Received May 24, 2017
Accepted November 30, 2017

Objective: This study was designed to investigate the effect of nicotine on serum progesterone and estradiol levels as possible cause of abortion during first trimester of gestation in female Wistar rats. Methods: Fourteen female rats with regular estrous cycles in the same phase of cycle were divided into two groups (Control and Nicotine-treated) with each group receiving 1ml of distilled water and 1mg/kg of nicotine respectively for the first seven days of pregnancy (GD1-7). The animals were sacrificed on the 8th day and blood samples were collected for hormonal analyses. Ovaries and uteruses were excised, weighed, and prepared for histological study. Results: This study revealed a significant decrease in serum progesterone and estradiol levels in the nicotine-treated group when compared to controls. The histological findings equally showed degeneration in the cytoarchitecture of the ovary of the nicotine-treated group. Conclusion: The observed hormonal imbalances and alteration in the cytoarchitecture of the ovary caused by nicotine in the first trimester of pregnancy may result in abortion during this period.