Single Dose Antenatal Corticosteroids (SNACS) for Women at Risk of Preterm Birth

Preterm infants are at risk of mortality and morbidity. Antenatal corticosteroids (ACS) reduce the risks of neonatal death and morbidities, such as respiratory distress syndrome.

Standard of care for women at risk of preterm birth includes 2 doses of 12 mg betamethasone (for a total of 24 mg) to accelerate fetal lung maturity. There are no published clinical trial data on the benefits or risks of a single dose of antenatal corticosteroid vs. standard double doses.

Pilot trials are now viewed as an "almost essential prerequisite" to large, expensive, full scale studies. Thus, we plan to conduct a pilot clinical trial to determine the feasibility of a trial comparing half the usual dose (12 mg of betamethasone + placebo) to the standard double dose (12 mg + 12 mg of betamethasone), as well as the feasibility of the study protocol. Secondary outcomes will include process outcomes and pilot clinical outcomes, that will be combined with the full-scale RCT for which we have received funding from CIHR.

We plan to conduct a 24-month corrected gestational age follow-up, which will consist principally of 2 validated parent-filled questionnaires:

• Ages and Stages Questionnaire-3 (ASQ)
• Child Behavior Checklist
• A single question parent report of whether there has been a physician diagnosis of cerebral palsy. (recommended by our parent partners)

Inclusion criteria

• Pregnant women at risk of preterm birth with a singleton or twins between =>22+0/7 and <=34+6/7 weeks' gestation
• Pregnant with either singletons or twins
• Has already received the first dose of 12 mg intramuscular betamethasone within the past 24 hours
• All fetuses are alive and without compromise as per ultrasound or fetal heart monitor
• Is capable of giving informed, written consent in English

Exclusion criteria

• Any contraindications to receiving corticosteroids
• Requires chronic doses of corticosteroids secondary to a medical condition (e.g. systemic lupus erythematosus, severe asthma, congenital adrenal hyperplasia, etc.)
• Received any prior doses of antenatal corticosteroids except for the 1st dose of 12 mg intramuscular betamethasone
• Had any previous participation in this trial
• Pregnant with a fetus with severe congenital anomaly (e.g. anencephaly, transposition of the great arteries, etc.) or major chromosomal abnormalities (e.g. Trisomy 18, Trisomy 21, etc.)
• Pregnant with monoamniotic/monochorionic (Mono/Mono) twins