Carbon monoxide poisoning: exposure during pregnancy increased the risk of foetal death or anoxia.

Clinical bottom line (level 4)

  1. Pregnant women who had mild symptoms following carbon monoxide poisoning were very likely to have normal births and children that developed normally.
  2. Pregnant women with decreased consciousness following CO poisoning were at increased risk of an adverse pregnancy (stillbirth or foetal anoxia). This may be reduced by hyperbaric oxygen.
Koren et al: Reproductive Toxicology 1991; 5: 397-403
Expires July 2003

The study

Prospective cohort study with objective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: seven university hospitals, USA and Canada

40 patients (aged ?, 100% female) pregnant women with accidental carbon monoxide poisoning giving birth to 38 babies. Women were exposed in all three trimesters.


100% followed for 3 years
Outcomes studied:
  • poor foetal outcome or neurodevelopmental delay among exposed offspring

    • Prognostic factors: Grade of severity of maternal CO exposure:
      • Grade 1- alert and oriented, but headache, dizziness and nausea
      • Grade 2- alterations of mental state
      • Grade 3- not alert, disorientation, loss of recent memory, muscle weakness, or incoordination
      • Grade 4- disoriented, depressed sensorium, limited and inappropriate response to simple commands
      • Grade 5- comatose

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    poor foetal outcome or neurodevelopmental delay among exposed offspring 3 years / 1%
    (% to %)

    prognostic factor for
    poor foetal outcome or neurodevelopmental delay among exposed offspring     		time to outcome unadjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    grade 4-5 3 years 100
    (14 to inf)     		1
    (1 to 8)

    • None of the women with grade 4-5 exposure and adverse outcomes received hyperbaric oxygen. This led to two stillbirths, and one case of cerebral palsy secondary to postpartum anoxia. The two women that did, had normal births.
    • All other children were developing normally at the end of follow-up.

    Citation

    1. Koren G, Sharav T, Pastuszak A, et al: A multicenter, prospective study of fetal outcome following accidental carbon monoxide poisoning in pregnancy. Reproductive Toxicology 1991; 5: 397-403
    Contributor: Joel Ray and Chris Ball, July 2000
    Reviewer: Lucia Balea

    Clinical Question.
    Patient pregnancy and CO poisoning
    Intervention or Exposure risk factors
    Outcome abnormal pregnancy/birth