Pregnancy Complications · 5 min read
Hypertensive Disorders of Pregnancy
Hypertensive disorders complicate roughly 1 in 10 pregnancies and are a leading cause of maternal death, most often from stroke, eclampsia, HELLP syndrome, and pulmonary edema. Hypertension in pregnancy is a systolic pressure of 140 mm Hg or higher or a diastolic pressure of 90 mm Hg or higher on two occasions at least 4 hours apart. Severe-range pressure is 160 systolic or 110 diastolic or higher.
Classification
| Disorder | Definition | Key point |
|---|---|---|
| Chronic hypertension | Hypertension before pregnancy or diagnosed before 20 weeks | Higher risk of superimposed preeclampsia, abruption, and fetal growth restriction |
| Gestational hypertension | New hypertension at or after 20 weeks without proteinuria or severe features | Up to half progress to preeclampsia; managed like preeclampsia if pressures reach the severe range |
| Preeclampsia | New hypertension at or after 20 weeks with proteinuria, or with new end-organ dysfunction even without proteinuria | Proteinuria: ≥300 mg per 24 h, protein/creatinine ratio ≥0.3, or dipstick 2+ when quantitative testing is unavailable |
| Chronic hypertension with superimposed preeclampsia | Preeclampsia features develop in a patient with chronic hypertension | Suggested by new proteinuria, worsening pressure, or new severe features |
| Eclampsia | New-onset tonic-clonic seizures in a patient with preeclampsia and no other cause | Can occur antepartum, intrapartum, or postpartum, including without prior severe features |
Pathophysiology of Preeclampsia
Preeclampsia begins with abnormal placentation: trophoblast cells fail to remodel the maternal spiral arteries into wide, low-resistance vessels. The resulting placental ischemia releases antiangiogenic factors that cause widespread maternal endothelial dysfunction, producing vasospasm, increased capillary permeability, platelet activation, and reduced organ perfusion. Plasma volume is often contracted even when the patient is edematous, which is why fluid overload easily causes pulmonary edema.
Severe Features
- Systolic ≥160 or diastolic ≥110 mm Hg on two occasions at least 4 hours apart (confirmed within minutes to allow timely treatment)
- Platelet count below 100,000/µL
- Liver transaminases twice the upper limit of normal, or severe persistent right upper quadrant or epigastric pain
- Serum creatinine above 1.1 mg/dL or doubling of baseline
- Pulmonary edema
- New headache unresponsive to medication, or visual disturbances
HELLP Syndrome
HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets) is a severe form of preeclampsia; up to 15% of patients have normal blood pressure at presentation. The typical complaint is right upper quadrant or epigastric pain, nausea, vomiting, and malaise, which is easily mistaken for gastroenteritis or gallbladder disease. Complications include disseminated intravascular coagulation (DIC), abruption, acute kidney injury, subcapsular liver hematoma, and hepatic rupture. Management is stabilization, magnesium sulfate, blood pressure control, and delivery.
Magnesium Sulfate
Magnesium sulfate is the drug of choice to prevent and treat eclamptic seizures; it is not an antihypertensive. A typical regimen is a 4–6 g IV loading dose over 15–20 minutes followed by 1–2 g/hour, continued for 24 hours after birth (or after the last seizure). It is a high-alert medication given by infusion pump as a secondary line, with independent double-checks.
| Serum magnesium | Expected finding |
|---|---|
| 4.8–8.4 mg/dL | Therapeutic range for seizure prophylaxis |
| ≈10 mg/dL | Loss of deep tendon reflexes (first sign of toxicity) |
| ≈12 mg/dL | Respiratory depression |
| >25 mg/dL | Cardiac arrest |
- Assess DTRs, respiratory rate, oxygen saturation, level of consciousness, and urine output at least hourly.
- Stop the infusion and notify the provider for absent reflexes, respirations below 12/min, or urine output below 30 mL/hour.
- The antidote is calcium gluconate 1 g IV (10 mL of a 10% solution) given slowly; keep it at the bedside.
- Magnesium is renally excreted, so oliguria rapidly raises serum levels.
- Magnesium relaxes the uterus: anticipate uterine atony and postpartum hemorrhage.
- Fetal heart rate variability may decrease during infusion; the newborn may be hypotonic.
Acute Treatment of Severe Hypertension
Severe-range pressure that persists for 15 minutes or more is a hypertensive emergency and should be treated within 30–60 minutes to prevent stroke. The goal is a pressure of about 140–150/90–100 mm Hg, not normal pressure, to protect placental perfusion.
| Drug | Typical initial dose | Nursing considerations |
|---|---|---|
| Labetalol IV | 20 mg IV over 2 minutes; then 40 mg, then 80 mg every 10 minutes | Avoid in asthma, heart block, and bradycardia; watch maternal heart rate |
| Hydralazine IV | 5–10 mg IV over 2 minutes; repeat in 20 minutes | Can cause maternal tachycardia, headache, and hypotension that affects the fetal heart rate |
| Nifedipine immediate-release (oral) | 10–20 mg orally; repeat in 20 minutes | Useful without IV access; do not give sublingually |
Eclampsia Management
Prevention and Delivery Timing
- Low-dose aspirin (81 mg daily) started between 12 and 28 weeks (ideally before 16 weeks) and continued until birth reduces preeclampsia in high-risk patients (prior preeclampsia, chronic hypertension, diabetes, renal or autoimmune disease, multifetal gestation).
- Gestational hypertension or preeclampsia without severe features: delivery at 37 weeks.
- Preeclampsia with severe features: delivery at 34 weeks or once stabilized if maternal or fetal condition worsens; expectant management before 34 weeks only in a tertiary center with corticosteroids.
- Preeclampsia can first appear postpartum, usually within 6 weeks; teach patients to report headache, visual changes, shortness of breath, and epigastric pain after discharge.
- Magnesium prevents seizures; labetalol, hydralazine, and oral nifedipine lower blood pressure.
- First sign of magnesium toxicity is loss of deep tendon reflexes; antidote is calcium gluconate.
- Treat severe-range pressure within 30–60 minutes of confirmation.
- RUQ or epigastric pain with low platelets suggests HELLP even when pressure is only mildly elevated.
- Anticipate postpartum hemorrhage in a patient who received magnesium.
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