1. Preterm labor;Amon,1999
2. The effect of preterm delivery on perinatal mortality;Rush;Br J Obstet Gynaecol,1978
3. Changing prognosis for very low birth weight infants;Ehrenhaft;Obstet Gynecol,1989
4. Characteristics of parturition;Challis,1999
5. Preterm and postterm pregnancy and fetal growth retardation;Cunningham,1997