title: Relationship of circadian rhythms of uterine activity with term and preterm delivery.
abstract: OBJECTIVE
  Our aim was to document the presence or significance of circadian uterine activity rhythms in pregnant women who delivered at term and preterm.
  
  
  METHODS
  We measured uterine activity in 19 women divided into a control group (low risk for preterm labor, term delivery, n = 7), a group at high risk for preterm labor, term delivery (n = 6), and a group at high risk for preterm labor, preterm delivery (n = 6). Patients were hospitalized for 24 hours every 2 weeks from 26 weeks' gestation until delivery. Uterine activity was measured continuously by external tocodynamometer.
  
  
  RESULTS
  Patients delivering at term demonstrated a nocturnal surge (4 to 7 AM) in uterine activity the last 80 days before delivery (p < 0.05, analysis of variance). Patients delivered preterm showed an initial nocturnal surge of uterine activity similar to those delivered at term, but this disappeared 24 days before delivery (p > 0.05, analysis of variance).
  
  
  CONCLUSIONS
  Uterine activity nocturnal surges normally precede term delivery. These surges are lost in women who deliver prematurely.
authors: Department of Obstetrics and Gynecology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago.
authors: A M
authors: AM
authors: Germain
authors: G J
authors: GJ
authors: Valenzuela
authors: M
authors: M
authors: Ivankovic
authors: C A
authors: CA
authors: Ducsay
authors: C
authors: C
authors: Gabella
authors: M
authors: M
authors: Serón-Ferré
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D005260:Female; D005865:Gestational Age; D006801:Humans; D007752:Obstetric Labor, Premature / Q000503:physiopathology*; D011247:Pregnancy / Q000502:physiology*; D012307:Risk Factors; D013997:Time Factors; D014590:Uterine Contraction / Q000502:physiology*