Prolonged Pregnancy
Dr Khaled Aba-Oub MD FRCOG
Consultant O&G Tripoli Fertility Centre
Consultant O&G St Helier Hospital,London UK
 Posterm pregnancy is defined as a pregnancy
that extends to 42 0/7 and beyond
 incidence: 3-12% however the actual biologic
variation is likely less since the most frequent
cause of a postterm pregnancy diagnosis is
inaccurate dating
Fetal &Neonatal risks:
 Perinatal mortality rate at 42 wks is twice that
at 40 wks
 increases to 4 folds @ 43 wks and to 5-7 folds
at 44 wks
20% of postterm fetuses have post maturity
syndrome,which is characterised with chronic
intrauterine growth restriction from uteroplacental
insufficiency.These pregnancies are at increased
risk of umbilical cord compression from
oligohydramnios,non-reassuring CTG,intrauterine
passage of mec,hypoglycemia,seizures,and
respiratory insufficiency
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Macrosomia and bith injury
fetal acidemia
Neonatal death
Cerebral palsy
Maternal Risks
increase in labour dystocia (9-12% vs 2-7% at
term)
Increase in severe perineal injury (3rd and 4th
degree tears) related to macrosomia (3.3% vs
2.6% @term) and operative vaginal delivery,and a
doubling in the rate of Caesarean delivery (14%
vs 7% at term) which is associated with higher
risks of endometritis,haemorrhage,and
thromboembolic disease
The emotional impact (anxiety and frustration) of
carrying a pregnancy 1-2 weeks beyond the
estimated du date should not be underestimated
20% of pregnant women will require IOL,the
majority for prolonged pregnancy
58% of women will have delivered by 40 wks of
gestation,74% by 41 wks of gestation and 82% by
42 wks of gestation
Ensure that the pregnancy has been dated
correctly
Dating U/S in the first trimester reduces rates of
IOL for post-term pregnancy NICE advise U/S
scans to determine gestational age using:
 CRL measurement from 10 wks 0 days to 13
wks 6 days
 Head circumference if CRL is above 84 mm
U/S dating should not be postponed further than
24 completed wks irrespective of how sure
women are of their menstrual dates
When to Induce
Women with uncomplicared pregnancies should
be given every opportunity to go into spontaneous
labour.Women with uncomplicated pregnancies
should usually be offered IOL between 41+0 and
42+0 wks to avoid the risks of prolonged
pregnancy,primarily increased intrauterine fetal
death
If a woman chooses not to have IOL,her decision
should be respected
Fom 42 wks,offer increased antenatal monitoring
consisting of at least twice weekly
cardiotocography and U/S estimation of
maximum amniotic pool depth
Why offer IOL
As pregnancy continues,the risk of the baby dying
in the uterus or soon after delivery increases
The stillbirth rate increases fom 1 in 1000 @ 37
wks of gestation to 3 in 1000 @ 42 wks of
gestation to 6 per 1000 @ 43 wks of gestation
The reported complications of induction include:
Hyperstimulation
Fetal distress
Failed Induction
Caesarean Section
Ruptured Uterus
Adverse effects of drugs used for induction
Membrane sweeping:
During vaginal examination,the clinician's finger
is introduced into the cervical os,then the inferior
pole of the membranes is detached from the lower
uterine segment by a circular movement of the
examining finger
Purpose:
To initiate labour by increasing local production
of prostaglandins and thus,reduce pregnancy
duration or pre-empt formal IOL with either
oxytocin,prostaglandins or amniotomy
Methods of IOL:
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Prostaglandins
Oxytocin
Misoprostol
Isosorbide mononitrate
Mechanical methods
Riks/Benefits of membrane sweep
 No increased risk of C.S
 Membrane sweep reduces the frequency of
pregnancy continuing beyond 41 and 42 wks
 No increase in the risk of maternal or neonatal
infection
 Discomfort during vaginal examination and
other adverse effects (bleeding,irregular
contractions) more frequently reported by women
who undergo membrane sweep
Pre-Induction Assessment:
Women are admitted to the maternity unit at
around term plus ten days.A cardiotocograph
(CTG) to ensure the fetus wellbeing is performed
This is followed by a vaginal examination to
determine the modified Bishop score and act as a
baseline against which to compare subsequent
examinations
Parameter
0
1
2
3
Dilatation
<1
1-2
2-4
>4
Length
>4
2-4
1-2
<1
Consistency firm
average
soft
Position
posterior
mid
anterior
Station
-3
-2
-1, 0
+1, +2
Prostaglandin induction is commenced on the
antenatal ward,IOL should not occur on the
antenatal ward if the pregnancy is high risk.These
women should be induced on the LW
After PG are inserted vaginally,the woman is
asked to lie down for half an hour and a
cardiotocograph is performed to establish fetal
wellbeing;this is essential once uterine activity
commences
Oxytocin is administered on the LW with
continuous fetal heart and uterine activity
monitoring and with one to one midwifery care
Thank You