Two clinical phenotypes of sPTB are (1) spontaneous preterm birth (SPTB) following the spontaneous onset of labour and (2) preterm premature rupture of membranes (PPROM) where the amniotic membrane spontaneously breaks and increases the risk of infection or preterm labour at a later date16. The gene discussed is SPTB; the disease is preterm premature rupture of the membranes.