(463) Characteristics of Gestational Surrogate Pregnancy in a Large Integrated Healthcare Setting

Thursday, January 30, 2025

4:00 PM – 6:00 PM

Submitting Author and Presenting Author(s)

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

Research Investigator II MD/Associate Professor
Kaiser Permanente Southern California, Department of Research & Evaluation / Kaiser Permanente Bernard J. Tyson School of Medicine, Department of Health Systems Science
Department of Research & Evaluation, Kaiser Permanente Southern California/Pasadena, CA, United States

Coauthor(s)

Fagen Xie, PhD (he/him/his)

Kaiser Permanente Southern California
Department of Research & Evaluation, Kaiser Permanente Southern California/Pasadena, California, United States
TI

Theresa M. Im, MPH

Kaiser Permanente Southern California
Department of Research & Evaluation, Kaiser Permanente Southern California/Pasadena, California, United States
DP

Daniella Park, MPH

Kaiser Permanente Southern California
Department of Research & Evaluation, Kaiser Permanente Southern California/Pasadena, California, United States
VC

Vicki Y. Chiu, MS

Programer/Analyst
Kaiser Permanente Southern California
Department of Research & Evaluation, Kaiser Permanente Southern California/Pasadena, California, United States
Yinka Oyelese, MD (he/him/his)

Director, Obstetric Imaging/Associate Professor
Beth Israel Deaconess Medical Center/Harvard Medical School
Boston, Massachusetts, United States
MP

Morgan R. Peltier, PhD

Jersey Shore University Medical Center
Department of Psychiatry and Behavioral Health, Jersey Shore University Medical Center/Neptune City, New Jersey, United States
MF

Michael J. Fassett, MD

Kaiser Permanente West Los Angeles Medical Center
Department of Obstetrics & Gynecology, Kaiser Permanente West Los Angeles Medical Center/Los Angeles, California, United States

Objective: To describe maternal and infant characteristics of gestational surrogate (GS) pregnancies in an integrated healthcare system with a large, diverse pregnant population.

Study Design: An electronic health records (EHR)-based retrospective cohort study of pregnant members delivered at 20-44 weeks’ gestation at Kaiser Permanente Southern California from 01/01/2008–12/31/2023 (N=636,300) was performed. Unstructured data abstracted from EHRs were used to determine GS status via natural language processing (NLP), validated by manual chart review (positive predictive value=96%). Hospital in- and outpatient physician encounters, and laboratory records were used to ascertain medical and obstetrical histories. Adjusted risk ratios (aRR) and 95% confidence intervals (CI) derived from robust Poisson regression were used to describe the magnitude of associations.

Results: Among pregnant members who delivered during the study period, 1,109 (1.7/1000) were GS pregnancies. Maternal age ≥ 25 years, non-Hispanic white, multiple gestation (aRR: 10.12, 95% CI: 8.6-11.92), and privately funded KP membership (aRR: 2.48, 95% CI: 2.12-2.89) were more likely to be associated with gestational surrogacy. GS patients were more likely to be overweight (aRR: 1.93, 95% CI: 1.56-2.14) and obese (aRR: 2.15, 95% CI: 1.80-2.56). Patients with a GS pregnancy were less likely to smoke (aRR: 0.34, 95% CI: 0.17-0.69) or drink alcohol (aRR: 0.54, 95% CI: 0.47-0.63) during pregnancy. Children of GS were more likely to be born preterm (20-33 weeks [aRR: 2.32, 95% CI: 1.73-3.10], 34-36 [aRR: 2.50, 95% CI: 2.08-3.01] weeks of gestation), and at a birthweight < 2500g (aRR: 1.57, 95% CI: 1.26-1.95), whereas no difference in child’s sex was observed.

Conclusion: The findings suggest that gestational surrogates tended to be older, non-Hispanic white, overweight or obese, and seldom smoked or consumed alcohol during pregnancy. They tended to have multiple gestation, preterm and low birthweight children, and privately funded KP membership.