Decline in stillbirths and perinatal mortality after implementation of a more aggressive induction policy in post-date pregnancies: a nationwide register study

Introduction: In 2011 Danish national guidelines were changed towards a more aggressive induction and fetal surveillance policy from (1) induction of labor at gestational age (GA) of 42⁺⁰ weeks and (2) no fetal surveillance after 40⁺⁰ weeks to (1) induction of labor between 41⁺² and 41⁺⁶ weeks, (2) earlier induction at 41⁺⁰ weeks in the case of maternal age >40 years or body mass index (BMI) >35 kg/m² and (3) fetal surveillance at GA 41⁺⁰ weeks. Material and methods: This national cohort study included all pregnancies that reached 41⁺⁰ weeks of gestation in 2008–2014 (n = 102 167). Multivariate logistic regression analyses were used to estimate risks in the years after (2012–2014) vs. before (2008–2010) new national guidelines, adjusted for maternal age, BMI, and parity. Results: We observed a decline in stillbirths from 0.9‰ to 0.5‰ [odds ratio (OR)_adjusted 0.50, 95% CI 0.29–0.89, p = 0.018]. Furthermore, a decline in perinatal deaths from 1.3‰ to 0.8‰ (OR_adjusted 0.62, 95% CI 0.39–0.96, p = 0.033) and vacuum extraction (OR_adjusted 0.86, 95% CI 0.82–0.90, p = 0.007) was observed. The risk of cesarean section (OR_adjusted 0.98, 95% CI 0.94–1.02, p = 0.251), Apgar score below 7 at five minutes (OR_adjusted 0.96, 95% CI 0.81–1.14, p = 0.0.678) and admissions to the neonatal department (OR_adjusted 1.04, 95% CI 1.00–1.14, p = 0.064) did not change, whereas induction of labor increased from 28.2 to 42.6% (OR_adjusted 1.89, 95% CI 1.84–1.95, p < 0.001). Conclusions: This study showed a decline in stillbirths and perinatal mortality after implementation of new Danish guidelines for post-date pregnancies. The risk of interventions as cesarean section and vacuum extraction remained stable despite an increase in labor inductions.