Maternal and neonatal characteristics of a Canadian urban cohort receiving treatment for opioid use disorder during pregnancy

Effects of medications for opioid use disorder (MOUD) on fetal brain and cranial measurements

BACKGROUND

The use and misuse of opioids, as well as opioid use disorder (OUD) have increased remarkably among reproductive-aged and pregnant women. As many as 25% of pregnant women who report non-medical opioid use in the past month also report concurrent alcohol use. While teratogenic effects of alcohol are well established, there are limited studies evaluating fetal intracranial effects associated with medications for OUD (MOUD) and concurrent use of MOUD and alcohol during pregnancy. The objective of this study was to determine the effect of MOUD, with and without concomitant alcohol use, on fetal intracranial measurements. The type of maternal MOUD therapy (methadone vs. buprenorphine) was also examined.

METHODS

This study was a secondary analysis of a prospective cohort study among participants (n = 196) assigned into three groups (MOUD [n = 94], MOUD+Alcohol [n = 47], and unexposed controls [n = 55]). Co-exposure with either methamphetamines or cocaine were exclusionary criteria; other co-exposures were carefully characterized with prospective repeated self-report measures and biomarkers. Fetal ultrasound measurements at 18-22 weeks (2nd trimester) and 28-32 weeks (early 3rd trimester) were compared among study groups. In addition to standard morphometrics, we performed specialized intracranial measurements of caval-calvarial distance (CCD), frontal lobe width (FLW), frontal lobe length (FLL), and fronto-thalamic distance (FTD).

RESULTS

Brain and cranial measurements between MOUD, with or without alcohol co-exposure, and unexposed controls were generally not significantly different in multivariable analyses. Subjects in the MOUD groups had earlier gestational age at delivery and lower birth weight and birth weight percentile compared to unexposed controls with differences driven primarily by the methadone subgroup. Significant differences in standard and specialized intracranial indices at both second and third trimester as well as differences in the change of HC percentile over time were observed in the methadone subgroup compared to controls, while no differences between buprenorphine subgroup and controls were observed for any measures.

CONCLUSION

Patients receiving methadone therapy might require closer monitoring during pregnancy; however, detailed imaging of the fetal brain other than the standard measurements might not be warranted.

Annual Research Review: Prenatal opioid exposure - a two-generation approach to conceptualizing neurodevelopmental outcomes

Opioid use during pregnancy impacts the health and well-being of two generations: the pregnant person and the child. The factors that increase risk for opioid use in the adult, as well as those that perpetuate risk for the caregiver and child, oftentimes replicate across generations and may be more likely to affect child neurodevelopment than the opioid exposure itself. In this article, we review the prenatal opioid exposure literature with the perspective that this is not a singular event but an intergenerational cascade of events. We highlight several mechanisms of transmission across generations: biological factors, including genetics and epigenetics and the gut-brain axis; parent-child mechanisms, such as prepregnancy experience of child maltreatment, quality of parenting, infant behaviors, neonatal opioid withdrawal diagnosis, and broader environmental contributors including poverty, violence exposure, stigma, and Child Protective Services involvement. We conclude by describing ways in which intergenerational transmission can be disrupted by early intervention.

Alterations of brain microstructures in a mouse model of prenatal opioid exposure detected by diffusion MRI

Growing opioid use among pregnant women is fueling a crisis of infants born with prenatal opioid exposure. A large body of research has been devoted to studying the management of opioid withdrawal during the neonatal period in these infants, but less substantive work has explored the long-term impact of prenatal opioid exposure on neurodevelopment. Using a translationally relevant mouse model of prenatal methadone exposure (PME), the aim of the study is to investigate the cerebral microstructural differences between the mice with PME and prenatal saline exposure (PSE). The brains of eight-week-old male offspring with either PME (n = 15) or PSE (n = 15) were imaged using high resolution in-vivo diffusion magnetic resonance imaging on a 9.4 Tesla small animal scanner. Brain microstructure was characterized using diffusion tensor imaging (DTI) and Bingham neurite orientation dispersion and density imaging (Bingham-NODDI). Voxel-based analysis (VBA) was performed using the calculated microstructural parametric maps. The VBA showed significant (p < 0.05) bilateral alterations in fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), orientation dispersion index (ODI) and dispersion anisotropy index (DAI) across several cortical and subcortical regions, compared to PSE. Particularly, in PME offspring, FA, MD and AD were significantly higher in the hippocampus, dorsal amygdala, thalamus, septal nuclei, dorsal striatum and nucleus accumbens. These DTI-based results suggest widespread bilateral microstructural alterations across cortical and subcortical regions in PME offspring. Consistent with the observations in DTI, Bingham-NODDI derived ODI exhibited significant reduction in PME offspring within the hippocampus, dorsal striatum and cortex. NODDI-based results further suggest reduction in dendritic arborization in PME offspring across multiple cortical and subcortical regions. To our best knowledge, this is the first study of prenatal opioid exposure to examine microstructural organization in vivo. Our findings demonstrate perturbed microstructural complexity in cortical and subcortical regions persisting into early adulthood which could interfere with critical neurodevelopmental processes in individuals with prenatal opioid exposure.

