During pregnancy, many diseases are correlated with different adverse outcomes. In turn, pregnancy affects the body, leading to increased disease susceptibility. This interplay between diseased states and pregnancy outcomes is illustrated in the effect of the chronic autoimmune disorder, rheumatoid arthritis (RA), and the adverse outcome, preterm birth (PTB). RA is a systemic disorder characterized by inflammation of the joints and other body organs. Joint pain and swelling are the most prominent manifestations of RA during pregnancy. However, the exact role of RA on PTB among pregnant women has yet to be established. This review highlighted the immunologic mechanisms involved in PTB in pregnant patients with RA. The immune cell population in pregnant women with RA exhibits higher activity of macrophages, dendritic cells, neutrophils, helper T (Th) 1 cells, and Vδ1 cells, but lower activity of CD4 + CD25 T regulatory (CD24 + CD25 T ), Th2, and Vδ2 cells. Increased pro-inflammatory cytokines IL-6, TNF-α, and IFN-γ and decreased anti-inflammatory cytokines IL-12 and IL-10 are also exhibited by pregnant patients with RA. This review also discussed factors that may predict the risk of PTB in RA. These include disease activity and severity of RA, laboratory parameters (cytokines and immune cell population), and sociodemographic factors such as ethnicity, smoking, alcohol intake, and the level of education. Current findings on the underlying immunological mechanisms of RA can help identify possible strategies to prevent PTB. This article is protected by copyright. All rights reserved.