Management-of-Postterm-Pregnancy

1. Management of
Postterm
Pregnancy
Dr Ufaque Batool
House Officer
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2. Postterm = 42 weeks
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3. Definition:
ACOG Bulletin 55, Sept 2004
Postterm pregnancy refers to pregnancies that
extend beyond 42 weeks gestation (294 days, or
estimated date of deliver (EDD) +14 days)
Accurate pregnancy dating is critical to the
diagnosis
The term “postdates” is poorly defined and
should be avoided
Although some cases are a result of the inability
to accurate define the EDD, many cases result
from a true prolongation of gestation
Reported frequency of postterm pregnancy is 7%
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4. Etiologic factors
Most frequent cause of prolonged gestation
A. Placental Sulfatase deficiency
B. Error in Dating
C. Fetal Anencephaly
Other Associations
Male Sex
Genetic Predisposition
Primiparity
h/o prior postterm pregnancy
When postterm pregnancy truly exists, the most common
cause is
Unknown
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5. Assessment of gestational age
Accurate dating is important for minimizing the false
diagnosis of postterm pregnancy
MOST RELIABLY AND ACCURATELY
DETERMINED EARLY IN PREGNANCY
Questions at new ob visit
When was the first date of your last period?
Do you have regular cycles?
Approx how many days between cycles?
Are you sure about the given date?
Where you on any birth control when you got pregnant?
When did you first find out you were pregnant?
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6. Accuracy of LMP
There are many inaccuracies in even the
“surest” of LMPs
Recall
Delayed Ovulation
Irregular cycles
Predicting delivery date by ultrasound and last
menstrual period in early gestation. Obstet Gynecol.
2001 Feb;97(2):189-94.
The last menstrual period (LMP) was considered certain in 13,541
When ultrasound was used instead of certain LMP, the number of
postterm pregnancies decreased from 10.3% to 2.7% (P <.001).
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7. Accuracy of LMP
Comparison of pregnancy dating by last menstrual
period, ultrasound scanning, and their combination .
Am J Obstet Gynecol. 2002 Dec;187(6):1660-6
3655 women with sure LMP
LMP reports prolonged gestation 2.8 days longer on average than
ultrasound scanning, yielded substantially more postterm births
(12.1% vs 3.4%), and predict delivery among term births less
accurately
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8. Ultrasound dating?
When sure LMP and US vary greater than 8%
Approx 7 days up to 20 weeks
 14 days between 20-30 weeks
 21 days beyond 30 weeks
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9. Risks to the fetus
Risk of perinatal mortality (stillbirth and early neonatal
deaths) TWICE that of term.
4-7 deaths vs 2-3 deaths per 1,000 deliveries
Increases SIX fold and higher at 43 weeks
Uteroplacental insufficiency
Meconium aspiration
Intrauterine infection
Postterm pregnancy is an independent risk factor for low
umbilical artery pH at delivery and low 5 min APGAR scors
Higher incidence of fetal macrosomia, although no evidence
supports inducing labor as a preventative measure in such
cases
Prolonged labor, CPD, Shoulder Dystocia
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10. Risks to the fetus
Approx 20% of postterm fetuses have dysmaturity
syndrome
Infants with characteristics resembling chronic IUGR
from uteroplacental insufficiency
Oligo, meconium aspiration, hypogycemia, seizures, respiratory
insufficency, non-reassuring fetal testing
Long term sequelae not clear
One large prospective follow up study of children 1-2 yrs, general
intelligence, physical milestones, and frequency of intercurrent
illnesses were not significantly different between normal infants
born at term and those born postterm
Fetuses born postterm are at increased risk of death
within the first year- most have no known cause
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11. Risks to the pregnant woman
Increased labor dystocia- 9-12% vs 2-7%
Increased risk in severe perineal injury related to
macrosomia- 3.3% vs 2.6%
Doubled rate of c-section----endometritis,
hemorrhage, thromboembolic events
ANXIETY
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12. Are there interventions that decrease
postterm pregnancy?
Accurate dating by early sono---not current
standard of prenatal care in the US
Membrane sweeping studies are conflicting
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13. When should antenatal testing begin?
No studies to state when the best time to start,
frequency, or type of testing to use (no one with
include an unmonitored control group)
No data that testing adversely affects patients
experiencing postterm pregnancy
●
So, DO IT
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14. Perinatal Mortality
Figure 1. (A) The rates of
stillbirth (-▪-) and infant
mortality (-) for each week of
gestation from 28 to 43+
weeks expressed per 1000
live births. (B) The rates of
stillbirth (dark gray) and
infant mortality (light gray)
in the same population of
171,527 singleton births
expressed as a function of
1000 ongoing (undelivered)
pregnancies.
