Objective: Our aim was to determine the effects of maternal serum and amniotic fluid levels of cluster of differentiation 146 (CD-146), transforming growth factor (TGF)-beta 1, interleukin (IL)-12, IL-18, and interferon (IFN)-gamma on intrauterine growth restriction and preterm labor. Methods: In this retrospective cohort study, we included pregnant women who underwent amniocentesis at Istanbul University Cerrahpasa Medical School. Women were followed up to labor. The study group comprised 23 women with adverse pregnancy outcomes (intrauterine growth restriction and preterm labor), and the control group comprised 105 women with normal pregnancy outcome. Results: The study group was further divided into two subgroups of preterm labor and intrauterine growth restriction. No significant differences were found for IL-12, IFN-gamma, TGF-beta 1, or CD-146 levels in either plasma or amniotic fluid between the study and control groups. Serum IL-18 levels were similar, but the amniotic fluid level of IL-18 was significantly higher in the intrauterine growth restriction subgroup than that in the preterm labor subgroup and that in the control group (p < 0.01). Conclusions: Increased IL-18 level in amniotic fluid may be a predictor for intrauterine growth restriction. IL-12, IFN-gamma, TGF-beta 1, and CD-146 were not related to adverse pregnancy outcome.