Prolonged Pregnancy

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Prolonged Pregnancy

• Ashley C. Lindell, MD
• Swedish Family Medicine

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Questions

• What is postterm pregnancy?
• Why does it matter?
• How should it be managed?

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A case...

• 26 year old G1 (?2) P1 presents with amenorrhea
  and nausea. The first day of her LMP was about 2
  months ago, she doesnt remember the exact date.
  It was a normal period. She reports pretty
  regular menses, about once a month. Her urine
  pregnancy test is positive.
• Question 1 What is her EDC?

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Definitions

• Postterm/prolonged pregnancy to or beyond 42
  weeks post first day of LMP
• perinatal mortality data derived from accurately
  dated pregnancies suggest increased risk from 41
  weeks onward

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Dating (all that stuff in the box on the
blue-border form)

• Clinical
• -certain LMP /- 14 days
• -fundal height, quickening, FHTs /- 15-17
  days
• problems with LMP dating
• 1. Approximately 1/3 of women dont remember the
  first day of their LMP
• 2. Variable length of menstrual cycle,
  particularly of the follicular phase -
  overestimation of GA

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Dating, part 2

• Ultrasound
• - early US (pregnancies diagnosed as postterm
• Accurate dates accurate diagnosis
• - most common cause of postterm is inaccurate
  dating
• - may be based on a definite LMP in women with
  regular, normal menses confirmatory uterine
  sizing any uncertainty in clinical dating
  parameters - US
• - some recommend universal early US for dating

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Back to your OB

• Since she cant remember her exact LMP, you
  decide to get an early US for dates. You draw
  prenatal labs, prescribe PNVs, and do an HP.
• Her first child was induced at 42 weeks. She
  tells you she had a long labor, that her doctor
  put a monitor on the babys scalp because the
  heart rate kept going down, and that the babys
  shoulder got stuck.
• You wonder
• A. Is she at increased risk of going postdates
  again?
• B. What should I be concerned about if she does ?
  
• C. Should I transfer her to perinatal?

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Postterm-who cares?

• You should
• Its common approximately 10 of US pregnancies
  - youll be managing it
• Risk is increased significantly (2-3 X) in women
  with a previous postterm delivery risk is
  increased slightly in primips and women who are
  the product of a postterm pregnancy
• Perinatal morbidity and mortality is increased in
  prolonged pregnancies

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Physiology Review

• uteroplacental insufficiency
• increased risk of oligo, abnormal FHTs,
  meconium/MAS, low Apgars, hypoglycemia, seizures,
  respiratory insufficiency
• fetal growth
• linear function of GA 37- 42 weeks bigger babies
  increased risk of cephalopelvic
  disproportion/macrosomia - dysfunctional labor,
  shoulder dystocia, maternal trauma, hemorrhage

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MM

• Mortality
• perinatal mortality (fetal early neonatal) 40
  weeks 2-3/1,000 42 weeks 4-7/1,000 (Feldman,
  Bakketeig)
• fetal loss/1,000 live births, OR vs. term
• 41 weeks 1.5, 42 weeks 1.8, 43 weeks 2.9
  (Divon)
• fetal loss/1,000 ongoing pregnancies
• 37 weeks 0.7, 40 weeks 2.4, 43 weeks 5.8
  (Hilder)

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MM, part 2

• Morbidity
• RR at / 42 weeks vs. term fetal distress
  1.7, shoulder dystocia 1.3, dysfunctional labor
  1.3, ob trauma 1.25, hemorrhage 1.1
  (Campbell)
• other studies (Clausson, Alexander, Tunon)
• increased labor complications -
  prolonged/dystotic labor, forceps, c-sections
• increased perinatal morbidity - convulsions, MAS,
  low Apgars, NICU admissions

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Back to your patient

• Her pregnancy proceeds normally
• At 37 weeks you
• A. Put her name to the moms and babes signout
• B. Start wondering how you should manage her
  pregnancy if she goes past her EDC.
• C. Review your ALSO material on shoulder
  dystocia.
• D. All of the above.

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Management To induce or not to induce? And when?

