Module 4 Unit A: Labor Progress

Question 1

Understand the relationship between the framework used for care related to labor progress and cesarean birth rates.

Answer 1

Friedmans labor curve may have contributed to an increase in cesearean sections and contemporary research is re-evaluating what is normal and updating recommendations.

Question 2

Define the stages and phases of labor as defined by Friedman. First stage:

Answer 2

Begins with the onset of regular contractions and ends with complete dilation. Includes: latent and active phases

Question 3

Define the stages and phases of labor as defined by Friedman. Latent phase:

Answer 3

Beginning with maternal perception of regular contractions

Question 4

Define the stages and phases of labor as defined by Friedman. Active phase:

Answer 4

The point at which the rate of change of cervical dilation significantly increases

Question 5

Define the stages and phases of labor as defined by Friedman. Second stage:

Answer 5

Begins with complete dilation and ends with the birth of the baby

Controversy Note: There is now an argument that it should begin with the urge to push

Question 6

Compare Friedman’s definition of the onset of the active phase vs. current research.

Answer 6

Friedman defined the onset of the active phase as the point at which the rate of dilation change rapidly increased; often, this was considered to be at 3cm despite Friedman stating this was not correct. Now active phase is considered 5-6 cm dilated.

Question 7

Define prolonged latent phase according to Friedman

Answer 7

> 20 hours in a nulliparous woman, and > 14 hours in a multiparous woman

Note: Protracted=slower than normal, arrested=complete cessation of progress

Question 8

Define protracted active phase according to Friedman

Answer 8

cervical dilation in the active phase of less than 1.2 cm/h in nullip and less than 1.5 cm/h in multip

Note: Protracted=slower than normal, arrested=complete cessation of progress

Question 9

Define protracted descent according to Friedman

Answer 9

<1 cm/hr descent in nulliparous and <2 cm/hr descent in multip

Note: Protracted=slower than normal, arrested=complete cessation of progress

Question 10

Define Secondary arrest of dilation (arrested active phase) according to Friedman

Answer 10

the absence of cervical change for 2+ hours

Note: Protracted=slower than normal, arrested=complete cessation of progress

Question 11

Define Arrest of descent according to Friedman

Answer 11

no descent in 1 hour

Note: Protracted=slower than normal, arrested=complete cessation of progress

Question 12

How did Friedman determine time limits for normal and prolonged labor?

Answer 12

Friedman calculate the upper and lower limits of normal with >95% and <5% being abnormal

Upper limit of normal for each stage and phase in total hours, then divided total hours by number of centimeters to calculate upper limit of normal in terms of hourly progress of dilation (first stage) and descent (second stage).

Question 13

What did Friedman consider a normal length of time for the first stage, latent phase?

Answer 13

Nullparas < 20 hours
Multiparas < 14 hours

note that latent phase is calculated based on total duration, not rate of change per hour

Question 14

What did Friedman consider a normal length of time for the first stage, active phase?

Answer 14

Nulliparas: At least 1.2 cm/hr dilation
Multiparas: At least 1.5 cm/hr dilation

Question 15

What did Friedman consider a normal length of time for the second stage?

Answer 15

Nulliparas: 1 cm/hr descent
Multiparas: 2 cm/hr descent

Question 16

How does contemporary research compare to what Freidman suggested?

Answer 16

Contemporary research shows patients dilate much slower than he suggested. Some show twice as long as he suggested. It is not uncommon for patients to take longer than two hours to make cervical change.

Question 17

How does the CSL define the slowest cervical progress that is considered normal?

Answer 17

0.5-0.7 cm/hr nulliparas
0.5-1.3 cm/hr multiparas
(Rate increases as labor progresses)

Question 18

What does Friedman say about the relationship between length of labor and perinatal complications?

Answer 18

Friedman said that protractions and arrest (excluding latent phase) were associated with a significant increase in fetal/neonatal morbidity and mortality

Much (though not all) of this increased morbidity and mortality associated with mid forceps births

In Friedman’s study, arrested labor associated with significant increase in perinatal mortality even with spontaneous birth.

Question 19

What does contemporary research say about the relationship between length of labor and perinatal complications?

