Maternal Pyrexia and Villitis of Unknown Etiology.

Background: Villitis of unknown etiology is an inflammatory placental condition associated with adverse pregnancy outcomes, including fetal growth restriction and preterm birth.
Case: We describe maternal pyrexia with daily rigors in the third trimester of two consecutive pregnancies in the same woman. In her second pregnancy, we found no evidence of infection despite an extensive antenatal investigation (blood and urine cultures, serologies, chest X-ray, abdominal ultrasonogram, echocardiogram). The fetus was closely monitored for growth and well-being until spontaneous labor ensued at 36 weeks of gestation, followed by the birth of a vigorous female neonate who weighed 2.235 kg and was healthy. Placental pathology was consistent with villitis of unknown etiology and displayed more prominent abscess formation than is usually described. The patient's first pregnancy 4 years previously followed a similar but milder pattern, without preterm delivery but with similar placental pathology.
Conclusion: Maternal pyrexia in both pregnancies was ultimately attributed to placental inflammation secondary to a maternal immunologic response to the fetal-placental unit. A placental origin for maternal pyrexia should be considered in cases in which a maternal cause cannot be identified and the pregnancy managed in light of the possible association with adverse fetal outcomes.