effect of chronic exposure to subanaesthetlc doses of a mixture of halothane, nitrous oxide and oxygen on pregnant rats and foeti

four hundreds female white albino rats were devidedinto four equal groups. The first 3 groups were exposedto a mixture of subanaesthetic concentrations ofhalothane (0.5%) nitrous oxide (5L/min.) and oxygenC5L/min.) for 2 hours daily for 90 days.The females of first 2 groups were served by anormal males(One male to 2 females)at the 90th day ofexposure. The female of group I were kept under thesame treatment and those of group 11 were kept withouttreatment until they were sacrified at 20th day ofpregnancy. The females of group III were left withoutexposure for )0 days before pregnancy.Half number of group IV rats (control) were allowed.to get pregnant with group I and 11 and the other halfwtre allowed to get pregnant with group III rats.The mortality rates were 6% , 5% , 5% and 2% forgroup I, group 11, group III and control grouprespectively through their period of experiment.The pregnancy rates were 9.5%, 66% and 94.7%for group I, group 11 and groupIII respectively incontrast to 100% for their control group.Histopathological changes, were more marked inseverity and of high percentage of occurence ingroup I than in groupII •. GroupJII showed minimalpatholoeical changes.