1) Cervical ripening is used to induce labor when the cervix is unfavorable (Bishop score <6) and involves using agents like prostaglandins, misoprostol, or mechanical methods to soften and dilate the cervix. 2) Oxytocin is commonly used for labor induction when the cervix is favorable but careful monitoring is needed due to risks of uterine tachysystole and changes in the fetal heart rate. 3) While prostaglandins are more effective cervical ripening agents compared to oxytocin alone, all methods have risks and more research is still needed to evaluate some traditional induction methods.

1. CERVICAL RIPENING
AND LABOUR
INDUCTION
FAHAD ZAKWAN

3. INDICATIONS FOR INDUCTION OF
LABOUR
•Not absolute: consider mom & baby’s health,
gestational age, cervix….
Ex indications:
• chorioamnionitis,
• fetal demise,
• gestational HTN,
• PROM,
• post term
• preeclampsia/eclampsia…

4. Fetal:
•oligohydramnios,
•severe IUGR,
•Isoimmunization
Logistic reasons:
•precipitous delivery,
•distance to hospital,
•psychosocial reasons

5. RISK OF INDUCTION OF LABOUR
•Nulliparous with unfavorable cervix:
•2 fold increased risk of cesarean
delivery
•labor progression differs significantly

6. CERVICAL STATUS
• Bishop score: an attempt to quantify how likely the
cervix is to respond to induction efforts

7. Bishop Score
What’s most important in score?
• Dilatation >effacement>station
• Unfavorable: score <6
• Ripening agent indicated
• Favorable: score >8
• Can induce
• Probability of vaginal delivery with spontaneous labor equals
probability of vaginal delivery with IOL

8. Cervical Remodeling:
What has to happen to get labor to start?
• Proteins associated with contractions are expressed:
• actin-myosin interactions
• myometrial cells excited
• intercellular connectivity allowing synchronous contractions
• myofibrils transmit electrical activity to other myocytes
• prostaglandins released & depolarize neighboring cells
• leads to wave of activity, lasting 1 min
• refractory period follows

9. Cervical Remodeling:
What has to happen to get labor to start?
Fetal Membrane Activation
• Amnion produces:
• Inflammatory mediators- cytokines
• Prostaglandin E2
• COX-2
Prostaglandins mediate release of metalloproteases
• Weaken placental membranes

10. Cervical Remodeling:
What has to happen to get labor to start?
Cervical Softening:
Inflammatory infiltrate moves into cervix
1. Release metalloproteases
degrade collagen – change cervical structure
2. Breakdown of junction between fetal membranes
occurs
fetal fibronectin (adhesive protein) present in vaginal
fluids

11. “Intravenous oxytocin alone for cervical
ripening and induction of labor”
• Oxytocin is less effective than prostaglandin to help bring on labor but
is as effective when used alone in women with ruptured membranes
• Oxytocin is the most common drug used to induce labor and has been
used either alone or with rupturing the membranes.
• A review of trials found that using PGE2, inserted either via the vagina
or cervix, rather than oxytocin was probably more effective.
• However, oxytocin alone compared to PGE2 used either way, in women
with ruptured membranes, showed that all three methods are probably
equally effective. More research is needed.

12. “Sexual intercourse for cervical ripening and
induction of labor”
• The role of sexual intercourse as a method for
induction of labor is uncertain.
• Human sperm contains a high amount of
prostaglandin, a hormone-like substance which ripens
the cervix and helps labor to start.
• nipple stimulation - >oxytocin
• lower uterine segment stimulated contractions occur
w. orgasm

13. “Breast stimulation for cervical ripening and
induction of labor”
• Breast stimulation appears beneficial in relation to the number of
women not in labor after 72 hours, and reduced postpartum
hemorrhage rates.
• Breast stimulation causes the womb to contract, though the
mechanism remains unclear.
• It may increase levels of the hormone oxytocin, which stimulates
contractions. It is a non-medical method allowing the woman greater
control over the process of attempting to induce labor.
• The review found insufficient research to evaluate the safety of breast
stimulation in a high-risk population and until safety issues have been
fully evaluated.

14. “Castor oil, bath and/or enema for cervical
priming and induction of labor”
• More research is needed into the effects of castor oil to induce labor.
• Castor oil has been widely used as a traditional method of inducing
labor in midwifery practice. It can be taken by mouth or as an enema.
• The review of trials found there has not been enough research done to
show the effects of castor oil on ripening the cervix or inducing labor or
compare it to other methods of induction.
• The review found that all women who took castor oil by mouth felt
nauseous. More research is needed “
• Evening primrose oil: unclear whether ripens or induces labor (also
commonly used amongst midwives)

15. “Acupuncture for induction of labor”
• “There is insufficient evidence describing the efficacy of
acupuncture to induce labor.
• Acupuncture is the insertion of fine needles into specific
energy points of the body and has been used to help induce
labor and reduce labor pains.
• The review included three trials involving 212 women. The
evidence regarding the clinical effectiveness of this
technique is limited, although small studies suggest women
receiving acupuncture compared to standard obstetric care
received fewer methods of induction.

