ETHNOPHARMACOLOGICAL RELEVANCEThe popularity of herbal medicine is expanding globally due to the common belief that herbal products are natural and nontoxic. Thymelaea hirsuta leaves are traditionally used for the treatment of recurrent abortion in humans and animals. However, a lack of safety evaluation of the plant, particularly in pregnant women, raises serious concerns regarding its potential embryotoxic effects.AIM OF THE STUDYTherefore, the present study investigated the safety of Thymelaea hirsuta leaves aqueous extract (THLE) during pregnancy and lactation following maternal rat treatment.MATERIALS AND METHODSTHLE phytochemical compounds were identified using high-performance liquid chromatography (HPLC). THLE was orally administered to pregnant rats and lactating dams at dosages of 0, 250, 500, and 1000 mg/kg/day. At the end of the study, dam s' and pups' body weights, serum biochemical and hematological indices, and histopathological changes were investigated. For the fetal observation and histopathological changes were also evaluated.RESULTSOur findings revealed that THLE is rich in different phenolic and flavonoid compounds. However, biochemical and hormonal parameters such as ALT, AST, and prolactin were significantly increased in dams treated with a higher dosage of THLE when compared to the control dams (P ≤ 0.05). Additionally, external, visceral and skeletal examinations of fetuses revealed a marked increase of malformation rates in treated fetuses.CONCLUSIONSThe results revealed that higher oral dosing of THLE during pregnancy could affect embryonic development in rats, while lower doses are safe and can be used during pregnancy and lactation to attain its beneficial effects.