Impact of treatment approach on maternal and neonatal outcome in pregnant opioid-maintained women

Investigating the neurobiology of maternal opioid use disorder and prenatal opioid exposure using brain organoid technology

Over the past two decades, Opioid Use Disorder (OUD) among pregnant women has become a major global public health concern. OUD has been characterized as a problematic pattern of opioid use despite adverse physical, psychological, behavioral, and or social consequences. Due to the relapsing-remitting nature of this disorder, pregnant mothers are chronically exposed to exogenous opioids, resulting in adverse neurological and neuropsychiatric outcomes. Collateral fetal exposure to opioids also precipitates severe neurodevelopmental and neurocognitive sequelae. At present, much of what is known regarding the neurobiological consequences of OUD and prenatal opioid exposure (POE) has been derived from preclinical studies in animal models and postnatal or postmortem investigations in humans. However, species-specific differences in brain development, variations in subject age/health/background, and disparities in sample collection or storage have complicated the interpretation of findings produced by these explorations. The ethical or logistical inaccessibility of human fetal brain tissue has also limited direct examinations of prenatal drug effects. To circumvent these confounding factors, recent groups have begun employing induced pluripotent stem cell (iPSC)-derived brain organoid technology, which provides access to key aspects of cellular and molecular brain development, structure, and function in vitro. In this review, we endeavor to encapsulate the advancements in brain organoid culture that have enabled scientists to model and dissect the neural underpinnings and effects of OUD and POE. We hope not only to emphasize the utility of brain organoids for investigating these conditions, but also to highlight opportunities for further technical and conceptual progress. Although the application of brain organoids to this critical field of research is still in its nascent stages, understanding the neurobiology of OUD and POE via this modality will provide critical insights for improving maternal and fetal outcomes.

Opioid, methamphetamine, and polysubstance use: perinatal outcomes for the mother and infant

The escalation in opioid pain relief (OPR) medications, heroin and fentanyl, has led to an increased use during pregnancy and a public health crisis. Methamphetamine use in women of childbearing age has now eclipsed the use of cocaine and other stimulants globally. Recent reports have shown increases in methamphetamine are selective to opioid use, particularly in rural regions in the US. This report compares the extent of our knowledge of the perinatal outcomes of OPRs, heroin, fentanyl, two long-acting substances used in the treatment of opioid use disorders (buprenorphine and methadone), and methamphetamine. The methodological limitations of the current research are examined, and two important initiatives that will address these limitations are reviewed. Current knowledge of the perinatal effects of short-acting opioids, OPRs, heroin, and fentanyl, is scarce. Most of what we know about the perinatal effects of opioids comes from research on the long-acting opioid agonist drugs used in the treatment of OUDs, methadone and buprenorphine. Both have better perinatal outcomes for the mother and newborn than heroin, but the uptake of these opioid substitution programs is poor (<50%). Current research on perinatal outcomes of methamphetamine is limited to retrospective epidemiological studies, chart reviews, one study from a treatment center in Hawaii, and the US and NZ cross-cultural infant Development, Environment And Lifestyle IDEAL studies. Characteristics of pregnant individuals in both opioid and MA studies were associated with poor maternal health, higher rates of mental illness, trauma, and poverty. Infant outcomes that differed between opioid and MA exposure included variations in neurobehavior at birth which could complicate the diagnosis and treatment of neonatal opioid withdrawal (NOWs). Given the complexity of OUDs in pregnant individuals and the increasing co-use of these opioids with MA, large studies are needed. These studies need to address the many confounders to perinatal outcomes and employ neurodevelopmental markers at birth that can help predict long-term neurodevelopmental outcomes. Two US initiatives that can provide critical research and treatment answers to this public health crisis are the US Environmental influences on Child Health Outcomes (ECHO) program and the Medication for Opioid Use Disorder During Pregnancy Network (MAT-LINK).

Comparative Safety Analysis of Opioid Agonist Treatment in Pregnant Women with Opioid Use Disorder: A Population-Based Study

INTRODUCTION AND OBJECTIVE

Receipt of opioid agonist treatment during early and late pregnancy for opioid use disorder may relate to varying perinatal risks. We aimed to assess the effect of time-varying prenatal exposure to opioid agonist treatment using buprenorphine or methadone on adverse neonatal and pregnancy outcomes.

METHODS

We conducted a retrospective cohort study of pregnant women with opioid use disorder using Rhode Island Medicaid claims data and vital statistics during 2008-16. Time-varying exposure was evaluated in early (0-20 weeks) and late (≥ 21 weeks) pregnancy. Marginal structural models with inverse probability of treatment weighting were applied.

