Maternal serum C-reactive protein (CRP) has been studied extensively as an adjunct in the diagnosis of subclinical infection among pregnant women with preterm labor or preterm rupture of membranes. However, before the utility of CRP can be studied in pregnancies with these complications, the effects of normal pregnancy and labor on maternal serum CRP levels must be established. We determined CRP levels serially from 22 weeks' gestation until delivery in healthy pregnant women without antepartum complications. Median CRP values for women not in labor ranged from 0.7-0.9 mg/dL, depending on gestational age; 95% of the values were 1.5 mg/dL or lower. No consistent change in CRP levels with gestational age was found among serially sampled women not in labor. The median CRP value for women in labor at term was 1.3 mg/dL, and 32% of values were over 1.5 mg/dL. Median CRP values in normal pregnancies appear to be higher than standardized values for nonpregnant individuals, and CRP values are further elevated in labor. Understanding the physiology and temporal course of the increase in CRP in normal pregnancy and labor may help to clarify the appropriate use of CRP in complicated pregnancies.
C-reactive protein normal pregnancy reference values, CRP levels gestational age serial measurement pregnancy, C-reactive protein labor term elevation physiology, Watts CRP normal pregnancy baseline values, inflammatory marker CRP pregnancy preterm labor diagnosis, serum CRP pregnancy subclinical infection screening, C-reactive protein reference range healthy pregnant women, CRP elevation labor versus antepartum pregnancy, maternal infection biomarker CRP pregnancy normal values, C-reactive protein preterm rupture membranes diagnostic utility
PMID 1988876 1988876 DOI 10.1097/00006250-199102000-00002 10.1097/00006250-199102000-00002
Cite this article
Watts, D. H., Krohn, M. A., Wener, M. H., & Eschenbach, D. A. (1991). C-reactive protein in normal pregnancy. Obstetrics and gynecology, 77(2), 176-180. https://doi.org/10.1097/00006250-199102000-00002
Watts DH, Krohn MA, Wener MH, Eschenbach DA. C-reactive protein in normal pregnancy. Obstet Gynecol. 1991;77(2):176-180. doi:10.1097/00006250-199102000-00002
Watts, D. H., et al. "C-reactive protein in normal pregnancy." Obstetrics and gynecology, vol. 77, no. 2, 1991, pp. 176-180.
The purpose of our study was to analyze the efficacy of serum C-reactive protein (CRP), white blood cell count (WBC) and erythrocyte sedimentation rate (ESR) serial evaluations in the prediction of chorioamnionitis in cases of premature rupture of membranes (PROM). A group of 80 patients with PROM before 35 weeks' gestation were evaluated prospectively and managed expectantly. We applied the expectant management with the permanent use of tocolysis, antibiotics, steroids, amnioinfusions of artificial amniotic fluid and intravaginal chemotherapeutics. Patients were monitored with frequent vital signs, fetal heart rate evaluation and everyday CRP, WBC and ESR. All afterbirths were examined to establish the presence of histologic chorioamnionitis (gold standard of intrauterine infection). S: 59 (73.7%) patients had significant chorioamnionitis on histopathology and only 15 of them had clinical chorioamnionitis. Serum CRP serial determinations (definition 1) > 1.2 mg/dl; 2) > 2.0 mg/dl; 3) > 1.2 mg/dl and increasing in two consecutive days) were found the most reliable with a sensitivity 1) 91.5%; 2) 85%; 3) 88%, specificity 57%; 76%; 86%, positive predictive value 86%; 90%; 94.5%, negative predictive value 70.5%; 64%; 72% and accuracy 82.5%; 82.5%; 87.5% respectively. The efficacy of WBC (abnormal > 12500/mm3; > 15000/mm3; > 12500/mm3 and increasing in two consecutive days) and ESR (abnormal > 60 mm/h; > 60 mm/h and increasing in two consecutive days) serial evaluations was significantly lower. Moreover, in cases of chorioamnionitis CRP increased above the upper limit of normal 3 days earlier than WBC or ESR. S: CRP was found the most reliable indicator of histologic chorioamnionitis and indicated the presence of intrauterine infection earlier than WBC or ESR.
PregnancyInfection ScreeningPuerperal EndometritisC-Reactive Protein in Pregnancy
Silent intrauterine infection as cause of preterm labour should be recognised early by measuring C-reactive protein (CRP) levels in the maternal serum. Ensuing antibiotic therapy may not only cause gestational prolongation, but also has a positive effect on pathology during the puerperal period. Consequently, we examined the rate of infectious puerperal complications of 181 patients who suffered from so-called idiopathic preterm labour. 84 patients showed normal CRP-levels at the onset of tocolysis (< 5 mg/l); an elevated level was found in 97 patients (> 5 mg/l). Patients with elevated CRP-levels and supplemented antibiotic therapy during pregnancy (n = 51) showed significantly fewer symptoms of postpartal endometritis than women with similarly elevated CRP-levels but without antibiotics (n = 46). This effect was not produced when preterm labour was associated with normal CRP-levels. Patients with premature contractions and elevated CRP-values at the onset of tocolysis seem to benefit from the antibiotic therapy during pregnancy because they show reduced infectious complications throughout the puerperal period.
PregnancyPremature Rupture of MembranesC-Reactive Protein in PregnancyChorioamnionitis Prediction
Physicians compared clinical history, examination, and laboratory data on 10 pregnant women at various gestational ages with intact membranes till labor began (controls) with data on 25 pregnant women also at various gestational ages who experienced premature rupture of membranes (PROM) (cases) to determine the value of C-reactive protein (CRP) in maternal and cord blood as a predictor of chorioamnionitis in women with PROM. 32% of cases had clinical chorioamnionitis and 44% histopathological chorioamnionitis. The maternal serum level of CRP in cases with and without chorioamnionitis at delivery was statistically higher than that of the controls (45.82 CRP mg/L and 9.71 CRP mg/L vs. 6.6 CRP mg/l; P.05). Further the CRP level in cord blood of cases with chorioamnionitis also stood much higher than that of the controls (p.001). In addition, the total leukocytic count (TLC) for cases with chorioamnionitis at delivery was much higher than it was for the control group at delivery (12,510 TLC/cubic mm vs. 18,231 TLC/cubic mm; p.05). A significant difference also existed between the temperature of the cases with chorioamnionitis and that of the controls (37.11 degrees Celsius vs. 63.97 degrees Celsius; p.05). Sensitivity and specificity tests showed that CRP 24 mg/L was the most reliable predictor of chorioamnionitis (100% and 93.3% respectively) followed by TLC (77.8% and 92.8% respectively) then temperature (55.6% and 78.6% respectively). Thus CRP can be used to predict premature delivery and simultaneously reduces unnecessary premature delivery of many PROM cases which occur due to fear of developing infections in both the mother and the fetus.
PregnancyPremature Rupture of MembranesC-Reactive Protein in PregnancyChorioamnionitis Diagnosis
The usefulness of maternal C-reactive protein (CRP) measurements in the diagnosis of chorioamnionitis and puerperal and neonatal infectious morbidity was studied among 147 patients with preterm rupture of the membranes (PROM). Thirty-three patients developed chorioamnionitis, 10 patients developed puerperal endometritis, and 21 newborn infants developed neonatal infections. There was no difference in the highest antepartum CRP between patients with or without chorioamnionitis. The overall test performance for CRP was poor suggesting that elevated antepartum CRP may be misleading in the diagnosis of chorioamnionitis. However, use of serial CRP measurements increases the test performance. The high negative predictive value suggests that CRP is useful in predicting the absence of chorioamnionitis.