Labor—To Wait or Not to Wait: To Push or Not to Push

Abstract & Commentary

Synopsis: This study underscores the need to re-evaluate periodically any concept of obstetrical management, no matter how solid the underlying scientific foundation.

Source: Rouse DJ, et al. Obstet Gynecol. 2001;98: 550-554.

Many guidelines have surfaced over the years to help practitioners manage labor. Some of these have evolved into solidly ingrained dicta drummed into obstetricians during their residency training. Rouse and associates recently tested the well-established concept that lack of progress in cervical dilatation for 2 hours during the active stage of labor was grounds for cesarean section.

They evaluated the labors of 501 consecutive patients whose lack of cervical progress in active labor required management according to a special protocol. Oxytocin was used to maintain at least 200 Montevideo units for at least 4 hours before C-section could be performed. During that time period, a section was only done for fetal distress and not for failure to progress.

They found that 38 patients did not make any progress for 2 hours despite adequate contractions, as defined above. Twenty-three of these women (61%) successfully delivered vaginally without any increase in neonatal morbidity. The only difference was in maternal morbidity, as indicated by a higher rate of endometritis or chorioamnionitis, mostly in nulliparas (7% and 17%). There were 3 cases of shoulder dystocia (13%), but none of these infants had any morbidity.

In the 501 patients managed with the oxytocin protocol, the median cervical change was 1.8 cm/h in multiparas and 1.3 cm/h in the nulliparous patients. Interestingly, the 5th percentile for all patients was 0.5 cm/h, a figure substantially below the 5th percentile of 1.2 cm/h in nulliparas and 1.5 cm/h in multiparas noted by Emanuel Friedman in his landmark study accomplished in the 1960s.1

Comment by John C. Hobbins, MD

This study underscores the need to re-evaluate periodically any concept of obstetrical management, no matter how solid the underlying scientific foundation. On the surface, it seems ludicrous to say that labors in the 1960s were different than labors in the 2000s. However, Friedman’s patients did not have epidurals and 84% of Rouse’s patients did, a distinction that could have an effect on the length of labors. Also, none of Friedman’s patients had oxytocin augmentation, while all of Rouse’s patients had it because their labors were already progressing too slowly.

Actually it is surprising that we have been setting unrealistic goals that no longer apply to some of today’s patients. The same could be said about the 2-hour limit for the second stage of labor. Recent studies show that many patients can deliver safely by extending the second stage of labor well beyond 2 hours after full cervical dilatation is attained. This also could be an epidural-related phenomenon.

Although cesarean section rates rose steadily through the 1980s, they have plateaued over the last 5 years. However, the cesarean rate is likely to soar again based on our reluctance to deliver breeches vaginally and the recent backlash against VBACs. Also, for a variety of reasons, patients of advanced maternal age tend to have much higher cesarean section rates, and the percentage of pregnant patients 35 years of age or older rose from 8.5% in 1987 to 12.6% in 1997. In some hospitals in California, 30% of laboring patients now are more than 35 years of age.

Certainly, we ought to give a little more time to the diminishing number of patients who not only want to, but can deliver vaginally.

On a tangential note, dealing in this publication with labor allows the opportunity to touch upon another common concept that can be counterproductive. Fortunately, it is well accepted that initiating maternal pushing prior to complete cervical dilatation is a bad idea. However, it seems that attaining full dilatation now represents an immediate license to push. Although the idea behind this practice has been to shorten the second stage of labor, and perhaps to diminish the total amount of patient discomfort, there is little evidence to support this concept, especially where epidurals are used.

In fact, 2 recent studies have yielded important information regarding the management of second stage of labor. One randomized clinical trial involving more than 1800 patients demonstrated that although the second stage of labor was lengthened by an average of 64 minutes when patients were interdicted from pushing for 2 hours (unless they had an urge to push), the overall time of pushing was significantly less in the delayed pushing group (68 vs 175 mins). Also, there were fewer "difficult" deliveries in the delayed pushers.2

The other smaller randomized study (153 patients) showed no difference in length of second stage, rate of descent, or neonatal morbidity when patients delayed their pushing efforts for 1 hour.3

The point here is that the uterus generally does a reasonable job of accomplishing descent through the pelvis without immediate help. Delaying pushing for at least 1 hour will result in less time pushing (resulting in less exhaustion) and possibly fewer difficult deliveries without appreciable lengthening of the second stage or increase in morbidity.

Although pelvic floor abnormalities have been possibly associated with length of second stage, there are no available data dealing with time spent during passive descent vs. time pushing. During maternal pushing, the musculature of the pelvic floor actually contracts, a phenomenon that would predispose to later problems. Therefore, theoretically pelvic floor abnormalities might be more related to length of time pushing rather than the length of the second stage.

References

1. Friedman E, Sachtleben M. Am J Obstet Gynecol. 1965;93:522-529.

2. Fraser WB, et al. Am J Obstet Gynecol. 2000;182: 1165-1172.

3. Mayberry LJ, et al. J Perinatol. 1999;19(1):26-30.