Background During pregnancy, the maternal immune system plays a central role in maintaining health and preventing disease. Attaining a healthy daily diet contributes to adequate immune fitness, maintaining health, and preventing disease. This pilot study evaluated the relatively underexplored relationships between the stage of pregnancy, immune fitness and the dietary patterns of pregnant women. Methods An online survey was conducted among n = 20 pregnant Turkish women. They reported the number of weeks that they were pregnant and completed the single-item Healthy Diet Scale (HDS) to determine to what extent they considered their daily diet to be healthy. Immune fitness was assessed with a single-item scale ranging from 0 (very poor) to 10 (excellent). Spearman’s correlations (including bootstrapping to account for the small sample size) were computed between weeks pregnant, daily diet scores, and immune fitness. Results A significant negative correlation was found between weeks pregnant and immune fitness ( r = −0.449, p = .047), and a significant negative correlation was also found between weeks pregnant and the percentage of daily diet considered healthy ( r = −0.642, p = .002). A significant positive correlation was found between immune fitness and the percentage of the daily diet considered healthy ( r = 0.622, p = .003). Discussion With progressing pregnancy, poorer immune fitness and a shift towards a less healthy diet were reported. The data suggest that attaining a healthy diet significantly contributes to maintaining adequate immune fitness, which is of particular importance to pregnant women. Future studies in larger cohorts should confirm these findings.