1. Post-dated Pregnancy & Induction Of Labor

2. Post-term Pregnancy (Syn:Post-dated Pregnancy or Post maturity Prolonged pregnancy)
A pregnancy that has reached or surpassed 42 weeks ( 294 days ) of gestation from the first day of the last menstrual period. ( ACOG,WHO,FIGO)
Incidence- Range 4-19%,Average incidence-10%

3. Aetiology
Wrong dates- The most common cause of prolonged pregnancy, due to inaccurate LMP
Hereditary- postdatism seems to run in families, showing a genetic predisposition
H/o previous prolonged pregnancy- recurrence 50%

4. Abnormal fetal HPA and adrenal hypoplasia as in
anencephaly deficiency of dehydro-epiandrosterone reduced fetal cortisol response.
Placental Salphatase deficiency- this enzyme play a critical role in synthesis of placental estrogens which are necessary for the expression of oxytocin & PG receptors in myometrial cells

5. Changes associated with prolonged pregnancy
A series of changes occur in
-amniotic fluid
-placenta and
- fetus
Amniotic Fluid Changes
In Postdated Pregnancy quantitative &qalitative
changes occur in Amniotic fluid

6. Quantitative Amniotic Fluid Changes
Amniotic fluid peak
38wks ml
40wks ml
42wks ml
43wks ml
44wks ml
After 42wks there is 33% decrease in amniotic fluid volume/wk
A decrease in fetal renal blood flow is associated with postdatism is the cause of oligohydromnios
Amniotic fluid less than 400ml is associated with fetal complications

7. Method to evaluate amniotic fluid volume
Most popular method to evaluate amniotic fluid volume is four quadrant technique to calculate Amniotic Fluid Index (AFI).
AFI is obtained by measuring the vertical diameter of largest pocket of amniotic fluid in 4 quadrants of uterus by USG and the sum of the result is AFI
AFI <5cm – oligohydromnios
5 – 10cm – decreased amniotic fluid volume
10 – 15cm – Normal
16 – 20cm – Increased amniotic fluid volume
>25cm - Polyhydromnios

8. Qualitative Changes in Amniotic fluid
AF become milky and cloudy because of presence of abundant flakes of vernix caseosa.
The Phospholipids composition changes due to presence of large number of lamellar bodies released from fetal lungs. Vernix raises the lecithin, Sphingomyelin ratio to 4: 1 & more
The liquor may be meconium stained as a result of intrauterine hypoxia

9. Placental Changes USG findings:
-Indentation in chorionic plate become more marked, giving the appearance of cotyledons
- Increased confluency of the comma- like densities that become the inter cotyledonary septations
- Appearance of hemorrhagic infarct & Calcification

10. Fetal Changes
The fetus grow in utero after term - macrosomic which lead to fetopelvic disproportion , Prolong labor
Shoulder dystosia
After term the fetus loses Vernix caseosa causing wrinkling of the skin due to direct contact with aqueous amniotic fluid
Growth of hair and nails
Wasting of subcutaneous tissue

11. Diagnosis of Postdated Pregnancy
The diagnostic accuracy of post term pregnancy hinges on the reliability of gestational age
We can get accurate EDD by:-
- LMP when >3 normal regular period before LMP & no ocp
- EDD calculated by LMP coincide with EDD from USG
perform between 12-20wks
- When LMP not known EDD established from USG
between 7-11wks
- EDD corresponds to 36wks since the patient had +ve upt
- A reliable P/V finding for GA age in 1st trimester

12. Management
Prior to deciding any line of action it is important to establish the diagnosis of post term gestation by history , examination and USG.
Fetal Surveillance by – NST
- AFI
- Biophysical Profile
- Doppler ( Facilities available)

13. Patient with Prolonged Pregnancy (>40wks) who need to be delivered :
* Women with medical or obstetrical complications
of pregnancy
* Favorable Cervix Bishop Score > 8
* Women with oligohydromnios
* Estimated fetal weight > 4.5kg
* Suspected fetal compromise
* Fetal congenital anomaly
* Hyper mature Placenta

14. Expectant management of prolonged pregnancy is justified only when:
- GA <41 wks with unripe cervix, normal AFI ,
normal size baby , normal BPP and reactive
NST
There is universal agreement that once pregnancy reaches 42wks delivery mandatory – Induction/ CS
-If there is signs of fetal distress ,wt. is > 4.5kg.or
obstetrical complicated pregnancy- CS

15. Complication of Postdated pregnancy
Maternal – Increased morbidity due to increased
Instrumental & operative delivery
Fetal - Intrapartum fetal distress
- MAS
- Fetal trauma due to macrosomia
- Increased Perinatal morbidity & mortality

16. INDUCTION OF LABOUR

17. Induction Initiation or stimulation of uterine contractions before the spontaneous onset of labour with or without ruptured membranes
Augmentation – refers to stimulation of uterine contractions that are already present but found to be inadequate.

