Mode of Anesthesia in Women undergoing Preterm Birth by Cesarean Delivery: An Epidemiologic Analysis
Abstract Number: F-44
Abstract Type: Original Research
Introduction: Preterm birth (PTB), birth before 37 weeks’ gestation, occurs in 11.5% of all U.S. births.(1) The rate of preterm cesarean delivery (CD) is higher than the rate of CD at term.(2) However there are limited data on mode of anesthesia and risk factors for general anesthesia for women undergoing preterm CD. Using the NIH-Maternal Fetal Medicine Unit (MFMU) Cesarean Registry, we performed an epidemiologic analysis of mode of anesthesia for preterm CD.
Methods: We performed a secondary analysis of the MFMU Cesarean Registry which contains data on 57,182 women who underwent CD at 19 academic centers between 1999-2002.(3) Inclusion criteria for the current study were women who underwent CD between 24+0 to 36+6 weeks’ gestation. We calculated rates of GA and neuraxial anesthesia (NA). Using multivariate logistic regression, we identified risk factors for GA based on demographic, medical, obstetric, and intrapartum characteristics. Emergency CD was defined by the presence of at least one of the following conditions: placental abruption, cord prolapse, placenta previa with antenatal bleeding, uterine rupture, a non-reassuring fetal tracing, failed vacuum delivery, or failed forceps delivery.
Results: Our cohort comprised 50,090 women who underwent preterm CD. Rates (95% CI) of NA and GA were 82.4% (81.7%-83.1%) and 17.6% (16.9%-18.3%) respectively. The following characteristics were associated with an increased risk of GA: gestational age at delivery (aOR =0.88 per 1 week increase in gestational age), an emergency indication for CD (aOR=3.42), HELLP syndrome (aOR=2.72), African-American race (aOR=1.93), Hispanic ethnicity (aOR=1.5), and other races (aOR = 1.37) (Table). Among women who underwent emergency preterm CD, the following indications were more common in those who underwent GA vs. NA: placental abruption (6.3% vs. 1.2%), cord prolapse (5.2% vs. 0.4%), previa + antenatal bleeding (1.2% vs. 0.09%); P<0.05 respectively.
Conclusion: In this large retrospective cohort, nearly 1 in 5 women underwent GA at preterm CD and the adjusted risk of GA increased with decreasing gestational age. Further etiologic research is needed to investigate how gestational age at delivery influences the risk of GA among women undergoing preterm CD.
References: (1) Births: Final Data for 2012. Nat Vital Stat Reports 2013; 62: no.9 (2) Am J Public Health 2010;100:2241-7 (3) NEJM 2004; 351: 2581-9.