For women undergoing induction of labor, do mechanical methods versus pharmacologic methods reduce the risk of a cesarean delivery?
For women undergoing induction of labor, do mechanical methods versus pharmacologic methods reduce the risk of a cesarean delivery?
The Association of Women’s Health, Obstetric and Neonatal Nurses (AWHONN) maintains that labor is a complex physiologic event involving the intricate interaction of multiple hormones that should not be initiated or altered without a medical indication. Reserving induction and augmentation of labor for pregnant women with medical indications promotes the best health outcomes for women and infants and is the best use of health care resources.
Women can make fully informed decisions about induction and augmentation of labor only when they understand the medical indications for induction or augmentation; potential harms or benefits associated with the pharmacologic and/or mechanical methods used to induce or augment labor; alternatives to induction or augmentation; and the benefits of waiting for and permitting labor to progress spontaneously.
Administering exogenous hormones and performing mechanical interventions to a vulnerable population (pregnant women and their fetuses) is not advisable unless the benefits of these interventions have been shown to outweigh the risks.
Induction of labor is the use of pharmacologic and/or mechanical methods to initiate uterine contractions before spontaneous labor occurs in order to affect vaginal birth (American College of Obstetricians and Gynecologists [ACOG], 2009).
Common methods of inducing labor are artificial rupture of membranes, administration of oxytocin (a high-alert medication), and use of cervical ripening agents. Augmentation of labor is the stimulation of uterine contractions using pharmacologic methods or artificial rupture of membranes to increase contraction strength and/or frequency following the onset of spontaneous labor.
Decisions about the need for medically-indicated induction or augmentation are made by weighing the benefits of expeditious birth against the risks of continuing the pregnancy and the risks of the pharmacologic and/or mechanical methods of inducing or augmenting labor.
Medical indications for induction can be related to the health of the mother, the fetus, or both. They include but are not limited to preeclampsia, gestational hypertension, premature rupture of membranes, and post-term pregnancy.
A woman with ruptured membranes who has been in labor and begins to show signs of infection has a medical indication for augmentation of labor. Labor induction performed for non-medical indications, often termed elective induction, may be requested for the convenience of women, families, or health care providers.
Spontaneous labor occurs when contractions begin and progress on their own without the use of pharmacologic or mechanical intervention. Spontaneous labor is a powerful physiologic process with significant benefits for the woman and her infant.
In the final weeks of pregnancy, fetal organs reach full maturity, and the passage of immune globulins across the placenta peaks. Naturally occurring hormones prepare the woman and her fetus for labor and birth.
These hormones make labor more efficient, with less stress for the fetus, than induced labor.
Health Effects Associated with Induction and Augmentation
The rate of induction in the United States (23.4% of all births) has more than doubled since 1990 (Martin et al., 2012). The rate of induction is calculated as a percentage of all births. However, many births occur as a result of planned, cesarean surgery during which neither spontaneous labor nor induction occurs. If the rate of induction was recalculated without including planned cesarean births, the percentage would be much higher.
Although limited data are available to distinguish between inductions performed for medical reasons versus those performed for nonmedical reasons, no data suggest that the significant increase in the induction rate is attributable to a similar rise in medical conditions in pregnancy (Moore & Kane Low, 2012). There are no good data sources on the number of women whose labor is augmented.