BACKGROUND AND PURPOSE:

• ACOG recommends antenatal corticosteroids between 24 and 34 weeks for women “at risk” for delivery within 7 days
• While there is demonstrated benefit to antenatal corticosteroids, there are also potential harms, especially with multiple doses
• A short cervix is a risk factor for preterm birth
• Richards et al. (Amer J Perinatol, 2017) sought to evaluate the number of asymptomatic women with a short cervix who would benefit from antenatal corticosteroids based on the recommended treatment window
• The authors also assessed whether waiting until patients were asymptomatic would allow for a full course prior to delivery

METHODS:

• Retrospective chart review
• Inclusion: Patients with short cervix between 23w0d and 33w6d who had a cervical length < 2.5 cm and were asymptomatic
• Antenatal corticosteroids were administered at the discretion of the MFM

RESULTS:

• 367 asymptomatic patients were included, with only two delivering within 7 days from the time a short cervix was identified
• 2/3 of asymptomatic patients with a short cervix received antenatal corticosteroids based on additional risk factors such as prior history of preterm birth
• Number needed to treat (NNT): 184 asymptomatic patients would need to be treated at the time a short cervix is identified for one patient to benefit
• If a more stringent cervical length criteria was used, e.g., 2.0 cm cutoff, NNT would be 130
• 6% of patients delivered within 48 hours after onset of symptoms with a median time to delivery of 4 hours
  • Waiting for symptoms would not have provided benefit due to short interval until delivery

CONCLUSION:

• The authors conclude that unless future studies demonstrate neonatal benefit of administration, antenatal corticosteroids should not be given to women solely because of shortened cervix

Learn More – Primary Sources:

Anticipatory Corticosteroid Administration to Asymptomatic Women with a Short Cervix

Related ObG Topics:

Do Progestogens Prevent Preterm Birth in Symptomatic Pregnancies with a Short Cervix?

Meta-analysis: Cerclage for Short Cervix but Without History of Preterm Birth 

Short Cervix and Risk for Preterm Birth: Do Pessaries Work?