Blood Pressure Control in Pregnancy
For pregnant women with hypertension, initiate antihypertensive therapy when blood pressure reaches ≥140/90 mmHg in those with gestational hypertension, pre-existing hypertension with superimposed gestational hypertension, or hypertension with organ damage/symptoms; target diastolic BP of 85 mmHg and systolic BP of 110–140 mmHg using extended-release nifedipine or labetalol as first-line agents, with methyldopa as an alternative despite its less favorable side-effect profile. 1, 2
Treatment Thresholds
Start pharmacologic therapy at ≥140/90 mmHg in women with gestational hypertension (with or without proteinuria), pre-existing hypertension with superimposed gestational hypertension, or hypertension with subclinical organ damage or symptoms at any gestational age. 1, 2
For uncomplicated chronic hypertension without organ involvement, initiate treatment at the higher threshold of ≥150/95 mmHg. 1, 3
Severe hypertension (≥160/110 mmHg sustained for ≥15 minutes) constitutes a hypertensive emergency requiring immediate hospitalization and treatment within 60 minutes to prevent maternal stroke. 1, 2, 4
Blood pressure ≥170/110 mmHg is an absolute emergency mandating immediate admission. 1
Blood Pressure Targets
Target diastolic BP of approximately 85 mmHg; never reduce diastolic pressure below 80 mmHg to avoid compromising uteroplacental perfusion and causing maternal hypotension. 1, 2, 5
Target systolic BP of 110–140 mmHg to balance maternal protection with adequate placental blood flow. 1, 2, 5
Reduce or discontinue antihypertensive medications if diastolic BP falls below 80 mmHg to protect fetal perfusion. 2, 6
First-Line Oral Agents for Chronic Control
Extended-Release Nifedipine (Preferred)
Extended-release nifedipine is the preferred first-line calcium channel blocker with established safety data and consistent guideline endorsement. 2
Dosing: Start at 30 mg once daily; titrate up to a maximum of 120 mg daily for maintenance therapy. 2, 5
Advantages: Once-daily dosing improves adherence compared to agents requiring multiple daily doses. 2
Common side effects: Headache, tachycardia, and peripheral edema may require switching to labetalol. 2, 5
Labetalol (Co-First-Line)
Labetalol has comparable efficacy and safety to nifedipine based on post-hoc analysis of the CHAP trial showing no difference in maternal or neonatal outcomes. 2
Dosing: Start at 100 mg twice daily; titrate up to a maximum of 2400 mg per day in divided doses (typically TID or QID due to accelerated metabolism in pregnancy). 2, 5
Contraindication: Avoid in women with reactive airway disease (asthma/COPD). 2
Potential risks: Fetal bradycardia, neonatal hypoglycemia, and possible small-for-gestational-age infants. 2
Methyldopa (Alternative)
Methyldopa has the longest documented safety record with pediatric follow-up to 7.5 years of age. 2, 5, 3
Major limitation: Less favorable side-effect profile, particularly risk of postpartum depression; must be switched to nifedipine or labetalol before hospital discharge. 2, 6, 5
Dosing: Typical maintenance doses range from 250 mg twice daily up to 2000 mg per day in divided doses. 7
Acute Management of Severe Hypertension (≥160/110 mmHg)
Immediate-Release Oral Nifedipine (First-Line for Acute)
Dose: 10–20 mg orally (never sublingual); repeat every 20–30 minutes if BP remains ≥160/110 mmHg. 2, 5
Critical safety warning: Never administer sublingual nifedipine—risk of uncontrolled hypotension and maternal myocardial infarction. 2, 5
Absolute contraindication: Do not combine with magnesium sulfate—risk of precipitous hypotension, myocardial depression, and fetal compromise. 2, 6, 5
Intravenous Labetalol (First-Line for Acute)
Escalation: 40 mg after 10 minutes, then 80 mg every 10 minutes for up to two additional doses. 2, 5
Intravenous Hydralazine (Second-Line)
Repeat dosing: 5–10 mg IV every 20–30 minutes as needed. 2, 5
Important caveat: Hydralazine is associated with more unpredictable hypotension and higher perinatal adverse effects compared to labetalol or nifedipine; reserve for when other agents are unavailable. 2, 5
Never use continuous IV hydralazine infusion—produces rapid, uncontrolled BP drops leading to unacceptable fetal distress rates. 5
Absolutely Contraindicated Medications
ACE inhibitors, angiotensin-receptor blockers (ARBs), direct renin inhibitors, and mineralocorticoid-receptor antagonists are strictly contraindicated throughout pregnancy due to severe fetotoxicity, renal dysgenesis, and oligohydramnios, with effects especially pronounced in the second and third trimesters. 1, 2, 3, 7
Atenolol should be avoided due to association with fetal growth restriction. 2, 6
Critical Pitfalls to Avoid
Never use immediate-release nifedipine for chronic maintenance therapy—reserve exclusively for acute severe hypertension; using it chronically carries risk of uncontrolled hypotension and maternal myocardial infarction. 2, 5
Never combine calcium-channel blockers with magnesium sulfate—synergistic effect causes precipitous hypotension and myocardial depression. 2, 6, 5
Never continue methyldopa postpartum—switch to nifedipine or labetalol before discharge due to depression risk. 2, 6, 5
Never target diastolic BP <80 mmHg—no maternal benefit and may compromise uteroplacental perfusion. 1, 2, 5
Do not withhold treatment at 140/90 mmHg in high-risk women—this threshold meets guideline criteria for intervention in gestational hypertension, superimposed hypertension, or hypertension with organ damage. 1, 6
Postpartum Management
Switch methyldopa to nifedipine or labetalol before hospital discharge to prevent postpartum depression. 2, 5
Treat urgently if postpartum BP reaches ≥160/110 mmHg lasting >15 minutes to prevent maternal stroke. 2, 5
Both labetalol and extended-release nifedipine are safe for breastfeeding mothers; do not discontinue for lactation. 2, 5
Avoid diuretics postpartum—may reduce milk production and suppress lactation. 2, 5
Blood pressure often worsens between postpartum days 3–6; maintain therapy during this window and monitor closely. 2, 5
Continue antihypertensive medication until BP normalizes, which may take days to several weeks postpartum. 2, 5
When tapering combination therapy (labetalol + nifedipine), taper labetalol first because nifedipine's once-daily dosing improves long-term adherence. 2
Monitoring Requirements
Home blood pressure monitoring is strongly recommended during pregnancy and postpartum; treatment decisions should be based on average readings over several days rather than single measurements. 2, 5
Check BP at least 4–6 times daily during the first 3 days postpartum when BP elevation risk is highest. 2, 5
Monitor for proteinuria, neurological symptoms, and laboratory abnormalities (hemoglobin, platelets, liver enzymes, creatinine) at least twice weekly in women with gestational hypertension or preeclampsia. 5
Fetal monitoring: Ultrasound assessment of biometry, amniotic fluid, and umbilical-artery Doppler at diagnosis, repeated every 2 weeks if stable. 5
Prevention Strategies
Low-dose aspirin (75–150 mg daily) from 12 weeks gestation until 36–37 weeks for women at high or moderate risk of preeclampsia. 5
Calcium supplementation (≥1 g daily) reduces preeclampsia risk, especially in women with low dietary calcium intake or chronic hypertension. 2, 5