Poster Session 1
Category: Labor
Poster Session 1
Antonina I. Frolova, MD, PhD (she/her/hers)
Assistant Professor of Ob&Gyn
Washington University School of Medicine
St. Louis, Missouri, United States
Methodius G. Tuuli, MBA, MD, MPH
Chace-Joukowsky Professor of Obstetrics and Gynecology, Chair of Obstetrics and Gynecology
Department of Obstetrics and Gynecology, Warren Alpert Medical School at Brown University, and Women & Infants Hospital of Rhode Island
Providence, Rhode Island, United States
Adam K. Lewkowitz, MD, MPHS
Assistant Professor
Women & Infants Hospital of Rhode Island / Warren Alpert Medical School of Brown University
Providence, Rhode Island, United States
Julie Tumbarello, MA
University of Michigan
Ann Arbor, Michigan, United States
Emily Diveley, BSN, BS
Washington University School of Medicine
Washington University School of Medicine, Missouri, United States
Crystal F. Ware, RN
Women & Infants Hospital of Rhode Island / Warren Alpert Medical School of Brown University
Providence, Rhode Island, United States
Madeline Felske, MS
University of Michigan
Ann Arbor, Michigan, United States
Peinan Zhao, PhD
Washington University School of Medicine
Washington University School of Medicine, Missouri, United States
Molly J. Stout, MD, MS (she/her/hers)
Associate Professor
University of Michigan
Ann Arbor, Michigan, United States
High BMI is associated with labor outcomes including delayed onset of labor and higher risk for cesarean. It is unclear whether these observations are physiologic, due to clinician behaviors, or both. Using a device that fully quantifies numeric cervical tissue stiffness (FQ-CES), we tested the association between BMI and cervical tissue stiffness across gestation.
Study Design:
This is a prospective cohort study of singleton pregnancies at 3 academic centers. Cervical tissue stiffness was measured using FQ-CES in all three trimesters. Linear mixed effects models tested the association between BMI and cervical softening patterns (log-scaled Young’s Modulus). BMI (kg/m²) characteristics examined were: BMI at start of prenatal care, BMI at the end of pregnancy, and BMI change over pregnancy. High BMI was dichotomized as >33 in early pregnancy, >38 at end of pregnancy (either delivery or last prenatal visit), and high BMI change >7.5 based on threshold testing of continuous data. Analyses were stratified by parity.
Results:
Of 372 individuals, median BMI was 27.4 in early and 31.8 in late pregnancy, with a median change of 4.1. High BMI in early pregnancy (p=0.03), at the end of pregnancy (P=0.002), and higher BMI change over pregnancy (p=0.001) were all associated with lower cervical stiffness (softer cervix). In a multivariable model including all three BMI metrics and parity, only higher BMI change remained significantly associated with reduced cervical stiffness (38.1% lower Youngs Modulus, p-value=0.005; Table and Figure). In multivariable analysis stratified by parity, change in BMI over pregnancy remains associated with cervical softening in multiparous patients (38.7% lower Youngs Modulus, p=0.01; Table).
Conclusion:
Higher BMI change over pregnancy is associated with softer cervixes. Delayed cervical remodeling processes may not explain previously documented associations between obesity and labor outcomes. These findings also support individualized approaches to labor induction that may account for clinical characteristics measurable with FQ-CES.