The biochemical changes in the cervix that take place gradually over the last few weeks of gestation in preparation for childbirth. The cervix softens, and its potential for stretching increases. Normally this occurs naturally, but in postterm pregnancies it may be necessary to use mechanical dilators or drugs. Placement of Laminaria digitata or prostaglandin E analogs (e.g., misoprostol) in the vagina or cervical canal promotes cervical ripening and onset of labor but does not reduce the rate of cesarean deliveries.