RESULTS

Of 400 eligible pregnancies, 85 and 137 individuals received buprenorphine and methadone, respectively, during early pregnancy. Compared with 152 untreated pregnancies with opioid use disorders, methadone exposure in both periods was associated with an increased risk of preterm birth (adjusted odds ratio [aOR]: 2.52; 95% confidence interval [CI] 1.07-5.95), low birth weight (aOR: 2.99; 95% CI 1.34-6.66), neonatal intensive care unit admission (aOR, 5.04; 95% CI 2.49-10.21), neonatal abstinence syndrome (aOR: 11.36; 95% CI 5.65-22.82), respiratory symptoms (aOR, 2.71; 95% CI 1.17-6.24), and maternal hospital stay > 7 days (aOR, 14.51; 95% CI 7.23-29.12). Similar patterns emerged for buprenorphine regarding neonatal abstinence syndrome (aOR: 10.27; 95% CI 4.91-21.47) and extended maternal hospital stay (aOR: 3.84; 95% CI 1.83-8.07). However, differences were found favoring the use of buprenorphine for preterm birth versus untreated pregnancies (aOR: 0.17; 95% CI 0.04-0.77), and for several outcomes versus methadone.

CONCLUSIONS

Methadone and buprenorphine prescribed for the treatment of opioid use disorder during pregnancy are associated with varying perinatal risks. However, buprenorphine may be preferred in the setting of pregnancy opioid agonist treatment. Further research is necessary to confirm our findings and minimize residual confounding.

Prediction model for nonopiate-induced neonatal abstinence syndrome

BACKGROUND

Neonatal abstinence syndrome (NAS) induced by opiate use is common worldwide. Psychiatric drugs are a more common cause of NAS in Japan but infants of mothers taking psychiatric medications do not always develop NAS. The purpose of this study was to develop a practical model for predicting the onset of nonopiate-induced NAS, using variables available at birth.

METHODS

In this diagnostic study, prediction models were developed using multivariable logistic regression with retrospective data collected at our hospital between 2010 and 2019. The NAS diagnosis was based on the Isobe score, and maternal medications were converted to dose equivalents.

RESULTS

A total of 164 maternal and infant dyads met the inclusion criteria; 91 were included in the analysis, of whom 29 infants (32%) were diagnosed with NAS. Final models were created with and without the drug indices. The model without the drug indices consisted of neonatal head circumference in z-scores and Apgar scores at 5 min < 9, and the model with the drug indices included these, as well as antipsychotics and hypnotics indices. The C-statistics were 0.747 (95% CI: 0.638-0.856), and 0.795 (95% CI: 0.683-0.907), respectively, indicating that the models possessed good predictive accuracy for NAS onset.

CONCLUSIONS

This study developed models that predicted nonopiate-induced NAS accurately. They may be further improved through the use of drug indices.

Buprenorphine-naloxone, buprenorphine, and methadone throughout pregnancy in maternal opioid use disorder

INTRODUCTION

Current WHO guidelines recommend using methadone or buprenorphine as maintenance treatments for maternal opioid use disorder. However, buprenorphine-naloxone, with a lower abuse risk than buprenorphine monotherapy or methadone, offers a potentially beneficial alternative, but scientific evidence on its effects on pregnancies, fetuses, and newborns is scarce. This paper compares the outcomes of the pregnancies, deliveries, and newborns of women on buprenorphine-naloxone, buprenorphine, or methadone maintenance treatments. According to the hypothesis, as a maintenance treatment, buprenorphine-naloxone does not have more adverse effects than buprenorphine, whereas methadone is more complicated.

MATERIAL AND METHODS

In this population-based study, 172 pregnant women on medical-assisted treatments were followed-up at Helsinki University Women's Hospital (Finland). Women receiving the same opioid maintenance treatment from conception to delivery and their newborns were included. Consequently, 67 mother-child dyads met the final inclusion criteria. They were divided into three groups based on their opioid pharmacotherapy. The outcomes were compared among the groups and, where applicable, with the Finnish population.

RESULTS

The buprenorphine-naloxone and buprenorphine groups showed similar outcomes and did not significantly differ from each other in terms of maternal health during pregnancies, deliveries, or newborns. Illicit drug use during the pregnancy was common in all groups, but in the methadone group it was most common (p = 0.001). Most neonates (96%) were born full-term with good Apgar scores. They were of relatively small birth size, with those in the methadone group tending to be the smallest. Of the neonates 63% needed pharmacological treatment for neonatal opioid withdrawal syndrome. The need was lower in the buprenorphine-based groups than in the methadone group (p = 0.029).

CONCLUSIONS

Buprenorphine-naloxone seems to be as safe for pharmacotherapy for maternal opioid use disorder as buprenorphine monotherapy for both mother and newborn. Hence it could be a choice for oral opioid maintenance treatment during pregnancy, but larger studies are needed before changing the official recommendations. Women on methadone treatment carry multifactorial risks and require particularly cautious follow up. Furthermore, illicit drug use is common in all treatment groups and needs to be considered for all patients with opioid use disorder.

