The Dystocia Epidemic in Nulliparous Women

1
The Dystocia Epidemic in Nulliparous Women

• June 12, 2005
• Nancy K. Lowe, CNM, PhD, FACNM, FAAN
• Professor, Division of Nurse-Midwifery
• School of Nursing
• Oregon Health Science University

2
Evidence for the problem

• Cesarean Section rates
• Healthy People 2000 goals
• Healthy People 2010 goals

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Healthy People 2000

• Background rise in overall c/sec rate from 5.5
  in 1970 to 24.4 in 1987
• Healthy People 2000 goal was a 15 overall
  national c/sec rate

4
Progress toward 2000 Goal

• Early 1990s progressive improvement occurred
• 20.7 in 1996
• Later 1990s this trend reversed
• 22.9 in 2000

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Essentially the Feds gave up

• Goal for overall c/sec rate was abandoned in
  Healthy People 2010 and the rate continues to
  climb
• 24.4 in 2001
• 26.1 in 2002
• 27.6 in 2003

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Percentage of All Births by Cesarean Section
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Percentage of Total and Primary C/Sec and VBAC
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Healthy People 2010

• One goal related to cesarean section
• 16-9. Reduce cesarean births among low-risk (full
  term, singleton, vertex presentation) women.
• 16-9a. Women giving birth for the first time.
• 16-9b. Prior cesarean birth.

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16-9 Reduce Cesarean Births among Low-Risk Women.
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Progress toward goals
16-9 Reduce Cesarean Births among Low-Risk,
First-Birth Women.
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16.9a Reduce Cesarean Births among Low-Risk Women
Giving Birth for the First Time Projection
based on trend
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State Specific Statistics

• 1998 16 states (32) met the 15 target
• 2000 only 9 states (17.6) met the 15 target

• 2001 only 3 states (Utah, New Mexico and Idaho)
  remain at or below the 15 target
• 2002 only 2 states (Utah NM) remain at or
  below the 15 target

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2002 State First Birth C/Section rates

• lt 15 2 states (Utah NM)
• 16 19 11 states
• 20 24 27 states
• gt 25 9 states (including D.C.)

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Significance of the problem

• 1998 estimate that gt 40 of cesareans were
  unnecessary a 25 reduction would save 750
  million annually
• ACOG 2000 Report
• Greatest variation in primary c/sec rates occur
  among nulliparous women at term with singleton
  fetus in vertex presentation without complications

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Questions?

• Why is the rate increasing rather than decreasing
  among the lowest risk women giving birth for the
  first-time?
• What can be done to reverse the trend?

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Why do low-risk women giving birth for the
first-time have cesareans?

• Breech Approximately 3 incidence
• Preeclampsia - Approximately 7.5 incidence
• Dystocia Accounts for at least 2/3 of cesareans
• Fetal Distress (Labor intolerance with non
  reassuring heart rate tracings)
• Elective social intolerance for labor

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Primary Cesarean Indications
Gregory et al. (1998). Changes in indications for
Cesarean delivery United States, 1985 and 1994.
American Journal of Public Health, 88, 1384-1387.
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Why do low-risk women giving birth for the
first-time have cesareans?

• Breech
• Preeclampsia
• Dystocia
• Fetal Distress (Labor Intolerance)
• Elective

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Dystocia What is it?

• General term for difficult or abnormal labor
• Clinical terms
• Dysfunctional labor
• Failure to progress
• Cephalopelvic or fetopelvic disproportion
• Malposition

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ACOG Diagnostic Criteria
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Are these criteria valid?

• Zhang, J., Troendle, J. F., Yancey, M. K.
  (2002). Reassessing the labor curve in
  nulliparous women. American Journal of Obstetrics
  Gynecology, 187, 824-828.
• Sample 1329 nulliparous women with a term,
  singleton, vertex fetus of normal birth weight
  after spontaneous onset of labor 1992-1996.
  Cesarean deliveries were excluded, n1162.

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Zhang et al.s findings

• Medium labor admission to complete 7.3 hrs (3.3
  hrs 10th and 13.7 hrs 90th)
• Transition from latent to active labor appears
  more gradual than the Friedman curve
• No deceleration phase was observed
• Median complete to birth 53 minutes (18 min
  10th and 138 min 90th)

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Friedman (1955 1978) Zhang et al. (2002)
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Average dilatation descent curves for nullips
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Dystocia Cesarean

• 50 70 of ALL cesareans can be attributed to
  this single diagnosis
• The criteria for dystocia are NOT met in 16 30
  of cases
• In gt 15 of cases, women were actually in latent
  labor when failure to progress was diagnosed
• In 36 of cesareans for failure to progress after
  full dilatation, the second stage was NOT
  prolonged.
• (Gifford et al, 2000).

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Reasons for Dystocia in Healthy Nulliparous Women

• Clinical decision-making
• Inherent labor inefficiency
• Aging of nulliparous population
• Genetic factors
• Anthropomorphic characteristics
• Fetal factors
• Psychophysiologic factors
• Labor management and care practices

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Reasons for Dystocia in Healthy Nulliparous Women

• Clinical decision-making leading to questionable
  diagnoses
• What are the parameters of normal labor?

