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Am J Perinatol 2023; 40(15): 1695-1703
DOI: 10.1055/s-0041-1740010
Original Article

A Comparison of Vaginal and Intramuscular Progesterone for the Prevention of Recurrent Preterm Birth

Authors

  • Heather A. Frey

    1   Department of Obstetrics and Gynecology, The Ohio State University College of Medicine, Columbus, Ohio

  • Matthew M. Finneran

    2   Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, South Carolina

  • Erinn M. Hade

    1   Department of Obstetrics and Gynecology, The Ohio State University College of Medicine, Columbus, Ohio
    3   Department of Biomedical Informatics, Center for Biostatistics, The Ohio State University College of Medicine, Columbus, Ohio

  • Colleen Waickman

    1   Department of Obstetrics and Gynecology, The Ohio State University College of Medicine, Columbus, Ohio

  • Courtney D. Lynch

    1   Department of Obstetrics and Gynecology, The Ohio State University College of Medicine, Columbus, Ohio

  • Jay D. Iams

    1   Department of Obstetrics and Gynecology, The Ohio State University College of Medicine, Columbus, Ohio

  • Mark B. Landon

    1   Department of Obstetrics and Gynecology, The Ohio State University College of Medicine, Columbus, Ohio

Funding None.
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Abstract

Objective This study aimed to examine whether vaginal progesterone is noninferior to 17-α hydroxyprogesterone caproate (17OHP-C) in the prevention of recurrent preterm birth (PTB).

Study Design This retrospective cohort study included singleton pregnancies among women with a history of spontaneous PTB who received prenatal care at a single tertiary center from 2011 to 2016. Pregnancies were excluded if progesterone was not initiated prior to 24 weeks or the fetus had a major congenital anomaly. The primary outcome was PTB <37 weeks. A priori, noninferiority was to be established if the upper bound of the adjusted two-sided 90% confidence interval (CI) for the difference in PTB fell below 9%. Inverse probability of treatment weighting (IPTW) was used to carefully control for confounding associated with choice of treatment and PTB. Adjusted differences in PTB proportions were estimated via IPTW regression, with standard errors adjustment for multiple pregnancies per woman. Secondary outcomes included PTB <34 and <28 weeks, spontaneous PTB, neonatal intensive care unit admission, and gestational age at delivery.

Results Among 858 pregnancies, 41% (n = 353) received vaginal progesterone and 59% (n = 505) were given 17OHP-C. Vaginal progesterone use was more common later in the study period, and among women who established prenatal care later, had prior PTBs at later gestational ages, and whose race/ethnicity was neither non-Hispanic white nor non-Hispanic Black. Vaginal progesterone did not meet noninferiority criteria compared with 17-OHPC in examining PTB <37 weeks, with an IPTW adjusted difference of 3.4% (90% CI: −3.5, 10.3). For secondary outcomes, IPTW adjusted differences between treatment groups were generally small and CIs were wide.

Conclusion We could not conclude noninferiority of vaginal progesterone to 17OHP-C; however, women and providers may be willing to accept a larger difference (>9%) when considering the cost and availability of vaginal progesterone versus 17OHP-C. A well-designed randomized trial is needed.

Key Points

  • Vaginal progesterone is not noninferior to 17OHP-C.

  • PTB risk may be 10% higher with vaginal progesterone.

  • Associations did not differ based on obesity status.

Keywords

route of progesterone administration - preterm birth - prevention of preterm birth


Publication History

Received: 26 October 2020

Accepted: 04 October 2021

Article published online:
14 December 2021

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