In addition to contractions, pelvic pressure, menstrual-like cramps, watery vaginal discharge, and lower back pain have been empirically associated with impending preterm birth. Such complaints are thought by some to be common in normal pregnancy and are therefore often minimized by patients and obstetrical care providers.
he importance of these symptoms as a harbinger of labor has been emphasized by some but not all investigators (lams, 1990; Kragt, 1990). lams and coworkers (1994) found that the signs and symptoms signaling preterm labor, including uterine contractions, appeared only within 24 hours of preterm labor.
Chao (2011) prospectively studied 843 women with a singleton fetus who presented to Parkland Hospital with preterm labor symptoms between 24°/7 and 336/7 weeks, intact membranes, and cervical dilation <2 em. hose whose cervix remained <2 em were sent home with a diagnosis of false preterm labor. When analyzed against the general obstetrical population, women sent home had a similar rate of birth before 34 weeks-2 versus 1 percent. However, these women did have significantly higher rates of birth between 34 and 36 weeks-5 percent compared with 2 percent. Women with cervical dilation of 1 em at discharge were signiicantly more likely to deliver before 34 weeks compared with women without cervical dilation-5 percent versus 1 percent. Importantly, almost 90 percent of the I-em group delivered within 21 days of the initial presentation.
Researchers have evaluated asymptomatic cervical changes that may predict preterm labor. Asymptomatic cervical dilation after midpregnancy is suspected to be a risk factor for preterm delivery, although some clinicians consider it to be a normal anatomical variant. Moreover, study results have suggested that parity alone is not suicient to explain cervical dilation discovered early in the third trimester.
Cook (1996) longitudinally evaluated cervical status with transvaginal sonography between 18 and 30 weeks in nulliparas and multiparas who all subsequently gave birth at term. Cervical length and diameter were identical in both groups throughout these critical weeks. In a study from Parkland Hospital, routine digital cervical examinations were performed between 26 and 30 weeks in 185 asymptomatic women. Approximately 25 percent of women whose cervix was dilated 2 or 3 em delivered before 34 weeks (Leveno, 1986a). Other investigators have verified cervical dilation as a predictor of increased preterm delivery risk (Copper, 1995) .
Although women with dilation and efacement in the third trimester are at greater risk for preterm birth, detection does not necessarily improve pregnancy outcome. Buekens and associates (1994) randomly assigned 2719 women to undergo routine cervical examinations at each prenatal visit and compared them with 2721 women in whom serial examinations were not performed. Knowledge of antenatal cervical dilation did not afect any pregnancy outcome related to preterm birth or the frequency of interventions for preterm labor. The investigators also reported that cervical examinations were not related to PPROM. hus, it seems that prenatal cervical examinations in asymptomatic women are neither beneficial nor harmful.