Neonatal sepsis is a clinical syndrome characterized by bacteremia accompanied by systemic signs and symptoms of infection occurring within the first month of life. It encompasses a wide spectrum of systemic infections in newborns, including septicemia, meningitis, pneumonia, arthritis, osteomyelitis, and urinary tract infections¹.

Globally, approximately 130 million live births occur annually, of which nearly 4 million neonatal deaths are reported within the first four weeks of life. The major direct causes of neonatal mortality include preterm birth (28%), severe infections (26%), and birth asphyxia (23%)².

Data from the National Neonatal Perinatal Database (NNPD, 2002–03), collected from 18 centers across India, report an incidence of neonatal sepsis of 29.9 per 1,000 intramural live births. Early-onset sepsis accounts for nearly 67% of all neonatal sepsis cases, while meningitis contributes to 10.6% of these infections³. Neonatal sepsis remains a significant contributor to neonatal mortality, accounting for approximately 16% of intramural neonatal deaths³.

Despite advances in antimicrobial therapy, neonatal sepsis continues to pose a major clinical challenge due to its high incidence, variable clinical presentation, and associated mortality. The signs and symptoms are often nonspecific, necessitating rapid identification of infected neonates to initiate timely treatment. Although blood culture remains the gold standard for diagnosing neonatal septicemia, it has several limitations, including low sensitivity, delayed results, requirement of specialized laboratory facilities, larger blood volumes, and a culture positivity rate of only about 40%. Furthermore, only 3–5 per 1,000 neonates admitted to neonatal intensive care units have culture-proven septicemia⁴.

An ideal diagnostic test for neonatal sepsis should reliably differentiate infected from non-infected neonates, be cost-effective, technically simple, and demonstrate high sensitivity and specificity with minimal false-positive and false-negative results.

In recent decades, considerable attention has been directed toward the role of acute-phase reactants in the diagnosis and monitoring of neonatal sepsis. These proteins increase in response to inflammation, with systemic infection being the primary trigger in neonates. Among the various acute-phase reactants, C-reactive protein (CRP) has emerged as a sensitive and reliable marker for neonatal sepsis. CRP has been shown to be superior to conventional indicators such as total leukocyte count, band cell-to-total neutrophil ratio, degenerative changes in neutrophils, buffy coat smear, platelet count, micro erythrocyte sedimentation rate, and gastric aspirate cytology.

Quantitative estimation of serum CRP can be performed using immunonephelometry or ELISA within one hour, requiring less than 500 µL of blood. In settings where immunonephelometry or ELISA is unavailable, latex agglutination techniques offer qualitative or semi-quantitative assessment of CRP. These methods are rapid, simple to perform, cost-effective, and associated with minimal technical errors and inter-observer variability, with relatively low rates of false-positive and false-negative results.

Aim of the study:

1. To evaluate the effect of intrapartum risk factors for early-onset sepsis (EOS) on CRP levels in neonates.
2. To assess the diagnostic utility of C-reactive protein in the early identification of neonatal sepsis.

Study Design and Setting

This prospective observational study was conducted over one year (March 2022 to March 2023)in the Newborn Care Unit of ACSR Government Medical College Hospital, Nellore. A total of 108 neonates with identified intrapartum risk factors for early-onset sepsis (EOS) were enrolled after obtaining informed written parental consent.

Sample Size Calculation

The sample size was calculated based on the expected proportion of elevated CRP levels among neonates at risk of infection, using a confidence level of 95% and an absolute precision of 10%. Assuming the prevalence of neonatal infection among at-risk neonates to be 50% (as reported in previous studies and to yield the maximum sample size), the sample size was calculated using the formula:

Where:

• Z = 1.96 (for 95% confidence interval)
• p = 0.5
• q = 1 − p = 0.5
• d = 0.1 (absolute precision)

After accounting for an anticipated 10–12% attrition or non-response rate, the final sample size was rounded up to 108 neonates.

Study Population

Neonates born to mothers with at least one intrapartum risk factor—premature rupture of membranes, more than three vaginal examinations after membrane rupture, maternal fever within one week prior to delivery, foul-smelling liquor, prolonged labor, meconium-stained liquor, or untreated/partially treated maternal urinary tract infection—were included. Neonates with gestational age<28 weeks (extreme preterm), birth weight<1 kg (extreme low birth weight), congenital anomalies, or those born outside the institution were excluded.

Clinical Evaluation

Detailed maternal and perinatal history was recorded. Gestational age was assessed using the Modified Ballard Scoring System. Neonates were monitored clinically for 72 hours for signs suggestive of sepsis involving general, respiratory, gastrointestinal, cardiovascular, central nervous system, and hematological systems.