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15. What form of Testing?
Options include: NST, BPP, modified BPP (NST with
AFI), Contraction Stress Test
No single method superior
Evaluation of AFI important
Definition of oligo in the postterm not been established
No vertical pocked more than 2-3 cm
AFI less than 5
My choice- starting at 41 weeks- twice weekly
monitoring including NST with modified BPP (NST +
AFI)
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16. Induce or wait
Management of “low-risk” postterm pregnancy is
controversial
Factors to include- gestational age, results of
antenatal testing, cervix, maternal preference
Many studies exclude those with favorable
cervices
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17. Unfavorable cervix
Small advantage using cervical ripening agents
Several large multicenter randomized studies of
management after 40 week report favorable outcomes with
routine inductions starting at 41 weeks
Largest study found that routine induction at 41 weeks, found
elective induction resulted in lower c-section rates primarily
related to fewer c/s for non-reassuirng fetal heart rate tracings
Patient satisfaction was also higher
Meta-analysis of 19 trials found that routine induction after 41
weeks was associated with a lower rate of perinatal mortality and
no increase in c/s rate and no effect on operative vag delivery, use
of analgesia, or FHRA
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18. Induce at 41 weeks?
Large amounts of evidence suggest that routine
induction at 41 weeks gestation has fetal benefit
without incurring the additional maternal risks
of a higher rate of c-section.
This conclusion has not been universally
accepted
Smaller studies report mixed results
Two studies reported an increase in c/s rate
among certain subgroups of patients – “high risk”
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19. Prostaglandins for induction
Valuable tool
Several placebo controlled trails have reported
significant changes in Bishop scores, duration of
labor, lower maximum doses of oxytocin, and reduced
incidence of c/s.
No standardized doses have been established
Higher doses (especially PGE1) have been associated
with tachysystole and hyperstimulation resulting in
non-reassuring fetal status
Lower doses are preferable with PG is used and FHR
monitoring should be done routinely before and after
placement
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20. VBAC
Do not use prostaglandins
Foley bulb + pitocin
Limited evidence on the efficacy or safety of
VBAC after 42 weeks- no firm recommendations
can be made
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21. Induction of labor
41 weeks?
Consistently shown to have no increased morbidity/mortality even
with nulliparous patients and unfavorable cervices
39 weeks?
Multiparous patients appear to have no increase risk of c/s, morbidity,
mortality
Do have increased use of resources
Conflicting data on nulliparous
Recent study found no increase risk of c/s with unfavorable cervix after
eliminating medical inductions (preeclampsia, diabetes, etc)

Elective Induction Compared With Expectant Management in Nulliparous Women With an Unfavorable Cervix Obstetrics & Gynecology.
117(3):583-587, March 2011.
May be a baseline risk for c/s un-related to gestational age or cervix
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22. 2447 women underwent c/s from 30 hospitals in LA and Iowa
25% c/s performed for “failure to progress” at 3 cm or less
40% of “prolonged 2nd stage” did not meet ACOG criteria (45%
nulliparous)
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23. Indications for c/s
-32,443 patients
undergoing c/s 2003-
2009
- Obstet &Gynecol 2011
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24. Friedman curve
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25. Zhang’s new labor curve- sept 2010
26,838 women in non-augmented, active labor
Multiparous do not enter active labor until 5 cm
Nulliparous do not ener active labor until 6 cm
Labor progresses more slowly than previously described
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26. Give ‘em a chance!!
Friedman was wrong ( or wrong for today)
Labor curve of modern times is slower with the active
phase in primips not occurring until 6cm dilated!
Many c-sections performed when not even in active
labor
Don’t be afraid of serial inductions
Use all your armamentarium- prostaglandins, foley
bulb, pitocin, AROM, FSE, IUPC, operative delivery
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27. summary
Postterm pregnancy may in itself be “high risk”
Establish a EDD early and as precisely as possible-
early sono?
Consider antenatal testing at 41 weeks vs
induction
An unfavorable cervix may not be as much of a
risk factor for c-section as underlying issues-
macrosomia, fetal intolerance to labor, etc.
Where is the nadir for fetal well-being and
maternal outcomes? 39 weeks? 41 weeks?
Patience is important for today’s labor curve
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28. Postterm Pregnancy is like Popcorn
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29. ________Thank you
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