Inflammation of the placental membranes (chorion; amnion) and connected tissues such as fetal blood vessels and umbilical cord. it is often associated with intrauterine ascending infections during pregnancy.

Chorioamnionitis, also known as amnionitis and intra-amniotic infection (IAI), is inflammation of the fetal membranes (amnion and chorion), usually due to bacterial infection. In 2015, a National Institute of Child Health and Human Development Workshop expert panel recommended use of the term "triple I" to address the heterogeneity of this disorder...