Objective: To evaluate the effect of norfloxacin on pregnant female rats.
Animals: 30 pregnant female rats (170-200 gm of weight and 3.5-4 months age).
Design: Randomized controlled study.
Procedures: The effect of orally administrated norfloxacin, given twice daily for 10 successive days, on the fetal development in pregnant female rats at therapeutic (35 mg/kg) and double therapeutic (70 mg/kg) doses was investigated in pregnant female rats. At 6^th -15^th day of pregnancy, 30 females were classified, in groups of ten rats, into 3 groups.Group 1 (control group): rats were given distilled water orally. Group 2: rats were given norfloxacin at a dose rate of 35 mg/kg bwt. Group 3: rats were given norfloxacin at a double therapeutic dose of 70 mg/kg bwt. At 20^th day of gestation all pregnant rats were anesthetized to determine the changes; if any; in fetal development (morphological, visceral, skeletal and histopathological examinations) and on treated dams (biochemical parameters of serum and histopathological alterations in placenta, liver and kidney).  
Results: Administration of norfloxacin, in both doses, to pregnant females decreased the number of viable feti, fetal body weight and crown-rump length, andincreased the number of resorbed feti (P< 0.05).It also induced visceral and skeletal abnormalities in feti. Histopathological examination of internal organs to both dams and feti revealed pathological alterations in liver and kidney of both, and placenta of the dam.Administration of norfloxacin at both therapeutic and double therapeutic doses increased maternal serum transferases levels (ALT and AST), decreased serum albumin and total portein levels, and increased serum levels of urea and creatinine (P< 0.05).
Conclusion and clinical relevance: High doses of norfloxacin induce fetal defects and abnormalities in early stage of gestation in rats.