Cesarean Section in Nulliparous Women Attended by the Oregon Health

1
Cesarean Section in Nulliparous Women Attended by
the Oregon Health Science University Certified
Nurse-Midwife Faculty in 2004 

• Noelle Lefitz, RN, BSN, SNM
• Nicole Carlson, RN, BSN, SNM
• Nancy K. Lowe, CNM, PhD, FACNM, FAAN

2
Background

• C-section rate for low-risk (full-term,
  singleton, vertex) nulliparous women
• In 2003, c-section rate was 23.6, a 33 increase
  since 1996.
• Healthy People 2010 goal is a 15 c-section rate
  for this population.
• Total c-section rate 27.5 in 2003 to 29.1 in
  2004
• Total c-section rate in 1970 5.5

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Risks of Cesarean Section

• Increased Risk of
• Infection
• More intense and longer lasting pain
• Difficulty with breastfeeding
• Less early contact with baby

• Long term Maternal Risks
• Bowel obstruction
• Infertility/reduced fertility
• Ectopic pregnancy
• Placenta previa
• Placenta accreta
• Placental abruption
• Uterine rupture

Maternity Center Association (MCA)(2004)
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More Risks of C-Section

• Risks to Infant
• Surgical cuts
• Respiratory Problems
• Asthma
• Increased risk of death to future infants in
  uterus with a scar
• (MCA, 2004)

• Increased risk of repeat cesarean section for
  next delivery
• In 1996, VBAC rate was 28.3
• In 2004, VBAC rate declined to 9.2
• (NCHS)

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Failure to Progress

• aka Labor Dystocia
• ACOG definition a lack of cervical dilation or
  descent for at least two hours during the active
  phase of labor.
• 50-70 of all c-sections attributed to this
  single diagnosis (Gifford, 2000).
• Primarily diagnosed using Friedmans labor curve
  and clinical judgment

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Aim of Study

• To compare the demographic and clinical
  characteristics of nulliparous women, attended by
  the faculty CNMs in 2004, who experienced
  cesarean section to those who delivered
  vaginally.
• To describe the demographic and practice
  characteristics of the faculty midwives related
  to the management of labor in nulliparous women.

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Review of Literature
8
Review of the LiteratureDystocia among
nulliparous women

• Characteristics of nulliparous women that are
  associated with operative delivery for dystocia
• Diagnostic decision-making practices about
  dystocia made by delivery providers in the United
  States

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Characteristics of nulliparous women associated
with CDD

• Body Mass Index (BMI)
• Maternal age
• Epidural
• Occiput Posterior (OP) presentation
• Anxiety
• Support in labor
• Hydration in labor
• Labor induction
• Bishop scores/engagement on hospital admission

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BMI

• If the percentage of U.S. nulliparas gaining
  excessive weight as defined by the IOM in
  pregnancy were to drop from current levels of 48
  to 0, nearly a quarter of the cesareans
  performed on nulliparas in the U.S. could be
  avoided. (projection by Stotland, Hopkins, and
  Caughey, 2004 following their retrospective
  cohort study of 9788 women)

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BMI

• Obese women significantly more likely to have
  cesarean birth
• Normal weight (BMI
• Obese (BMI 30-34.9), cesarean rate 33.8
• Morbidly obese (BMI 35) cesarean rate 47.4
• Multi-center investigation of 16,102 records by
  Weiss et al, 2004

• Higher cesarean rate with increased BMI is
  largely due to a diagnosis of dystocia
• Nulliparas with BMI 30 had a 6-fold increased
  risk for cesarean, and this effect was primarily
  mediated through an increase in cesarean delivery
  carried out for CPD/failure to progress (i.e.
  dystocia)
• Pregnancy weight gain 35 lbs. also had a
  significant positive relationship with cesarean
  rate.
• Retrospective cohort study of 3375 nulliparous
  women by Young and Woodmansee, 2002

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Advanced Maternal Age

• In three large population studies, nulliparous
  women over the age of 35 years had a
  significantly increased risk for cesarean birth
  when compared to younger nulliparous women
• Ecker et al., 2004
• Heffner, Elkin, Fretts, 2003
• Joseph et al., 2003
• WHY???

