ObGyn Intelligence
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Short Cervix Pathway

Short Cervix & Preterm Birth Prevention

A clinical decision-support pathway for screening and managing cervical length in singleton pregnancy — by risk group, cervical length, and gestational age.

Practice update — 17-OHPC. The FDA withdrew approval of 17-hydroxyprogesterone caproate (Makena and all generics, intramuscular and subcutaneous) on April 5, 2023, for lack of demonstrated efficacy in preventing recurrent preterm birth. SMFM discourages continued prescribing, including via compounding pharmacies (reaffirmed 2025). This tool reflects that withdrawal: vaginal progesterone is the remaining progestogen option in the U.S. The 2022 VIP trial below predates the withdrawal and is presented for comparative context only.
Evidence base — what this tool is built on
  1. Boelig RC, Kripalu V, Chen SL, Cruz Y, Roman A, Berghella V. Utility of follow-up cervical length screening in low-risk women with a cervical length of 26 to 29 mm. Am J Obstet Gynecol 2021;225:179.e1-6. doi:10.1016/j.ajog.2021.02.027 Retrospective cohort (n=144 with follow-up). Defines management of the borderline 26–29 mm cervix in low-risk women.
  2. Boelig RC, Schoen CN, Frey H, Gimovsky AC, Springel E, Backley S, Berghella V. Vaginal progesterone vs intramuscular 17-hydroxyprogesterone caproate for prevention of recurrent preterm birth (VIP): a randomized controlled trial. Am J Obstet Gynecol 2022;226:722.e1-12. doi:10.1016/j.ajog.2022.02.012 Open-label RCT (n=188 analyzed). Head-to-head comparison; supports vaginal progesterone, including earlier initiation and longer latency.
  3. Boelig RC, Zuppa AF, Kraft WK, Caritis S. Pharmacokinetics of vaginal progesterone in pregnancy. Am J Obstet Gynecol 2019;221:263.e1-7. doi:10.1016/j.ajog.2019.06.019 Prospective PK study (n=6). Minimal systemic exposure in pregnancy — supports a predominantly local (uterine first-pass) mechanism.
  4. American College of Obstetricians and Gynecologists. Prediction and prevention of spontaneous preterm birth. ACOG Practice Bulletin No. 234. Obstet Gynecol 2021;138:e65-90. Guideline framework for cervical length screening, progesterone, and cerclage.
  5. Society for Maternal-Fetal Medicine. Statement: response to the FDA withdrawal of 17-alpha hydroxyprogesterone caproate. 2023 (reaffirmed 2025). Basis for removing 17-OHPC as a recommended option.

Evidence base is singleton pregnancy. Decision support only — does not replace clinical judgment.