A 27-year-old primigravid with a history of opioid use disorder, on buprenorphine, presented to the OB suite in active labor. She underwent an emergent cesarean section under a spinal anesthetic due to persistent late decelerations. Her operative course was uneventful. Postoperatively, she complains of unrelenting pain around the incision site.
Opioid use disorder is defined as a chronic disease characterized by tolerance, craving, inability to control use, and continued use despite adverse consequences. This condition results in significant impairment and disability in daily activities at home and at work (asamonitor.pub/3ywlSdb). Opioid use in pregnancy poses a paramount public health concern for the pregnant patient and the fetus. There has been an escalation in opioid use in pregnancy, paralleling the increase seen in the nonpregnant population during the opioid epidemic.
According to the Centers for Disease Control and Prevention, the national prevalence of opioid use disorder in the years 1999-2014 increased 333%, from 1.5 cases per 1,000 delivery hospitalizations to 6.5 (MMWR Morb Mortal Wkly Rep 2018;67:845-9). Actual increases in prevalence or improved screening and diagnosis may explain increasing trends (MMWR Morb Mortal Wkly Rep 2018;67:845-9). In a review of over 57 million American women admitted for obstetric delivery in the National (Nationwide) Inpatient Sample, the prevalence of opioid abuse and dependence more than doubled between 1998 and 2011 (Anesthesiology 2014;121:1158-65).
Chronic conditions such as back, pelvic, and leg pains, headaches, and many others can co-exist with pregnancy. More than one-fifth of pregnant women have used opioids routinely for chronic pain management (Tech Reg Anesth Pain Manag 2014;18:166-71). Anesthesiologists should be aware of the potential for pain control difficulties in these subsets of patients and the potential for drug withdrawal. Opioid tolerance is common, and patients may need increased doses of opioids, necessitating close monitoring for respiratory depression.
Taking care of this diverse patient population requires comprehensive obstetric care. Various screening tools for substance abuse can be utilized during the prenatal visit to help detect substance use and misuse (Obstet Gynecol 2017;130:e81-94).
Appropriate opioid prescribing is important to provide compassionate care to these patients, especially after delivery, which should not be a reason to abstain from treatment due to concerns of opioid misuse. It is necessary to implement strategies to avoid or minimize the chronic use of opioids by highlighting the importance of nonpharmacologic, multimodal, and nonopioid treatments.
Opioid abuse or dependence during pregnancy markedly increases the odds of major obstetric morbidity and mortality (Anesthesiology 2014;121:1158-65). Opioids can cross the placenta as well as the infant blood-brain barrier, potentially increasing fetal risks such as congenital malformations and cardiac, neural tube, and abdominal wall defects (Eur J Clin Pharmacol 2011;67:1253-61; PLoS One 2019;14:e0219061; Obstet Gynecol 2013;122:838-44).
One of the most common outcomes initially described among infants exposed to maternal heroin use is neonatal abstinence syndrome (NAS), defined as a postnatal opioid withdrawal syndrome that presents with a wide spectrum of clinical signs, from feeding issues, irritability, hypertonia, and tremors, to seizures and respiratory distress. This syndrome has increased threefold from the year 2000 to 2009 (J Perinatol 2015;35:650-5). In 2009, Patrick et al. reported that one infant born per hour has NAS, accounting for an estimated $720 million in hospital charges (JAMA 2012;307:1934-40). It is vital to collaborate with pediatricians to care for these infants since NAS can be expected following exposure to opioid agonists.
The usual opioid agonist therapy is seen with buprenorphine or methadone. Methadone is a full agonist with high intrinsic activity at mu-opioid receptors, whereas buprenorphine is a high-affinity partial agonist with low intrinsic activity (JAMA 2012;307:1934-40). There are differences between the use of methadone and buprenorphine for opioid use disorder. Methadone is administered daily, and most pregnant women are placed in an outpatient treatment program. Dose adjustment may be necessary as pharmacokinetic and physiologic changes happen during pregnancy, especially in the third trimester (Obstet Gynecol 2017;130:e81-94). Methadone significantly interacts with several medications that can prolong QTc, which may lead to arrhythmia. Buprenorphine, on the other hand, can be administered by any licensed provider in an office-based setting. In contrast to methadone, buprenorphine has fewer drug interactions, less need for dosage adjustment throughout pregnancy, and less severe neonatal abstinence syndrome.
In a cohort study done by Suarez et al., they concluded that the use of buprenorphine in pregnancy was associated with a lower risk of adverse neonatal outcomes than methadone use; however, the risk of adverse maternal outcomes was similar among those who received buprenorphine and those who received methadone (N Engl J Med 2022;387:2033-44). Patients who are not treated appropriately may experience more adverse outcomes, such as withdrawal symptoms, overdose, higher relapse rate, inadequate prenatal care, and unfavorable neonatal outcomes.
When presented with a parturient on buprenorphine (or methadone), such as in our case above, it is important to continue these medications during labor, keeping in mind that these medications cannot be the sole anesthetic. Regional anesthesia and multimodal analgesics play an important role. Epidural and spinal anesthesia are still the mainstays for anesthesia in this case, unless otherwise contraindicated. The dose of opioids should be monitored to avoid unwanted side effects. Other adjuncts like peripheral nerve blocks can be useful as well.
Postpartum women receiving either methadone or buprenorphine for opioid use disorders should be encouraged to breastfeed, unless specifically contraindicated (e.g., maternal human immunodeficiency virus-positive) (N Engl J Med 2022;387:2033-44; J Addict Med 2017;11:178-90). Studies have shown that methadone and buprenorphine are safe for breastfeeding (Can Fam Physician 2008;54:1689-90; Br J Clin Pharmacol 1997;44:543-7; Addiction 2012;107:5-27).
Opioid use disorder in pregnancy is prevalent in women across all racial and ethnic groups and socioeconomic strata. It requires a multidisciplinary team approach to not only provide medical help but also counseling and social support on a long-term basis. An active role needs to be maintained by physicians, mental health professionals, social workers, and family members, as well as neonatology staff, to ensure optimal patient care.