Aims: To measure maternal serum interleukins (IL) in pregnancy, delivery and early puerperium, and to identify their potential determinants. Methods: Prospective longitudinal measures of serum IL-1β, IL-6 and IL-8 in 38 healthy pregnant women at antenatal visits, through labor and delivery, with clinical correlates (infection, vaginal hemorrhage and anemia) recorded by questionnaire. Results: Pregnancy IL levels remained consistently low. IL-1β increased shortly before delivery, then returned to pregnant levels, except where blood loss exceeded 500 ml. IL-6 and IL-8 rose at labor onset and exceeded pregnancy levels through postpartum day three. Postpartum IL-6 was higher after non-elective cesarean section than after spontaneous delivery (P < 0.0001), and where blood loss exceeded 500 ml. IL-6 and IL-8 were higher with systemic infection during delivery (P < 0.0001) and on postpartum day one (P < 0.05); IL-8 was higher in anemia (delivery: P < 0.005; postpartum day 1: P < 0.05). Differences due to delivery mode and systemic infection remained significant after correction for other conditions. Conclusions: Labor-dependent inflammation increases all IL levels at delivery. Further studies with larger sample sizes are required to establish reference values differentiating physiology from pathology as an aid to peripartum managemen
