Abstract & Commentary
By John C. Hobbins, MD, Professor, Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Aurora, CO, is Associate Editor for OB/GYN Clinical Alert.
Dr. Hobbins reports no financial relationships relevant to this field of study.
Synopsis: Patients with preterm contractions, who subsequently were diagnosed to have false labor and discharged, do not have an increased risk for early preterm birth, neonatal mortality, or lower Apgar scores. However, they do have a slightly greater chance of delivering in the late preterm period (34 to 36 weeks).
Source: Chao TT, et al. The diagnosis and natural history of false preterm labor. Obstet Gynecol 2011;118:1301-1308.
A number of previous reviews in OB/GYN Clinical Alert, including a Special Feature, have been devoted to preterm birth (PTB), a problem that has been on the rise in the United States despite significant efforts to curb it. Despite this gloomy trend, a recent report from Parkland Hospital in Dallas actually may provide some reassurance to patients suspected of having preterm labor. Unlike other PTB outcome studies, this study specifically addresses the fate of pregnancies when the diagnosis of false labor is made.
The authors reviewed the records of 843 patients with gestations between 24 weeks 0 days and 33 weeks 6 days who presented to the labor and delivery with persistent preterm contractions (PTC).1 If the patients had a cervical dilation of 2 cm or greater, they were admitted. If not, they were monitored in a triage area for 2 hours. If the contractions continued at a frequency of more than 1 per 10 minutes and/or if there was a cervical change, they were admitted. However, if the contractions were less frequent, and if there was no change in the cervix by digital examination, they were discharged.
Six hundred ninety (82%) patients were discharged with the diagnosis of false labor. The outcomes of these pregnancies were compared to the outcomes observed in the overall population during the same 12-month period. The false labor group had a non-significant rate of PTB before 34 weeks of 2% vs 1% in the control group (P = 0.28; NS). However there was a statistically significant, but modest, increase in the rate of late PTB (34 to 36 weeks) compared to the baseline population (5% vs 1%, P = 0.02, respectively). Interestingly, only 1 out of 10 in the false labor group with 1 cm cervical dilatation delivered within 3 weeks of her episode of false labor. Although there were no differences between admissions to the NICU, Apgar scores, or neonatal death compared with controls, there was an increase in respiratory distress syndrome (RDS) in the study population (2% vs 1%; P = 0.001). The authors concluded that patients discharged with false labor between 24 and 34 weeks gestation are at slightly greater risk for late PTB (34-36 weeks), but not for early PTB (< 34 weeks) or neonatal mortality.
This paper again confirms that about four out of five patients presenting with PTC are not in labor. Yet, because of our heightened awareness of the impact of PTB, and, perhaps, our obsession to prevent it, we often commit patients with PTC to many days in the hospital in an effort to keep an occasional patient from delivering early. Of course, the problem is that once admitted, we are not very good at keeping those with true preterm labor from delivering anyway. In the meantime, these patients, now away from family support, are being housed and fed for up to $3,000 a day while being exposed to institutional food and our own special brand of pathogens.
The study did not include transvaginal cervical length measurements or fetal fibronectin in the diagnostic mix. Recent investigation has shown that the negative predictive value of either of these tests is greater than 90%,2,3 and one wonders if the few late PTBs in the false labor patients might have been picked up with the addition of these methods.
In the past, the investigative thrust had been to focus on stopping a process that is already underway, which is like trying to detain a runaway truck with a stop sign. Fortunately, most current investigation has been directed toward identifying the causes of PTB so that preemptive measures can be undertaken. Nevertheless, while waiting for new information to evolve, it should be kept in mind that most clusters of PTC are of no consequence, and we need to concentrate on identifying those patients with these contractions who can be safely discharged. The Dallas group was able to send 690 patients with PTC home over the space of 1 year. Let's say there was a policy to observe all of these false labor patients in the hospital for 4 days (at a very conservative cost of $2,000 per day). That represents a total outlay of $1.3 million, with the only downside being that the 5% probability of preventing a late PTB delivery (34-36 weeks).
Cost aside, the data from this and other studies can give patients reasonable reassurance that false labor is really the opposite of "true" labor, and not a reason to panic.
- Chao TT, et al. The diagnosis and natural history of false preterm labor. Obstet Gynecol 2011;118:1301-1308.
- Gomez R, et al. Cervicovaginal fibronectin improves prediction of preterm delivery based on sonographic cervical length in patients with preterm contractions and intact membranes. Am J Obstet Gynecol 2005;192: 350-359.
- Sotiriadis A, et al. Transvaginal cervical length measurement for prediction of preterm birth in women with threatened labor: A meta-analysis. Ultrasound Obstet Gynecol 2010;35:54-64.