Neonatal outcome in late preterm twin gestation: impact of antenatal corticosteroids therapy before 34 weeks

The effects of antenatal corticosteroid (ACS) exposure before 34 weeks on neonates born in the late preterm period are a subject of controversy. We aimed to investigate the impact of ACS exposure before 34 weeks on neonates of dichorionic diamniotic (DCDA) twins born in the late preterm period.

This retrospective cohort study included all DCDA twin gestations born at 34.0-36.6 weeks between January 2014 and December 2020 at a single tertiary medical center. Neonatal outcomes were compared between twin gestations treated with ACS before 34 weeks (ACS group) and those not treated with ACS (control group). A sub-analysis examined neonatal outcomes between those treated with ACS within 14 days of delivery and those treated more than 14 days before delivery.

A total of 297 twin gestations were included, with 122 in the ACS group and 175 in the control group. Maternal age, BMI, hypertensive disorders and diabetes mellitus did not differ between the groups. ACS was given for suspected preterm birth (85.2%), fetal growth restriction (4.9%), preeclampsia (3.2%), placental abruption (2.4%), and placenta previa-related bleeding (2.4%). Gestational age (GA) at delivery was lower in the ACS group than in the control group (35.06 ± 0.8 weeks vs. 35.49 ± 0.69 weeks, p < 0.001). The ACS group had higher rates of neonatal admission to the 'neonatal intensive care unit' (NICU)-36.1% vs.16.6%, p < 0.001, and small for gestational age (SGA), 7.2% vs. 9.4%, p = 0.004. By multivariable logistic regression analysis ACS treatment was found to be independently associated with SGA birth (OR 1.997, 95% CI 1.225-3.257, p = 0.006). Within the ACS group, neonates who delivered within 14 days of ACS treatment had higher rates of NICU admission compared to those born > 14 days from ACS treatment (p < 0.004).

Twin pregnancies that were born in the late-preterm period and were exposed to ACS before 34 weeks, showed increased rates of SGA and neonatal NICU admission. Caution is needed when administering ACS in twin gestations to avoid unnecessary exposure.