Non-pharmacological care for opioid withdrawal in newborns

BACKGROUND

The prevalence of substance use, both prescribed and non-prescribed, is increasing in many areas of the world. Substance use by women of childbearing age contributes to increasing rates of neonatal abstinence syndrome (NAS). Neonatal opioid withdrawal syndrome (NOWS) is a newer term describing the subset of NAS related to opioid exposure. Non-pharmacological care is the first-line treatment for substance withdrawal in newborns. Despite the widespread use of non-pharmacological care to mitigate symptoms of NAS, there is not an established definition of, and standard for, non-pharmacological care practices in this population. Evaluation of safety and efficacy of non-pharmacological practices could provide clear guidance for clinical practice.

OBJECTIVES

To evaluate the safety and efficacy of non-pharmacological treatment of infants at risk for, or having symptoms consistent with, opioid withdrawal on the length of hospitalization and use of pharmacological treatment for symptom management. Comparison 1: in infants at risk for, or having early symptoms consistent with, opioid withdrawal, does non-pharmacological treatment reduce the length of hospitalization and use of pharmacological treatment? Comparison 2: in infants receiving pharmacological treatment for symptoms consistent with opioid withdrawal, does concurrent non-pharmacological treatment reduce duration of pharmacological treatment, maximum and cumulative doses of opioid medication, and length of hospitalization?

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search CENTRAL (2019, Issue 10); Ovid MEDLINE; and CINAHL on 11 October 2019. We also searched clinical trials databases and the reference lists of retrieved articles for randomized controlled trials (RCTs), quasi-RCTs, and cluster trials.

SELECTION CRITERIA

We included trials comparing single or bundled non-pharmacological interventions to no non-pharmacological treatment or different single or bundled non-pharmacological interventions. We assessed non-pharmacological interventions independently and in combination based on sufficient similarity in population, intervention, and comparison groups studied. We categorized non-pharmacological interventions as: modifying environmental stimulation, feeding practices, and support of the mother-infant dyad. We presented non-randomized studies identified in the search process narratively.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We used the GRADE approach to assess the certainty of evidence. Primary outcomes in infants at risk for, or having early symptoms consistent with, opioid withdrawal included length of hospitalization and pharmacological treatment with one or more doses of opioid or sedative medication. Primary outcomes in infants receiving opioid treatment for symptoms consistent with opioid withdrawal included length of hospitalization, length of pharmacological treatment with opioid or sedative medication, and maximum and cumulative doses of opioid medication.

MAIN RESULTS

We identified six RCTs (353 infants) in which infants at risk for, or having symptoms consistent with, opioid withdrawal participated between 1975 and 2018. We identified no RCTs in which infants receiving opioid treatment for symptoms consistent with opioid withdrawal participated. The certainty of evidence for all outcomes was very low to low. We also identified and excluded 34 non-randomized studies published between 2005 and 2018, including 29 in which infants at risk for, or having symptoms consistent with, opioid withdrawal participated and five in which infants receiving opioid treatment for symptoms consistent with opioid withdrawal participated. We identified seven preregistered interventional clinical trials that may qualify for inclusion at review update when complete. Of the six RCTs, four studies assessed modifying environmental stimulation in the form of a mechanical rocking bed, prone positioning, non-oscillating waterbed, or a low-stimulation nursery; one study assessed feeding practices (comparing 24 kcal/oz to 20 kcal/oz formula); and one study assessed support of the maternal-infant dyad (tailored breastfeeding support). There was no evidence of a difference in length of hospitalization in the one study that assessed modifying environmental stimulation (mean difference [MD) -1 day, 95% confidence interval [CI) -2.82 to 0.82; 30 infants; very low-certainty evidence) and the one study of support of the maternal-infant dyad (MD -8.9 days, 95% CI -19.84 to 2.04; 14 infants; very low-certainty evidence). No studies of feeding practices evaluated the length of hospitalization. There was no evidence of a difference in use of pharmacological treatment in three studies of modifying environmental stimulation (typical risk ratio [RR) 1.00, 95% CI 0.86 to 1.16; 92 infants; low-certainty evidence), one study of feeding practices (RR 0.92, 95% CI 0.63 to 1.33; 49 infants; very low-certainty evidence), and one study of support of the maternal-infant dyad (RR 0.50, 95% CI 0.13 to 1.90; 14 infants; very low-certainty evidence). Reported secondary outcomes included neonatal intensive care unit (NICU) admission, days to regain birth weight, and weight nadir. One study of support of the maternal-infant dyad reported NICU admission (RR 0.50, 95% CI 0.13 to 1.90; 14 infants; very low-certainty evidence). One study of feeding practices reported days to regain birth weight (MD 1.10 days, 95% CI 2.76 to 0.56; 46 infants; very low-certainty evidence). One study that assessed modifying environmental stimulation reported weight nadir (MD -0.28, 95% CI -1.15 to 0.59; 194 infants; very low-certainty evidence) and one study of feeding practices reported weight nadir (MD -0.8, 95% CI -2.24 to 0.64; 46 infants; very low-certainty evidence).