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Advanced Maternal Age

• Three factors found to almost completely explain
  the increased rate of cesarean in older
  nulliparas
• Increased incidence of elective induction
• Increased diagnosis of failure to progress
• Increased diagnosis of fetal distress
• Ecker et al., 2004

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Epidural

• Epidural use associated with increases in
  oxytocin use and second stage labor length
• Epidural not found to increase the rate of
  cesarean deliveries.
• Leighton and Halpern (2002) meta-analysis of RCTs
  and prospective cohort (PC) studies on epidural
  outcomes

• Design of RCTs done on epidurals cannot allow
  their results to be generalized.
• Women allowed to switch between study and control
  groups in all RCTs
• Lieberman and ODonoghue (2002) meta analysis of
  RCTs, PC, and observational studies on epidural
  outcomes

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Occiput Posterior (OP) Presentation

• Persistent OP (POP) accounts for 12 of all
  cesarean deliveries (Fitzpatrick et al 2001)
• Nulliparous women twice as likely as multiparas
  to have POP (Ponkey et al, 2003 and Fitzpatrick
  et al, 2001).
• vaginally
• The other 2/3 of nulliparous women with POP have
  prolonged labor with increased use of oxytocin
  and epidurals

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Anxiety

• No general association found between anxiety and
  obstetric complications in review of studies
• Johnson and Slade 2003
• However, anxiety around particular issues is
  associated with prolonged labor and cesarean.
• Fears of childbirth
• Anxiety about family functioning

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Continuous Labor Support

• Cochrane review of 15 randomized controlled
  trials with 12,791 women found a decrease the
  likelihood of operative birth and intrapartum
  analgesia with continuous support in labor
• Support of greatest benefit when
• Provider not a member of the hospital staff
• Support began early in labor
• Hodnett et al., 2005.

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Decreased Hydration in Labor

• RCT of IV hydration among 195 low risk
  nulliparous women in spontaneous labor (125 ml/hr
  vs 250 ml/hr of lactated ringers)
• Less hydration significantly associated with
• Longer labors
• More interventions
• A trend toward more cesareans in the 125 ml/hr
  hydration group
• Garite, Weeks, Peters-Phair, Pattillo,
  Brewster, 2000

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Induction of Labor

• Induction of labor, and particularly elective
  induction of labor, is the most powerful
  predictor of dystocia and operative delivery in
  nulliparous women
• Cammu, Martens, Ruyssinck, Jean-Jaques, 2002
  Foley et al., 2004 Heffner, Elkin, Fretts,
  2003 Johnston, Davis, Brown, 2003 Luthy,
  Malmgren, Zingheim, 2004 Vahratian, Zhang,
  Troendle, Sciscione, Hoffman, 2005Vrouenraets et
  al., 2005
• 3-fold increase in rate of cesarean among
  nulliparous women being induced with unfavorable
  cervix over spontaneous labor

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Low Bishop Score/Unengaged Vertex Presentation

• Bishop score induction status among nulliparas
• Prospective cohort study of 1,389 nulliparous
  women
• Vrouenraets et al, 2005
• Nulliparas with unengaged vertex (higher than
  -3 station) were 88 more likely to have
  inductions (did not have SOL)
• Among those who were induced, half ended their
  TOL with cesarean delivery
• Retrospective review of 448 nulliparas 41 weeks
  gestation
• Shin, Brubaker and Ackerson 2004

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Diagnostic decision-making practices around
dystocia

• The Definition of Dystocia
• Recommendations SOGC ACOG
• The Real World
• Elective Induction
• Medical Induction
• Questioning the Definition
• CNMs

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The Definition of Dystocia

• ACOG (1995) stated dystocia can not be diagnosed
  until a woman is in active labor
• Active labor is defined as strong, regular
  contractions 2-3 min. apart with a cervix greater
  than or equal to 3 cm. for nulliparous women.
• Two types of dystocia
• Protraction disorder dystocia between 5-10 cm
  of dilation.
• Nulliparas dilation
• Prolonged second stage dystocia after complete
  cervical dilation.
• Nulliparas no progress for 3 hours with an
  epidural or 2 hours without an epidural.