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Labor inefficiency

• Labor is on average longer in the nulliparous
  woman
• Influence of the active management protocol on
  the concept of uterine function
• Is the nulliparous uterus by nature
  inefficient? Or is its activity simply
  different?

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Active Management 1970s

• Dublin Maternity Hospital
• Specifically developed for restricted to
  first-time mothers
• Basic premiseaggressive response to the early
  correction of myometrial dysfunction ineffective
  in promoting cervical dilatation according to
  pre-set criteria

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Components of Active Management

• Strict criteria for admission in spontaneous
  labor
• Early amniotomy
• Early recognition of dystocia
• Intravenous pitocin administration for dystocia
• Midwifery care

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Dublin Results

• Total length of labor kept under 12 hours for the
  majority of nulliparous women
• Cesarean section rate remained low at just over
  5
• Operative vaginal births remained at 19
• (ODriscoll et al., 1973)

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Subsequent reviews re Active Management

• Only a modest effect on cesarean section and the
  primary ingredient is supportive care rather than
  medical intervention (Thornton Lilford, 1994).
• Meta-analysis concluded that active management is
  associated with a 34 decrease in the rate of
  cesarean delivery for dystocia in nulliparas
  (Glantz McNanley, 1997).

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Other potential causes of dystocia in nulliparas

• Maternal age
• Genetics
• Maternal anthropomorphic characteristics
• Fetal factors
• Psychophysiologic factors
• Labor environment and care practices

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Maternal Age

• Nulliparas gt 35 yrs experience cesarean at twice
  the rate
• Dystocia is the cause at 30 200 higher rate
• Nulliparas gt 35 are more likely to be white,
  married have private insurance

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Average age at first birth

• Mean age at first birth in the U.S.
• 21.4 years in 1970
• 24.6 years in 2000
• 25.1 years in 2002

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Maternal Age

• Ecker et al, 2001 Main et al., 2000
• Two large nulliparous cohorts with women grouped
  in 5-yr age brackets
• Incidences of FTP, fetal distress, and c/sec
  during labor increased progressively after age
  25, with large increases after 35 and 40

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Maternal Age

• Do these observations point to a progressive,
  age-related deterioration in myometrial function?
• and/or
• Are other maternal characteristics and provider
  behaviors functioning?

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Genetics

• Potential genetic mechanism of inefficient
  uterine action
• Sweden Berg-Lekas, Hogberg Winkvist, 1998
• Utah Varner, Fraser, Hunter, Corneli, Ward,
  1996

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Anthropomorphic Characteristics

• Short-stature, particularly lt 150 cm.
• Maternal overweight (BMI gt 26) and obesity (BMI gt
  29) prior to pregnancy
• Pregnancy weight gain in excess of 35 40 pounds
• Key is that the incidences of overweight,
  obesity and high pregnancy weight gain are
  increasing in the U.S.

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Fetal factors

• Fetal weight and C/sec rate
• lt 20 with birth weight lt 4000 g
• gt 30 at 4000 4499 g
• 60 at gt 4500 g
• Persistent occipitoposterior position
• Occurrence of 2.4 7.2 in nulliparas
• 2 to 3-fold increase in operative delivery
• 3 to 4-fold increase in cesarean section
• Unengaged head at labor onset

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Reasons for Dystocia in Healthy Nulliparous Women

• Clinical decision-making leading to inaccurate
  diagnosis
• Inherent inefficiency of nulliparous labor

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Maternal Psychophysiology Dystocia The Stress
Response

• Fears of childbirth in pregnancy negatively
  correlated with uterine function in Montevideo
  units anxiety and EPI during labor and length of
  labor
• NEP EPI rise significantly and independently
  during labor
• EPI positively correlated with state anxiety and
  to total length of labor
• EPI negatively correlated with uterine function.

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Catecholamines uterine function

• Human myometrium richly supplied with
  beta-adrenergic receptors
• High levels of EPI (or other beta-sympathomimetic
  agents) stimulate these receptors and decrease
  uterine contractility
• Chronic stress, stress responsivity, acute stress
  dystocia
• Coping and situation-specific psychological
  attributes

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Environment Dystocia

• Location of birth
• Provider characteristics
• Care practices
• Continuous supportive care

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Care Practices dystocia

• Admission to hospital
• Induction of labor
• Epidural analgesia
• Maternal nutrition

• SUPPORTIVE CARE
• Information
• Comfort measures
• Coping strategies
• Advocacy
• Techniques to support physiologic labor

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Questions about Dystocia

• Is there an epidemic of social intolerance for
  labor? (Is FTP really FTT?)
• Do we need new norms for the progress of labor
  for older first-time mothers? For women who are
  overweight or obese?
• Are the boundaries of dystocia becoming blurred
  so that clinical decision-making is affected?

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Questions about Dystocia

• Is the social acceptability of cesarean section
  making the concept of dystocia an archaic
  discussion?
• Will national goals to reduce cesarean section
  rates persist beyond 2010?

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? Individual Dystocia Risk ?
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?
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What is needed to stop the epidemic?

• A re-examination of labor norms and diagnostic
  criteria for dystocia for first-time mothers
• A social reconstruction of the process and
  experience of childbirth

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What is needed to stop the epidemic?

• A revolution in the acute care system of care for
  birthing women
• Application of the midwifery model of care as the
  standard of care for all healthy women