AUTHORS' CONCLUSIONS

We are uncertain whether non-pharmacological care for opioid withdrawal in newborns affects important clinical outcomes including length of hospitalization and use of pharmacological treatment based on the six included studies. The outcomes identified for this review were of very low- to low-certainty evidence. Combined analysis was limited by heterogeneity in study design and intervention definitions as well as the number of studies. Many prespecified outcomes were not reported. Although caregivers are encouraged by experts to optimize non-pharmacological care for opioid withdrawal in newborns prior to initiating pharmacological care, we do not have sufficient evidence to inform specific clinical practices. Larger well-designed studies are needed to determine the effect of non-pharmacological care for opioid withdrawal in newborns.

Childhood neurodevelopment after prescription of maintenance methadone for opioid dependency in pregnancy: a systematic review and meta-analysis

AIM

To systematically review and meta-analyse studies of neurodevelopmental outcome of children born to mothers prescribed methadone in pregnancy.

METHOD

MEDLINE, Embase, and PsycINFO were searched for studies published from 1975 to 2017 reporting neurodevelopmental outcomes in children with prenatal methadone exposure.

RESULTS

Forty-one studies were identified (2283 participants). Eight studies were amenable to meta-analysis: at 2 years the Mental Development Index weighted mean difference of children with prenatal methadone exposure compared with unexposed infants was -4.3 (95% confidence interval [CI] -7.24 to -1.63), and the Psychomotor Development Index weighted mean difference was -5.42 (95% CI -10.55 to -0.28). Seven studies reported behavioural scores and six found scores to be lower among methadone-exposed children. Twelve studies reported visual outcomes: nystagmus and strabismus were common; five studies reported visual evoked potentials of which four described abnormalities. Factors that limited the quality of some studies, and introduced risk of bias, included absence of blinding, small sample size, high attrition, uncertainty about polydrug exposure, and lack of comparison group validity.

INTERPRETATION

Children born to mothers prescribed methadone in pregnancy are at risk of neurodevelopmental problems but risk of bias limits inference about harm. Research into management of opioid use disorder in pregnancy should include evaluation of childhood neurodevelopmental outcome.

WHAT THIS PAPER ADDS

Children born to opioid-dependent mothers prescribed methadone are at risk of neurodevelopmental impairment. Exposed infants have lower Mental Development Index and Psychomotor Development Index scores than unexposed children. Atypical visual evoked potentials, strabismus, and nystagmus have increased prevalence. Estimates of impairment may be biased by intermediate to poor quality evidence.

Methadone Versus Buprenorphine for Opioid Use Dependence and Risk of Neonatal Abstinence Syndrome

BACKGROUND

Our objective was to estimate the association between methadone and neonatal abstinence syndrome compared with buprenorphine using a probabilistic bias analysis to account for unmeasured confounding by severity of addiction.

METHODS

We used a cohort of live-born infants exposed in utero to methadone or buprenorphine for maternal opioid maintenance therapy at Magee-Womens Hospital in Pittsburgh, PA, from 2013 to 2015 (n = 716). We determined exposure and outcome status using pharmacy billing claims. We used log-binomial regression models to assess association of treatment with neonatal abstinence syndrome after adjusting for parity, maternal race, age, delivery year, employment, hepatitis c, smoking, marital, and insurance status. We implemented probabilistic bias analysis, informed by an internal validation study, to assess the impact of unmeasured confounding by severity of addiction.

RESULTS

Infants exposed to methadone in utero were more likely to experience neonatal abstinence syndrome compared with those exposed to buprenorphine (RR, 1.3; 95% CI, 1.2, 1.5). After adjustment, infants exposed to methadone were more likely (adjusted RR, 1.3; 95% CI, 1.1, 1.5) than infants exposed to buprenorphine to have the syndrome. In the validation cohort (n = 200), severe addiction was more common in methadone- versus buprenorphine-exposed deliveries (77% vs. 32%). However, adjustment for severe addiction in the bias analysis only slightly attenuated the association (RR, 1.2; 95% CI, 1.0, 1.4), supporting conventional analysis.

CONCLUSIONS

Methadone is associated with increased risk of neonatal abstinence syndrome compared with buprenorphine in infants exposed in utero. This association is subject to minimal bias due to unmeasured confounding by severity of addiction.

