Background: Hypertensive disorders in pregnancy are one of the most serious complications and their early diagnosis is one of the most important goals of prenatal care.

Objectives: The objective of this study was to determine the association of first trimester Hemoglobin (Hb) and Hematocrit (Hct) with preeclampsia.

Patients and Methods: This descriptive-analytic, prospective study was performed on 1376, less than 12 weeks of gestation, singleton pregnancies, visited for their prenatal care in health and medical clinics of the Qazvin province during years 2013 and 2014. At first, demographic data were recorded in a questionnaire and then all pregnant cases were referred to one of the three reference laboratories for their first trimester routine tests. After hemoglobin and hematocrit date collection, women were categorized in three groups: Hb < 11, Hb ≥ 12.49 and 11 ≤ Hb < 12.49, and based on Hct, two groups: Hct < 38% and Hct ≥ 38. The analysis was done by χ² (chi-square) and t-test with SPSS 16. Receiver operator characteristics (ROC) curve and Youden’s index were utilized for finding the optimum cut off for each. P values of < 0.05 were considered significant.

Results: Preeclampsia incidence was 5.1% in our study. Mean Hb was 12.38 ± 1.69 g/dL in the preeclampsia group and 11.8 ± 1.18 in the non-preeclampsia group, and mean Hct was 37.74 ± 5.15% in the preeclampsia group and 35.45 ± 3.58% in the preeclampsia group and 35.45 ± 3.58% in the non-preeclampsia group, (P = 0.016) (P = 0.001). Furthermore, 43 out of 68 patients with preeclampsia (10.9%) had high hemoglobin (Hb ≥ 12.5 g/dL). We found a significant association between the 1^st trimester Hb, Hct and preeclampsia (P < 0.001, P < 0.001). Assessed relative risk in high Hb group was 5.82 (3.14 – 10.18: CI 95%), and likewise 7.41 in high Hct group (Hct > 38%) (4.41 – 12.044: CI 95%). According to Youden’s Index, optimum cut-off for 1st trimester Hb was 12.65 and for Hct, this was 38.05%.

Conclusions: The association of the 1^st trimester high Hb and Hct with preeclampsia was revealed in this study, therefore it could be used as a prediction factor for early preeclampsia diagnosis.