Background and Objective: Fennel seeds, which are incorporated in many drugs and drinks, act as agents to increase appetite, energy, calmness, and milk secretion. This study was set to investigate the effects of fennel seeds on pregnancy.

Materials and Methods: Four doses of 50,100,200,400 mg / kg of fennel seeds were prepared. Then, 4 groups of 7 BALB/ C female mice weighting 21 to 25 grams for injection of 4 different experimental doses and two groups of 5 BALB/ C female mice were considered as sham and control. The fetus and uterus of the pregnant mice were removed and photographed by photo-stereomicroscope. Afterwards, microtome cutting sections of central portion of samples was prepared and studied. The results were analyzed using ANOVA with significance level of
P <0.05 and P <0.01.

Results: At a dose of 50 mg/kg, fetuses exhibited subcutaneous bleeding. At doses of 100, 200 and 400 mg/kg, abnormalities such as severe subcutaneous bleeding, protrusion of the liver (Exohepatic) and protrusion of the brain (Exencephaly) were observed in embryos. All 4 doses indicated uterine wall thickening which similarly happened in uterine with atrophied fetus.

Conclusion: The observed abnormalities provide evidence that fennel seed can act as a teratogen agent during pregnancy.