Preterm Labor (Threatened / Active) — ED / Inpatient Order Set (Example)

1. Location, Triage & Team

• Initial evaluation in: ☐ Labor & Delivery   ☐ ED   ☐ Antepartum unit   ☐ ICU (if maternal instability)
• Notify and involve: ☐ OB/MFM   ☐ Anesthesia   ☐ NICU / Neonatology   ☐ Social work / case management
• Document planned level of neonatal care (e.g., Level III/IV NICU) and whether neonatal resuscitation is planned (important at 22–25 weeks).

2. Diagnosis & Initial Evaluation

• Definition (document): regular uterine contractions with cervical change (dilation and/or effacement) occurring before 37 0/7 weeks.
• Focused history:
  • Gestational age (dating method), prior preterm birth, cerclage, PPROM history, infections, bleeding, trauma, recent intercourse, tocolytic/medication use.
• Physical exam:
  • Maternal vitals, abdominal exam, uterine activity, fetal presentation, sterile speculum exam if indicated (r/o ROM, bleeding source).
  • Digital cervical exam only when clinically necessary and after ROM/placenta previa considerations.
• Consider adjunct testing if diagnosis uncertain and membranes intact (per local protocol):
  • Transvaginal cervical length
  • Fetal fibronectin or other biomarkers (only if results will change management)

3. Maternal Labs, Cultures & Ultrasound

4. Assess for Contraindications to Tocolysis

Tocolysis is generally used to delay delivery for 48 hours to allow antenatal corticosteroids and/or transfer to appropriate facility; it does not prevent preterm birth long-term.

• Do not use tocolysis when any of the following are present:
  • Intrauterine fetal demise or lethal fetal anomaly
  • Non-reassuring fetal status requiring delivery
  • Clinical chorioamnionitis or maternal sepsis
  • Significant vaginal bleeding from suspected placental abruption or placenta previa
  • Severe preeclampsia/eclampsia, HELLP, or other indication for delivery
  • Advanced cervical dilation (e.g., ≥ 6 cm) or inevitable delivery
  • Maternal contraindications to specific agents (e.g., cardiac disease, severe renal/hepatic dysfunction, platelet disorder, drug allergy)
• Tocolysis is usually not recommended at ≥ 34 0/7 weeks solely to complete steroids.

5. Antenatal Corticosteroids

Antenatal corticosteroids reduce neonatal death, RDS, IVH, and NEC when given to patients at risk of preterm birth, particularly between 24 0/7 and 33 6/7 weeks, and may be considered earlier or in late-preterm windows per updated ACOG/SMFM guidance.

• Indications (document):
  • Imminent risk of preterm birth within 7 days, typically between 24 0/7 and 33 6/7 weeks.
  • May consider at 23 0/7–23 6/7 weeks if neonatal resuscitation is planned; late-preterm (34–36 weeks) dosing per institutional protocol.
• Regimen (choose one):
  • Betamethasone 12 mg IM every 24 hours × 2 doses
  • OR dexamethasone 6 mg IM every 12 hours × 4 doses
• Consider single “rescue” course before 34 weeks if > 7–14 days from prior course and renewed high risk of delivery within 7 days, per guideline/local policy.

6. Magnesium Sulfate for Fetal Neuroprotection

Magnesium sulfate given immediately before early preterm birth (< 32 weeks in many protocols) reduces cerebral palsy and composite death/cerebral palsy.

• Indications:
  • Gestational age typically < 32 weeks with high likelihood of delivery within 24 hours (e.g., advanced preterm labor, planned indicated preterm delivery).
• Example regimen (adapt to local protocol):
  • 4–6 g IV loading dose over 20–30 minutes, then 1–2 g/hour IV maintenance up to 12–24 hours or until birth.
• Monitor maternal reflexes, respiratory rate, urine output, and serum magnesium as indicated; keep calcium gluconate readily available.
• Do not use magnesium sulfate solely as a tocolytic; primary purpose is neuroprotection.

7. Tocolytic Therapy (Short-Term)

Goal: delay delivery up to 48 hours to complete corticosteroids and arrange transfer if needed. Choice of tocolytic depends on gestational age, contraindications, and provider/institution preference.

7A. Candidate Criteria

• Gestational age generally 24 0/7–33 6/7 weeks.
• Intact membranes (or PPROM where brief tocolysis is used selectively for steroid completion — coordinate with PPROM protocol).
• No contraindications listed in Section 4.

7B. Nifedipine (Calcium Channel Blocker) — Common First-Line

• Loading:
  • 10–20 mg nifedipine PO immediate release; may repeat q 20–30 minutes up to 40–60 mg in first hour as tolerated (per local regimen).
• Maintenance:
  • 10–20 mg PO q 4–6 hours (maximum daily dose per institutional protocol, often 160 mg/day).
• Monitor maternal BP and heart rate; use caution in hypotension, cardiac disease, or concurrent magnesium therapy (hypotension risk).

7C. Indomethacin (NSAID) — Typically < 32 Weeks

• Use generally limited to gestational age < 32 weeks and short duration (e.g., ≤ 48–72 hours) because of risk of ductus arteriosus constriction and oligohydramnios.
• Example regimen:
  • Loading dose: 50–100 mg PO or PR once
  • Then: 25–50 mg PO q 6 hours for up to 48 hours.
• Avoid in renal dysfunction, platelet/bleeding disorders, GI ulcer disease; monitor amniotic fluid and fetal ductus by ultrasound if prolonged use considered.

