Objective To explore the effects of exposure to perfluorooctane sulphonate (PFOS) at different doses on embryonic development and expression of placental insulin-like growth factor 1 ( IGF-1) in rats. Methods At gestational day 12, pregnant rats were exposed to different doses of PFOS (0, 5, 10, and 20 mg/ kg) by gavage for 7 d. At gestational day 19, the body masses of pregnant and fetal rats, liver organ coefficient of fetal rats, serum PFOS and glucocorticoid (GC) levels of pregnant rats, and IGF-1 mRNA level of placenta were measured. Results Compared with those in the control group, the serum PFOS levels of pregnant rats in the treatment groups were significantly higher with increasing PFOS dose, while the body mass of pregnant rats and the body mass and length of fetal rats exposed to 20 mg/ kg PFOS were significantly lower ( P < 0. 001). Fetal rat liver organ coefficient in the treatment group showed the same trend of a marked decrease ( P < 0. 05). Blood biochemical alanine aminotransferase (ALT) and aspartate aminotransferase (AST) also increased with the dose of PFOS ( P < 0. 05). Treatment with 10 mg/ kg PFOS increased the serum GC level of pregnant rats ( P < 0. 05). IGF-1 mRNA level decreased with the increasing PFOS dose in placenta. Conclusions PFOS exposure during pregnancy can lead to liver toxicity in fetal rats through the maternal accumulation of PFOS in the serum,increased GC concentration, and decreased IGF-1 mRNA expression, thereby affecting the growth and development of offsprings.