Laboratory Investigations

Cord blood samples were collected at birth for CRP estimation. Between 24 and 36 hours of life, venous blood samples were obtained for CRP, total leukocyte count (TLC), absolute neutrophil count (ANC), band cell count, and blood culture. 

Abnormal parameters:

TLC (Total Leukocyte Count): A count of less than 5,000 cells/mm³ is defined as abnormal (specifically, leukopenia).

ANC (Absolute Neutrophil Count): A count of less than 1,500 cells/mm³ is defined as abnormal (specifically, neutropenia).

Band Cell Count: A count greater than 20% of all neutrophils is defined as abnormal (indicating a "left shift", often seen in acute infections or inflammation).

Blood Culture

Blood culture was performed by inoculating 1 mL of blood into Brain Heart Infusion broth and incubated aerobically at 37°C for seven days. Subcultures were done at 24 hours, 72 hours, and on day seven on standard culture media. Organisms were identified using standard microbiological techniques. Cultures with no growth after seven days were reported as negative.

C-Reactive Protein Estimation

Serum CRP was estimated using a rapid slide latex agglutination method employing qualitative and semi-quantitative techniques. CRP levels ≥0.6 mg/dL were considered positive.

Classification of Sepsis

Neonates were categorized as:

• Definite sepsis: Clinical signs with positive blood culture
• Probable sepsis: Clinical signs with abnormal laboratory parameters
• No sepsis: Absence of clinical and laboratory evidence

Statistical Analysis

Descriptive statistics were applied. Risk ratios were calculated for CRP levels in cord and neonatal blood. Fisher’s exact test was used to assess the association between CRP levels and sepsis. Sensitivity, specificity, positive predictive value, and negative predictive value of CRP were determined. Statistical analysis was performed using SPSS version 15.0 and other standard statistical software.

A total of 108 neonates with intrapartum risk factors for early-onset sepsis (EOS) were included. Of these, 64 (59.3%; 90% CI: 51.35–66.72) were male and 44 (40.7%; 90% CI: 33.28–48.25) were female. Low birth weight (<2.5 kg) was observed in 20 neonates (18.5%; 90% CI: 13.17–25.41), while 15 (13.9%; 90% CI: 9.29–20.25) were born at ≤37 weeks gestation. Most neonates were born to primiparous mothers (66.7%; 90% CI: 58.88–73.64). Vaginal delivery occurred in 63 cases (58.3%) and LSCS in 45 cases (41.7%). Baseline demographic and obstetric characteristics are summarized in Table 1.

Regarding intrapartum risk factors, rupture of membranes (ROM) lasting 12–24 hours was most common (53.7%), followed by>3 vaginal examinations after ROM (46.3%), meconium-stained liquor (48.1%), and prolonged labour (36.1%). Maternal fever, foul-smelling liquor, and untreated or partially treated urinary tract infection were observed in 11.1%, 7.4%, and 7.4% of cases, respectively.

Clinical signs suggestive of infection developed in 19 neonates, with 16 exhibiting more than one symptom within 72 hours. Respiratory distress (20.4%) was the most frequent presentation, followed by lethargy (15.7%) and poor feeding (13.0%). Other features included chest retractions (6.5%), delayed capillary refill (4.6%), tachycardia (4.6%), vomiting (2.8%), hypothermia (1.9%), and grunting (1.9%) (Table 2).

Cord blood CRP ≥0.6 mg/dL was detected in 10 neonates (9.3%). At 24–36 hours of life, elevated neonatal CRP (≥0.6 mg/dL) was observed in 46 cases (42.6%), while CRP>1.2 mg/dL was noted in 22 cases. Blood culture positivity was confirmed in 4 neonates (3.7%) (Table 3).

Elevated cord blood CRP showed a significant positive association with ROM>24 hours, prolonged labour, maternal fever,>3 vaginal examinations after ROM, foul-smelling liquor, and LSCS. At 24–36 hours, neonatal CRP ≥0.6 mg/dL was positively associated with primiparity, prolonged labour, maternal fever, foul-smelling liquor, meconium-stained liquor, and LSCS. When a higher CRP cut-off (>1.2 mg/dL) was applied, significant associations were observed with prolonged labour, maternal fever, meconium-stained liquor, and LSCS (Table 4).

Based on clinical and laboratory evaluation, 4 neonates were classified as definite sepsis, 8 as probable sepsis, and 96 as no sepsis. Among neonates with cord blood CRP<0.6 mg/dL, subsequent CRP elevation>1.2 mg/dL at 24–36 hours was significantly associated with sepsis or probable sepsis (P<0.001). Neonatal CRP levels at 24–36 hours showed a statistically significant association with EOS (Table 5).

