Arslan A, et al. - Researchers here evaluated pregnant carbon monoxide (CO) poisoning patients that received hyperbaric oxygen (HBO) treatment as well as their fetal status. Treatment of a total number of 32 pregnant cases was reported. COHb values of over 20% (min 6.9- max 40.2) was noted in 23 patients, 11 patients had a history of syncope. HBO treatment was administered to all patients under 2.4 ATA pressure for 120 min. Except for CO poisoning, HBO should not be performed in pregnant patients. HBO treatment under 2.4 ATA pressure for 120 min was not associated with any harmful effects on the mother and the fetus in this study. Beneficial effects were observed in the cases with fetal distress in correlation with continuation of HBO treatment. They identified no significant effect of COHb levels and syncope on clinical symptoms and on blood tests.