1. Goldenberg RL, Culhane JF, Iams JD, Romero R (2008) Epidemiology and causes of preterm birth. Lancet 371:75–84
2. López Bernal A (2007) Overview Preterm labour: mechanisms and management. BMC Pregnancy Childbirth 7:2
3. Romero R, Lockwood CJ (2009) Pathogenesis of spontaneous preterm labor. In: Creasy RK, Rednik R, Iams JD, Lockeood CJ, Moore TR (eds) Creasy and Resnik’s maternal–fetal medicine. Saunders Elsevier, Philadelphia, pp 521–543
4. Romero R, Creasy RK (2009) Preterm labor and birth. In: Creasy RK, Rednik R, Iams JD, Lockeood CJ, Moore TR (eds) Creasy and Resnik’s maternal–fetal Medicine. Saunders Elsevier, Philadelphia, pp 545–575
5. Garite TJ, Bentley DL, Hamer CA, Porto ML (1990) Uterine activity characteristics in multiple gestations. Obstet Gynecol 76:56–59