Design Preterm Labor Prevention Plan

---
name: design-preterm-labor-prevention-plan
description: Use when managing preterm birth risk — e.g., "preventing preterm labor", "short cervix in pregnancy", "progesterone injections pregnancy", "history of preterm birth", "cerclage for short cervix"
source: ACOG Practice Bulletin 234 (2021); Romero et al. AJOG 2012 (vaginal progesterone); Fonseca et al. NEJM 2007 (cervical length + progesterone)
tags: [pregnancy, preterm-birth, progesterone, cervical-length, cerclage, prevention, health]
verified: true
---

# Design Preterm Labor Prevention Plan

Apply risk-stratified interventions — progesterone, cervical monitoring, and cerclage — to reduce preterm birth.

## Why This Is Best Practice

**Adopted by:** ACOG, SMFM, RCOG — risk-stratified prevention is the standard of care for women with identified preterm birth risk factors.
**Impact:** Progesterone therapy reduces preterm birth before 34 weeks by 33–45% in high-risk women (Cochrane 2013, 36 RCTs). Short cervix (<25 mm at 16–24 weeks) with vaginal progesterone reduces preterm delivery <33 weeks by 58% (Fonseca et al., NEJM 2007).
**Why best:** Preterm birth is the leading cause of neonatal mortality and morbidity globally. Most cases are not preventable, but identifiable risk factors allow targeted intervention.

## Steps

1. **Risk stratification at first visit:**
   - **High risk:** prior spontaneous preterm birth <37 weeks (strongest predictor, 20–30% recurrence)
   - **Moderate risk:** uterine anomalies, prior LEEP/cone biopsy, short cervix in prior pregnancy, smoking, underweight, multiple prior D&Cs
   - **Multiple gestation:** separate high-risk category; interventions differ
2. **Prior preterm birth (singleton):**
   - Start 17-alpha-hydroxyprogesterone caproate (17-OHPC, Makena) 250 mg IM weekly from weeks 16–20 through 36 weeks
   - OR vaginal progesterone 200 mg/night (evidence equivalent; patient preference)
3. **Universal cervical length screening (weeks 18–24):**
   - Transvaginal ultrasound (TVU) cervical length — standard of care in many centers
   - Cervical length <25 mm → offer vaginal progesterone 200 mg/night
4. **Short cervix with prior preterm birth:**
   - Cervical length <25 mm + prior spontaneous PTB → offer cerclage (surgical cervical suture); SMFM 2020
5. **Signs of preterm labor — educate patient to recognize:**
   - Regular contractions before 37 weeks (>4/hour)
   - Lower back pain, pelvic pressure, vaginal discharge change
   - Any signs before 37 weeks → go to L&D triage same day
6. **For cerclage patients:** remove at 36–37 weeks; no intercourse or vaginal exams that could dislodge suture.

## Rules

- 17-OHPC evidence was contested by FDA in 2023 — discuss current evidence with MFM before prescribing; vaginal progesterone remains well-supported.
- Do not use tocolytics (nifedipine, indomethacin) as long-term prevention — they are for acute preterm labor only.
- Cervical length shortening is often asymptomatic — it is only detectable by TVU, not clinical exam.

## Examples

**Prior 33-week delivery (singleton):** Cervical length check at 16, 18, 20, 22 weeks; start vaginal progesterone at 16 weeks; cerclage if CL <25 mm at 18 weeks.
**Asymptomatic short cervix (22 mm at 20 weeks), no prior PTB:** Start vaginal progesterone 200 mg nightly; re-check CL in 2–3 weeks.

## Common Mistakes

- Waiting for symptoms to start intervention — by the time contractions begin, cervix may already be dilated.
- Using multiple gestation protocols for singleton — progesterone does not prevent preterm birth in multiples (increases risk in some studies).
- Not referring to MFM for cerclage decision — cerclage has specific indications; placing without criteria increases preterm labor risk.

> **Health Disclaimer:** This is not medical advice. Preterm birth prevention requires specialist involvement. Consult your healthcare provider or a maternal-fetal medicine (MFM) specialist for cervical length <25 mm, prior preterm birth, or any suspected preterm labor. Go to L&D triage for any contractions before 37 weeks.