The impact of a national cardiotocography education program on neonatal and maternal outcomes: A historical cohort study

Abstract

Introduction: Studies indicate an association between errors in cardiotocography (CTG) management and hypoxic brain injuries among newborns. Continuing professional education is recommended. We aimed to examine whether the implementation of a national interprofessional CTG education program in Denmark was associated with a decrease in risk of fetal hypoxia measured by umbilical cord pH < 7.00, 5-minute Apgar score <7 or neonatal therapeutic hypothermia. As a secondary aim, we assessed whether the educational intervention was associated with an increase in operative deliveries. Material and methods: We conducted a historical cohort study from 2009 to 2015 including all intended vaginal deliveries with liveborn singletons in cephalic presentation and gestational age ≥37 weeks. Data were retrieved from the Medical Birth Register and the National Patient Register. The study period was divided in three: pre-implementation (2009-2012), implementation (2013) and post-implementation (2014-2015). Using logistic regression we estimated odds ratios (OR) of fetal hypoxia outcomes using the pre-implementation period as reference. Analyses were adjusted for potential maternal, neonatal and delivery-associated confounders. Missing data were accounted for by multiple imputation. Results: In all, 331 282 deliveries were included. Overall risks of pH < 7.00, Apgar score <7 and therapeutic hypothermia were respectively 0.45%, 0.58% and 0.06%. Adjusted OR in the post-implementation period were 1.12 (95% confidence interval [CI] 1.00-1.26), 0.99 (95% CI 0.90-1.10) and 1.34 (95% CI 0.99-1.82) for the three outcomes, respectively. The pH missingness equaled 12.4%. Odds of emergency cesarean section was unaltered, whereas the odds of assisted vaginal delivery decreased by 14% (0.86, 95% CI 0.84-0.89). Conclusions: Healthcare professionals are considered the weakest link of CTG technology. We did not find that increasing healthcare professionals’ CTG interpretation skills affected the risk of fetal hypoxia. Missing data for pH values were substantial and represent a limitation of the study. We cannot with certainty rule out that missingness masked a true effect of the intervention. Our study indicates that assisted vaginal deliveries can be decreased without an increased risk of fetal hypoxia. Dilution of effect in a complex clinical setting, rare outcomes, insufficient intervention and a possible overestimation of the impact of errors in CTG management might explain the lack of effect.