Intrapartum epidural analgesia and low Apgar score among singleton infants born at term: A propensity score matched study

Introduction: The associations of epidural analgesia and low Apgar score found in the Swedish Registry might be a result of confounding by indication. The objective of this study was to assess the possible effect of intrapartum epidural analgesia on low Apgar score and neonatal intensive care unit (NICU) admission in term born singletons with propensity score matching. Material and methods: This was a propensity score matched study (n = 257 872) conducted in a national cohort of 715 449 term live born singletons without congenital anomalies in the Netherlands. Mothers with prelabor cesarean section were excluded. Main outcome measures were 5-minute Apgar score <7, 5-minute Apgar score <4 and admission to a NICU for at least 24 hours. First, an analysis of the underlying risk factors for low Apgar score <7 was performed. Multivariable analyses were applied to assess the effect of the main risk factor, intrapartum epidural analgesia, on low Apgar score to adjust the results for confounding factors. Second, a propensity score matched analysis on the main risk factors for epidural analgesia was applied. By propensity score matching the (confounding) characteristics of the women who received epidural analgesia with the characteristics of the control women without epidural analgesia, the effect of possible confounding by indication is minimized. Results: Intrapartum epidural analgesia was performed in 128 936 women (18%). Apgar score <7 was present in 1.0%, Apgar score <4 in.2% and NICU admission in.4% of the deliveries. The strongest risk factor for Apgar score <7 was epidural analgesia (adjusted odds ratio [aOR] 1.9, 95% confidence interval [CI] 1.8-2.0). The propensity score matched adjusted analysis of women with epidural analgesia showed significant adverse neonatal outcomes: aOR 1.8 (95% CI 1.7-1.9) for AS <7, aOR 1.6 (95% CI 1.4-1.9) for AS <4 and aOR 1.7 (95% CI 1.6-1.9) for NICU admission. The results of epidural analgesia on AS <7 were also significantly increased for spontaneous start of labor (aOR 2.0, 95% CI 1.8-2.1) and for spontaneous delivery. Conclusions: Intrapartum epidural analgesia at term is strongly associated with low Apgar score and more NICU admissions, especially in spontaneous deliveries. This association needs further research and awareness.