Platelet to lymphocyte and neutrophil to lymphocyte ratio in the first trimester of pregnancy, are they useful for predicting spontaneous miscarriage? A case-control study.

Background: In 15% of all clinical pregnancies, a miscarriage can occur, but the exact cause of this phenomenon is not fully understood. However, it is believed that a faulty placenta, which triggers an inflammatory response in the mother's body, may be one of the causes. Medical literature has increasingly focused on 2 indicators of inflammation, the platelet-lymphocyte ratio (PLR) and neutrophil-lymphocyte ratio (NLR). Despite this, there has yet to be a study conducted that examines the rates of PLR and NLR in cases of miscarriage.

Objective: This study aims to determine whether there is an increase in complete blood count inflammatory parameters such as NLR and PLR in women who experience miscarriages.

Materials and methods: This retrospective case-control study was conducted from March 2021 to March 2022, across 3 academic hospitals in Tehran, Iran. A total of 240 participants were enrolled comprising individuals with either miscarriages or normal pregnancies (n = 120/each). Data were collected from the medical records of participants aged between 18-42 yr old, with gestational age ranging from 6-13 wk. The demographic information, including age, body mass index, parity, history of abortion, number of abortions, number of living children, hematocrit and hemoglobin levels, platelet distribution width (PDW), PLR, NLR, mean platelet volume, and platelet were extracted from their records. The gestational age was also recorded.

Results: A total of 240 participants were recruited for the study. PDW, NLR, PLR, and lymphocyte values were higher in the miscarriage group compared to the healthy normal pregnant women (p $<$ 0.001). Mean platelet volumes were found to be lower in the miscarriage group compared to the healthy normal pregnant women (p $<$ 0.001).

Conclusion: Although, no statistically significant difference was observed in the hemoglobin, hematocrit, platelets, and neutrophils in these 2 groups of pregnant women. The higher inflammatory markers including PDW, NLR, and PLR could potentially aid in the speculation of defective placentation as a contributing factor to the development of miscarriage. Measurement of these markers may be useful to predict pregnancy leading to miscarriage.