C‑Reactive Protein (CRP) for Infection Assessment in Pregnancy

Measurement and Reference Intervals

High‑sensitivity CRP assays should be used, with results reported to one decimal place in mg/L. This ensures accurate detection of modest elevations relevant to pregnancy‑related infection assessment. 1
CRP can be measured in either fasting or non‑fasting states for metabolically stable pregnant patients. This provides flexibility in clinical workflow without compromising result validity. 1
If a CRP value exceeds 10 mg/L, repeat testing and a focused evaluation for infection or inflammatory sources are recommended. This threshold helps trigger further diagnostic work‑up. 1

CRP must be interpreted as part of a multimodal assessment and never in isolation when evaluating suspected chorioamnionitis or other infection‑related complications. Combining laboratory and clinical data improves diagnostic accuracy. 2
Clinical assessment should include maternal vital signs (pulse, blood pressure, temperature), symptoms (lower abdominal pain, abnormal vaginal discharge, fever, malaise, reduced fetal movements), and fetal heart rate monitoring via cardiotocography. Integration of these parameters with CRP enhances detection of infection. 2
White‑blood‑cell (WBC) count should be incorporated, recognizing that WBC rises 24 hours after corticosteroid administration and returns to baseline after approximately 3 days. This temporal effect must be accounted for when interpreting infection markers. 2

A CRP threshold of ≥8 mg/L yields a specificity of 63.3 %–77.1 % for diagnosing chorioamnionitis. While not definitive, this level helps rule in infection when combined with other findings. 2
CRP has an overall sensitivity of approximately 68.7 % for histological chorioamnionitis, indicating that normal CRP does not completely exclude infection. Clinicians should remain vigilant despite a low CRP. 2

Record maternal vital signs on obstetric early‑warning charts at regular intervals. Continuous monitoring supports early detection of clinical deterioration. 3
Perform ongoing clinical surveillance for signs and symptoms of infection. Prompt identification of new symptoms guides timely intervention. 2
Measure CRP and WBC as components of routine infection surveillance. Serial trends are more informative than isolated values. 2

Schedule regular reviews (once or twice weekly) in day‑care, maternity triage, or antenatal clinics. Structured follow‑up maintains oversight of maternal‑fetal status. 2
At each visit, obtain blood tests (CRP and WBC), document clinical findings, and perform fetal heart‑rate monitoring. This comprehensive approach ensures early recognition of infection. 2
Advise patients to seek immediate hospital care if concerning symptoms (e.g., fever, abdominal pain, abnormal discharge) develop. Early presentation can prevent progression of infection. 2

When laboratory results (e.g., CRP) and clinical assessment are discordant, continue observation and repeat testing rather than making immediate management decisions. This cautious strategy reduces the risk of overtreatment. 2
Other inflammatory conditions such as inflammatory bowel disease or rheumatoid arthritis may cause mild‑to‑moderate CRP elevations in pregnancy, potentially confounding interpretation. Clinicians should consider alternative diagnoses. 1

CRP levels are relatively unaffected by corticosteroid therapy, unlike WBC counts which are transiently elevated. This property makes CRP a more reliable marker for infection in patients receiving antenatal steroids. 1

All bullet points are supported by the cited references and reflect current evidence‑based guidance for the use of CRP in pregnant patients.