title: Spontaneous delivery is related to barometric pressure.
abstract: BACKGROUND
  Many studies have shown that changes in the weather affect health. In the field of obstetrics and gynecology, several events have been empirically shown to be related to the weather. Labor pain is controlled by the autonomic nervous system and various hormones, and is expected to be influenced by the weather and environmental changes. Several studies have been conducted on the relationship between delivery and barometric pressure, which shows constant changes with changes in weather, but there is no generally accepted view on this.
  
  
  METHODS
  We conducted a retrospective study in our patients who had a spontaneous cephalic delivery in this hospital between January 1997 and December 2003, in order to determine whether low barometric pressure induces labor pains, premature rupture of the membranes, and delivery, and whether changes in barometric pressure affect delivery.
  
  
  RESULTS
  There was a significant increase in the number of deliveries and rupture of the membranes at low barometric pressure (P < 0.01), although there was no significant correlation between onset of labor and barometric pressure. This tendency was noted in both women with spontaneous rupture of the fetal membranes and those with premature rupture of the membranes (P < 0.01). On days with a larger change in barometric pressure, regardless of whether it was increasing or decreasing, the number of deliveries increased and the relationship was statistically significant (P < 0.01).
  
  
  CONCLUSIONS
  A causal relationship was noted between the number of rupture of the fetal membranes, delivery and barometric pressure, suggesting that low barometric pressure induces rupture of the fetal membranes and delivery.
authors.affiliation: Department of Obstetrics and Gynecology, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Akutagawa
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Nishi
authors.forename: Keiichi
authors.initials: K
authors.lastname: Isaka
mesh_terms: D000293:Adolescent; D000328:Adult; D001274:Atmospheric Pressure; D036861:Delivery, Obstetric / Q000706:statistics & numerical data*; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000453:epidemiology*; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007745:Labor Onset; D011247:Pregnancy; D012189:Retrospective Studies; D012422:Rupture, Spontaneous