title: Effects of chronic carbon monoxide exposure on fetal growth and development in mice.
abstract: BACKGROUND
  Carbon monoxide (CO) is produced endogenously, and can also be acquired from many exogenous sources: ie. cigarette smoking, automobile exhaust. Although toxic at high levels, low level production or exposure lends to normal physiologic functions: smooth muscle cell relaxation, control of vascular tone, platelet aggregation, anti- inflammatory and anti-apoptotic events. In pregnancy, it is unclear at what level maternal CO exposure becomes toxic to the fetus. In this study, we hypothesized that CO would be embryotoxic, and we sought to determine at what level of chronic CO exposure in pregnancy embryo/fetotoxic effects are observed.
  
  
  METHODS
  Pregnant CD1 mice were exposed to continuous levels of CO (0 to 400 ppm) from conception to gestation day 17. The effect on fetal/placental growth and development, and fetal/maternal CO concentrations were determined.
  
  
  RESULTS
  Maternal and fetal CO blood concentrations ranged from 1.12- 15.6 percent carboxyhemoglobin (%COHb) and 1.0- 28.6%COHb, respectively. No significant difference was observed in placental histological morphology or in placental mass with any CO exposure. At 400 ppm CO vs. control, decreased litter size and fetal mass (p < 0.05), increased fetal early/late gestational deaths (p < 0.05), and increased CO content in the placenta and the maternal spleen, heart, liver, kidney and lung (p < 0.05) were observed.
  
  
  CONCLUSIONS
  Exposure to levels at or below 300 ppm CO throughout pregnancy has little demonstrable effect on fetal growth and development in the mouse.
authors.affiliation: Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada.
authors.forename: Carolina C
authors.initials: CC
authors.lastname: Venditti
authors.forename: Richard
authors.initials: R
authors.lastname: Casselman
authors.forename: Graeme N
authors.initials: GN
authors.lastname: Smith
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002248:Carbon Monoxide / Q000032:analysis / Q000633:toxicity*; D002263:Carboxyhemoglobin / Q000032:analysis*; D005260:Female; D005313:Fetal Death / Q000473:pathology*; D047109:Fetal Development / Q000187:drug effects*; D005865:Gestational Age; D008098:Litter Size / Q000187:drug effects; D051379:Mice; D008815:Mice, Inbred Strains; D010920:Placenta / Q000033:anatomy & histology / Q000187:drug effects*; D010929:Placentation; D011247:Pregnancy
chemical_list: D002248:Carbon Monoxide; D002263:Carboxyhemoglobin