Effect of cigarette smoke inhalation during pregnancy in Sprague-Dawley rats.

Pregnant 9 weeks old Sprague-Dawley rats were exposed to the smoke of different research cigarettes (C1-C7). The cigarettes were different in smoke nicotine, condensate and carbon monoxide. The animals were divided in groups inhaling different smoke concentrations, numbers of inhalations per day and time periods per pregnancy. Carbon monoxide and dioxide content in the inhalation chamber increased dependent on time and concentration of smoke inhalation. Both parameters were highest after inhalation of smoke from cigarette C2. The weight of the pregnant rats was reduced after inhalation of high concentrations of smoke from cigarette C1 and c2. Weight and length of fetuses were reduced dependent on number and duration of smoke inhalation. High concentrations of cigarette smoke, twice daily for 21 days were more effective than smoke inhalation in the second part of the pregnancy. Inhalation of cigarette smoke during the second half of the pregnancy was more effective than smoke inhalation in the first ten days of pregnancy. cigarette C1 reduced the length and weight of fetuses more than cigarette C2 when concentration and number of inhalations per day were the same. The vapor phase in both cigarettes was not as effective as the total smoke. Resorptions and stillbirths were independent of treatment. Malformations were diagnosed only in one fetus.