• Factors to consider
• gestational age (arent you happy you got that
  
• cervix-favorable vs. unfavorable
• results of antepartum fetal monitoring
• patient preference
• overall balance of risks of expectant management
  vs. risks of induction

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Antenatal testing

• goal prevent fetal death by detecting early
  signs of placental dysfunction/ fetal compromise
• abnormal test results (oligo, abnormal fetal
  heart rate tracing) delivery
• Options BPP, NST AFI, CST
• -all have low false negative rates demise within 1 week of normal test result)
  (ACOG Practice Bulletin)
• -all have high false positive rates (abnormal
  test, no fetal compromise intrapartum) 40 for
  BPP, 60 for NST AFI, 65 for CST (Miller,
  ACOG Practice Bulletin)

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Antenatal Testing, part 2

• Whats the data?
• Efficacy of antenatal testing in improving
  outcomes has not been validated (ACOG, UTD).
• No specific protocol of antenatal testing has
  been shown to be superior. (ACOG, UTD)
• So what am I supposed to do?
• -ACOG begin testing by 42 weeks, insufficient
  evidence testing at 40-42 weeks improves
  outcomes, no recommendation on protocol
• -community standard of care/expert opinion 2X
  weekly testing including AFI beginning in 41st
  week

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IOL vs monitoring the data

• largest trial routine postterm IOL (41 weeks) vs
  monitoring perinatal MM rates same, lower
  c-section rate with IOL (Hannah)
• Multiple other trials- mixed results
• Cochrane meta-analysis (1999) 19 trials routine
  IOL at 41 weeks vs monitoring perinatal
  mortality rates lower with IOL, c-section rates
  same
• systematic review (2003) of 16 RCTs IOL at 41
  weeks vs expectant management perinatal MM not
  significantly different c-section rates lower
  with IOL

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IOL vs Monitoring Recommendations

• ACOG Practice Bulletin (1997!)
• Favorable cervix Unknown whether IOL or
  expectant management preferable labor is usually
  induced.
• Unfavorable cervix Good evidence that either
  option results in good outcomes.
• Up to Date Recommend routine IOL at 41 weeks.
  Risks IOL lower with cervical ripening agents.
  Risks expectant management low, but risk of fetal
  death exists.
• Cochrane (2000) Routine IOL at 41 weeks appears
  to reduce perinatal mortality

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Your patient...

• You add her to the signout and review shoulder
  dystocia.
• You discuss the options and decide on IOL at 41
  weeks.
• In clinic at 40 1/2 weeks you do a cervical exam
  and note her Bishop score to be 3.
• You wonder What should I do about that cervix?

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Cervical ripening /IOL- nonpharmacologic

• mechanisms mechanical dilation, prostaglandin
  release
• risks infection, bleeding, ROM, discomfort
• Mechanical foley, laminaria
• effective for ripening, similar failure rates
  (evidence level A)
• Surgical stripping of membranes
• -Cochrane SOM alone does not produce clinically
  significant benefit as an adjunct it is
  associated with decreased mean pit dose,
  increased rate of normal vaginal deliveries
• -meta-analysis SOM at term shortens duration of
  pregnancy by a mean of 4 days NNT to prevent 1
  postterm pregnancy 25 (Gabbe)

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Pharmacologic Methods

• Prostaglandins
• increase likelihood of vaginal delivery within 24
  hrs (Cochrane)
• risks uterine hyperstim, FHR changes
• 1. PGE2 dinoprostone-gel (prepidil)
• -insert
  (cervadil)
• 2. PGE1 misoprostol decreased c-section rate,
  reduced need for pit vs placebo (evidence level
  A) CI with previous c-section

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What about sex?

• Herbs traditional use, case reports (AFP, 5/03)
• Castor oil, hot baths, enemas, sex
• -1 study on castor oil - no difference in
  outcomes (AFP 5/03)
• -sex 1 study - minimally useful data (AFP
  5/03) a nice theory, though- nipple lower
  uterine segment stimulation-prostaglandin
  release, orgasm-uterine contractions
• nipple stimulation
• 2 studies-difference in intervention group,
  study design poor (AFP 5/03)
• 1 study 3 hrs/day starting at 39 weeks-
  decreased incidence of reaching 42 weeks without
  spontaneous onset of labor (Clinics FP 2001)

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LD

• You get her on the induction schedule at 41 weeks
  
• After 2 rounds of misoprostol, her Bishop score
  is 10 (4/60/soft/anterior/-1) and you start pit
• She progresses well on pit, is complete 4 hours
  later, and pushes for 1 1/2 hours to deliver a 7
  lb 2 oz girl with good Apgars (and no shoulder
  dystocia!)
• Was it the week earlier that made the difference?
  Was it being a multip? Was it luck? Do you care?

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Summary

• Accurate dating is important have a low
  threshold for getting an early (establish dates.
• Postterm pregnancy is associated with increased
  maternal and fetal risks.
• Either routine IOL at 41 weeks or 2X/week
  monitoring starting in the 41st week with IOL for
  abnormal test results is reasonable literature
  reviews suggest slightly improved outcomes with
  routine IOL.
• With a Bishop score recommended before IOL. Mechanical dilators, PGE1
  and PGE2 are all effective. Stripping of
  membranes may be useful in decreasing the number
  of pregnancies reaching 41 or 42 weeks and as an
  adjuct to pit.