Risk factors associated with preterm (< 37 + 0 weeks) and early preterm birth (< 32 + 0 weeks): univariate and multivariate analysis of 106 345 singleton births from the statewide perinatal survey of Bavaria. - Martius,J.; Steck,T.; Oehler,M.K.; Wulf,K.H. (Europ J Obstet Gynecol Reprod Biol, 1998)