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Recommendations SOGC ( ACOG)

• SOGC recommends
• Continuous support
• Upright posture in the first stage of labor
• Cervical ripening
• Low-dose epidurals
• Amniotomy and oxytocin as promising approaches
  (further evaluation is needed)

• SOGC discourages
• Labor induction for macrosomia or elective
  reasons (ACOG also)
• Intra-uterine pressure catheter-based titration
  of oxytocin infusion
• Termination of epidurals prior to pushing.

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The Real World

• Gifford et al. (2000) found in 2,447 low-risk
  women with parity of 0 (70) or 1 (30)
• Cesarean rate of nearly 50
• Dystocia was the indication for 68 of the
  unplanned, vertex cesareans
• 16 of these done in the latent phase of labor
  according to ACOG guidelines
• Of those women having CDD during the second stage
  of labor, 36 did not meet ACOG standards for
  prolonged second stage

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Elective Induction

• Strongest recommendation for the prevention of
  dystocia made by SOGC (1995) and ACOG (1995) is
  avoidance of elective induction in nulliparas
• Rate of induction of labor has increased by 125
  in the U.S. since 1990 (NCHS, 2005)
• 20.6 of U.S. women delivering in 2003 were
  induced
• 25 percent of inductions have no apparent medical
  indication (i.e. elective) (Glantz 2003)

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Medically Indicated Induction

• Induction for Macrosomia
• ACOG (2000) does not recommend no evidence of
  improved maternal or fetal outcomes
• Estimate that elective and macrosomia inductions
  together account for 2/3 of all inductions done
  in U.S. (Ramsey, Ramin and Ramin, 2000)

• Induction for Post-Dates
• Defined by ACOG as those extending beyond 42
  weeks
• Providers in the U.S. and abroad routinely induce
  women with gestations between 40-42 weeks as
  postterm without appropriate testing for
  expectant managment

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Questioning the Definition

• Retrospective review of 1,329 low-risk, term
  nulliparas who had vaginal delivery and
  spontaneous labor
• 5th percentile of rate of cervical dilation was 1cm/hour
• Zhang, Troendle, and Yancey 2002
• Prospective study of 501 nulliparas
  oxytocin-managed labors
• Average dilation 1.4cm/hr
• 5th percentile of rate of cervical dilation was
  0.5 cm/hr
• Rouse and colleagues 2001

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Questioning the Definition

• ACOG dystocia definitions particularly
  problematic when applied to women with increased
  BMI
• ACOG outer time limit for dilation 4-10 cm 5
  hours (1.2cm/hr)
• Prospective cohort study comparing the labors of
  obese and overweight women with normal-weight
  women
• 6.2 hours for normal (BMI 19.8-26.0)
• 7.5 hrs for overweight (BMI 26.1-29.0)
• 7.9 hours for obese (BMI29)
• Vahratian et al., 2004

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CNMs The Protective Effect from Cesarean Birth

• Prospective cohort study of 2,196 low-risk women
  admitted with spontaneous labor compared the
  outcomes of those managed by CNMs to those
  managed by OBs
• 2 groups of women similar in medical/prior
  pregnancy history risk factors major antepartum
  complications
• CNM-managed had 22.1 more spontaneous vaginal
  deliveries when compared to the OB-managed group
• OBs admitted 23.4 more women in early labor than
  CNMs (

Jackson, Lang, Ecker, Swartz, Heeren, 2003
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Study Design
31
Study Design

• Retrospective Chart Review
• Nulliparous women admitted to labor and delivery
  under the care of faculty CNMs at OHSU during
  2004.
• A brief written survey of the faculty CNMs

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Sampling

• Inclusion Criteria
• Nulliparous
• Singleton, IUP, vertex presentation
• Admitted to the OHSU Nurse-Midwifery Practice
• Delivered between 01/01/04 and 12/31/04
• Women who had spontaneous or therapeutic
  abortions were included in the sample
• Women who were later transferred to OB/GYN care
  were also included

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Sampling cont..

• Total of 205 maternal names medical record
  numbers were initially retrieved
• 3 were excluded due to lack of electronic record
  or woman did not meet initial criteria.
• 202 were included in the review

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Instrument

• Chart Review Data Collection Form
• 44 items that were related to maternal and
  newborn characteristics admission, intrapartum,
  and postpartum characteristics and management.
• Survey of CNM practice
• 10 items 7 demographic characteristics, 3
  open-ended questions related to labor management
  decisions.

