Low-dose aspirin in nulliparous women: safety of continuous epidural block and correlation between bleeding time and maternal-neonatal bleeding complications. National Institute of Child Health and Human Developmental Maternal-Fetal Medicine Network

Am J Obstet Gynecol. 1995 May;172(5):1553-7. doi: 10.1016/0002-9378(95)90495-6.


Objective: Our purpose was to determine the frequency and safety of the use of epidural anesthesia and the correlation between bleeding time and maternal-neonatal bleeding complications in a group of pregnant women who participated in a multicenter trial of low-dose aspirin in pregnancy.

Study design: Data regarding type of anesthesia used for labor and delivery were available in 1629 nulliparous women who were randomly assigned at 13 to 27 weeks to receive 60 mg/day aspirin or a placebo. A total of 891 (55%) received epidural anesthesia, and the remaining 738 did not.

Results: Among the 891 women known to have received epidural anesthesia, 451 were assigned to low-dose aspirin and 440 to placebo. There was no instance of bleeding related to epidural use. In addition, there were no differences in maternal and neonatal complications between those receiving or not receiving epidural anesthesia. Within the group receiving epidural anesthesia there were no differences in bleeding complications between those assigned to aspirin on placebo. One of the five centers also obtained bleeding times in 303 women (149 received aspirin and 154 received placebo). The mean +/- SD bleeding time in women assigned to low-dose aspirin was significantly higher than in women assigned to placebo (6.99 +/- 2.95 minutes vs 5.99 +/- 2.43 minutes, p = 0.004). In addition, the frequency of women having a bleeding time > 10 minutes was higher in the aspirin group (14.1% vs 5.2%, p = 0.01). Interestingly, women who received an epidural anesthetic had a lower bleeding time than those not receiving an epidural (p = 0.003), irrespective of the treatment used.

Conclusions: In women assigned to low-dose aspirin there were no adverse effects related to epidural anesthesia. In spite of an increased bleeding time in a subset of pregnant women assigned to low-dose aspirin, maternal-neonatal bleeding complications were not increased.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Analysis of Variance
  • Anesthesia, Epidural*
  • Anesthesia, Obstetrical*
  • Aspirin / administration & dosage*
  • Aspirin / therapeutic use
  • Bleeding Time
  • Blood Coagulation / drug effects
  • Chi-Square Distribution
  • Contraindications
  • Double-Blind Method
  • Female
  • Hemorrhage / blood*
  • Humans
  • Infant, Newborn
  • National Institutes of Health (U.S.)
  • Obstetric Labor Complications / blood*
  • Parity
  • Postpartum Hemorrhage / blood
  • Pre-Eclampsia / prevention & control
  • Pregnancy
  • Risk Factors
  • United States
  • Uterine Hemorrhage / blood*


  • Aspirin