Neonatal Outcomes in a Medicaid Population With Opioid Dependence

Confounding may account for the apparently improved infant outcomes after prenatal exposure to buprenorphine versus methadone. We used Massachusetts Medicaid Analytic eXtract (MAX) data to identify a cohort of opioid-dependent mother-infant pairs (2006-2011), supplemented with confounder data from an external Boston, Massachusetts, cohort (2015-2016). Associations between prenatal buprenorphine exposure versus methadone exposure and infant outcomes in the MAX cohort were adjusted for measured MAX confounders and were additionally adjusted for unmeasured confounders with bias analysis using external cohort data. A total of 477 women in MAX were treated with methadone and 543 with buprenorphine. More buprenorphine users than methadone users were white and used psychotropic medications. After adjustment for MAX confounders, risk ratios among infants exposed to buprenorphine versus those exposed to methadone were 0.45 (95% confidence interval (CI): 0.34, 0.61) for preterm birth (birth at <37 weeks) and 0.75 (95% CI: 0.51, 1.11) for low birth weight for gestational age. The mean difference in infant hospitalization was -7.35 days (95% CI: -9.16, -5.55). After further adjustment with bias analysis, the risk ratios were 0.53 (95% CI: 0.39, 0.71) for preterm birth and 1.14 (95% CI: 0.77, 1.69) for low birth weight for gestational age, and the mean difference in infant hospitalization was -3.66 days (95% CI: -5.46, -1.87). External confounder data can be used to adjust for unmeasured confounding in studies of prenatal outcomes among women on opioid agonist therapy based on administrative databases.

Maternal buprenorphine treatment and infant outcome

BACKGROUND AND OBJECTIVES

Maternal buprenorphine maintenance predisposes the infant to exhibit neonatal abstinence syndrome (NAS), but there is insufficient published information regarding the nature of NAS and factors that contribute to its severity in buprenorphine-exposed infants.

METHODS

The present study evaluated forty-one infants of buprenorphine-maintained women in comprehensive substance use disorder treatment who participated in an open-label study examining the effects of maternal buprenorphine maintenance on infant outcomes. Modifiers of the infant outcomes, including maternal treatment and substance use disorder parameters, were also evaluated.

RESULTS

Fifty-nine percent of offspring exhibited NAS that required pharmacologic management. Both maternal buprenorphine dose as well as prenatal polysubstance exposure to illicit substance use/licit substance misuse were independently associated with NAS expression. Polysubstance exposure was associated with more severe NAS expression after controlling for the effects of buprenorphine dose. Other exposures, including cigarette smoking and SRI use, were not related to outcomes. Maternal buprenorphine dose was positively associated with lower birth weight and length.

CONCLUSIONS

Polysubstance exposure was the most potent predictor of NAS severity in this sample of buprenorphine-exposed neonates. This finding suggests the need for interventions that reduce maternal polysubstance use during medication assisted treatment for opioid use disorder, and highlights the necessity of a comprehensive approach, beyond buprenorphine treatment alone, for the optimal care for pregnant women with opioid use disorders.

Opioid Use Disorder in Pregnancy: Health Policy and Practice in the Midst of an Epidemic

Opioid abuse among pregnant women has reached epidemic proportions and has influenced maternal and child health policy at the federal, state, and local levels. As a result, we review the current state of opioid use in pregnancy and evaluate recent legislative and health policy initiatives designed to combat opioid addiction in pregnancy. We emphasize the importance of safe and responsible opioid-prescribing practices, expanding the availability and accessibility of medication-assisted treatment and standardizing care for neonates at risk of neonatal abstinence syndrome. Efforts to penalize pregnant women and negative consequences for disclosing substance use to health care providers are harmful and may prevent women from seeking prenatal care and other beneficial health care services during pregnancy. Instead, health care providers should advocate for health policy informed by scientific research and evidence-based practice to reduce the burden of prenatal opioid abuse and optimize outcomes for mothers and their neonates.

Prenatal treatment for opioid dependency: observations from a large inner-city clinic

Background

The objective of this study was to review changes in the prevalence of opioid use disorder in pregnancy, and to describe the prenatal care and neonatal outcomes following the implementation of buprenorphine treatment at a large US obstetrical clinic during the on-going opioid epidemic.

Methods

We conducted a retrospective cohort study of 310 women (332 pregnancies) with opioid use disorders and their neonates delivered between June 2006 and December 2010 at an obstetrical clinic in the US. Trends in patient volume, characteristics and outcomes by calendar year were assessed using the Cochran–Armitage test and linear regression.

Results

There was an almost two-fold increase in the volume of pregnant women treated annually from 2006 through 2010. Most women were treated with methadone (74%), with buprenorphine becoming more common over calendar time: 3.0% in 2006 to 41% in 2010. The mean dose of buprenorphine at delivery was: 11.4 mg in 2007, 14.1 mg in 2008, 14.1 mg in 2009, and 16.8 mg in 2010; an average increase of 2.1 mg year. There were no differences in mean methadone dose over time. From 2006 to 2010 there were increases in the prevalence of prescribed concomitant psychotropic medications and vaginal deliveries, and in the proportion of neonates treated pharmacologically for neonatal abstinence syndrome (NAS). NAS pharmacologic management also varied by calendar year with more use of neonatal morphine and clonidine in later years.

