Residency · Residency · Family Medicine
Hypertensive Disorders of Pregnancy
Introduction
Hypertensive disorders complicate approximately 5 to 10% of pregnancies and are a leading cause of maternal morbidity and mortality worldwide. Accurate classification, timely recognition, and appropriate management are essential skills for family physicians who provide prenatal and intrapartum care.
Classification
| Disorder | Definition | Key Features |
|---|---|---|
| Chronic Hypertension | BP ≥140/90 before pregnancy or <20 weeks | Persists >12 weeks postpartum |
| Gestational Hypertension | New BP ≥140/90 at ≥20 weeks, no proteinuria | Resolves by 12 weeks postpartum; 15-25% progress to preeclampsia |
| Preeclampsia | New BP ≥140/90 at ≥20 weeks + proteinuria or end-organ dysfunction | Delivery is definitive treatment |
| Preeclampsia with Severe Features | BP ≥160/110 or end-organ dysfunction | Requires stabilization and delivery planning |
| HELLP Syndrome | Hemolysis + elevated liver enzymes + low platelets | Medical emergency; may lack marked HTN |
| Eclampsia | New-onset seizures in preeclampsia | Treat with IV magnesium sulfate |
Chronic Hypertension
Chronic hypertension is defined as blood pressure of 140/90 mmHg or greater documented before pregnancy or before 20 weeks gestation. It persists beyond 12 weeks postpartum and requires continued antihypertensive therapy during pregnancy with appropriate agent selection.
Gestational Hypertension
Gestational hypertension is new-onset hypertension (140/90 mmHg or greater) at or after 20 weeks gestation without proteinuria or other features of preeclampsia. It resolves by 12 weeks postpartum and progresses to preeclampsia in approximately 15 to 25% of cases.
Preeclampsia
Preeclampsia is defined as new-onset hypertension at or after 20 weeks gestation with proteinuria (300 mg or greater per 24 hours or a protein-to-creatinine ratio of 0.3 or greater) or end-organ dysfunction. End-organ dysfunction criteria include any one of the following: thrombocytopenia with platelets below 100,000/mcL, renal insufficiency with creatinine greater than 1.1 mg/dL or doubling of baseline, liver dysfunction with transaminases at twice normal or greater, pulmonary edema, or cerebral or visual symptoms such as headache, scotomata, or altered mental status.
Preeclampsia with Severe Features
Preeclampsia with severe features is diagnosed when systolic blood pressure reaches 160 mmHg or greater or diastolic reaches 110 mmHg or greater on two occasions at least 4 hours apart, or when any of the end-organ dysfunction criteria listed above are met. Delivery is the definitive management, with timing based on gestational age.
HELLP Syndrome
HELLP syndrome, characterized by hemolysis, elevated liver enzymes, and low platelets, is a severe variant of preeclampsia that may occur without marked hypertension. It is a medical emergency requiring stabilization and delivery.
Eclampsia
Eclampsia involves new-onset generalized tonic-clonic seizures in a patient with preeclampsia. It can occur antepartum, intrapartum, or postpartum up to 6 weeks after delivery. Treatment is with IV magnesium sulfate.
Risk Factors and Prevention
Risk Factors
Risk factors include nulliparity, advanced maternal age (35 or older), obesity, history of preeclampsia in a prior pregnancy (with a recurrence risk of 15 to 20%), chronic hypertension, chronic kidney disease, autoimmune disease (including SLE and antiphospholipid syndrome), multiple gestation, assisted reproductive technology, and family history of preeclampsia.
Prevention
Low-dose aspirin (81 to 162 mg daily) starting at 12 to 16 weeks is recommended for patients with high-risk factors. The USPSTF recommends aspirin for patients with one or more high-risk factors or two or more moderate-risk factors. Adequate calcium intake of 1.5 to 2 g daily may reduce risk, particularly in calcium-deficient populations. There is no evidence supporting salt restriction, bed rest, or vitamin supplementation for preeclampsia prevention.