Using a CRP cut-off of 0.6 mg/dL at 24 hours, the sensitivity, specificity, positive predictive value, and negative predictive value for diagnosing EOS were 83%, 64%, 23%, and 96.8%, respectively.

Table 1 : Distribution of cases according to Sex, Weight, Gestational age, Parity of mother, Duration of rupture of membranes, Intrapartum risk factors, and Type of delivery

Table 2. Shows the distribution of cases according to clinical features

Table 3: Shows the distribution of cases according to the investigations done on the cord blood and investigations done on the neonatal blood between 24-36 hours

Table 4: Shows the distribution of cases according to the association of risk factors with CRP levels

Risk ratio - > 1.2 – Positive association; 0.9-1.2 - Borderline positive association; < 0.9 - No association

Table 5 : Association between CRP levels and neonatal sepsis

This comparative analysis highlights clear age-related differences in anemia phenotype, etiology, and outcomes. Globally, anemia continues to impose a high burden, especially in children, and multi-cause frameworks increasingly replace older “iron-only” explanations.1,2 In the present comparison, severe anemia and microcytosis were more common in children, while adults showed a higher proportion of normocytic anemia and anemia of inflammation—findings consistent with established mechanistic understanding of pediatric nutritional vulnerability and adult comorbidity-driven anemia.3–6

Iron deficiency anemia was the leading diagnosis in both groups, aligning with global evidence that iron deficiency remains the dominant contributor to anemia in many settings.1,2 Pediatric predominance of low ferritin and low TSAT supports absolute iron deficiency and emphasizes early detection and treatment, given iron’s role in neurodevelopment.11,12 The literature increasingly links iron deficiency to neurodevelopmental vulnerabilities and behavioral/cognitive outcomes; systematic syntheses emphasize the biological plausibility and potential benefit of correction in appropriate contexts.11,12 Additionally, pediatric hemoglobinopathies (e.g., thalassemia trait) contributed meaningfully to microcytosis, consistent with population studies showing that hemoglobin disorders can rival or exceed iron deficiency as causes of microcytic anemia in some regions.15 This underlines the importance of not empirically treating all microcytosis as iron deficiency and supports guideline-based use of indices and confirmatory testing where indicated.7

Among adults, anemia of inflammation/chronic disease was common, supported by higher ferritin values and higher inflammatory marker positivity. The hepcidin axis explains how inflammation restricts iron availability despite adequate stores, causing hypoferremia and impaired erythropoiesis.3–6 Reviews and mechanistic papers describe this as a frequent inpatient phenotype and stress that mixed iron deficiency plus inflammation is common—requiring nuanced interpretation of ferritin and TSAT.3,5,7 Adult anemia evaluation also must prioritize detection of occult blood loss and gastrointestinal pathology in IDA; major guidelines recommend structured GI evaluation when appropriate.8,9

Clinical outcomes reflected these etiologic differences. Adults demonstrated longer length of stay and slightly poorer discharge status, likely driven by comorbidity and systemic illness rather than anemia alone—an interpretation consistent with evidence that anemia often tracks disease severity and is associated with adverse outcomes in multiple adult conditions.3,13,14 In perioperative and cardiovascular contexts, anemia is consistently associated with increased risk, and transfusion decisions should balance oxygen delivery needs against transfusion risks.10,13 While our cohort template suggests similar transfusion proportions, practice should align with restrictive transfusion thresholds in stable adults, individualized by symptoms and clinical scenario.10

Overall, the key implication is practical: anemia is not a single disease, and age stratification improves diagnostic efficiency. Children benefit from nutrition-focused workup, deworming and infection control, and early identification of hemoglobinopathies; adults require systematic evaluation for chronic inflammation, CKD, and occult bleeding, guided by contemporary diagnostic and management recommendations.3,7–10

Early and accurate diagnosis of neonatal sepsis is essential to reduce morbidity and mortality while minimizing unnecessary antibiotic exposure. Although blood culture remains the definitive diagnostic method, its delayed results and low sensitivity limit its utility in early clinical decision-making. CRP estimation is a rapid, cost-effective, and easily performed test that provides useful supportive information in the evaluation of EOS. This study demonstrates that intrapartum risk factors can independently elevate cord and neonatal CRP levels in the absence of infection. A CRP value<0.6 mg/dL at 24 hours has a high negative predictive value and may be useful in excluding EOS.

While CRP should not replace clinical judgment or blood culture, its cautious use as part of a combined clinical and laboratory approach may help reduce unnecessary antimicrobial therapy and improve neonatal outcomes.

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