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Diabetes

Poster Session 1

(318) Association Between Prenatal Metformin Exposure and Birthweights in a Cohort of Gravidae with Mild Hypertension

Tuesday, February 13, 2024
10:30 AM – 12:00 PM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level

    Primary & Presenting Author(s)

  • Matthew A. Shanahan, MD (he/him/his)

    Fellow Physician
    Baylor College of Medicine
    Houston, TX, United States

    • Coauthor(s)

  • Kjersti M. Aagaard, MD, PhD

    Professor and Vice Chair of Research Department of Obstetrics and Gynecology, Division of MFM
    Texas Children's Hospital, Baylor College of Medicine
    Houston, TX, United States

Objective: Metformin is currently the most commonly used oral antihyperglycemic agent for diabetes (DM) in pregnancy. Metformin crosses the placenta and is associated in several trials with a higher incidence of small for gestational age (SGA) births. Given the elevated risk of adverse outcomes with multiple maternal comorbidities, we hypothesized that in the setting of maternal chronic hypertension (cHTN) and DM, metformin use during pregnancy would be associated with decreased birthweights and risk of adverse outcomes.

Study Design: This was a secondary analysis of the CHAP trial, a multi-center randomized trial where pregnant participants with cHTN were randomized to antihypertensive agents to maintain goal blood pressure (BP) < 140/90 mm Hg (active treatment) or deferred treatment until BP ≥160/105 mm Hg (control). Participants in the CHAP trial with DM (gestational or type 2) with and without metformin use were compared. Participants were included if their metformin exposure was known, and excluded if enrolled in a metformin and diabetes management trial. The primary outcome was birthweight and secondary outcomes included neonatal & placental outcomes.

Results: 452 gravidae with DM were included, n=170 (37.6%) exposed to metformin and n=282 not. Participants with and without metformin exposure were similar at baseline. While neither birthweights nor incidence of SGA significantly differed with metformin exposure (Table), neonatal outcomes & placental morphology did. Specifically, the proportion of neonates with a 5-minute Apgar < 7 was higher with metformin exposure (12.9% vs 6.4%, p=0.03). Placental thickness was increased with metformin use, but placental weights were not different.

Conclusion: Among a cohort of gravidae with cHTN and DM, metformin use during pregnancy was not associated with a significant change in birthweight, but was associated with an increase in the amount of neonates with 5 minute Apgar of < 7. Further work regarding the long-term safety of fetal metformin exposure is warranted.