labor%20induction
LABOR INDUCTION
Labor induction is when an external agent is employed to stimulate contractions before the onset of spontaneous labor.
Labor augmentation uses the same techniques as labor induction but uterine contractions (frequency, duration and strength) are enhanced once labor has started.
Labor induction is generally indicated when the benefits of delivery outweigh the risks of continuing the pregnancy.
Women at 42 weeks of gestation who chose not to undergo labor induction should be monitored more often with at least twice-weekly assessment of fetal well-being (cardiotocography & estimation of maximum amniotic pool depth by ultrasound).

Pharmacotherapy

Prostaglandin

Prostaglandin E2 (PGE2) [eg Dinoprostone]

  • Effective agent for ripening of cervix and labor induction if cervix is unfavorable
  • May be used as a ripening agent or for induction with premature rupture of membranes (PROM) at term except in patients with lower segment cesarean section (CS) scar due to increased risk of uterine rupture
    • Prostaglandin E2 (PGE2) may be preferred for labor induction in nulliparous or multiparous women with intact membranes regardless of cervical favorability
  • Causes disintegration of collagen bundles and increase in submucosal water content of the cervix, like those observed in early labor
  • Associated with increase in successful vaginal delivery within 24 hr and decrease in both CS rate and risk of cervix remaining unfavorable at 24-48 hr
  • Efficacy is equivalent to Oxytocin for labor induction in nulliparous or multiparous women with ruptured membranes regardless of cervical status
  • May be given in various routes but local administration in the vagina is the route of choice due to fewer side effects and acceptable clinical response
    • Intravaginal PGE2 is the preferred method of labor induction except in those at risk of uterine tachysystole
    • Recommended regimen is one cycle of vaginal PGE2 (tab or gel): One dose followed by a 2nd dose if labor does not ensue (if controlled pessary is used, one dose over 24 hr)

Misoprostol

  • A synthetic Prostaglandin E1 analog that can cause cervical ripening of an unfavorable cervix and induce uterine contractions
    • Can be used directly for induction of labor with a favorable cervix
  • Oral or vaginal route is recommended for induction of labor in women with non-scarred uterus
    • Considered an effective and safe drug for labor induction in patients with intact membranes
    • Contraindicated in women with previous cesarean section
  • Also used to induce labor in women with intrauterine fetal death (IUFD)
    • Same dose and regimen as for induction of labor at term is recommended
  • A tocolytic agent, ie terbutaline, must be available during labor induction
  • Uterine tachysystole can occur with all Misoprostol doses

Oxytocin

  • Mother and fetus should be carefully monitored and drug infusion accurately titrated
  • Intravenous (IV) Oxytocin has been widely used for induction and augmentation of labor
    • It induces uterine activity that is sufficient to produce cervical change and fetal descent while avoiding uterine tachysystole
    • If prostaglandins are unavailable, IV Oxytocin with or without a balloon catheter is appropriate
  • Use of Oxytocin has not been shown to be effective in ripening the cervix but is the preferred pharmacologic agent for inducing labor when the cervix is favorable or ripe
  • Decision to augment labor using Oxytocin is based upon clinical judgment with consideration to fetal size, presentation, position, pelvic size, and fetal condition
    • Dose should be titrated to prevent excessive uterine activity and to give 4-5 uterine contractions in 10 min
  • Amniotomy should be done when feasible prior to the start of Oxytocin infusion in women with intact membranes
    • Oxytocin should be considered prior expectant management in patients with ruptured membranes at term

Antiprogestogen

  • Oral Mifepristone is given to induce labor in women with IUFD, followed by vaginal PGEor Misoprostol
    • Patients that appear physically well and with membranes that are intact or with no signs of infection or bleeding should be given an option of immediate labor induction or expectant management
    • Patients with ruptured membranes or signs of infection or bleeding should undergo immediate labor induction

Mechanical Methods

  • Promote cervical ripening and/or labor induction through mechanical pressure and release of endogenous prostaglandins from the membranes and maternal decidua
  • Proposed advantages include potential reversibility, simplicity of use, low cost, and decrease in side effects [eg excessive uterine activity and risk of uterine rupture in a previous cesarean section (CS) patient]
  • Disadvantages include the risk of infection, some maternal discomfort on manipulation of the cervix and disruption of a low-lying placenta

Membrane Sweeping

  • Women should be offered a vaginal examination for membrane sweeping before labor induction
  • Membrane sweeping separates the chorioamniotic membrane from the lower uterine segment
  • Membrane sweep can be performed with the examining finger during vaginal exam
    • Place the finger through the internal os and sweep in a circumferential motion separating the amniotic membrane from the lower uterine segment
  • Action: Postulated to trigger onset of labor by increasing the local Prostaglandin F2-α production and releasing it from the decidua and adjacent membranes
  • Sweeping the membranes prevents labor induction as it increases the chance of spontaneous labor within 48 hours and birth within 1 week
  • Membrane sweeping at term can reduce the duration of pregnancy and rate of postterm pregnancy
  • Technique is not associated with increased infection or major maternal side effects, but patient may experience some discomfort during the procedure

Amniotomy

  • Also called artificial rupture of membranes
  • It is the deliberate perforation of the chorioamniotic membranes performed in multiparous women with favorable cervix during labor induction
    • Oxytocin should be given early after amniotomy to establish labor (amniotomy alone should not be used for labor induction)
    • Amniotomy and Oxytocin should be considered once dystocia is diagnosed in either the 1st or 2nd stage of labor 
  • Cord prolapse is a risk in the unengaged presentation
  • Should not be used as a primary method of labor induction except in cases where PGE2 cannot be employed (eg risk of uterine hyperstimulation)

Balloon Devices

  • Inflated bulb of a Foley catheter exerts pressure to the internal os of the cervix which then stretches the lower uterine segment and stimulates release of prostaglandin (PG)
    • An option for cervical ripening or induction in an unfavorable cervix
  • Safe to perform in vaginal delivery after CS
  • Foley catheter causes less uterine tachysystole and is not related to increased rates of maternal or neonatal infection
  • Contraindicated in patients with low-lying placenta
Digital Edition
Asia's trusted medical magazine for healthcare professionals. Get your MIMS JPOG - Malaysia digital copy today!
DOWNLOAD
Editor's Recommendations
Most Read Articles
14 Oct 2017
In pregnant women, adherence to recommended dietary intake of fat and fibre is associated with a more beneficial and richer gut microbiota which, in turn, decreases levels of the inflammation marker glycoprotein acetylation (GlycA), a study has shown.
16 Oct 2017
Elagolix is safe and effective for reducing heavy menstrual bleeding in females with fibroids, a new dose-ranging, multiple-cohort study has shown.
13 Oct 2017
Dr Joon Kiong Lee discusses pharmacotherapy for osteoporosis and the role of FLS in fracture prevention
Tristan Manalac, 06 Oct 2017
In women with polycystic ovary syndrome (PCOS), combined oral contraceptive (COC) with spironolactone is more effective than metformin in reducing symptoms while showing a similar safety profile, according to a new randomized clinical trial (RCT).