Evaluation and Monitoring
Laboratory Assessment
The laboratory evaluation includes a CBC with platelet count, comprehensive metabolic panel (creatinine, liver enzymes, albumin), 24-hour urine protein or spot protein-to-creatinine ratio, and LDH, haptoglobin, and peripheral smear if HELLP is suspected. Uric acid levels, while not diagnostic, correlate with disease severity.
Fetal Surveillance
Fetal surveillance involves non-stress testing and biophysical profile, serial growth ultrasounds to assess for fetal growth restriction, umbilical artery Doppler velocimetry in cases of growth restriction, and amniotic fluid assessment.
Management
Gestational Hypertension and Preeclampsia Without Severe Features
Close outpatient monitoring with serial blood pressure measurements, laboratory tests, and fetal surveillance is the approach. The CHAP trial (2022) demonstrated benefit of treating chronic hypertension to a target below 140/90 in pregnancy. First-line antihypertensive agents include labetalol, nifedipine, and methyldopa. ACE inhibitors, ARBs, and direct renin inhibitors are avoided due to teratogenicity. Delivery is recommended at 37 weeks gestation for preeclampsia without severe features.
Preeclampsia with Severe Features
Hospitalization is required for maternal and fetal stabilization. IV magnesium sulfate is administered for seizure prophylaxis with a 4 to 6 g loading dose followed by a 1 to 2 g per hour infusion. Acute hypertension is managed with IV labetalol, IV hydralazine, or oral nifedipine for blood pressure of 160/110 or greater. Delivery is the definitive treatment: at 34 weeks or greater, delivery proceeds after stabilization; at less than 34 weeks, expectant management may be considered at a tertiary center with continuous monitoring, and betamethasone is administered for fetal lung maturity. Antenatal corticosteroids are given if delivery is anticipated within 7 days at less than 34 weeks.
Eclampsia Management
Magnesium sulfate is the treatment of choice for eclamptic seizures, not other anticonvulsants. The airway is maintained with lateral positioning and supplemental oxygen. The patient is stabilized and delivered regardless of gestational age. Monitoring for magnesium toxicity includes assessing for loss of deep tendon reflexes and respiratory depression, with calcium gluconate available as the antidote.
Postpartum Considerations
Blood pressure monitoring continues for at least 72 hours after delivery. Preeclampsia can develop or worsen postpartum, and vigilance should be maintained through 6 weeks. Antihypertensive therapy continues if blood pressure remains elevated, with labetalol and nifedipine being compatible with breastfeeding. Cardiovascular risk counseling is important because women with a history of preeclampsia have a 2- to 4-fold increased lifetime risk of cardiovascular disease, stroke, and chronic hypertension.
Key Clinical Pearls
Low-dose aspirin starting at 12 to 16 weeks is the only proven preventive intervention, and eligible patients should be identified early. Preeclampsia is a clinical diagnosis that does not require proteinuria if end-organ dysfunction is present. Magnesium sulfate is the first-line agent for seizure prophylaxis in severe preeclampsia and for treatment of eclampsia, and it is superior to phenytoin and benzodiazepines. All patients with a history of preeclampsia should be counseled about their increased lifetime cardiovascular risk and the importance of long-term primary care follow-up.
References
- ACOG Practice Bulletin No. 222: Gestational Hypertension and Preeclampsia. Obstet Gynecol. 2020;135(6):e237-e260.
- Tita AT, et al. Treatment for mild chronic hypertension during pregnancy (CHAP). N Engl J Med. 2022;386(19):1781-1792.
- Magee LA, et al. The CHIPS trial: less-tight versus tight control of hypertension in pregnancy. N Engl J Med. 2015;372(5):407-417.
- USPSTF. Aspirin Use to Prevent Preeclampsia and Related Morbidity and Mortality. JAMA. 2021;326(12):1186-1191.