Prolonged PregnancyProlonged Pregnancy(Evidence Based)(Evidence Based)

Prolonged PregnancyProlonged Pregnancy(Evidence Based)(Evidence Based)

Dr. Ashraf FoudaDr. Ashraf Fouda

Ob./Gyn. ConsultantOb./Gyn. Consultant

Damietta Specialized Damietta Specialized HospitalHospital

SourcesSources

RCOG 2003RCOG 2003

ACOG (ACOG (SEPTEMBER 2004)

COCHRANE LIBRARY 2006COCHRANE LIBRARY 2006

AFP (AMERICAN FAMILY AFP (AMERICAN FAMILY

PHYSICIAN) (May 15, 2005) PHYSICIAN) (May 15, 2005)

PUBMED (MEDLINE)PUBMED (MEDLINE)

Prolonged pregnancy Prolonged pregnancy

( ( postterm pregnancy )postterm pregnancy ) It It

is one that has lasted longer than 42 is one that has lasted longer than 42

weeks or 294 days beyond the first weeks or 294 days beyond the first

day of the last menstrual period day of the last menstrual period

DEFINITIONDEFINITION

( (WHO & FIGOWHO & FIGO) )

PostdatismPostdatism is pregnancy lasting is pregnancy lasting

beyond the estimated due date at beyond the estimated due date at

40 weeks. 40 weeks.

““Postmature”Postmature” is reserved for the is reserved for the

pathologic syndrome in which the pathologic syndrome in which the

fetus experiences fetus experiences placental placental

insufficiencyinsufficiency and resultant and resultant IUGR .IUGR .

DEFINITIONDEFINITION

Representing Representing 20 % cases 20 % cases of prolonged of prolonged pregnancy and is associated with :pregnancy and is associated with :

1.1. Meconium -stained amniotic fluid, Meconium -stained amniotic fluid,

2.2. Oligohydramnios Oligohydramnios

3.3. Fetal distress Fetal distress

4.4. Evidence of loss of subcutaneous fat Evidence of loss of subcutaneous fat andand

5.5. Dry, cracked skinDry, cracked skin

Reflecting placental insufficiency.Reflecting placental insufficiency.

Post-maturity syndromePost-maturity syndrome

Etiologic FactorsEtiologic Factors The most frequent cause is an

error in dating.

When truly exists, the cause usually

is unknown.

Primiparity and prior postterm

pregnancy are the most common

identifiable risk factors.

Etiologic FactorsEtiologic Factors

Rarely, it may be associated with

placental sulfatase deficiency or fetal

anencephaly.

Male sex also has been associated.

Genetic predisposition may play a

role .

Using the definition of Using the definition of 294 days294 days, ,

the the incidence ofincidence of

postterm pregnancy is postterm pregnancy is 9 - 10 %. 9 - 10 %.

EPIDEMIOLOGYEPIDEMIOLOGY

Risks to the FetusRisks to the Fetus

The perinatal mortality:

> 42 weeks twice that at term

> 43 weeks > 6-fold that at term

In some cases, the risks appear to be due In some cases, the risks appear to be due to to uteroplacental insufficiencyuteroplacental insufficiency, , resulting in resulting in fetal hypoxiafetal hypoxia , , meconium meconium aspirationaspiration, , growth restrictiongrowth restriction, and , and oligohydramniosoligohydramnios . .

Fetal distress and meconiumFetal distress and meconium release release were were twicetwice as common (at or after 42 as common (at or after 42 weeks) than at term. weeks) than at term.

There was anThere was an eight-fold eight-fold increase in increase in meconium aspiration meconium aspiration

Risks to the FetusRisks to the Fetus

- In other cases, continued growth of the - In other cases, continued growth of the

fetus leads tofetus leads to macrosomiamacrosomia, ,

increasing the risk of increasing the risk of

labor abnormalitieslabor abnormalities, , shoulder shoulder

dystocia dystocia with resultant risks of

orthopedic or neurologic injury.

- Macrosomia is far more common in - Macrosomia is far more common in

postterm than term pregnancies . postterm than term pregnancies .

MacrosomiaMacrosomia

OligohydramniosOligohydramnios

It is a marker for It is a marker for fetal compromisefetal compromise and it and it

puts the puts the fetus at risk for cord accidentsfetus at risk for cord accidents..

U/S diagnosis :U/S diagnosis :

No vertical pocket > 2 cm orNo vertical pocket > 2 cm or

Amniotic fluid index (AFI) 5 cm or lessAmniotic fluid index (AFI) 5 cm or less . .

It is considered an indication for delivery.It is considered an indication for delivery.

Fetuses born postterm also are at increased

risk of : Sudden

infant death syndrome

(death within the first year of life).

Some of these deaths clearly result from

peripartum complications

(such as meconium aspiration syndrome),

but most have no known cause.

Risks to the FetusRisks to the Fetus

Maternal risksMaternal risks

1) Labor dystocia

2) Severe perineal injury

related to macrosomia

3) Doubling in the rate of cesarean

delivery.

4) A source of extreme anxiety for

the pregnant woman.

