a 5-mg dexamethasone group or 6-mg group.

Treatment was administered every 12 hours for 48 hours, with cases considered an incomplete course if delivery occurred prior to dexamethasone completion. Hospital standard procedures were employed to manage preterm labor, and women with severe reactions to dexamethasone were excluded from the analysis.

Data evaluated included demographic information, obstetrical details, medical histories, and pregnancy and delivery information. Neonatal RDS was measured as the primary outcome, while secondary measures included adverse maternal or neonatal outcomes.

There were 370 women included in the final analysis, 185 of whom received 5-mg dexamethasone and 185 received 6-mg dexamethasone. Similar demographic characteristics were reported between groups, and the mean gestational age at trial entry and delivery was approximately 35 weeks.

A complete dexamethasone course was reported in 31.1% of women, nulliparous status in 48.6%, and vaginal delivery in 50.2%. One, 2, and 3 does of dexamethasone were received by 120, 13, and 2 women, respectively, in the 5-mg group, vs 95, 16, and 8, respectively, in the 6-mg group.

In the 5-mg group, 2.2% of newborns presented with neonatal RDS, vs 1.6% in the 6-mg group. This indicated a 0.6% risk difference, falling within the a priori 10% noninferiority margin.

A statistically significant difference of 7.6% was found for neonatal hypoglycemia, at 5.9% in the 5-mg group and 13.5% of the 6-mg group. This difference remained significant following multiple comparison correction and when accounting for fetal growth restriction.

No cases of chorioamnionitis, postpartum endometritis, or neonatal infection were reported across the entire study cohort. These outcomes did not differ between the 32 to 33 6/7 weeks’ and 34 to 36 6/7 weeks’ gestational periods.

These results indicated noninferiority from a 5-mg dexamethasone dose in preventing neonatal RDS in preterm birth when compared to a 6-mg dose, but significant differences in neonatal hypoglycemia. Investigators recommended further research about ACS therapy timing.

Reference

Chawanpaiboon S, Chukaew R, Pooliam J. A comparison of 2 doses of antenatal dexamethasone for the prevention of respiratory distress syndrome: an open-label, noninferiority, pragmatic randomized trial. Am J Obstet Gynecol. 2024;230:260.e1-19. doi:10.1016/j.ajog.2023.07.006