Relation between frequency of uterine contractions and human fetal cerebral oxygen saturation studied during labour by near infrared spectroscopy

Br J Obstet Gynaecol. 1994 Jan;101(1):44-8. doi: 10.1111/j.1471-0528.1994.tb13008.x.


Objective: To investigate the effect of the frequency of uterine contractions on fetal cerebral oxygenation, using near infrared spectroscopy.

Design: An observational study relating changes in the fetal cerebral concentrations of oxyhaemoglobin and deoxyhaemoglobin, measured from the start of one contraction to that of the next, to the time interval between contraction peaks observed by external tocography.

Setting: A teaching hospital obstetric and neonatal unit.

Subjects: Ten term fetuses during labour.

Results: Changes in cerebral oxyhaemoglobin concentration were positively, and in deoxyhaemoglobin negatively, correlated with the time interval between contractions (P < 0.001). A mean contraction interval of 2.3 min was found below which the concentration of oxyhaemoglobin usually fell and that of deoxyhaemoglobin rose, indicating a fall in cerebral haemoglobin saturation. Conversely, longer contraction intervals were associated with findings indicative of a rise in cerebral haemoglobin saturation.

Conclusion: Short contraction intervals (< 2.3 min) were associated with a decrease, and longer contraction intervals with an increase in fetal cerebral oxygen saturation. Contractions occurring repeatedly at intervals less than 2.3 min are likely to result in progressive cerebral desaturation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brain Chemistry*
  • Delivery, Obstetric
  • Female
  • Fetus / physiology*
  • Hemoglobins / analysis
  • Humans
  • Oxygen / blood*
  • Pregnancy
  • Spectrophotometry, Infrared
  • Time Factors
  • Uterine Contraction / physiology*


  • Hemoglobins
  • deoxyhemoglobin
  • Oxygen