Changes in fetal position during labor and their association with epidural analgesia

Obstet Gynecol. 2005 May;105(5 Pt 1):974-82. doi: 10.1097/01.AOG.0000158861.43593.49.


Objective: To evaluate whether epidural analgesia is associated with a higher rate of abnormal fetal head position at delivery.

Methods: We conducted a prospective cohort study of 1,562 women to evaluate changes in fetal position during labor by using serial ultrasound examinations. Ultrasound examinations were performed at enrollment, epidural administration, 4 hours after the initial ultrasonography if epidural had not been administered, and late in labor (> 8 cm). Information about fetal head position at delivery was obtained from the provider.

Results: Regardless of fetal head position at enrollment (occiput transverse, occiput posterior, or occiput anterior), most fetuses were occiput anterior at delivery (enrollment position: occiput transverse 78%, occiput posterior 80%, occiput anterior 83%, P = .1). Final fetal position was established close to delivery. Of fetuses that were occiput posterior late in labor, only 20.7% were occiput posterior at delivery. Changes in fetal head position were common, and 36% of women had an occiput posterior fetus on at least one ultrasound examination. Women receiving epidural did not have more occiput posterior fetuses at the enrollment (23.4% epidural versus 26.0 no epidural, P = .9) or the epidural/4-hour ultrasound examination (24.9% epidural, 28.3% no epidural), but did have more occiput posterior fetuses at delivery (12.9% epidural versus 3.3% no epidural, P = .002); the association remained in a multivariate model (adjusted odds ratio 4.0, 95% confidence interval 1.4-11.1).

Conclusion: Fetal position changes are common during labor, with the final fetal position established close to delivery. Our demonstration of a strong association of epidural with fetal occiput posterior position at delivery represents a mechanism that may contribute to the lower rate of spontaneous vaginal delivery consistently observed with epidural.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Analgesia, Epidural*
  • Cesarean Section / statistics & numerical data
  • Cohort Studies
  • Confidence Intervals
  • Female
  • Fetal Monitoring / methods
  • Humans
  • Labor Presentation*
  • Labor Stage, Second
  • Labor, Obstetric*
  • Logistic Models
  • Maternal Age
  • Natural Childbirth / statistics & numerical data
  • Odds Ratio
  • Parity
  • Pregnancy
  • Pregnancy Outcome
  • Probability
  • Prospective Studies
  • Ultrasonography, Prenatal*