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Mackenzie Naert, MD




Clinical Fellow




Resident Physician


Obstetrics & Gynecology


Mackenzie N. Naert, MD*, Keizra Mecklai, BS**, Thomas F. McElrath, MD, PhD*, Sarah E. Little, MD, MPH*

The role of progesterone in the prevention of recurrent preterm birth

I am currently a third-year resident in Obstetrics and Gynecology. I am fortunate to work in a surgical field with a large proportion of female physicians to serve as research mentors and role models, although I recognize that not all female physicians and specifically trainees have this same opportunity. I am excited to participate in the Symposium to engage with other female researchers within the greater health system. My current research interests include preventing adverse birth outcomes and improving access to fertility preservation for patients with cancer.


The PROLONG trial found that 17-hydroxyprogesterone caproate (17-OHP) did not lead to a reduction in recurrent preterm birth (PTB) prior to 35 weeks. The objective of this study is to assess use of 17-OHP before and after the publication of PROLONG and whether there was any change in the rate of recurrent PTB.


We included all women with a history of spontaneous PTB who delivered at a single tertiary care hospital. We compared 17-OHP use and birth outcomes among patients who delivered before and after the PROLONG trial.


There were 417 patients included in the study (196 in Year 1 and 221 in Year 2). There were no differences in baseline characteristics. The use of 17-OHP declined dramatically, from 62.2% in Year 1 to 14.9% in Year 2: p< 0.01. However, there was no difference in birth outcomes. The mean gestational age of delivery was similar between years (37.1 weeks vs 37.2 weeks, p= 0.72). There was also no difference in the proportion of preterm birth that was spontaneous versus indicated.


Despite a 4-fold reduction in 17-OHP use at our hospital, we found no difference in the rate of recurrent preterm birth.