Chronic low level maternal carbon monoxide exposure and fetal growth and development

Abstract

The authors investigated the effects on fetal growth and development of continuous exposure of pregnant rats to low level carbon monoxide (30 or 90 ppm CO) and a low oxygen atmosphere (13% O2). While neither CO concentration induced a hematologic response in the pregnant animals, 13% O2 exposure elicited an increase in hematocrit, the number of erythrocytes and hemoglobin concentration. Fetal body growth was unaffected by either CO concentration; however, it was reduced significantly in fetuses exposed to 13% O2. The individual organ weights were differentially affected by 90 ppm CO. The fetal brain wet weight increased 14%, whereas the lung weight decreased 24%. We attribute the brain enlargement in the 90 ppm CO fetuses to an increased water content as evidenced by decreased concentrations of brain protein, DNA, norepinephrine and serotonin and a reduced dry-wet weight ratio. The results indicate that the fetus in utero is affected by relatively low CO concentrations in the maternal environment.