Aim: To investigate whether complete blood count parameters of early pregnancy or biochemical markers of first-trimester trisomy screening were related to the prediction of early onset preeclampsia. Material and Method: Group 1 (n-214) was composed of patients between 18-40 years old with a single pregnancy who was diagnosed with preeclampsia at <34 gestational weeks and had delivery at >= 37 weeks of gestation. Group 2 (n=240) was a control. Women who became pregnant by assisted reproductive technologies or had a body mass index (BMI) >30kg/m2, had a history of delivery complicated by chromosomal anomalies, current or previous medical problems, or multiple pregnancies and patients who had vaginal bleeding in the antenatal period or a history of preterm delivery were excluded. Preeclampsia for pregnancy is defined as having a systolic blood pressure >= 140 and diastolic blood pressure >= 90 as well proteinuria after the 20th gestational week Blood samples for complete blood count, PAPP-A, and free beta-HCG were collected between 11+0 to 13+6 gestational weeks. Results: The mean gestational weeks at delivery and birth weight were significantly lower in Group 1 (preeclampsia) than in Group 2 (control). NRL and PDW were found significantly higher in Group 1. Lymphocyte count was significantly lower in Group 1. PAPP-A was lower in Group 1. Discussion: We found a strong relation between high levels of NLR and PDW. as well as low levels of lymphocyte count and PAPP-A, with early onset preeclampsia development during the current pregnancy.