One of the insecticides in the neonicotinoid group is thiacloprid (THIA), the first chloronicotinyl pesticide with significant insecticidal action, which is applied to numerous crops to manage a variety of pest species. THIA may target the liver primarily, although reports of nephrotoxicity, teratogenicity, and carcinogenicity have indeed surfaced. The current study endeavors to investigate the teratogenic, oxidative stress, and genotoxic effect of THIA (1/40 and 1/20 of median lethal dose "LD₅₀") on the rat pregnant dams and their fetuses from 6^th to 20^th days of gestation. The two THIA-treated groups displayed teratogenic anomalies including fetuses not evenly distributed across the uterine horns, dead fetuses, and resorption sites in the uteri. Histologically, both maternal and fetal hepatic and renal tissues exhibited some histopathological alterations. Additionally, hepatic tissues from both the mother and their fetuses displayed a significant increase (P<0.05) in malondialdehyde level (indicating lipid peroxidation), a significant decrease (P<0.05) in the catalase and superoxide dismutase activities, and reduced glutathione level (indicating a defect in the antioxidant defense system), with a significant rise (P<0.05) in the comet parameter (indicating DNA damage). In conclusion, THIA treatment during the gestational period has a high potential for causing teratogenic and genotoxic effects, as well as oxidative stress, in pregnant dams and their fetuses. According to the study's findings, both pregnant females and their fetuses exposed to THIA may be at risk.