Résumé : In order to evaluate a new indicator of the foeto-maternal bacterial infection, we have measured the level of procalcitonine (PCT) by an ultrasensitive immunoluminometric method in a group of 202 non-infected women, aged from 20 to 40. Twenty-four patients with a CRP> 1 have been excluded; the others were divided into two groups: Group I: pregnant women (n = 97) with a gestational age between 20 and 36 weeks; Group II: non-pregnant women (n = 81). The PCT is significantly higher (Student's t-test P < 0.001) for pregnant women compared to the control group (means for the Group I: 26.75 pg/ ml and for the Group II: 14.15 pg/ml). This physiological increase requires additional studies to better understand its physiopathology. © 2003 Éditions scientifiques et médicales Elsevier SAS. Tous droits réservés.