Pregnancy is accompanied by an array of adaptive changes that play an important role in pre- and postnatal events. In rats, urocortin 1, a corticotropin-releasing factor-like peptide, is expressed mainly in the non-preganglionic Edinger-Westphal nucleus. We investigated the number of neurons immunoreactive for urocortin 1 at three different levels of the Edinger-Westphal nucleus in female rats by immunohistochemistry. The number of urocortin 1 immunoreactive cells was found to be decreased in pregnant rats compared to virgin rats. These results indicate that the hormonal status of the female rat affects urocortin 1 immunoreactive neurons in the non-preganglionic Edinger-Westphal nucleus and its signaling to target brain areas.