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CME Credit Offered
CME Credit Offered
Abstract Award
Abstract Award
Recording available 2/16-5/2
Recording available 2/16-5/2
AIUM Credit
AIUM Credit
Foundation Awardee
Foundation Awardee
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Abstract Award
Abstract Award
Foundation Awardee
Foundation Awardee

Poster Session 3

Category: Medical/Surgical/Diseases/Complications

Poster Session 3

(996) Longitudinal MRI Comparison of Placental Immune and Oxygenation Profiles in Opioid-Exposed versus Spontaneous Preterm Pregnancies

Thursday, February 12, 2026
10:30 AM - 12:00 PM  
Objective:
Prenatal opioid exposure (POE) and spontaneous preterm birth (SPTB) are both associated with placental dysregulation, but underlying mechanisms remain unclear. We hypothesized that placental immune activity and oxygenation are similarly disrupted in POE and SPTB pregnancies. Using longitudinal MRI, we compared placental profiles among POE, SPTB, and control pregnancies.

Study Design:
Pregnant individuals with chronic POE were enrolled and matched to unexposed controls by fetal sex, maternal race, and Area Deprivation Index. Additional matches were identified in a previously imaged cohort of patients who experienced SPTB (spontaneous labor and delivery < 37 weeks). Participants underwent up to one MRI per trimester. Placental immune cell infiltration (“cell ratio”) was assessed using a validated imaging method developed by our team (Fig. A), and oxygenation was evaluated via T2* mapping. A fuzzy clustering algorithm segmented placental compartments using T2*, apparent diffusion coefficient, and fractional anisotropy. Exponential regression and likelihood ratio tests were used to evaluate group differences.

Results:

21 participants (6 POE; 4 controls; 11 SPTB) with similar demographics were included; The control patients were all term births with no POE. SPTB occurred at a mean gestation of 34 weeks. Immune cell ratios in placental vessels increased over pregnancy in both SPTB (R2 = 0.714, p < 0.0001) and POE (R2 = 0.690, p=0.0055), but not controls (R2 = 0.018, p = 0.6809); SPTB demonstrated a steeper increase than both POE (F = 3.69, p =0.0389) and controls (F = 10.02, p = 0.0005) (Fig. B). No longitudinal changes in tissue T2* were observed within groups, but SPTB showed persistently lower oxygenation compared to controls (F=14.96, p < 0.0001), but not POE (F=0.89, p=0.4196) (Fig. C).

Conclusion:
Both POE and SPTB demonstrated increasing immune cells within placental vessels and persistently lower oxygenation within placental tissue, suggesting shared pathways for placental dysregulation. However, SPTB showed a steeper immune response, potentially distinguishing a threshold for risk of preterm birth.