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Recording available 2/16-5/2
Recording available 2/16-5/2
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Oral Concurrent Session 1 - Medical and Surgical Complications of Pregnancy

Oral Concurrent Sessions

Oral Concurrent Session 1 - Medical and Surgical Complications of Pregnancy

(18) Placental Immune Cell and Oxygenation Profiles in Opioid-Exposed Pregnancies: A Longitudinal MRI Study

Wednesday, February 11, 2026
3:15 PM - 3:30 PM  
Location: Summit 201 - 204
Objective:
Prenatal opioid exposure (POE) is linked to adverse perinatal outcomes and impaired neurodevelopment. Animal models have demonstrated opioid-induced neuroinflammation; however, effects on the human placenta remain poorly defined. We hypothesized that POE disrupts both placental immune response and oxygenation. To test this hypothesis, we compared immune and oxygenation profiles between opioid-exposed and unexposed pregnancies using longitudinal MRI.

Study Design:
Pregnant patients with chronic POE were prospectively recruited and matched 1:1 (fetal sex, maternal race, Area Deprivation Index) to unexposed controls confirmed by urine screens. Participants underwent up to one MRI per trimester (12–36 weeks). Immune cell infiltration (“cell ratio”) was assessed using a previously validated imaging method developed by our team (Fig. A); T2* mapping assessed oxygenation. A fuzzy clustering algorithm segmented placental tissue, vessels, and intervillous space using T2*, apparent diffusion coefficient, and fractional anisotropy. Differences were assessed with Wilcoxon Rank-Sum and likelihood ratio tests.

Results:

20 participants (10 POE; 10 controls) with similar demographics were included (Table). Longitudinal analysis showed a progressive increase in immune cell infiltration from the first to the third trimester in POE cases, which was not observed in controls (Fig. B). Consistently, immune cell ratios in the third trimester were higher in POE cases than in controls (Fig. C). Although overall mean T2* values did not differ between groups (54.4±16.9 vs. 71.3±9.6 ms; p = 0.095), longitudinal analysis revealed persistently lower T2* values in POE placental tissue (F = 11.04, p = 0.0005; Fig. D), with no differences in placental vessels or intervillous space.

Conclusion:
POE reshapes the placental environment, with increased immune cell infiltration in the third trimester and reduced placental tissue oxygenation throughout gestation. This study provides the first noninvasive evidence of POE-induced placental immune pathology, suggesting a mechanism for adverse outcomes and a target for future interventions.