Medline ® Abstract for Reference 54

OBJECTIVES: To determine if the association of cerebral palsy (CP) with umbilical cord around the fetal neck (nuchal cord) is the result of recording bias.

STUDY DESIGN: Population-based case control study.

RESULTS: There were 68 cases with cerebral palsy and 157 controls (singleton term infants matched for gestational age and hospital of birth). CP was associated with tight nuchal cord overall (OR=2.8, 95% CI 1.1-6.8). Where cord around the neck is recorded at the discretion of the accoucheur (37 cases, 97 controls), there was an association between tight nuchal cord and CP (OR=5.4, 95% CI 1.4-20.4) and, in controls only, between Apgar score<7 at 1 min (OR=16.9, 95% CI 1.4-456.3). In the hospital where records included a tick box for nuchal cord (31 cases, 60 controls), an association between CP and tight nuchal cord could not be demonstrated (OR=1.4, 95% CI 0.4-4.9). Nor was there an apparent association between nuchal cord and Apgar score<7 at 1 min (OR=2.6, 95% CI 0.4-15.9) in controls.

CONCLUSIONS: The presence of nuchal cord is subject to recording bias. In a retrospective study, this can lead to an association of CP with nuchal cord that is not evident where documentation is systematic.