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Variables Examined

• Demographics
• Maternal Age
• Prepregnancy Wt.
• Total Wt. Gain
• Gestational Age
• Ethnicity
• Marital Status
• Gender of Baby
• Birth Outcomes
• Birth Weight
• Apgar Scorse, 1 min. 5 min.
• Postpartum Hemorrhage
• Postpartum Fever

• Labor Characteristics
• Cervical Dilation _at_ Admission
• Membrane Status _at_ Admission
• Amniotic Fluid on Rupture
• ROM method
• GBS Status
• Hemorrhage during Labor
• Induction of Labor
• Augmentation of Labor
• Regional Anesthesia
• IM/IV Narcotic
• Method of FHR Monitoring
• IUPC use
• Fever during labor
• Antibiotics during Labor
• Labor in Water
• Hydration in Labor

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Results

• 33 / 202 nulliparous women delivered by cesarean
  section (16.3)
• 60.6 of those delivered by cesarean had
  dystocia as primary indication.
• Fetal distress was indication for 24.2

37
Results

• Maternal Characteristics
• Mean maternal age 25.6 years (range 15-41 yrs)
• Mean gestational age 40.0 weeks (range
  34.3-43.3)
• 52 Caucasian, 43.6 Hispanic/Latino
• 64.4 married/living with partner, 35.1 single
• Data on maternal height was unreliable due to the
  large number (n 112) of records missing this
  information.
• Unable to determine BMI

38
Maternal Age

• The mean age of women who had a cesarean section
  for dystocia was significantly greater (p.039)
  than the mean age of women who had a vaginal
  delivery.
• (cesarean mean age 27.8 yrs vs. vaginal birth
  mean age 24.9)

39
Results Labor Management

• Six variables found to have statistically
  significant relationship with cesarean for
  dystocia

40
Results Labor Outcomes

• Two variables were statistically different
• Postpartum hemorrhage (1000mL) (n2)
• Hemorrhage during labor (n1)
• very small sample size for both of these
  variables, limiting the significance of this
  information.

41
CNM Faculty Characteristics

• Mean age 47.6 years
• Mean of years working as CNM 19
• Majority of CNMs estimate supervising SNMs 50
  of the time on call.

42
Conclusions
43
Rate of Cesarean Delivery and CDD

• The cesarean rate in this study 16.3 (33/202)
• 2003 national average cesarean rate among
  low-risk, nulliparous women at term 19.1
  (NCHS, 2005).

• CDD rate in this study 60.6 (20/33)
• This rate similar to published rates of 60-68
  (Gifford et al, 2000).

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Significant Associations with CDD

• Maternal Age only maternal characteristic found
  to be significantly associated with CDD
• This finding is analogous to the results of
  several published studies that found an increased
  risk of dystocia among older (35 years) women.

• Older nulliparas significantly more likely to
  experience CDD despite the fact that the OHSU
  Nurse-Midwives do not offer elective induction of
  labor.
• Ecker study (2004) found that increased use of
  elective inductions among older nulliparas was
  one of three factors that explained the increased
  cesarean rate in this population.

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Significant Associations with CDD

• 6 variables were significantly associated with
  CDD in the labor management practices of the OHSU
  Nurse-Midwives
• induction of labor
• augmentation of labor
• epidural anesthesia
• continuous external fetal monitoring (EFM),
• use of parenteral fluids
• use of intra-uterine pressure catheters (IUPC)

46
Induction

• Induction of labor was carried out for 21.3 of
  the women in this study.
• This rate of inductions is comparable to the
  national rate of inductions for term women, 21.6
  (NCHS, 2005).

• Women in this study who were induced were 2x
  likely to experience a CDD (8.2 for spontaneous
  labor vs. 16.3 CDD for induced labors).
• This risk for CDD with induction is on the low
  side of published studies citing a 2-3 fold
  increase in cesarean deliveries with induction

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Pain Control

• 49.5 (100/202) of the women in this study used
  epidural analgesia in labor.
• MCA survey (2002) identified that 59 of U.S.
  women use epidurals in labor.

