Nonpregnant cattle represent a financial and logistical problem for the industry, making early pregnancy detection essential for the economical progression of operations. For example, a dairy farm with 5,000 cows could save $180,000 every year by diagnosing pregnancy 11 days earlier. Obtaining pregnancy rates from artificial insemination (AI) or natural service at an earlier time impacts how soon the cow can be resynchronized, culled, or have reproductive challenges diagnosed. Currently, the gold standard for pregnancy diagnosis is ultrasonography, which can be done commercially no earlier than day 28 (D28) of gestation. Interferon-tau (IFNT) is a protein secreted by the bovine conceptus (embryo plus extraembryonic membranes) which is essential for maternal recognition and pregnancy establishment in cattle. IFNT secretion by the developing conceptus increases around D16 and stimulates the expression of interferon-stimulated genes (ISGs) in circulating white blood cells (WBCs). The objective of this study was to evaluate circulating WBCs in bred cows for ISG expression, which could potentially lead to the ability to detect pregnancy via a blood test as early as D19. The methods include drawing blood from heifers at D19 and D30 following AI. Whole blood was centrifuged in the laboratory, proceeding with the isolation of the WBC. Total RNA was extracted from WBC followed by cDNA synthesis and real-time PCR, for measuring expression of a variety of INTF-stimulated genes: ISG15, MX1, MX2, and OAS1. These genes are interferon-stimulated, which means that their expression levels can be associated with the presence of a developing conceptus secreting IFNT. Ultrasonography was performed at D30 of gestation to confirm pregnancy. MX2 mRNA expression was higher (P = 0.02) in pregnant compared to nonpregnant heifers. Similarly, ISG15 mRNA expression tended (P = 0.09) to increase in pregnant compared to nonpregnant heifers on D19 after AI. Results from the current study reinforces the idea that ISGs can be used to estimate early pregnancy in cattle. Further research needs to be conducted for the development of methods with high sensitivity and specificity for early detection of pregnancy in cattle.