16. Mechanical Options for Cervical Ripening
1. Foley: insert no 18 foley catheter w. 30 mL balloon
past internal os, inflate balloon and place traction
on catheter (tape to thigh)
• Outpatient or inpatient option
• dilation>effacement>station
2. Laminaria: hydrophilic seaweed that absorbs water
like sponge & slowly dilates cervix, doesn’t change
consistency or effacement

17. 3. Stripping membranes: commonly used &
thought to be helpful in inducing labor. Freeing
chorionic membrane from decidua of lower
uterine segment
• Increased PROM

18. “Amniotomy alone for induction of labor”
• There is not enough evidence about the effects of amniotomy alone
(deliberate rupture of the membranes) to induce labor.
• Amniotomy has been used as either the only method of inducing
labour if the membranes can be reached, or used with drugs such as
oxytocin or prostaglandin.
• Amniotomy may be preferred by women wanting a drug-free labor
and it is cheap.
• However, it can be uncomfortable and, if after amniotomy there is a
long time interval before the baby is born, there is a risk of infection.
There is also the risk of the cord coming out before the baby.
• This review of trials found that there is not enough evidence about
the effects of amniotomy alone for the induction of labor “

19. Amniotomy
• helpful if labor stalls
• less effective with oligohydramnios
Considerations before amniotomy:
• FHR tracing before & after amniotomy
• Fetal head well applied?
• Palpate for cord? Vasa previa?
• HIV?
• Clock starts ticking…. ABX prophylaxis

20. “Induction of labor for improving birth outcomes
for women at or beyond term”
• A policy of labor induction at 41 completed weeks or beyond was
associated with fewer (all-cause) perinatal deaths
• There was no evidence of a statistically significant difference in the risk
of caesarean section for women induced at 41 and 42 completed weeks
respectively.
• Women induced at 37 to 40 completed weeks were more likely to have
a caesarean section with expectant management than those in the
labor induction group
• A policy of labor induction after 41 completed weeks or later compared
to awaiting spontaneous labor either indefinitely or at least one week is
associated with fewer perinatal deaths. However, the absolute risk is
extremely small.

21. Cervical ripening, why?
Bishop score 6 or higher predicts
successful induction and vaginal
delivery, if not at >=6, then cervical
ripening indicated for achieving
dilation

22. Foley catheter:
• Foley catheter - balloon inflated past
cervical os
• Foley catheter has been used to ripen
cervix to inducible Bishop's scores,
• 97% effective in study of 88 patients
with minimal complication

24. Vaginal misoprostol
• In doses above 25 mcg four-hourly was more effective than
conventional methods of labor induction,
• More uterine hyperstimulation.
• The studies reviewed were not large enough to exclude the
possibility of rare but serious adverse events,
• Rare uterine rupture has been reported anecdotally
following misoprostol induction, in women with uterine
scarring.

25. “Intracervical prostaglandins for
induction of labor”
Prostaglandins inserted into the cervix
are effective in starting labor, but are
inferior to vaginal administration.

26. Ripening Agents
(Bishop < 8)
Options:
1. Dinoprostone (PGE2)
– Gel or insert
2. Misoprostol (PGE1)
3. Mechanical options
– Foley bulb
– Laminaria
– Membrane stripping
4. Alternatives

27. Labor Induction
Oxytocin: low & high dose regimens safe
• Preferred for IOL when cervix favorable
Low: less tachysystole w. concerning FHR
High: shorter labor, less chorioamnionitis, less C-section for
dystocia but more tachysystole/concerning FHR
• Numeric value not established for max pitocin dose
• Continuous monitoring necessary

28. Pitocin Induction

29. Management of complications associated
with oxytocin
Uterine tachysystole & FHR with persistent decels, minimal-
absent variability, fetal tachycardia….
• Stop or decrease pitocin
• Change position: side lying or hands-knees
• Oxygen
• IVF bolus
• Terbutaline sc

30. Labor Induction
Nipple stimulation: release oxytocin
PROM at term:
• Expectant Management: higher rates of chorio & less need for
neonatal ABX treatment
• No difference in oxytocin vs PGE2: with IOL, no increase in c
section rates (ACOG)
• Misoprostol 25 mcg q 6 hrs x 2 doses vs pitocin: delivery time
shown to be the same (Wing 2006)