Conclusions

The number of mother–infant pairs increased significantly from 2006 to 2010 and the clinical characteristics of these patients changed over time. Our experience reflects the rising increase in opioid use disorders in pregnancy and NAS, mandating the need for expansion of comprehensive prenatal care options for these women and their children.

The comparative safety of buprenorphine versus methadone in pregnancy-what about confounding?

Preferential treatment of high-risk opioid-dependent pregnant women with methadone limits evidence of the comparative safety of buprenorphine versus methadone on infant outcomes. Adjustment for maternal characteristics that affect both treatment choices and birth outcomes is necessary to provide valid estimates of the effect of prenatal opioid agonist therapy exposure.

Buprenorphine compared with methadone to treat pregnant women with opioid use disorder: a systematic review and meta-analysis of safety in the mother, fetus and child

AIMS

To assess the safety of buprenorphine compared with methadone to treat pregnant women with opioid use disorder.

METHODS

We searched PubMed, Embase and the Cochrane Library from inception to February 2015 for randomized controlled trials (RCT) and observational cohort studies (OBS) that compared buprenorphine with methadone for treating opioid-dependent pregnant women. Two reviewers assessed independently the titles and abstracts of all search results and full texts of potentially eligible studies reporting original data for maternal/fetal/infant death, preterm birth, fetal growth outcomes, fetal/congenital anomalies, fetal/child neurodevelopment and/or maternal adverse events. We ascertained each study's risk of bias using validated instruments and assessed the strength of evidence for each outcome using established methods. We computed effect sizes using random-effects models for each outcome with two or more studies.

RESULTS

Three RCTs (n = 223) and 15 cohort OBSs (n = 1923) met inclusion criteria. In meta-analyses using unadjusted data and methadone as comparator, buprenorphine was associated with lower risk of preterm birth [RCT risk ratio (RR) = 0.40, 95% confidence interval (CI) = 0.18, 0.91; OBS RR = 0.67, 95% CI = 0.50, 0.90], greater birth weight [RCT weighted mean difference (WMD) = 277 g, 95% CI = 104, 450; OBS WMD = 265 g, 95% CI = 196, 335] and larger head circumference [RCT WMD = 0.90 cm, 95% CI = 0.14, 1.66; OBS WMD = 0.68 cm, 95% CI = 0.41, 0.94]. No treatment differences were observed for spontaneous fetal death, fetal/congenital anomalies and other fetal growth measures, although the power to detect such differences may be inadequate due to small sample sizes.

CONCLUSIONS

Moderately strong evidence indicates lower risk of preterm birth, greater birth weight and larger head circumference with buprenorphine treatment of maternal opioid use disorder during pregnancy compared with methadone treatment, and no greater harms.

A Swedish Population-based Study of Adverse Birth Outcomes among Pregnant Women Treated with Buprenorphine or Methadone: Preliminary Findings

BACKGROUND

Untreated opioid dependence in pregnant women is associated with adverse birth outcomes. Buprenorphine and methadone are options for opioid agonist medication-assisted treatment during pregnancy.

OBJECTIVE

The aim of this study was to describe adverse birth outcomes observed with buprenorphine or methadone treatment compared to the general population in Sweden.

METHODS

Pregnant women and their corresponding births during 2005–2011 were identified in the Swedish Medical Birth Register. Data on stillbirth, neonatal/infant death, mode of delivery, gestational age at birth, Apgar score, growth outcomes, neonatal abstinence syndrome, and congenital malformations were examined. Frequencies were compared using two-sided Fisher’s exact tests. Unadjusted estimates of birth outcomes for women treated with buprenorphine or methadone were compared to the registered general population.

RESULTS

A total of 746,257 pregnancies among 538,178 unique women resulted in 746,485 live births. Among the 194 women treated with buprenorphine (N = 176) or methadone (N = 52), no stillbirths or neonatal/infant deaths occurred. Neonatal abstinence syndrome developed in 23.3% and 38.5% of infants born to mothers treated with buprenorphine and methadone, respectively. The frequency of the selected adverse birth outcomes assessed in women treated with buprenorphine as compared to the general population was not significantly different. However, a significantly higher frequency of preterm birth and congenital malformations was observed in women treated with methadone as compared to the general population. Compared with the general population, methadone-treated women were significantly older than buprenorphine-treated women, and both treatment groups began prenatal care later, were more likely to smoke cigarettes, and did not cohabitate with the baby’s father.

