Beyond Blood Pressure: Decoding Pregnancy Risks Through Neutrophil-to-Lymphocyte Ratio in Gestational Hypertension

Abstract

Background: Gestational hypertension (GH) is one of the most prevalent hypertensive disorders of pregnancy, complicating approximately 6%–10% of all pregnancies and contributing substantially to maternal and perinatal morbidity. Despite established diagnostic criteria, risk stratification within the GH spectrum remains challenging, as blood pressure elevation alone inadequately predicts adverse outcomes. The neutrophil-to-lymphocyte ratio (NLR), a readily available haematological index of systemic inflammation, has emerged as a potential biomarker in various inflammatory and vascular conditions. Its utility in predicting maternal and neonatal outcomes in gestational hypertension beyond 20 weeks of gestation has not been systematically evaluated. Objective: To evaluate whether the NLR, measured at the time of gestational hypertension diagnosis, is associated with adverse maternal and neonatal outcomes, and to determine an optimal NLR threshold for risk stratification in women with gestational hypertension diagnosed after 20 weeks of gestation Methods: A retrospective, record-based observational study was conducted at a tertiary care teaching hospital. All women diagnosed with gestational hypertension (systolic blood pressure ≥0140 mmHg or diastolic blood pressure ≥90 mmHg on two occasions, at least four hours apart, after 20 weeks of gestation, without proteinuria) who delivered during a defined study period were included. The NLR was calculated from the complete blood count obtained at the time of diagnosis. The study population comprised 300 eligible participants. Women were classified into elevated NLR (≥3.5) and normal NLR (<3.5) groups. Primary outcomes were preterm birth, small for gestational age (SGA), and NICU admission. Secondary outcomes included superimposed preeclampsia, mode of delivery, and maternal complications. Logistic regression was performed to assess independent associations, adjusting for maternal age, BMI, gestational age at diagnosis, and parity. Results: Of 300 women with gestational hypertension, 112 (37.3%) had an elevated NLR (≥3.5) and 188 (62.7%) had a normal NLR (<3.5). Women in the elevated NLR group were more likely to develop superimposed preeclampsia (29.5% vs. 11.2%; p<0.001). Preterm birth was significantly more frequent in the elevated NLR group (33.9% vs. 16.0%; p=0.001). SGA occurred in 24.1% of neonates born to women with elevated NLR versus 12.2% in the normal NLR group (p=0.009). NICU admission was higher in the elevated NLR group (31.3% vs. 17.0%; p=0.006). On multivariable analysis, elevated NLR was independently associated with preterm birth (adjusted OR 2.21; 95% CI 1.24–3.94; p=0.007), superimposed preeclampsia (adjusted OR 2.76; 95% CI 1.42–5.35; p=0.003), and NICU admission (adjusted OR 2.01; 95% CI 1.09–3.71; p=0.03). Conclusion: In women with gestational hypertension after 20 weeks of gestation, an elevated NLR at the time of diagnosis is independently associated with increased risk of preterm birth, superimposed preeclampsia, and neonatal intensive care admission. The NLR represents a low-cost, universally available inflammatory biomarker that may augment blood pressure-based risk stratification in gestational hypertension. Prospective studies are warranted to validate these findings and assess the clinical utility of NLR-guided surveillance.