Maternal C-reactive protein in early pregnancy.

Objective: To compare maternal C-reactive protein concentration in the first 18 weeks of pregnancy with the nonpregnant adult reference range.

Study Design: Serum samples from healthy women with a pregnancy <18 weeks' gestation were retrieved from a Hospital biological resource bank. C-reactive protein was measured using an immunoturbidimetric assay. Clinical and sociodemographic details were retrieved from the Hospital's computerized database.

Results: Of the 146 women, 85 (58.2%) were nulliparous, 11 (7.5%) were smokers and 22 (15.1%) were obese. Mean gestational age at phlebotomy was 12.5 (range 8.1-17.4) weeks. Median C-reactive protein was 3.2 (interquartile range 0.3-12.1)mg/L. There were 74 women (50.7%) with C-reactive protein level >3.0mg/L which is above the nonpregnant adult reference range. C-reactive protein levels were positively correlated with increasing Body Mass Index. No relationship was found between C-reactive protein and age, smoking or gestational age.

Conclusion: C-reactive protein concentration in a well-characterized population in early pregnancy was higher than that cited for the nonpregnant adult, and C-reactive protein was positively associated with Body Mass Index. Therefore, caution is needed in the use and interpretation of C-reactive protein measurements in early pregnancy to avoid unnecessary interventions in women with suspected illness.