7D. β-Agonist (e.g., Terbutaline) — Rescue / Short-Term

• Reserve for short-term rescue or when other agents contraindicated; avoid prolonged use because of maternal cardiac risks.
• Example:
  • Terbutaline 0.25 mg SC q 20–30 minutes × up to 3 doses as rescue (per institutional limits).
• Contraindications: maternal tachyarrhythmia, significant cardiac disease, poorly controlled hyperthyroidism, uncontrolled diabetes. Monitor HR, BP, glucose, and potassium.

7E. Agents Not Routinely Recommended

• Routine long-term tocolysis and repeated cycles are not supported by evidence.
• Atosiban not currently available in the United States; its use should follow local formulary and national guidance where available.

8. GBS Prophylaxis & Antibiotic Use

• GBS culture status:
  • Obtain if not done; plan to give intrapartum prophylaxis if culture positive/unknown at delivery per ACOG guidance.
• Do not give routine latency antibiotics for intact membranes; reserve antibiotics for:
  • PPROM (see PPROM order set), confirmed infection (e.g., UTI, pneumonia), or GBS prophylaxis at time of labor.
• Choose pregnancy-appropriate antibiotics and adjust for allergies and local resistance patterns.

9. Cerclage, Pessary & Short Cervix Considerations

• If cerclage in situ and patient presents with preterm labor:
  • Discuss with MFM: removal vs attempts at tocolysis depending on gestational age, cervical exam, and presence of infection/bleeding.
• Do not place a new emergent cerclage in true preterm labor with significant dilation and contractions; follow SMFM cervical insufficiency guidance.
• Progesterone after successfully treated preterm labor has limited evidence; follow most recent ACOG practice advisory and local protocol.

10. Analgesia, Hydration & Nursing Orders

• IV access: ☐ Peripheral IV ×1–2
• Hydration:
  • Isotonic fluids (e.g., LR or NS) at maintenance or slightly above, avoiding fluid overload (especially with preeclampsia or cardiac disease).
• Analgesia/Anxiolysis:
  • Non-opioid options first; consider epidural analgesia during active labor if delivery is proceeding.
• Nursing:
  • Vital signs at least q 4 hours (or more frequent with tocolytics or magnesium).
  • Monitor uterine activity and fetal heart rate per unit protocol.

11. Disposition, Delivery Planning & Follow-up

• Admit for continued observation if:
  • Persistent contractions, cervical change, need for tocolysis, steroid course ongoing, or high risk of imminent delivery.
• Discharge may be considered if:
  • No cervical change after observation, contractions resolve, membranes intact, and maternal/fetal status reassuring.
• Route of delivery:
  • Based on standard obstetric indications (presentation, prior uterine scar, fetal status). Preterm labor alone is not an indication for cesarean.
• Arrange follow-up:
  • OB/MFM visit within 1 week (or sooner if symptoms persist).
  • Reinforce return precautions: contractions, bleeding, fluid leakage, decreased fetal movement, fever.

12. Patient Education & Counseling

• Explain signs of preterm labor and when to call triage vs present to L&D/ED.
• Discuss neonatal outcomes and NICU capabilities at current gestational age; involve NICU in counseling as appropriate.
• Review modifiable risk factors (tobacco, substance use, interpregnancy interval, infection treatment) and plan for future pregnancy risk reduction.

References (Selected)

1. American College of Obstetricians and Gynecologists. Practice Bulletin No. 171: Management of Preterm Labor. Obstet Gynecol. 2016;128(4):e155–e164.
2. American College of Obstetricians and Gynecologists. Committee Opinion: Antenatal Corticosteroid Therapy for Fetal Maturation; and ACOG/SMFM Practice Advisory on Antenatal Corticosteroids at 22 Weeks’ Gestation.
3. ACOG Committee Opinion: Magnesium Sulfate Before Anticipated Preterm Birth for Neuroprotection; updated data from Shepherd ES, et al. 2024 Cochrane systematic review and related literature.
4. Lee HH, et al. Tocolytic Treatment for the Prevention of Preterm Birth from Threatened Preterm Labor: A Review of the Literature. Obstet Gynecol Sci. 2022;65(3):203–214.
5. Rundell K, Panchal B. Preterm Labor: Prevention and Management. Am Fam Physician. 2017;95(6):366–372.
6. SMFM Consult Series documents on short cervix, cervical insufficiency, and periviable birth; updated guidance on cerclage and antenatal therapies.
7. ACOG Practice Advisory 2023: Updated Clinical Guidance for the Use of Progestogen Supplementation for Prevention of Recurrent Preterm Birth; and recent SMFM trial showing no benefit of progesterone after successfully arrested preterm labor.

Disclaimer

This OBPharm order set is an educational template for instructional purposes only. It does not replace institutional preterm labor protocols, ACOG/SMFM guidance, or consultation with MFM, neonatology, anesthesia, and critical care.

Medication choices, doses, and monitoring intervals must be verified against current institutional policies, pharmacy guidance, and patient-specific factors (e.g., comorbidities, renal/hepatic function, gestational age, and fetal status). For EHR implementation, each bullet should be mapped to local orderables and named to match system-specific conventions.