18. Indications Obstetrical indication Post term pregnancy
Severe pre eclampsia/ eclampsia
PROM
Ruptured membrane with chorioamniotis
Intrauterine death
Fetal growth restriction
Nonreassuring fetal testing

19. Chronic nephritis/ renal disease Chronic Hypertension Diabetes
Rh iso-immunization
Malformed fetus
Abruptio Planctae
Severe hydramnios
Medical indication
Chronic nephritis/ renal disease
Chronic Hypertension
Diabetes

20. Contraindication Fetal macrosomia Multifetal gestation Malpresentation
Prior classical caesarean
Contracted pelvis
Major degree placenta previa
Active genital herpes infection
Cervical cancer

21. PREREQUISITES
Prior to initiation of induction the following should be assessed
indication for induction/any contraindications
gestational age
cervical favourability (Bishop score assessment)
assessment of pelvis and fetal size/presentation
membrane status (intact or ruptured)
fetal well being/fetal heart rate monitoring prior to labour Induction
documentation of discussion with the patient including indication for induction and disclosure of risk factors

22. CERVICAL RIPENING PRIOR TO INDUCTION
Cervical ripening is a component of induction of labor employed when the cervix is unfavorable in order to facilitate dilatation when labor is established.

23. Bishop’s Score (Modified)
Parameters
Score
Cervix 1 2 3
Dilatation (Cm)
Closed
1-2
3-4 5+
Effacement(%) Or
Cervical Length (Cm)
0-30
>4
40-50 or
2-4
60-70
≥ 80
<1
Consistency
Firm
Medium
Soft -
Position
Posterior
Midline
Anterior
Head Station
- 3
- 2
- 1, 0
+1, +2

24. Total Score – 13
Unfavorable Score – 0-5
Favorable Score
Bishop score >8 is a good index of inducibility

25. Methods of cervical ripening
Pharmacological methods
Oxytocin
Prostaglandins
-E2(dinoprostone,prepidil,cervidil)
-E1(misoprost)
Steroid receptor antagonists
-Mifepristone (RU486)
-Onapristone
Relaxin

26. Mechanical methods
Membrane stripping
Amniotomy
Mechanical dilators
Transcervical balloon catheters
With extraamniotic saline infusion
With concomitant oxytocin administration

27. Methods of Induction of labor
Medical – Prostaglandins (PGE2, PGE1)
- Oxytocin
- Mifepristone
Surgical Artificial rupture of membranes
- Stripping the membranes
Combined - Medical + Surgical

28. Prostaglandin E2
Gel preparation with 0.5mg in 2.5ml in a prefilled syringe for intracervical administration (prepidil/ dinoprostone
With the woman in dorsal the tip of a prefilled syringe is placed intracervically and the gel is deposited just below the internal cervical os.The woman should remain reclined for at least 30 minutes.
Dose repeated every 6 hours with a maximum of 3 doses
Subsequent augmentation with oxytocin if needed to be started after 6 hours
Side effects- uterine tachysystole
Contraindication- asthma, glaucoma , liver disease

29. Prostaglandin E1
Used as 25µg per vaginally every 4 hours or 50µg per orally every 3-6 hours
Sublingual and buccal routes associated with rapid onset action and more bioavalibility
Maximum dose of 200µg given
Synto augmentation if required to be started after 6 hours
Side effects- uterine tachysystole, fetal distress, uterine rupture
Contraindicated in patients with previous uterine scar, liver disease and renal disease
synto

30. Oxytocin
Polypeptide hormone produced in hypothalamus, secreted from posterior pituitary
Synthetic analogue of used as uterotonic and for induction
Myometrial sensitivity increases with gestational age, with rapid increase during labour
Effective means of induction in women with ripe cervix
Because of short half life (3-4min) used as iv infusion. Plasma levels falls rapidly when iv infusion stopped.
Oxytocin infusion is commenced at the rate of miu/min and gradually dose increment at 15-30min

31. 2. 5 IU Oxytocin in 500ml RL(concentration- 5mIU/ml) 8 drops- 2
2.5 IU Oxytocin in 500ml RL(concentration- 5mIU/ml) 8 drops- 2.5mIU/ml 16 drops- 5mIU/ml 24 drops- 7.5mIU/ml 32 drops- 10 mIU/ml 40 drops- 12.5mIU/ml 48 drops- 15 mIU/ml 56 drops mIU/ml 60 drops- 20 mIU/ml

32. Complications Uterine overactivity Water intoxication Hypotension
Uterine rupture
Neonatal jaundice

33. Mifepristone Progestrone receptor antagonist
Blocks both progestrone and glucocorticoid receptors
200mg vaginally daily for 2days has been found to ripen the cervix and to induce labour

34. Membrane stripping
Digital separation of chorioamniotic membrane from wall of cervix and lower uterine segment
Results in local release of endogenous prostaglandins
Vertex should be well applied to cervix and os should be dilated to allow examining finger
Complications- membrane rupture, haemorrhage from disruption of occult placenta praevia, chorioamnionitis

35. Transcervical Foley’s catheter
placed through cervical os inflated with 30-50cc saline
Downward tension that is created by taping the catheter to the thigh can lead to cervical ripening
The catheter is left in place until it spontaneously falls out or upto 24 hours
Intracervical foley’s catheter can be combined with oxytocin or vaginal misoprostol or they can be started hours after insertion.
Preferred in woman where prostaglandins are contraindicated.
Cotraindication-low lying placenta,APH, rupture of membrane, cervicitis

36. Factors that increase success of labour induction
Favourable cervix
Multiparity
Bodymass index<30
Birthweight<3500gm