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Poster Session 1

Category: Epidemiology

Poster Session 1

(175) Fetal/Neonatal Alloimmune Thrombocytopenia and Childhood Neuropsychiatric Disorders: Role of Sex, Race/Ethnicity, and Gestational Age

Wednesday, February 11, 2026

10:30 AM - 12:00 PM

Submitting Author and Presenting Author(s)

Darios Getahun, MD, MPH, PhD (he/him/his)

Research Investigator II MD
Department of Research & Evaluation, Kaiser Permanente Southern California
Pasadena, California, United States

Coauthor(s)

MP

Morgan R. Peltier, PhD

Psychiatry and Behavioral Health, Jersey Shore University Medical Center
Neptune City, New Jersey, United States
TI

Theresa M. Im, MPH

Senior Research Project Manager
Department of Research & Evaluation, Kaiser Permanente Southern California
Pasadena, California, United States
VC

Vicki Y. Chiu, MS

Biostatistician
Department of Research & Evaluation, Kaiser Permanente Southern California
Pasadena, California, United States
MF

Michael J. Fassett, MD

Regional Chief, Maternal-Fetal Medicine
Department of Obstetrics and Gynecology, Kaiser Permanente West Los Angeles Medical Center
Los Angeles, California, United States

Objective:
Fetal and neonatal alloimmune thrombocytopenia (FNAIT), caused by a mismatch in human platelet antigens between mother and fetus, can lead to bleeding and bruising. Prompt treatment is essential to prevent life-threatening intracranial hemorrhage and neuronal injury. We examined the association between FNAIT and mental, emotional, behavioral, or developmental (MEBD) disorders, and whether these vary by child’s sex, race/ethnicity, and gestational age at birth in a large healthcare system.

Study Design:
This retrospective cohort study included pregnant women and their children delivered at Kaiser Permanente Southern California (2011-2021). FNAIT cases were identified using ICD-9/10 codes from inpatient and outpatient records for singleton births at ≥20 weeks gestation. MEBD outcomes, including attention-deficit/hyperactivity (ADHD), autism spectrum (ASD), major depressive (MDD), generalized anxiety (GAD), and disruptive behavior (DBD) disorders, were identified using validated diagnostic codes. Modifying effects of child’s sex, race/ethnicity, and gestational age were examined. Adjusted hazard ratios (aHRs) quantified associations.

Results:
Among 281,628 pregnancies, 2,755 FNAIT cases (9.8 per 1,000) were identified. Compared to non-FNAIT births, these cases were more likely to be preterm (52% vs. 22%, P < 0.001) and have any MEBD diagnosis (23.8% vs. 15.1%, P < 0.001). FNAIT was associated with increased risks of ASD (aHR 2.10, 95% confidence intervals [CI] 1.89–2.33), ADHD (aHR 1.23, 95% CI 1.04–1.44), and DBD (aHR 1.23, 95% CI 1.07–1.41), but not GAD or MDD. Stratified analyses showed significant associations for ASD (aHR 1.96, 95% CI 1.74–2.21) and ADHD (aHR 1.21, 95% CI 1.01–1.45) in boys, and ASD (aHR 2.68, 95% CI 2.16–3.33) and DBD (aHR 1.47, 95% CI 1.14–1.90) in girls. Risk varied by race/ethnicity and gestational age.

Conclusion:
FNAIT exposure is associated with a higher burden of MEBDs in children, with risk differing by sex, race/ethnicity, and gestational age, underscoring the need for early surveillance and intervention.