Answer 19

No increase in neurologic abnormalities with labor abnormalities

No difference in: PPH, Postpartum fever, Neonatal resuscitation, 5 minutes Apgar < 7

No difference in perinatal mortality, postpartum hemorrhage

More cesarean births (13.1% vs. 6.1%), chorioamnionitis (23.5% vs. 12.5%) admissions to NICU (9.8% vs. 4.7%) for unspecified reasons

No difference in 3rd/4th degree lacerations, pp endometritis, pp hemorrhage, Apgars, meconium aspiration, neonatal sepsis, shoulder dystocia, birth trauma

Authors conclude longer labor associated with more cesareans but no increase in adverse neonatal outcomes.

Question 20

Understand evidence and expert opinion regarding when we should intervene in slow or non-progressive labor.

Answer 20

There is little evidence on which to base the decision about when to intervene.

Almost all the contemporary research concerns defining normal rates of progress (our first question), so we do not have strong recommendations regarding when intervention should begin. And there is a wide array of possible interventions. Obstetricians generally think amniotomy, oxytocin or cesarean birth when referring to timing of interventions. Midwives tend to consider a longer list including non-pharmacologic options.

Question 21

What does the contemporary evidence show in regard to intervening in slow labor?

Answer 21

Faster intervention=faster delivery. Otherwise no significant differences. There is no optimal waiting times suggested.

Question 22

Are there current recommendations on how to intervene in regard to slow labor?

Answer 22

No

Only one study: Oxytocin vs Water immersion=less epidurals and oxytocin in water group but no other differences in terms of outcomes.

Question 23

What does ACOG say about when a c/s should be recommended for slow labor?

Answer 23

“Slow but progressive labor should not be an indication for cesarean section” and “Cesarean delivery for active phase arrest in the first stage of labor should be reserved for women at or beyond 6 cm with ruptured membranes who fail to progress despite 4 hours of adequate uterine activity or at least 6 hours of oxytocin with no cervical change.”

Question 24

List some indications for induction of labor.

Answer 24

-Gestational hypertension
-Preeclampsia/eclampsia
-Fetal growth restriction
-Cholestasis of pregnancy
-Diabetes mellitus
-Fetal demise
-Intra-amniotic infection
-Oligohydramnios
-Nonreassuring fetal status
-Prelabor rupture of membranes
-Post-term pregnancy.

Question 25

List some contraindications for induction of labor.

Answer 25

-OOH Birth (Inductions should occur in the hospital) Contraindications=anything that would contraindicate a vaginal birth: -Placenta previa -Vasa previa -Transverse lie -Umbilical cord prolapse -Myomectomy entering the endometrial cavity -Previous classical uterine incision -Active genital herpes infection -Category III fetal heart rate (FHR) tracing

Question 26

List possible complications associated with induction and augmentation of labor with oxytocin.

Answer 26

-**Risk for tachysystole -Is an antidiuretic: use cautiously in those at risk of pulmonary edema -Hypotension, tachycardia -Transient myocardial ischemia if given as bolus -PP Hemorrhage (with prolonged use or high doses) -Uterine rupture

Question 27

Understand the controversies and pertinent pharmacokinetics and pharmacodynamics regarding dosage regimens for oxytocin as used for induction and augmentation of labor.

Answer 27

The onset of action of synthetic oxytocin is 3 to 4 minutes, and the half-life is approximately 15 minutes. The uterine response reaches a steady state after 30 to 40 minutes.49 The individual response to a particular dose is both variable and dose dependent: As the infusion rate increases, the frequency and intensity of contractions follow. "High dose" Pitocin increases the risk of tachysystole and other complications and is associated with shorter labor. Evidence of C/S risk is inconsistent. There is a trend towards low-dose Pitocin.

Question 28

What is the physiologic function of prostaglandins and why can we use prostaglandins at any gestational age?

Answer 28

Physiologic function: the ability to cause contraction or relaxation of smooth muscle. Decreases collagen in the cervix. Prostaglandin receptors are always present in myometrial tissue.

Question 29

What are the three prostaglandins discussed in this class? What are their uses?

Answer 29

Misoprostol (Cytotec®): synthetic PGE1 analog used for pre-induction cervical ripening, and first and second-trimester abortions. Dinoprostone (Cervidil® or Prepidil®): PGE2 used for pre-induction cervical ripening and first or second-trimester abortion. Carboprost (Hemabate®): PGF2 used for control of postpartum hemorrhage and first or second-trimester abortion.

Question 30

Discuss the effectiveness and possible adverse effects of PGE2 (dinoprostone) and PGE1 (misoprostol) as used for cervical ripening.

Answer 30

Risk of tachysystole, both are effective cervical ripeners.

Question 31

Analyze the controversy generated by Searle’s (the pharmaceutical company that manufactures Cytotec® [misoprostol]) warning against use of misoprostol in pregnant clients.