CONCLUSIONS

An increased frequency of the selected adverse birth outcomes was not observed with buprenorphine treatment during pregnancy. Twofold increased frequency of preterm birth [2.21 (1.11, 4,41)] and congenital malformations [2.05 (1.08, 3.87)] was observed in the methadone group, which may be partly explained by older average maternal age and differences in other measured and unmeasured confounders.

Buprenorphine Versus Methadone for Opioid Dependence in Pregnancy

Objective: To evaluate maternal and neonatal safety outcomes for methadone and buprenorphine in the obstetric population. Data Sources: A literature search of PubMed (1966 to March 2016) and EMBASE (1973 to March 2016) was completed using the search terms buprenorphine, methadone, pregnancy, opioid, and neonatal abstinence syndrome. Priority was given to randomized controlled trials and trials directly comparing buprenorphine and methadone during pregnancy. The bibliographies were reviewed for other relevant articles. Study Selection and Data Extraction: All human studies published in English, that compared methadone and buprenorphine use in pregnancy were evaluated. Because of the limited number of obstetric studies, only 5 critical studies were found. Data Synthesis: Buprenorphine significantly improved or had similar outcomes to methadone for development of neonatal abstinence syndrome (NAS), percentage of infants requiring treatment for NAS (20%-47% vs 45.5%-57%, respectively), total amount of morphine used to treat NAS (0.472-3.4 vs 1.862-10.4 mg, respectively), duration of NAS (4.1-5.6 vs 5.3-9.9 days, respectively), peak NAS (3.9-11 vs 4.9-12.8 score, respectively), infant hospital stay (6.8-10.6 vs 8.1-17.5 days, respectively), and gestational age at delivery (38.8-39.7 vs 37.9-38.8 weeks, respectively). No difference was found with other neonatal or maternal outcomes. Conclusions: Both methadone and buprenorphine are effective agents, with improved safety compared with continued nonmedical opioid use during pregnancy. There is evidence to suggest that buprenorphine should be considered as an equivalent option to methadone for use in pregnancy; however, larger studies are still needed to fully evaluate buprenorphine safety and advantages over methadone in the obstetric population.

Factors associated with buprenorphine versus methadone use in pregnancy

BACKGROUND

Buprenorphine has recently emerged as a safe and effective treatment option for pregnant women with opioid use disorder (OUD) and is associated with superior neonatal outcomes. This study characterized and compared patient populations who used buprenorphine versus methadone during pregnancy in an academic medical center.

METHODS

Observational retrospective cohort evaluation of 791 pregnant women with OUD on opioid maintenance treatment from 2009 to 2012. Buprenorphine versus methadone use was defined as use after either (a) conversion from illicit opioid use during pregnancy or (b) ongoing prepregnancy use. Multivariable logistic regression was used to identify patient characteristics predictive of buprenorphine use.

RESULTS

Among 791 pregnant women, 608 (76.9%) used methadone and 183 (23.1%) used buprenorphine. From 2009 to 2012, buprenorphine use during pregnancy increased from 10.1% to 33.2%. Pregnant women using buprenorphine were significantly more likely to be older, married, employed, have more education, and have a history of prescription opioid use compared with women using methadone. In contrast, pregnant women using methadone were significantly more likely to have hepatitis C virus infection, use cocaine, benzodiazepines, or marijuana, and have a history of heroin and/or intravenous opioid use. In multivariable analysis, pregnant women who were older (odds ratio [OR] = 1.01; 95% confidence interval [CI]: 1.02, 1.11), were employed (1.87; 1.20, 2.90), and had a history of opioid maintenance treatment prior to pregnancy (2.68; 1.78, 4.02) were more likely to use buprenorphine during pregnancy. Pregnant women with a history of benzodiazepine use (0.48; 0.30, 0.77), who had children no longer in their legal custody (0.63; 0.40, 0.99), and who had a partner with a substance use history (0.37; 0.22, 0.63) were less likely to use buprenorphine during pregnancy.

CONCLUSIONS

Disparities exist among patients who use buprenorphine versus methadone during pregnancy and indicate the need to improve the availability and accessibility of buprenorphine for many pregnant women.

Confounding of the Comparative Safety of Prenatal Opioid Agonist Therapy

Prenatal opioid agonist therapy with methadone or buprenorphine prevents maternal illicit opioid use and withdrawal and improves pregnancy outcomes compared to heroin use alone. Historically, methadone has been the first-line opioid agonist therapy for pregnant opioid dependent women; in recent years buprenorphine has become first-line treatment for some opioid dependent pregnant women. While there is some evidence of better outcomes in neonates exposed to buprenorphine vs. methadone, the effect of confounding from differences in women who use buprenorphine and methadone has not been carefully examined in most studies. This review explores mechanisms by which confounding can arise in measuring associations between prenatal buprenorphine vs. methadone exposure on neonatal outcomes using a graphical approach, directed acyclic graphs. The goal of this paper is to facilitate better understanding of the factors influencing neonatal abstinence syndrome and accurate assessment of the comparative safety of opioid agonist therapies on the neonate.

