What are the guidelines for managing gestational hypertension in pregnant women in the Philippines?

Guidelines for Managing Gestational Hypertension in the Philippines

For pregnant women in the Philippines with gestational hypertension, initiate antihypertensive treatment when blood pressure reaches ≥140/90 mmHg, targeting a diastolic BP of 85 mmHg and systolic BP of 110-140 mmHg, using methyldopa, labetalol, or long-acting nifedipine as first-line agents. 1, 2

Definition and Diagnosis

• Gestational hypertension is defined as blood pressure ≥140/90 mmHg developing after 20 weeks of gestation that typically resolves within 6 weeks postpartum 2, 3
• Diagnosis requires at least two elevated blood pressure readings on separate occasions 3
• Critical distinction: Approximately 25% of gestational hypertension cases progress to preeclampsia, with higher risk when diagnosed before 34 weeks gestation 3, 4

Blood Pressure Measurement

• Use either manual auscultatory devices or automated upper-arm cuff devices validated specifically for pregnancy and preeclampsia 2
• Home blood pressure monitoring can evaluate white-coat hypertension, particularly in women with diabetes or nephropathy 2

Treatment Thresholds and Targets

Non-Severe Hypertension (140-159/90-109 mmHg)

Initiate pharmacological treatment at BP ≥140/90 mmHg rather than waiting for severe hypertension 1, 2. This recommendation is based on the landmark CHAP trial (2022), which demonstrated that treating mild chronic hypertension (targeting <140/90 mmHg) reduced adverse pregnancy outcomes by 18% compared to reserving treatment for severe hypertension only, without increasing risk of small-for-gestational-age infants 5.

• Target diastolic BP: 85 mmHg 1, 2, 3
• Target systolic BP: 110-140 mmHg 1, 2, 3

Severe Hypertension (≥160/110 mmHg)

Blood pressure ≥160/110 mmHg constitutes a hypertensive emergency requiring immediate treatment within 15 minutes in a monitored setting to prevent maternal stroke 1, 2, 3.

First-Line Antihypertensive Medications

For Chronic Control

The three preferred agents for ongoing blood pressure control are:

• Methyldopa - drug of choice with most extensive safety data 1, 6, 7
• Labetalol - efficacy comparable to methyldopa 1, 6, 7
• Long-acting nifedipine - calcium channel blocker option 1, 6, 8
• Metoprolol is an acceptable alternative, though atenolol should be used with caution due to association with fetal growth retardation when used long-term 4, 6

For Acute Severe Hypertension

First-line agents for urgent treatment include:

• Oral immediate-release nifedipine 1, 2, 3
• Intravenous labetalol 1, 2, 3
• Intravenous hydralazine 1, 2, 3

Important caveat: Intravenous hydralazine should no longer be considered first-line because its use is associated with more perinatal adverse effects than other drugs 4. Sodium nitroprusside remains an option for hypertensive crises but carries risk of fetal cyanide poisoning with prolonged use 4.

Absolutely Contraindicated Medications

ACE inhibitors, angiotensin receptor blockers (ARBs), and direct renin inhibitors are strictly contraindicated throughout pregnancy due to severe fetotoxicity, particularly in the second and third trimesters 1, 6, 7.

Initial Assessment and Baseline Testing

When gestational hypertension is first diagnosed, all women should have the following baseline tests performed 4:

• Full blood count (hemoglobin and platelet count) 4
• Liver enzymes (AST, ALT, LDH) and function tests (INR, bilirubin, albumin) 4
• Serum creatinine, electrolytes, and uric acid 4
• Urinalysis and microscopy, plus protein-to-creatinine ratio or albumin-to-creatinine ratio 4
• Renal ultrasound if serum creatinine or urine testing are abnormal 4

These baseline tests are essential because up to 25% of women with chronic hypertension will develop superimposed preeclampsia, and baseline values allow detection of this complication 4.

Ongoing Maternal Monitoring

• All women should be assessed in hospital when first diagnosed 2
• Regular clinical evaluation including assessment for clonus and neurological signs/symptoms 2, 3
• Urinalysis at each visit to detect proteinuria 2, 3
• Laboratory tests (hemoglobin, platelet count, liver enzymes, uric acid, creatinine) at minimum at 28 and 34 weeks gestation 3

Common pitfall: Elevated gestation-corrected uric acid levels are associated with worse maternal and fetal outcomes and should prompt detailed fetal growth assessment, but uric acid should not be used to determine timing of delivery 4.

Fetal Monitoring

• Ultrasound assessment of fetal well-being starting from 26 weeks gestation 2, 3
• Subsequent evaluations every 2-4 weeks if fetal biometry is normal 3
• More frequent monitoring (potentially weekly) in presence of suspected fetal growth restriction 3
• Regular monitoring includes fetal biometry, amniotic fluid assessment, and umbilical artery Doppler 2

Indications for Immediate Hospitalization

Admit immediately for any of the following 1, 2, 3:

• Blood pressure ≥160/110 mmHg 1, 2, 3
• Development of preeclampsia features 1, 2, 3
• Neurological signs or symptoms (new headache, visual disturbances, altered mental status) 1, 2, 3
• Laboratory abnormalities suggesting disease progression 3
• Inability to control blood pressure with ≥3 antihypertensive drug classes 1

Preeclampsia-Specific Management

All women with preeclampsia who have proteinuria and severe hypertension, or hypertension with neurological signs/symptoms, should receive magnesium sulfate for seizure prophylaxis 1, 2, 7.

Important distinction: Proteinuria is not required for diagnosis of preeclampsia but is present in approximately 75% of cases 4. Preeclampsia can be diagnosed with hypertension plus any new-onset maternal organ dysfunction, including thrombocytopenia, renal insufficiency, liver involvement, pulmonary edema, or cerebral/visual symptoms 4.

Prevention Strategies

Low-Dose Aspirin

Women at high risk (history of early-onset preeclampsia before 28 weeks) should receive low-dose aspirin 75-162 mg daily at bedtime, starting pre-pregnancy or from diagnosis of pregnancy but before 16 weeks gestation, and continued until delivery 1, 2.

Calcium Supplementation

Calcium supplementation of at least 1 gram daily during pregnancy almost halved the risk of preeclampsia, with greatest effect in high-risk women 1.

What NOT to do: Fish oil supplementation and routine low-dose aspirin for all women have failed to consistently produce benefits and are not recommended for routine prevention 4. Weight reduction is not recommended during pregnancy in obese women due to possible association with reduced neonatal weight 4.

Delivery Planning

• For women with gestational hypertension without preeclampsia, delivery can be delayed until 39+6 weeks if blood pressure is controlled and fetal monitoring is reassuring 2, 3
• Optimal timing appears to be between 38-39 weeks based on retrospective data, though this requires confirmation with randomized trials 3

Postpartum Management

• Monitor blood pressure for at least 6 weeks postpartum 2
• Women with gestational hypertension or preeclampsia have significantly increased lifetime cardiovascular risk, with relative risk of ischemic heart disease more than doubled 1, 9
• Annual medical review lifelong is recommended for cardiovascular risk assessment, lifestyle modifications, regular blood pressure control, and control of metabolic factors 1, 8

Non-Pharmacological Management

For blood pressure 140-149/90-95 mmHg without severe features:

• Close supervision and limitation of activities 4
• Normal diet without salt restriction 4
• Avoid extreme dietary approaches; realistic goal is 7-10% weight reduction over 6-12 months postpartum via modest caloric reduction of 500-1000 calories/day 4