• Many of the mothers delivered by the OHSU CNMs
  used non-pharmacological pain relief, including
  laboring in water (34.2, 69/202)
• No significant association seen between water
  laboring and CDD (possibly secondary to the small
  numbers of women in this study)

48
Additional Significant Associations with CDD

• Continuous electronic fetal monitoring (EFM)
  (p0.035), the use of parenteral fluids (p IUPC usage (passociated with CDD in this study.
• Impossible to know from the retrospective nature
  of this study if these associations were
  secondary to the onset of problems that would
  eventually result in the diagnosis of dystocia,
  or if their use somehow impacted the normal
  progression of labor and delivery.

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Outcomes of Labor CDD

• Hemorrhage greater than 1000ml in labor and
  postpartum were both found to be significantly
  associated with CDD (ppostpartum).
• Increased blood loss in labor associated with
  complications not a surprising association to
  find with CDD.
• Likewise, blood loss 1000ml is normal following
  cesarean delivery not a surprising association.

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The OHSU CNMs

• 8 midwives
• Mature (average age 47.6 years)
• Experienced (average years of CNM practice 19
  years)
• Spend the majority of their time while on call
  supervising student nurse-midwives
• Majority of them (5/8) have worked outside Oregon
  and attended births outside the hospital setting.
  
• Believe that low-risk women with no complications
  should not be admitted to the hospital prior to
  the onset of active labor (defined by the
  presence of strong, regular contracts 2-3 minutes
  apart with evidence of cervical change, usually
  with dilation at 4 cm or more)

51
OHSU CNMs Citizen Alien Waived Emergency
Medical (CAWEM)

• Over forty percent (43.6) of the women in this
  study were Latina, and most are covered with
  CAWEM
• Emergency Medicaid plan for undocumented
  immigrants
• Prenatal care and non-emergency visits to the
  hospital (including triage for labor) are not
  covered under CAWEM.
• CNM triaging a nulliparous woman with CAWEM
  insurance must make a difficult choice between
  what is best for her patients labor and what her
  patient can afford

52
Triage Practices of OHSU CNMs

• In the Jackson study, admitting women later in
  labor was associated with decreased rate of
  cesarean delivery.
• Although the OHSUs midwives triaged patients
  similar to the CNMs in Jacksons study, no
  association was found with CDD.

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Limitations of Study

• Limited by its retrospective design, small sample
  size (N202), and limited time period of one
  year.
• Associations seen here as significant are
  therefore only suggestive of needs for future
  research and not appropriate for inferences of
  causality.

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Limitations of Study

• Limitation of chart review design
• Some differences in the way that each reviewer
  interpreted pieces of information that were not
  noted recorded consistently in the charts.
• Incomplete BMI data
• Identified in literature as a significant risk
  factor for CDD.
• Height data necessary for the computation of BMI
  unavailable in over half of the charts reviewed.
• Incomplete Bishop Score data
• Identified in literature as significant risk
  factor for CDD
• Critical information for the computation of
  Bishop score was often omitted in charts
  (including the position and consistency of the
  cervix).

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Strengths of Study

• Attempt to analyze the practice of nurse-midwives
  at OHSU.
• CNMs deliver over 10 of the babies born in the
  U.S. each year (ACNM, 2006), yet only a handful
  of studies have examined how CNMs manage labor
  and birth.
• Provides an important window into the ways that
  CNMs care for their patients. Information is
  useful for
• other groups of midwives
• obstetricians who practice alongside midwives
• Valuable in its analysis of the maternal
  characteristics associated with CDD in the
  faculty practice

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Recommendations for Future Research/Policy

• More research needed to understand the factors
  involved in the association between maternal age
  and CDD.
• It is vital that information like BMI and Bishop
  scores be consistently collected and used in
  counseling patients and making practice
  decisions.
• New studies needed to investigate the ways that
  obstetricians differ from CNMs in their
  management of similar groups of low-risk
  nulliparous women.
• This study could be expanded to include
  nulliparous women cared for by the OHSU CNMs over
  the past five years, or to include a cohort of
  low-risk, nulliparous women managed by the
  medical residents at OHSU for comparison.

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For more information

• Nicole Carlson, RN, SNM smithem_at_ohsu.ed
• Noelle Lefitz, RN, SNM shipmann_at_ohsu.edu
• Nancy K. Lowe, CNM, PhD, FACNM, FAAN
  lowen_at_ohsu.edu