Pathogenesis of preterm birth: bidirectional inflammation in mother and fetus.

Preterm birth (PTB) complicates 5-18% of pregnancies globally and is a leading cause of maternal and fetal morbidity and mortality. Most PTB is spontaneous and idiopathic, with largely undefined causes. To increase understanding of PTB, much research in recent years has focused on using animal models to recapitulate the pathophysiology of PTB.