Abstract: The pregnant SD rats were divided into 4 groups as follows： group A and group B, passive smoking for 2h everyday in isolator from 1st and 10th day to 20th day after mating;group C, the control group without passive smoking under normal condition; and group D, the control group without passive smoking, placed in isolator for 2h everyday. The results showed that there were significant difference between group A，B, and group C in the average body weight of live fetal rats (2.0±0.71，2.82±0.50g vs 3.74±0.40g)，the incidence of IUGR (87%, 59.6% vs 5%), the average body length (2. 84±0.42，3.24±0.30cm vs 3.94±0.22cm) and the average weight of placenta (0.48±0.12, 0.50±0.llg vs 0.6±0.40g) . There is no difference between control group C and D. The early resorption rate of embryo and fetal death rate of group A and B were 32.4% and 19. 2% , which were significantly higher than that of control group C and D (3.45% and 4.19% ), this suggests that passive smoking even threaten the survival of fetal rat. These results showed that the IUGR rat model established in isolator was easy to control, could be easily repeated, short in experimental period and high in incidence of IUGR.

Key words: Rat, Passive smoking, intrauterine growth retardation