Association between neutrophil to lymphocyte ratio and carotid artery wall thickness in healthy pregnant women

Objective: Pregnancy may elicit a state of mild inflammation that might affect, either directly or indirectly, haematological parameters associated with systemic inflammation. In particular, both Neutrophil-to-lymphocyte ratio (NLR) and Red blood cells Distribution Width (RDW) have been found to be elevated in complicated pregnancy. However, data regarding the association of these haematological parameters with common carotid artery (CCA) intima-media thickness (IMT) in healthy pregnancy are scanty. Aim of this study was to evaluate possible changes in CCA-IMT during normal pregnancy and in the postpartum period, and to correlate these changes with NLR and RDW. Study Design: Between October 2019 and February 2020, a prospective study was carried out on 73 consecutive healthy pregnant women (32.8 ± 4.9 yrs/old). Women underwent obstetric assessment, complete blood cell counts with calculation of NLR and RDW, two-dimensional transthoracic echocardiography and carotid Doppler ultrasonography. Results: During normal pregnancy, both NLR and RDW progressively increased (p < 0.0001); likewise, parameters of carotid dimensions also significantly increased (p < 0.0001). Hematological and morphological changes all decreased in postpartum period. By univariable logistic regression, the variables which showed the greatest independent association with CCA-IMT (defined as CCA-IMT ≥0.55 mm) were: age (HR 1.33, 95% CI 1.15-1.53, p < 0.0001), pre-pregnant BMI (HR 2.75, 95% CI 1.72-4.41, p < 0.0001), third trimester E/e’ ratio (HR 1.64, 95% CI 1.34-2.02, p < 0.0001), and third trimester NLR (HR 3.00, 95% CI 1.64-5.50, p < 0.0001). Multivariable logistic regression analysis demonstrated that third trimester NLR was the only variable that retained statistical significance (HR 2.49, 95% CI 1.35-4.59, p = 0.003). An NLR ≥ 2 reached 83% of sensitivity and 99% of specificity in identifying a CCA-IMT ≥0.55 mm (AUC = 0.95). A strong linear correlation of both third trimester NLR and RDW with CCA-IMT was observed (r = 0.89 and 0.83, respectively). Conclusions: Pregnancy is a state of chronic mild inflammation and the progressive increase in NLR and RDW during normal pregnancy is significantly associated with CCA intimal-medial thickening.