OBJECTIVE: In a rabbit model using hysteroscopy-guided inoculation of E.coli with antibiotic administration, we determine the effects of persistent intrauterine infection on perinatal outcome including fetal death, congenital sepsis, and abnormal fetal-placental growth and amniotic fluid volume in live fetuses. METHODS: Rabbits with timed pregnancies underwent hysteroscopy at 20 to 21 days of gestation(70%). Animals were inoculated with E. coli (0.2 ml containing 10 cfu/ml) and administered ampicillin-sulbactam(100 mg/kg/day; Unasyn; Pfizer) every 8 hours beginning 30 minutes after microbial inoculation until they were killed 5 days after hysteroscopy. In the first study, the following outcome parameters were evaluated between fetuses with and without pe#rsistent intrauterine infection: fetal survival, congenital sepsis, maternal morbidity, and placental pathology. In second study was performed in 16 rabbits having only both live fetuses with and without persistent intrauterine infection in a rabbit simultaneously. We evaluate the effects of persistent intrauterine infection on fetal-placental weight and amniotic fluid volume in live fetuses. RESULTS: 1) Fetuses with persistent intrauterine infection had significantly fewer live fetuses, more positive cord blood cultures than those without (live fetuses: 44% vs 82%, p<0.000001; positive cord blood cultures: 44% vs 3%, p<0.000001, respectively; Fishers exact test). However the rates of maternal morbidity and placental inflammatory lesions were similar between the two groups. 2) The placental weight and amniotic fluid volume were significantly less in live fetuses with than in those without persistent intrauterine infection. Moreover the fetal weight was decreased in live fetuses with persistent intrauterine infection, but it was not statistically significant(placental weight: p<0.05; amniotic fluid volume: p<0.05; fetal weight: p 0.051, respectively; Wilcoxon matched-pairs signed ranks test). CONCLUSION: Fetal complications including fetal death, congenital sepsis, and decreased fetal-placental weight and amniotic fluid volume wae produced in utero when pasistent intrauterine infection was present with antibiotics administration after inoculstion of E. coli. Therefore, when treating with antibiotics in intrauterine infection, it is needed to observe and monitar the presence of persistent intrauterine infection, and if it is peristent, delivery may be considered for the improvement of pregnancy outcome.