Labor induction is when mechanical or pharmacological methods are used to induce labor. It’s typically done when either mom, baby or both are at risk, and these risks would be alleviated by the birth of the child. It can be elective, but today we’re talking about labor induced as a way to prevent harm to either individual. We’ll talk about some indications for inducing labor further on.

Method #1: Cervical Ripening for Labor Induction

Cervical ripening is done to help the cervix soften so it will dilate effectively for labor. This can be done mechanically or pharmacologically, and the decision to perform ripening is based off the patient’s Bishop score. This is a standardized method for evaluating the cervix and a Bishop score less than eight typically warrants cervical ripening.

The most common method is to utilize a prostaglandin such as misoprostol (Cytotec) which can be taken PO, sublingually or inserted vaginally…or dinoprostone (brand name Cervidil or Prepidil), which is a topical medication in the form of a tampon-like device that can be easily inserted and removed.

These medications are not to be taken lightly. They come with significant potential adverse effects such as miscarriage and uterine rupture. For this reason, they are typically not given to anyone who has had a prior cesarean section or uterine surgery of any kind. They are also avoided in multiparity above 5 or 6 pregnancies carried to term, those with cephalopelvic disproportion, placenta previa, vasa previa, fetal distress, traumatic or difficult labor, unexplained vaginal bleeding, ruptured membranes, active genital herpes, hyperactive or hypertonic uterus, and concurrent oxytocin use…if using an insert you’d want to remove it at least 30 minutes prior to administering oxytocin.

There are also devices that can dilate the cervix such as a Foley catheter with the inflatable balloon placed at the internal os, or a Cook catheter that has two balloons – one places pressure on the internal os and one exerts pressure on the external os.

Laminaria dilators are made from highly absorbent seaweed and designed to be inserted into the cervix. The laminaria takes in surrounding moisture to gradually increase in size, which causes the cervix to dilate.

Method #2: Membrane Sweeping

Membrane sweeping (may also see “stripping of membranes”) is a mechanical method of labor induction. It is a process by which the MD or nurse midwife sweeps a finger over the membranes that connect the amniotic sac to the uterine wall. This can cause a release of prostaglandins and other hormones which leads to cervical ripening and contractions.

A Cochrane review conducted in 2020 looked at the effectiveness of membrane sweeping for inducing spontaneous labor and concluded that individuals who underwent membrane sweeping were more likely to go into labor without the need for further medical intervention.

There is, however, a bit of controversy around membrane sweeping in that some providers view it as a routine part of the exam while it is technically a medical procedure that should require informed consent. If you’re interested in diving deeper into this topic, I invite you to check out the Evidence-Based Birth podcast by Dr. Rebecca Dekker.

Method #3: Amniotomy

An amniotomy may be performed when the cervix is ready and baby is in the head-down and engaged position. To perform an amniotomy, the MD uses a small device to create a hole in the amniotic sac and most patients will go into labor within a few hours. Note that an amniotomy can make contractions stronger if labor has already begun, so pain management could definitely be a challenge. You will see this abbreviated as AROM – artificial rupture of membranes.

An amniotomy can be advantageous over medicinal induction in that there is less risk of hypertonic or ruptured uterus, it doesn’t require intense monitoring like an oxytocin infusion would, and it gives you an opportunity to evaluate the amniotic fluid.

Some disadvantages, especially when done too early in labor, are:

  • increased risk of infection including neonatal sepsis
  • increased risk for cord prolapse due to baby’s head not being fully engaged
  • increased risk of chorioamnionitis
  • increased risk of variable decels
  • if vasa previa is present and undiagnosed, it could cause significant bleeding.

Additionally, a 2013 Cochrane review of the literature evaluated the effect of amniotomy on the labor of more than 5,500 women. It showed no shortening of the first stage of labor and increases in cesarean section procedures. As such, the FPQC (Florida Perinatal Quality Collaborative) recommends reducing the use of amniotomy and increasing the use of cervical ripening methods instead.

Method #4: Oxytocin Infusion for Labor Induction

When we think of labor induction, we often think of oxytocin (Pitocin) which is a hormone that occurs naturally in the body to cause the uterus to contract. The MD may order an oxytocin infusion to initiate or speed up labor, and it generally takes effect in thirty minutes or less.

Note that the contractions with oxytocin can be intense and there’s not the normal ramping up period that occurs with spontaneous labor, so the laboring individual can get hit hard with intense contractions right from the start. Your textbooks may say that all patients with oxytocin infusion will have an epidural for this reason. In the real world, pain management is decided on a case-by-case basis as everyone labors differently. We’ll talk about pain management in another article.

Indications for Labor Induction

There are many indications for inducing labor, which take into account the patient’s medical and obstetrical history. Obstetrical factors include:

  • Placental abnormalities
  • Intrauterine growth restriction
  • PROM – premature rupture of membranes
  • Oligohydramnios
  • Polyhydramnios
  • Alloimmunization
  • Post-term gestation

Medical factors for labor induction can include:

  • Hypertension (pre-eclampsia/eclampsia)
  • Diabetes (both pregestational and gestational diabetes)
  • Chronic renal disease
  • Cardiovascular disease

Interested in L&D nursing? Check out episode 134 of the Straight A Nursing podcast. In this episode, I talk with Hannah, a nurse who forged a path to her dream job in one of the most respected L&D services in northern California.

 

REFERENCES:

American College of Obstetricians and Gynecologists. (2018, June). Labor induction. ACOG. https://www.acog.org/en/womens-health/faqs/labor-induction

Drugs.com. (2021, January 19). Laminaria. Drugs.Com. https://www.drugs.com/npp/laminaria.html

FPQC. (2020). FPQC Guidance for the Promoting Primary Vaginal Deliveries (PROVIDE) Initiative: Early Amniotomy—Helpful or Harmful?? https://health.usf.edu/-/media/Files/Public-Health/Chiles-Center/FPQC/PROVIDE-FPQCEarlyAROMStatement-2020.ashx?la=en&hash=8AC21C1FAE32ED0250056A5CD05625CD6F477C81

Gill, P., Lende, M. N., & Van Hook, J. W. (2021). Induction of labor. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK459264/

Smyth RMD, Markham, C., & Dowswell, T. (2013, June 18). Amniotomy for shortening spontaneous labour. Cochrane. https://doi.org/10.1002/14651858.CD006167.pub4