Drug Therapy During Labor and Delivery, Part 1

Abstract and Introduction

Abstract

Purpose: The drug therapy of common conditions and complications during labor and delivery and the fetal and neonatal effects of this therapy are examined.
Summary: The pharmacologic therapy of common conditions that occur in labor and delivery primarily involves oxytocin and prostaglandins for cervical ripening and labor induction and systemic and regional narcotic analgesics for pain. Because most medications used in women during labor and delivery do not have Food and Drug Administration-approved labeling, pharmacists should understand the benefits and limitations of medications used in the mother. Although induction and augmentation of labor and the control of pain often require drug therapy, other, less frequent, complications may occur in labor. Drug therapies for these complications include anti-infective agents to treat maternal infection and prevent neonatal diseases; antiretrovirals to reduce perinatal HIV-1 transmission from the mother to the fetus; corticosteroids to prevent fetal lung immaturity; antihypertensives to treat preeclampsia; anticonvulsants to treat eclampsia; antibiotics to prolong pregnancy and improve neonatal outcomes after premature rupture of the membranes; tocolytics for premature labor; and oxytocin, ergot alkaloids, and prostaglandin analogues for postpartum hemorrhage. The fetal and neonatal effects of therapy for the conditions that occur during labor and delivery are usually benign, but significant morbidity and mortality involving the mother, the fetus, and the newborn are ever-present risks.
Conclusion: Awareness of the conditions and complications requiring drug therapy during labor and delivery will allow hospital pharmacists to make knowledgeable decisions about the rapid accessibility of critical medications in the labor and delivery unit.

Introduction

In an uncomplicated pregnancy, drug use during labor and delivery involves primarily oxytocin and narcotic analgesics. Oxytocin is a uterotonic agent, and it induces or augments labor. Pain is a frequent occurrence that requires drug therapy at or near term. Less frequently encountered pregnancy conditions and complications requiring drug treatment include infections or infection prophylaxis, fetal lung immaturity, preeclampsia and eclampsia, cervical ripening and labor induction, preterm labor and delivery, and postpartum hemorrhage (PPH). Medications routinely used in a labor-delivery unit are a small fraction of those used in some other patient care areas of a hospital, such as the intensive care or general medical units. However, a unique characteristic of drug therapy during labor is that treatment is intended for one patient (mother or fetus) but a second patient is always exposed (mother or fetus). Maternal status is usually the primary focus of drug administration, but it must also focus on the fetus and the risk of developmental toxicity.

The components of developmental toxicity are fetal growth restriction, structural defects, functional and behavioral deficits, and embryonic or fetal death.^[1] Neither growth restriction nor structural defects are a concern with drug therapy used during labor and delivery because these toxicities occur after prolonged therapy or exposure earlier in pregnancy, respectively. In contrast, fetal functional or behavioral deficits and death are of great concern when treating a patient in labor.

Examples of functional or behavioral deficits include blood dyscrasia, renal impairment, premature closure of the ductus arteriosus, respiratory depression, lethargy, irritability, and depressed attention and social responsiveness. Fetal death may occur if placental perfusion is jeopardized, such as in drug-induced maternal hypotension.

This review summarizes the drug therapy of common conditions and complications during labor and delivery and examines the fetal and neonatal effects of this therapy. Most of the medications used in the woman during labor do not have Food and Drug Administration (FDA)-approved labeling for these indications. Therefore, pharmacists providing drugs and services to these patients should understand their benefits and limitations. Because of space limitations, we frequently refer to publications from the American College of Obstetricians and Gynecologists (ACOG), such as the Educational Bulletin and Committee Opinion. These peer-reviewed sources have extensively evaluated the pathophysiology and treatment of many common complications and conditions in obstetric and gynecologic patients. Those looking for more in-depth discussions on a particular topic should refer to these publications.

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