Objective. This study was designed to investigate the effect of sublethal doses (10, 60, and 120 mg/kg of pirimiphos-methyl on implantation and pregnancy in female Sprague-Dawley rats. Pirimiphos-methyl is a pesticide widely used worldwide, especially in Africa to protect food against pests and has gained widespread acceptance.
Methods. Pregnant Sprague-Dawley rats used for this study had access to food and water ad libitum and were divided into a control group and three experimental groups based on dose of chemical given. The pregnant rats were given pirimiphos-methyl orally on days 1–5, 1–7, 7–18th day of gestation and from day 1 to term. Implantation studies were carried out on days 6 and 8 of pregnancy, while the fetal parameters were ascertained on day 19 of pregnancy and at term. Serum levels of progesterone and estradiol were measured on days 6, 8 and 19 of pregnancy.
Results. Sublethal administration of pirimiphos-methyl showed decreased number of implantation sites on days 6 and 8, fetal weight, crown-to-rump length, length of umbilical cord and placenta weight (day 19), birth weight, litter size and total number (at term) in rats administered with pirimiphos-methyl when compared with control.
Conclusion. Administration of pirimiphos-methyl resulted in a reduced implantation rate due to decreased uterine receptivity caused by an imbalance in the level of estradiol and progesterone and impaired reproductive outcome during pregnancy.