Answer 31

Part of the controversy stems from our inability to answer the question of whether misoprostol used in low doses to induce labor in clients without prior cesareans, is any less safe than other agents used for the same purpose. In September 2000, mifepristone was approved by the FDA to be used in conjunction with misoprostol for early pregnancy termination, yet misoprostol was not approved for the same purpose. In fact, product labeling formerly included a warning that misoprostol is contraindicated in pregnancy because of its abortifacient properties. That warning was changed in May of 2002 to state that misoprostol is contraindicated for use as an antiulcer drug in pregnant people. However, misoprostol is still not FDA approved for any obstetric or gynecologic indication, and warnings about risks associated with its use for induction of labor remain on the label.

Question 32

Discuss the mechanism of action, safety and effectiveness of cervical balloons as used for cervical ripening.

Answer 32

Mechanical methods of IOL work by softening and stretching the cervix, exposing endometrial decidual cells and stimulating the release of endogenous prostaglandins PGE2 and PGF2alpha locally and systemically

Question 33

Know the components and significance of the Bishop Score, and what Bishop score indicates a need for cervical ripening for nulliparas and multiparas. (You do not need to memorize the entire Bishop Score.)

Answer 33

The Bishop’s score is a numeric assessment of four different characteristics of the cervix and fetal station; it is used to predict the success of induction. Score includes: cerical position, consistency, length, dilation and fetal station. The degree of ripening can be quantified using the modified Bishop’s score, which takes into consideration all of the factors associated with cervical remodeling (Table 29-5). This scoring system indicates whether the woman’s cervix is “favorable” or “unfavorable” with regard to predicting the success of labor induction and is the best predictor of induction success known to date. A modified Bishops score of >8 is considered favorable and has a high probability of vaginal delivery. A score of **6 or less is considered unfavorable, and ripening may improve induction success. (Varney) Bishop of 6+ for multip or 8+ for primip (Review of E-B Methods...)

Question 34

List some other methods of induction aside from oxytocin, arom, ripening and balloons.

Answer 34

-Nipple stimulation -Herbs: castor oil, evening primrose oil, rasberry lead, blue/black cohosh. These methods are safe and inexpensive. They can be use OOH

Question 35

Analyze the impact of elective induction on rates of induction and the risk of cesarean birth.

Answer 35

The rate of labor induction has increased greatly in recent decades. Exact figures are difficult to determine, but we can accurately state that the rate has gone from about 9 % in 1990 to more than 20% currently. ​​Though the protocol was intended to shorten labor, an unanticipated finding was a decrease in the cesarean birth rate from about 10% to about 5%. (note: the epidural rate was 5%) **The take-home point is research is mixed on the effect of active management of labor (AMOL) on cesarean birth rates in the United States.

Question 36

Define active management of labor.

Answer 36

Active management of labor (AMOL) is a package of care that originated in Dublin Ireland in the 1970s. It was developed by several Irish obstetricians to guarantee birth within 12 hours of admission to the hospital. The package included: no admission until active labor, continuous labor support by a midwife, strict protocols for labor progress and interventions in the absence of "adequate" progress. This was done as follows: If progress was less than one centimeter per hour, amniotomy was performed and an aggressive Pitocin augmentation begun with dosage increased every 15 minutes.

Question 37

Discuss the evidence of PO misoprostol vs. vaginal dinoprostone.

Answer 37

A Cochrane Review on misoprostol for labor induction found that use of oral misoprostol resulted in fewer cesarean births than vaginal dinoprostone, with no differences in negative outcomes for client or baby

Question 37

Discuss the evidence of PO misoprostol vs. vaginal dinoprostone.

Answer 37

A Cochrane Review on misoprostol for labor induction found that use of oral misoprostol resulted in fewer cesarean births than vaginal dinoprostone, with no differences in negative outcomes for client or baby

Question 38

What differences were found with AMOL in the US?

Answer 38

The epidural rate was higher, and continuous labor support by a midwife was not included in the package of care.

Question 39

What did the original AMOL package include?

Answer 39

No admission until active labor, continuous labor support by a midwife, strict protocols for labor progress and interventions in the absence of "adequate" progress. This was done as follows: If progress was less than one centimeter per hour, amniotomy was performed and an aggressive Pitocin augmentation begun with dosage increased every 15 minutes. (As a side note, the concept of high-dose Pitocin protocols-discussed elsewhere in this unit comes from AMOL.)