Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio in Twins Compared with Singletons

It is well known that twin pregnancies confer a high degree of adverse perinatal outcomes. Fetal growth restriction, preterm labor/delivery, and hypertensive disorders of pregnancy are among the causal etiologies associated. Hematologic parameters, specifically, the neutrophil:lymphocyte ratio (NLR), the platelet:lymphocyte ratio (PLR), and some of the routine complete blood cell count components denote a peculiar inflammatory and immunologic profile and have been used as clinical markers for specific obstetric syndromes. To our knowledge, no study has ever evaluated NLR/PLR in twins as a distinct population from singletons. Our primary objective was to analyze NLR/PLR in twins compared with singletons. Our secondary objective was to compare white blood cells, neutrophils, lymphocytes, and platelets between twins and singletons.

We conducted a retrospective case-control study comparing NLR/PLR markers in twin gestations (dichorionic/diamniotic and monochorionic/dichorionic) versus singleton pregnancies, from January 2019 to April 2020. We excluded pregnancies with potential confounding factors such as human immunodeficiency virus, chronic hypertension, smoking, pregestational diabetes mellitus, or cases with miscarriage/intrauterine fetal demise. We included twin pregnancies (two fetuses) as cases and singletons as controls.

We recruited 29 twins and 29 singletons, matched for age, body mass index, and parity. NLR was statistically significantly higher in the first trimester in twins compared with singletons (3.3 vs 2.7, P < 0.01) and the platelet value was lower in the second trimester in twins compared with singletons (199 vs 251, P = 0.01).

We speculate that a decrease in NLR from the first to the second trimester and a decrease in platelet in the second trimester reflect both the physiologic inflammatory/immune reaction of early pregnancy and denote a vital response for the development of normal placentation in twin gestations.