Preeclampsia (PE) occurs annually in 8% of pregnancies. Patients without risk factors represent 10% of these. There are currently no first‐trimester biochemical markers that accurately predict PE. An increase in serum 60‐ and 70‐KDa extracellular heat shock proteins (eHsp) has been shown in patients who developed PE at 34 weeks. We sought to determine whether there is a relationship between first‐trimester eHsp and the development of PE. This was a prospective cohort study performed at a third level hospital in Mexico City from 2019 to 2020. eHsp levels were measured during the first‐trimester ultrasound in singleton pregnancies with no comorbidities. First‐trimester eHsp levels and biochemical parameters of organ dysfunction were compared between patients who developed preeclampsia and those who did not. All statistical analyses and model of correlation (r) between eHsp and clinical parameter were performed using bootstrapping R‐software. p‐values <0.05 were considered significant. The final analysis included 41 patients. PE occurred in 11 cases. eHsp‐60 and eHsp−70 were significantly higher at 12 weeks in patients who developed PE (p = 0.001), while eHsp‐27 was significantly lower (p = 0.004). Significant differences in first‐trimester eHsp concentration suggest that these are possible early biomarkers useful for the prediction of PE.