Background:Autoimmune rheumatic diseases (ARDs) are chronic problems that disproportionately impact females of childbearing age. Objective: To evaluate the effect of pregnancy on rheumatic disease activity Patients and Methods: This prospective study was conducted on (70) pregnant patients aged from 18 to 35 years old. They were divided into four groups; (30) with Rheumatoid arthritis, (20) with SLE, (10) with Systemic Sclerosis and (10) with Ankylosing Spondylitis. Routine baseline investigations, auto antibodies and imaging. Results: There were significant differences between the current study groups as regards the history of hormonal therapy (p<0.001); family history of rheumatic disease (p=0.037). There was statistically significant higher RBCs (p<0.001), Hb (p=0.006), WBCs (p<0.001), platelets count (p<0.001) and HCT (p<0.001) value in RA patients versus other patients groups. The acute phase reactant was significant in AS patients; also both ALT and AST were significantly higher in AS patients (p<0.001). RA patients had (Anti-CCP + ) and (RF +) in 80% of cases and other 20% were negative , SLE had (ANA+ ) in all cases , Low (C3-C4) in 87.5% , (RF + ) in 12.5% of cases , in SS all cases had (ACA  +) ,(Anti-SCL70 + ) and in AS all cases had (HLA-B27 +) . Conclusion: The present study pointed to the importance of tight disease control and diagnosis before and during pregnancy as well as the importance of disease activity assessment