title: End-tidal breath carbon monoxide measurements are lower in pregnant women with uterine contractions.
abstract: OBJECTIVE
  To compare the levels of end-tidal carbon monoxide (ETCOc) among women with and without uterine contractions in term and preterm pregnancies.
  
  
  METHODS
  In all, 55 nonsmoking healthy pregnant women were enrolled. ETCOc levels were compared among women with contractions (10 preterm and 13 term) and 32 women without contractions (34-41 weeks gestation).
  
  
  RESULTS
  Maternal age, gravidity and parity were similar among study and control groups. ETCOc levels were significantly lower among women that had uterine contractions (0.99+/-0.38 parts per million (ppm) and 1.15+/-0.34 p.p.m. respectively), compared to women with no contractions (1.70+/-0.52 p.p.m., P<0.002). However, there was no significant difference in the ETCOc levels between women with preterm or term contractions (P=0.48).
  
  
  CONCLUSIONS
  Low levels of ETCOc are associated with preterm and term uterine contractions.
authors.affiliation: Department of Obstetrics and Gynecology, Sheba Medical Center, Tel-Hashomer, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Israel
authors.initials: I
authors.lastname: Hendler
authors.forename: Micha
authors.initials: M
authors.lastname: Baum
authors.forename: Doron
authors.initials: D
authors.lastname: Kreiser
authors.forename: Eyal
authors.initials: E
authors.lastname: Schiff
authors.forename: Maurice
authors.initials: M
authors.lastname: Druzin
authors.forename: David K
authors.initials: DK
authors.lastname: Stevenson
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Seidman
mesh_terms: D000328:Adult; D001944:Breath Tests; D002248:Carbon Monoxide / Q000378:metabolism*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D013990:Tidal Volume / Q000502:physiology; D014590:Uterine Contraction / Q000502:physiology*
chemical_list: D002248:Carbon Monoxide