Pregnancy represents a major challenge to animal based on the analysis of immunological and metabolic responses. Thus, the aim of this study to assess the potential changes in adenosine deaminase (ADA) enzyme activity level, representative indicators of liver function, and some markers of oxidative stress. This study was conducted on 36 Saidi ewes divided into four equal groups (n=9). The first group (non pregnant) was kept as control, while the other three groups were classified according to the time intervals of pregnancy (4-5, 11-12 and 16-17 weeks). The study showed that ADA level exhibited a bimodal pattern with highly significant increase in early pregnancy, decline in mid pregnancy, and further increase in late pregnancy. A significant increase in total protein (TP) was observed at early pregnancy, and returned to the basal level followed by further significant decrease at the late stage of pregnancy. Albumin (ALB) and triglyceride (TG) undergone significant decreased at the late stage. Mean while, total bilrubin (TB), total cholesterol (TC) and aspartate aminotransferase (AST) remained significantly lower than the pre-pregnancy values. The maximum level of gamma-glutamyl-transferase (GGT) appeared at early pregnancy, and the minimum level was observed at the late period. Malondialdhyde (MDA) has undergone a significant reduction along all time intervals in comparison to its non pregnant value. At the mid and late periods, significant reductions in nitric oxide (NO) levels were observed relative to the non pregnant values. Using Pearson correlation, ADA correlated positively with TP, globulin (GLOB) and GGT, and negatively with TB. In conclusion, the pregnancy in Saidi ewes is marked with biphasic modulation in ADA, impairment in liver functionality and adaptation in the face of oxidative stress at least on the level of lipid peroxidation. In addition, monitoring of the biochemical measurements in the blood of ewes in the different stages of pregnancy gives the basis for carrying out the treatment more effectively, and implementation of preventive measures against the metabolic disorders of ewes in order to reduce the economic losses.