Antenatal Corticosteroids and Risk of Cerebral Palsy: A Regression Discontinuity Study

Area of Science:

• Perinatal medicine
• Neonatology
• Developmental neurology

Background:

• Antenatal corticosteroids are recommended for preterm birth risk before 34 weeks gestation.
• A sharp decline in treatment occurs at 34 weeks, creating a natural experiment.
• Cerebral palsy is a significant concern in preterm infants.

Purpose of the Study:

• To investigate the effect of antenatal corticosteroids on cerebral palsy risk.
• To analyze the impact of the treatment guideline change at 34 weeks gestation.

Main Methods:

• Natural experiment design using singleton livebirths (2000-2015) in British Columbia.
• Analysis of births between 31+0 and 36+6 weeks gestation.
• Cerebral palsy diagnosis using billing records, corrected for misclassification.

Main Results:

• No convincing evidence of an abrupt change in cerebral palsy risk around 34+0 weeks.
• Risk ratio for cerebral palsy near 34+0 weeks was 0.98 (95% CI: 0.50 to 1.98).
• Similar results observed for composite outcomes including death.

Conclusions:

• The study did not find evidence that reduced antenatal corticosteroid use at 34 weeks impacts cerebral palsy risk.
• Estimates were imprecise, leaving room for potential benefits or harms.
• Further research with larger sample sizes may be needed.