Abstract: Objective To investigate the effects of ascorbic acid(AA)on lipopolysaccharide(LPS)-induced intra-uterine fetal death(IUFD),intra-uterine growth retardation(IUGR)and skeletal development retardation in mice.Methods Experiment 1:all pregnant mice except controls(either saline or AA)received an intraperitoneal(75μg/kg,ip)injection of LPS on gd 15～17.In LPS+AA groups,the pregnant mice were treated with AA at 0.5 h before LPS and/or 3 h after LPS.All dams were sacrificed on gd 18.Experiment 2:all pregnant mice except controls(either saline or AA)received an intraperitoneal(75μg/kg,ip)injection of LPS on gd 16.In LPS+AA groups,the pregnant mice were treated with AA at 0.5 h before LPS and/or 3 h after LPS.All dams were sacrificed at 6 h after LPS.Results Pretreatment with AA significantly attenuated LPS-induced lipid peroxidation,decreased fetal mortality,and reversed LPS-induced fetal growth and skeletal development retardation.However,post-treatment with AA had less effect on LPS-induced IUFD,although post-treatment significantly attenuated LPS-induced lipid peroxidation and reversed LPS-induced fetal growth and skeletal development retardation.Furthermore,post-treatment with AA reduced the protective effects of pretreatment on LPS-induced IUFD.Conclusion Pretreatment with AA protected against LPS-induced fetal death and reversed LPS-induced growth and skeletal developmen tretardation via counteracting LPS-induced oxidative stress,whereas post-treatment and pre-+post-treatmenthad less effect on LPS-induced IUFD.