Gest. age must be assessed carefully Gest. age must be assessed carefully

to avoid delivery of a preterm infant.to avoid delivery of a preterm infant.

Women who Women who attend lateattend late for ANC may for ANC may

be of uncertain gestation and may be be of uncertain gestation and may be

over-represented in populations of over-represented in populations of

postterm pregnancies.postterm pregnancies.

Dating by the last menstrual period (LMP) Dating by the last menstrual period (LMP)

alonealone has a tendency to has a tendency to overestimateoverestimate

the gestational age. the gestational age.

Gestational age calculationGestational age calculation

Gestational age calculationGestational age calculation Because actual dates of conception are Because actual dates of conception are

rarely known, therarely known, the

LMPLMP is used as the reference point. is used as the reference point.

This can make the accuracy of gest. age This can make the accuracy of gest. age

determination determination unreliableunreliable because of :because of :

1.1. Irregular menses .Irregular menses .

2.2. Recent cessation of birth control pills.Recent cessation of birth control pills.

3.3. Inconsistent ovulation times.Inconsistent ovulation times.

Routine early pregnancy Routine early pregnancy

ultrasoundultrasound♣ Reduces the number of women who

require induction of labour for apparent

postterm pregnancy .♣ It is recommended that all pregnant

ladies (and certainly those who do not

have regular menses), should have an

ultrasound examination for gestational

age determination, prior to 20 weeks

RCOG,COCHRANE

Crown-rump length Crown-rump length (CRL) (CRL) till till 1212 weeks is weeks is 3-5 days,3-5 days,

Biparietal diameter (BPD) Biparietal diameter (BPD) atat 12-2012-20 weeks weeks is is 1 week1 week, ,

BPD BPD at at 20-30 20-30 weeksweeks is is 2 weeks2 weeks, and , and BPD BPD after after 30 weeks30 weeks is is 3 weeks3 weeks.. If there is more than a one week

discrepancy between the LMP and the ultrasound findings, the ultrasound data should be used to determine the EDD .

Ultrasound biometry margins of error

Transcerebellar diameter When When composite biometrycomposite biometry is not is not

consistent in all of the parameters consistent in all of the parameters (i.e. (i.e.

BPD, head circumference, abdominal BPD, head circumference, abdominal

circumference, femur length),circumference, femur length),

using the using the transcerebellar diameter transcerebellar diameter is a is a

way to more accurately date a pregnancy way to more accurately date a pregnancy

The diameter in The diameter in millimeters corresponds millimeters corresponds

to weeks of to weeks of

gestation up to 24 weeks.gestation up to 24 weeks.

Transcerebellar diameter

The available evidences are The available evidences are

strongly in support that strongly in support that dating dating

by by Early Early

ultrasonographyultrasonography alone alone

is the most is the most

accurate method for predicting accurate method for predicting

EDDEDD. . RCOG (GRADE A)

The use of The use of early ultra sound early ultra sound alonealone to to

calculate the rate of postterm calculate the rate of postterm

pregnancy in women who delivered pregnancy in women who delivered

spontaneously significantly spontaneously significantly

reduced the postterm rate reduced the postterm rate

from 10 % to 1.5 %.from 10 % to 1.5 %.

Routine early pregnancy Routine early pregnancy ultrasoundultrasound

RCOG (GRADE A)

Are there interventions that decrease Are there interventions that decrease the rate of postterm pregnancythe rate of postterm pregnancy??

Accurate dating on the basis of ultrasonography performed early in pregnancy .

Breast and nipple stimulation at term have not been shown to affect the incidence of postterm pregnancy.

Sweeping of the membranes at term : the data are still conflicting .

ACOG Guidelines 2004

1) Gestational age,

2) Absence/presence of maternal risk factors

and / or

3) Evidence of fetal compromise, and

4) Maternal preferences .

Successful management depends on Successful management depends on

effective counselling of womeneffective counselling of women

and their full involvement in the and their full involvement in the

decision making process.decision making process.

Management options depend on:Management options depend on:

a.a. Inducing labour at 41-42 weeks Inducing labour at 41-42 weeks

gestationgestation or or

b.b. Awaiting the onset of spontaneous Awaiting the onset of spontaneous

labour, while monitoring the fetal labour, while monitoring the fetal

wellbeing .wellbeing .

The decision is difficult and should The decision is difficult and should

not be taken lightly.not be taken lightly.

Historically, prolonged pregnancy has Historically, prolonged pregnancy has

been managed in 2 ways , either :been managed in 2 ways , either :

Routine induction of labour Routine induction of labour at 41 weeksat 41 weeks

Although postterm pregnancy is defined

as a pregnancy of 42 weeks or more of

gestation, several large multicenter

randomized studies reported favorable

outcomes with routine induction as early

as the beginning of 41 weeks of

gestation.

Cochrane 2006

A recent review in the Cochrane Library A recent review in the Cochrane Library concluded that concluded that

routine induction in low-risk routine induction in low-risk pregnancies at or after 41 weeks' pregnancies at or after 41 weeks'

gestationgestation is associated with : is associated with :

1.1. A reduction in perinatal mortality,A reduction in perinatal mortality,

2.2. No increase in the rate of instrumental No increase in the rate of instrumental or cesarean delivery. or cesarean delivery.