Preterm Birth Associates With Increased Placental Expression of MDR Transporters Irrespective of Prepregnancy BMI

CONTEXT

Preterm birth (PTB) and suboptimal prepregnancy body mass index (BMI) operate through inflammatory pathways to impair fetoplacental development. Placental efflux transporters mediate fetal protection and nutrition; however, few studies consider the effect of both PTB and BMI on fetal protection. We hypothesized that PTB would alter the expression of placental multidrug resistance (MDR) transporters and selected proinflammatory cytokines, and that maternal underweight and obesity would further impair placental phenotype.

OBJECTIVE

To determine whether placental MDR transporters P-glycoprotein (P-gp, encoded by ABCB1) and breast cancer resistance protein (BCRP/ABCG2), and proinflammatory cytokine levels are altered by PTB and maternal BMI.

METHODS

A cross-sectional study was conducted to assess the effect of PTB (with/without chorioamnionitis), or the effect of maternal prepregnancy BMI on placental MDR transporter and interleukin (IL)-6 and -8 expression in 60 preterm and 36 term pregnancies.

RESULTS

ABCB1 expression was increased in preterm compared to term placentae (P = .04). P-gp (P = .008) and BCRP (P = .01) immunolabeling was increased among all preterm compared to term placentae, with P-gp expression further increased in preterm pregnancies with chorioamnionitis (PTC, P = .007). Placental IL-6 mRNA expression was decreased in PTC compared to term placentae (P = .0005) and PTC associated with the greatest proportion of anti-inflammatory medications administered during pregnancy. Maternal BMI group did not influence placental outcomes.

CONCLUSION

PTB and infection, but not prepregnancy BMI, alter placental expression of MDR transporters and IL-6. This may have implications for fetal exposure to xenobiotics that may be present in the maternal circulation in pregnancies complicated by PTB.

The Effects of opioids on female fertility, pregnancy and the breastfeeding mother-infant dyad: A Review

Opioids cover a broad class of natural, synthetic and semi-synthetic drugs that act on opioid receptors to produce powerful analgesic effects. Rates of opioid use and opioid agonist maintenance treatment have increased substantially in recent years, particularly among women. Trends and outcomes of opioids use on fertility, pregnancy and breastfeeding, and longer-term child developmental outcomes have not been well-described. Here, we review the existing literature on the health effects of opioid use on female fertility, pregnancy, breastmilk and the exposed infant. We find that the current literature is primarily concentrated on the impact of opioid use in pregnancy and neonatal outcomes, with little exploration of effects on fertility. Studies are limited in number, some with small sample sizes, and many are hampered by methodological challenges related to confounding and other potential biases. Opioid use is becoming more prevalent due to environmental pressures such as COVID-19. More research is needed to better elucidate its effects on reproductive health among younger women and support the development of evidence-based recommendations for safe prescription practices and public health messaging.

Educational achievement at age 9.5 years of children born to mothers maintained on methadone during pregnancy

Recent research shows that preschool children born to opioid-dependent mothers are at increased risk for cognitive, psychomotor, attention, and social-emotional adjustment problems. But very little is known about their school-age functioning, particularly their educational achievement. This analysis examined the educational outcomes of a regional cohort of 100 prenatally methadone-exposed children who were prospectively studied from birth to age 9.5 years alongside a comparison group of 110 randomly identified non-exposed children born between 2003 and 2008. At age 9.5, as part of a comprehensive neurodevelopmental evaluation, children's teachers rated their achievement across the school curriculum, and children completed the Woodcock Johnson-III Tests of Achievement (WJ-III). Detailed information about the birth mother's social background, pregnancy substance use, and mental health was also collected during pregnancy/at term. Infant clinical data were collected after birth. Methadone-exposed children performed less well than non-exposed children across seven school curriculum areas rated by teachers (ps ≤.001), performed less well than non-exposed children on all reading and mathematics subtests of the WJ-III, and had higher rates of any educational delay on the WJ-III (57% vs. 15%), OR = 7.47 (3.71-15.02). Results were similar when children with severe intellectual impairment were excluded. After adjusting for confounding factors, methadone-exposed children had increased odds of educational delay, but this was only marginally significant (OR = 3.62, [1.01-13.01], p = .049). Maternal educational attainment level (OR = 0.69, [0.50-0.89], p = .006), and maternal benzodiazepine use during pregnancy (OR = 2.70 [1.03-7.12], p = .044) were also associated with later educational risk. Findings suggest that children born to opioid-dependent women enrolled in methadone maintenance are at high risk of educational delay by age 9.5 years. Children's academic difficulties appeared to reflect the effects of both adverse prenatal exposures and postnatal social risk.