Prescription Opioids in Pregnancy and Birth Outcomes: A Review of the Literature

Prescription opioids are used prenatally for the management of pain, as well as for opiate dependency. Opioids are known to cross the placenta and despite the evidence of possible adverse effects on fetal development, studies have consistently shown prescription opioids are among the most commonly prescribed medications and the prevalence of use is increasing among pregnant women. This article summarizes the available literature documenting potential harms associated with prescription opioid use during pregnancy, including poor fetal growth, preterm birth, birth defects, and neonatal abstinence syndrome.

Neonatal outcomes and their relationship to maternal buprenorphine dose during pregnancy

BACKGROUND

Buprenorphine pharmacotherapy for opioid-dependent pregnant women is associated with maternal and neonatal outcomes superior to untreated opioid dependence. However, the literature is inconsistent regarding the possible existence of a dose-response relationship between maternal buprenorphine dose and neonatal clinical outcomes.

METHODS

The present secondary analysis study (1) examined the relationship between maternal buprenorphine dose at delivery and neonatal abstinence syndrome (NAS) peak score, estimated gestational age at delivery, Apgar scores at 1 and 5 min, neonatal head circumference, length, and weight at birth, amount of morphine needed to treat NAS, duration of NAS treatment, and duration of neonatal hospital stay and (2) compared neonates who required pharmacotherapy for NAS to neonates who did not require such pharmacotherapy on these same outcomes, in 58 opioid-dependent pregnant women receiving buprenorphine as participants in a randomized clinical trial.

RESULTS

(1) Analyses failed to provide evidence of a relationship between maternal buprenorphine dose at delivery and any of the 10 outcomes (all p-values>.48) and (2) significant mean differences between the untreated (n=31) and treated (n=27) for NAS groups were found for duration of neonatal hospital stay and NAS peak score (both p-values<.001).

CONCLUSIONS

(1) Findings failed to support the existence of a dose-response relationship between maternal buprenorphine dose at delivery and any of 10 neonatal clinical outcomes, including NAS severity and (2) that infants treated for NAS had a higher mean NAS peak score and, spent a longer time in the hospital than did the group not treated for NAS is unsurprising.

A Comparison of Buprenorphine + Naloxone to Buprenorphine and Methadone in the Treatment of Opioid Dependence during Pregnancy: Maternal and Neonatal Outcomes

Given that buprenorphine + naloxone is prescribed for opioid-dependent pregnant women, it is important to examine the extent to which it differs from buprenorphine alone, methadone, or methadone-assisted withdrawal on neonatal and maternal outcomes. Summary statistics on maternal and neonatal outcomes were collected from 7 previously published studies examining treatment for opioid-dependent pregnant women that represented a range of research methodologies. Outcomes from these studies were compared to the same outcomes for 10 women treated with the combined buprenorphine + naloxone product. There were no significant differences in maternal outcomes for buprenorphine + naloxone compared to buprenorphine, methadone, or methadone-assisted withdrawal. Preliminary findings suggest no significant adverse maternal or neonatal outcomes related to the use of buprenorphine + naloxone for the treatment of opioid dependence during pregnancy. However, further research should examine possible differences between buprenorphine + naloxone and buprenorphine alone or methadone in fetal physical development.

Lessons learned from a comparison of evidence-based research in pregnant opioid-dependent women

OBJECTIVES

Lessons learned in research and treatment of opioid dependence demonstrate the need to include pregnant women in clinical trials.

METHODS

Two double-blind, double-dummy, randomized controlled trials (Pilot study, European sample(†) of MOTHER-trial) comparing buprenorphine and methadone in opioid-dependent pregnant women were conducted. In both studies, participants received voucher-based incentives for attendance and completion of study assessments. In the MOTHER trial, participants additionally received escalating voucher incentives for drug-free urine samples. Neonatal abstinence syndrome was treated with oral morphine solution based on standardized modified Finnegan scores.

RESULTS

After a mean treatment period of 13.79 weeks in the Pilot study (PS, n = 18) and 20.78 weeks in the MOTHER-trial (MT, n = 41), respectively (p < 0.001), PS patients delivered at mean doses of 14.00 mg buprenorphine/52.50 mg methadone and MT participants at 13.44 mg buprenorphine/63.68 mg methadone. Nonsignificant differences regarding dropout rates were found (22% in PS versus 10% in MT), but dropout was significantly earlier in the MT (p = 0.013). Significantly higher rates of concomitant consumption of opioids and benzodiazepines occurred in the PS compared with the MT (p < 0.001), however, with no significant differences in neonatal data between both settings.

CONCLUSIONS

Early treatment enrolment combined with contingency management contributes to reduced illicit drug use throughout pregnancy, surprisingly without influencing neonatal outcome parameters.