title: Maternal heart rate changes during labour.
abstract: OBJECTIVE
  Labour and delivery represent a considerable effort for pregnant women. Lack of aerobic fitness may limit pushing efforts during childbirth and represents increased cardiovascular strain and risk. Increasing prevalence of sedentary behaviour and lack of aerobic fitness may reduce heart rate reserve during labour.
  
  
  METHODS
  We quantified maternal heart rate reserve (maximum heart rate minus resting heart rate) of 30 healthy pregnant women during labour and delivery and related it to habitual daily physical activity levels quantified during the third pregnancy trimester by the Pregnancy Physical Activity Questionnaire.
  
  
  RESULTS
  Heart rates during labour reached values similar to those observed during moderate to heavy physical exercise. During active pushing one out of five women reached heart rates more than 90% of their heart rate reserve (188 ± 7 beats per min). Half of the women reached more than 70% of heart rate reserve (172 ± 14 beats per min). Physically inactive women used more of their heart rate reserve as physically more active women (87 ± 20% vs. 65 ± 12%, upper and lower tertile respectively, p<0.05).
  
  
  CONCLUSIONS
  Use of heart rate reserve for the effort of labour is increased in physically inactive women and may potentially limit the intensity and duration of pushing efforts. Such higher cardiovascular strain in physically less active women may represent increased cardiovascular risk during labour.
authors.affiliation: Department of Obstetrics and Gynaecology, University Hospitals of Geneva and Faculty of Medicine, University of Geneva, Switzerland.
authors.forename: N
authors.initials: N
authors.lastname: Söhnchen
authors.forename: K
authors.initials: K
authors.lastname: Melzer
authors.forename: B Martinez de
authors.initials: BM
authors.lastname: Tejada
authors.forename: N
authors.initials: N
authors.lastname: Jastrow-Meyer
authors.forename: V
authors.initials: V
authors.lastname: Othenin-Girard
authors.forename: O
authors.initials: O
authors.lastname: Irion
authors.forename: M
authors.initials: M
authors.lastname: Boulvain
authors.forename: B
authors.initials: B
authors.lastname: Kayser
mesh_terms: D000328:Adult; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007743:Labor, Obstetric / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D011247:Pregnancy