Can complete blood count parameters that change according to trimester in pregnancy be used to predict severe preeclampsia?

We aimed to evaluate the effectiveness of changes over time in complete blood count (CBC) parameters to estimate the diagnosis of preeclampsia. Data on 161 severe preeclampsia patients and 161 healthy pregnant patients who met the study criteria of pregnant women whose CBC had been measured at 10-12, 22-24 and 28-30 weeks of pregnancy were compared. In the preeclampsia group, an increase in the mean platelet volume (MPV) value and a decrease in the number of platelets were statistically significant in the transition from the second to the third trimester. MPV and lymphocyte counts were more significant in the third trimester and neutrophil lymphocyte ratio (NLR) were more significant in the second trimester. We found that evaluation of the changes in lymphocyte, MPV and NLR values in three different trimesters of pregnancy rather than a single trimester was more meaningful to predict severe preeclampsia.Impact Statement Studies have shown that MPV and NLR can predict preeclampsia. However, a clear cut off value could not be determined. The reasons for this may be that the gestational week during which the measurement is made is not standard and the patient groups are not homogeneous. In this study, CBC parameters at different stages of the preeclampsia process were compared in the severe preeclampsia group. According to our results, lymphocytes, NLR and MPV can be used to predict severe preeclampsia. In addition, NLR measurements in the second trimester and MPV and lymphocyte measurements in the third trimester were found to be more significant in predicting severe preeclampsia. In order to predict severe preeclampsia, instead of a single measurement of CBC parameters, new calculations should be made that add change over time.