RCOG Grade ARCOG Grade A

Routine induction of labour Routine induction of labour at 41 weeks at 41 weeks

Contrary to what many obstetricians believe, Contrary to what many obstetricians believe,

induction of labor for prolonged pregnancy induction of labor for prolonged pregnancy

does not increase the rate of cesarean does not increase the rate of cesarean

sectionsection, rather, it decreases it., rather, it decreases it.

The risk of The risk of fetal distressfetal distress from uteroplacental from uteroplacental

insufficiency due to prolonged pregnancy insufficiency due to prolonged pregnancy

can be reduced by induction of laborcan be reduced by induction of labor, even to , even to

the point of preventing perinatal death from the point of preventing perinatal death from

asphyxia. asphyxia.

Routine induction of labour Routine induction of labour at 41 weeksat 41 weeks

There is insufficient evidence to indicate

whether routine antenatal surveillance

of low-risk patients between

40 and 42 weeks of gestation

improves perinatal outcome

but it is

often performed during this period.

ANTEPARTUM FETAL ANTEPARTUM FETAL SURVEILLANCESURVEILLANCE

The The condition of the fetus can change condition of the fetus can change

quicklyquickly and thus, monitoring should be and thus, monitoring should be at at

frequent intervalsfrequent intervals, and that none of , and that none of

the tests are immune from false the tests are immune from false

positives, false negativespositives, false negatives

Boehm et al, demonstrated that Boehm et al, demonstrated that twice-twice-

weeklyweekly testing of patients at risk for fetal testing of patients at risk for fetal

distress was distress was superior to weekly testingsuperior to weekly testing. .

ANTEPARTUM FETAL SURVEILLANCE    ANTEPARTUM FETAL SURVEILLANCE    

A A modified biophysical profilemodified biophysical profile

consisting of a: consisting of a:

non stress test and an non stress test and an

amniotic fluid indexamniotic fluid index

have been shown to be have been shown to be

as sensitive as a as sensitive as a full biophysical full biophysical

profileprofile. .

FETAL SURVEILLANCEFETAL SURVEILLANCE

RCOG Grade ARCOG Grade A

Favorable cervixFavorable cervix : : Labor generally is induced because the risk of failed induction and subsequent cesarean delivery is low.

Unfavorable cervixUnfavorable cervix : :a small advantage to labor induction using cervical ripening agents (prostaglandins), when indicated, regardless of parity or method of induction.

Induction of labour or Induction of labour or expectant management?expectant management?

ACOG 2004 ACOG 2004 (Level C)

A .Healthy, uncomplicated pregnancy and

fetal growth/ amniotic fluid normal:

No evidence to support elective

induction of labour

No evidence to support use of serial

antenatal monitoring :

non stress test (NST) or

amniotic fluid index (AFI) .

Management from 40Management from 40-41-41 weeks weeks gestationgestation

B. Presence of maternal risk factors or

evidence of fetal compromise :

Recommend cervical ripening

as necessary and

induction of labour

Management at 40 Management at 40 - 41- 41 weeks weeks gestationgestation

A. Healthy, uncomplicated pregnancy

Inform the woman of the options and

risks/ benefits of labour induction versus

expectant management, and

offer her labour induction.

Establish the cervical (Bishop) Score and

ensure a ripening agent (prostaglandin)

prior to induction.

Management at 41 weeks Management at 41 weeks gestationgestation

B. If mother declines induction , then provide expectant management:

Daily fetal movement counts

Non stress test (NST) and Amniotic fluid index (AFI) twice/ week to 42 weeks.

If the NST or AFI is abnormal , then initiate induction immediately

Management at 41 weeks Management at 41 weeks

gestationgestation

Induce at 42 weeks Induce at 42 weeks even if NST and AFI are normal.even if NST and AFI are normal.

۞ Consider amniotomy to diagnose thick

meconium.

۞ If meconium is present then consider risk

of meconium aspiration , continuous fetal

assessment with electronic fetal monitoring

(EFM) is recommended.

۞ Be prepared for shoulder dystocia and

neonatal resuscitation at delivery.

Management during labour and Management during labour and

deliverydelivery

Labour induction at 41 weeks

gestation is recommended over

expectant management in women

with postterm pregnancy to reduce

the rate of cesarean delivery &

perinatal mortality .

Key Clinical RecommendationsKey Clinical Recommendations

(RCOG Grade A)

If Expectant management (41-

42 weeks) is chosen, the

fetus should be monitored with

twice weekly non-stress test ,

amniotic fluid index .

- However, evidence of benefit

is lacking.

Key Clinical RecommendationsKey Clinical Recommendations

(RCOG Grade C )

Prostaglandin can be used in postterm

pregnancies to promote cervical ripening

and induce labor.

Delivery should be effected if there is

evidence of :

fetal compromise or

oligohydramnios.ACOG 2004 ACOG 2004 (Level A)

Key Clinical RecommendationsKey Clinical Recommendations