What are the recommended treatment and monitoring approaches for a pregnant female with Pregnancy-Induced Hypertension (PIH)?

Management of Pregnancy-Induced Hypertension (PIH)

Blood Pressure Treatment Thresholds and Targets

Initiate antihypertensive treatment when blood pressure reaches ≥140/90 mmHg in the office (or ≥135/85 mmHg at home), targeting a diastolic BP of 85 mmHg and systolic BP of 110-140 mmHg. 1, 2

• This threshold applies to both gestational hypertension (new onset after 20 weeks) and chronic hypertension during pregnancy 1, 2
• Severe hypertension (≥160/110 mmHg) constitutes a hypertensive emergency requiring immediate treatment within 15 minutes in a monitored setting to prevent maternal stroke 1, 3, 2

First-Line Antihypertensive Medications

Use methyldopa, labetalol, or long-acting nifedipine as first-line agents for ongoing blood pressure control in pregnancy. 1, 2

• Methyldopa is traditionally considered the drug of choice with extensive safety data showing no significant adverse effects on children followed up to age 7.5 years 4, 5
• Labetalol has comparable efficacy to methyldopa and is widely used 5, 6
• Long-acting nifedipine is equally effective as a first-line option 1, 2

Acute Management of Severe Hypertension

For BP ≥160/110 mmHg, use one of the following immediately:

• Oral nifedipine (immediate-release) 2, 6
• Intravenous labetalol 3, 2, 6
• Intravenous hydralazine 3, 2, 6

Monitoring Strategy

Maternal Surveillance

Perform continuous blood pressure monitoring throughout pregnancy, with measurements taken at baseline, then at intervals determined by BP control and presence of risk factors. 1, 3

• Record BP shortly after any clinical visit and again within 6 hours if normal 1
• For women with elevated BP in early pregnancy, remeasure after 12 weeks to distinguish chronic from gestational hypertension 1
• Continuous BP monitoring is essential during labor for patients with hypertensive disorders 3

Laboratory Assessment

Obtain baseline laboratory tests at diagnosis including: 1, 3

• Complete blood count (hemoglobin, platelet count)
• Liver transaminases (AST/ALT)
• Serum creatinine and electrolytes
• Uric acid
• Urinalysis for proteinuria

Repeat these tests serially to detect progression to preeclampsia or HELLP syndrome, particularly monitoring for: 3

• Thrombocytopenia (platelets <100,000)
• Elevated liver enzymes
• Rising creatinine
• New or worsening proteinuria (urine albumin-to-creatinine ratio >30 mg/mmol) 7

Clinical Assessment for Preeclampsia Progression

Monitor for warning signs at each visit: 3

• Severe headaches or visual disturbances
• Epigastric or right upper quadrant pain
• Nausea and vomiting
• Oliguria (<500 mL/24 hours)
• Proteinuria development or worsening

Fetal Surveillance

Implement enhanced fetal monitoring when PIH is present: 3

• Serial ultrasound for fetal growth assessment (growth restriction is a key risk)
• Doppler ultrasound of uterine arteries after 20 weeks to detect those at higher risk of complications 7
• Continuous electronic fetal heart rate monitoring during labor 3

Prevention Strategies

Administer low-dose aspirin (75-162 mg daily) starting at 12 weeks gestation through 36 weeks in women at high or moderate risk of preeclampsia. 7

High-risk factors include: 7

• Hypertension in previous pregnancy
• Chronic kidney disease
• Autoimmune disease
• Diabetes
• Chronic hypertension

Moderate-risk factors include: 7

• First pregnancy in women >40 years
• Pregnancy interval >10 years
• BMI >35 kg/m²
• Family history of preeclampsia
• Multiple pregnancies

Provide oral calcium supplementation of 1.5-2 g/day in women with low dietary calcium intake (<600 mg/day). 7

Indications for Hospitalization

Admit to hospital for: 2

• BP ≥160/110 mmHg (severe hypertension)
• Development of preeclampsia features (proteinuria, symptoms, laboratory abnormalities)
• Neurological signs or symptoms
• Inability to control BP with ≥3 antihypertensive drug classes

Special Considerations for Severe Preeclampsia/Eclampsia

Administer magnesium sulfate for seizure prophylaxis when: 3, 2

• Severe hypertension develops (≥160/110 mmHg)
• Any neurological symptoms appear
• Preeclampsia with severe features is diagnosed

Give antenatal corticosteroids between 24+0 and 34+0 weeks gestation if delivery is anticipated within 7 days. 2

Timing of Delivery

Delivery timing depends on hypertension severity and presence of preeclampsia: 2

• Gestational hypertension without preeclampsia: Can delay until 39+6 weeks if BP remains controlled and fetal monitoring is reassuring
• Preeclampsia without severe features: Deliver at term (≥37 weeks)
• Severe preeclampsia or eclampsia: Immediate delivery after maternal stabilization 7, 6

Postpartum Management

Continue vigilant monitoring in the postpartum period as PIH may develop or worsen after delivery: 1, 8

• Record BP shortly after birth and within 6 hours
• Follow-up within 48-72 hours of birth
• Reassess at 7-14 days postpartum
• Final evaluation at 6 weeks postpartum with BP check and urinalysis 1
• Continue antihypertensive treatment as needed to maintain BP <140/90 mmHg 2
• Women with persistent hypertension or proteinuria at 6 weeks require specialist referral 3

Long-Term Cardiovascular Risk

Women with gestational hypertension or preeclampsia have substantially increased lifetime cardiovascular risk and require annual medical review lifelong. 1, 2, 9

• Approximately 25% of gestational hypertension cases progress to preeclampsia, and this risk extends to future cardiovascular disease 3, 8
• These women are at higher risk for chronic hypertension, coronary artery disease, stroke, and metabolic syndrome in later life 9

Critical Pitfalls to Avoid

• Do not wait for proteinuria to treat hypertension - gestational hypertension without proteinuria still requires treatment at ≥140/90 mmHg 1, 2
• Do not use ACE inhibitors or angiotensin II receptor blockers during pregnancy - these are contraindicated due to fetopathy risk 5
• Do not rely on BP alone to assess disease severity - serious organ dysfunction can develop at relatively mild BP elevations 3
• Do not assume resolution postpartum - up to 25% of eclamptic seizures occur after delivery, requiring continued vigilance 8
• Avoid atenolol in early pregnancy - it may be used in late pregnancy but methyldopa, labetalol, or nifedipine are preferred throughout 5