NurseSavvy™
Log inSign Up
side by side comparison

Preterm Labor vs Preeclampsia: Same Drug, Different Reason — Why Magnesium Changes Purpose

Magnesium sulfate hangs on the IV pole for both patients — but if you can't articulate why, you'll pick the wrong nursing priority. The NCLEX asks "why is this client receiving mag?" and choosing "to stop contractions" when the answer is "to prevent seizures" costs you the question.

Master this comparison — play it or drill it.

Play the gamePractice questions on this

Practice 47 NCLEX-style questions

Practice now

Comparison

Side-by-side2 compared
Focus
Dimension
Preterm Labor
Preeclampsia
Pathophysiology & risk
  • Contractions + cervical change <37 wk
  • Infection, prior preterm birth
  • Multiple gestation
  • New HTN ≥140/90 after 20 wk
  • Nulliparity, chronic HTN
  • Multiple gestation
Signs & symptoms
  • Regular contractions
  • Cervical dilation/effacement
  • Low back pain, pelvic pressure
  • Hyperreflexia, clonus
  • Proteinuria ≥300 mg/24 hr
  • Severe: headache, vision change, RUQ pain
Diagnostics & labs
  • Transvaginal cervical length
  • Fetal fibronectin
  • GBS culture
  • BP ≥140/90 twice, 4 hr apart
  • Urine protein:creatinine ratio
  • Platelets, LFTs, creatinine (HELLP)
Nursing priorities
  • Tocolytics to delay birth ~48 hr
  • Betamethasone for fetal lungs
  • ★Mag for fetal neuroprotection < 32 wk
  • Hourly I&O on mag
  • ★Mag for seizure prophylaxis
  • Hourly I&O on mag
  • Seizure precautions
Treatment & meds
  • Mag therapeutic range 4–7 mEq/L
  • Mag = neuroprotection, NOT tocolysis
  • Tocolytics: nifedipine, indomethacin
  • Mag therapeutic range 4–7 mEq/L
  • Mag prevents seizures, does NOT lower BP
  • BP: labetalol, hydralazine, nifedipine
Patient teaching
  • Report contractions or leaking fluid
  • Betamethasone: 2 IM doses, 24 hr apart
  • Report headache, vision changes, RUQ pain
  • Daily weights
  • Home BP monitoring
Red flags — escalate
  • Mag toxicity: ↓DTRs, RR <12, UOP <30
  • Mag toxicity: give calcium gluconate
  • Fever, uterine tenderness = chorioamnionitis
  • ★Eclamptic seizure
  • BP ≥160/110 → stroke risk
  • Mag toxicity: give calcium gluconate
  • Mag toxicity: ↓DTRs, RR <12, UOP <30
Complications
  • Neonatal RDS, IVH, NEC
  • Eclampsia, HELLP, stroke, organ damage
Pathophysiology & risk

Preterm Labor

  • Contractions + cervical change <37 wk
  • Infection, prior preterm birth
  • Multiple gestation

Preeclampsia

  • New HTN ≥140/90 after 20 wk
  • Nulliparity, chronic HTN
  • Multiple gestation
Signs & symptoms

Preterm Labor

  • Regular contractions
  • Cervical dilation/effacement
  • Low back pain, pelvic pressure

Preeclampsia

  • Hyperreflexia, clonus
  • Proteinuria ≥300 mg/24 hr
  • Severe: headache, vision change, RUQ pain
Diagnostics & labs

Preterm Labor

  • Transvaginal cervical length
  • Fetal fibronectin
  • GBS culture

Preeclampsia

  • BP ≥140/90 twice, 4 hr apart
  • Urine protein:creatinine ratio
  • Platelets, LFTs, creatinine (HELLP)
Nursing priorities

Preterm Labor

  • Tocolytics to delay birth ~48 hr
  • Betamethasone for fetal lungs
  • ★Mag for fetal neuroprotection < 32 wk
  • Hourly I&O on mag

Preeclampsia

  • ★Mag for seizure prophylaxis
  • Hourly I&O on mag
  • Seizure precautions
Treatment & meds

Preterm Labor

  • Mag therapeutic range 4–7 mEq/L
  • Mag = neuroprotection, NOT tocolysis
  • Tocolytics: nifedipine, indomethacin

Preeclampsia

  • Mag therapeutic range 4–7 mEq/L
  • Mag prevents seizures, does NOT lower BP
  • BP: labetalol, hydralazine, nifedipine
Patient teaching

Preterm Labor

  • Report contractions or leaking fluid
  • Betamethasone: 2 IM doses, 24 hr apart

Preeclampsia

  • Report headache, vision changes, RUQ pain
  • Daily weights
  • Home BP monitoring
Red flags — escalate

Preterm Labor

  • Mag toxicity: ↓DTRs, RR <12, UOP <30
  • Mag toxicity: give calcium gluconate
  • Fever, uterine tenderness = chorioamnionitis

Preeclampsia

  • ★Eclamptic seizure
  • BP ≥160/110 → stroke risk
  • Mag toxicity: give calcium gluconate
  • Mag toxicity: ↓DTRs, RR <12, UOP <30
Complications

Preterm Labor

  • Neonatal RDS, IVH, NEC

Preeclampsia

  • Eclampsia, HELLP, stroke, organ damage

★ marks the fact that sets a column apart.

Clinical Pearl

Preterm mag protects the fetal brain; preeclampsia mag protects the maternal brain — same drug, opposite patient.

Component Topics

PreeclampsiaPreterm Labor

Ready to master this comparison?

Get a personalized study plan built around this topic — free to try, no card needed.

Play the gamePractice questions on this

Go further

See all Maternal & Newborn topics