This study aimed to assess the effect of the inflammatory process on fetal cardiac functions in pregnant women with autoimmune diseases (AID). This prospective study included 36 pregnant women with diagnosed AID. Nineteen systemic lupus erythematosus, 12 antiphospholipid syndrome, 5 Sjögren's syndrome, and 72 healthy pregnancies were included. Fetal cardiac functions were evaluated with pulsed-wave, tissue Doppler, and M-mode echocardiography. Sociodemographic data were similar in both groups. Significant increases were found in tricuspid E (43.5± 0.9, p<0.001) and A (59.2 ± 2.2, p<0.001) and E/A (0.74 ± 0.03, p<0.001), E'/A' (0.64 ± 0.15, p<0.001), E/E' (6.5 ± 0.6, p<0.001), and left ventricular myocardial performance index (0.54 ± 0.03, p=0.005). We demonstrated a significant decrease in tricuspid E' (6.7 ± 0.6, p<0.001) and S' (6.9 ± 1, p<0.001) and in TAPSE (7.7± 0.5, p=0.002). We also found a significantly prolonged PRinterval (130 ± 8, p<0.001). There was a significant increase in E' (6.8, p=0.033) and a significant decrease in E/E' ratio (6.4,p=0.027) in the group using hydroxychloroquine (HCQ) compared to non-users. We found that pregnancy with autoimmune diseases affects fetal heart functions. Additionally, hydroxychloroquine may positively affect the heart of AID fetuses. This information might be useful to clinicians in the follow-up of cardiovascular diseases.