European Journal of Cardiovascular Medicine

Hypertensive disorders complicate approximately 5–10% of all pregnancies and remain a significant cause of maternal and perinatal morbidity and mortality globally¹. Hypertensive emergencies during pregnancy, including severe preeclampsia and eclampsia, require immediate management to prevent end-organ damage and reduce the risk of maternal death².

The two most commonly used antihypertensive agents in such situations are intravenous labetalol and oral nifedipine. Labetalol is a combined α- and β-blocker which reduces systemic vascular resistance without significantly altering cardiac output³. Nifedipine, a calcium channel blocker, reduces blood pressure by inducing vasodilation⁴. Both drugs have been used extensively and are recommended by ACOG and WHO for managing acute severe hypertension in pregnancy⁵.

However, due to variation in onset, route of administration, and side-effect profiles, clinicians often debate the choice between these agents. Several studies have attempted to compare the two; yet, findings remain inconclusive in terms of efficacy, speed of action, and safety⁶˒⁷.

A 2013 meta-analysis by Duley et al. suggested both drugs are nearly equally effective in lowering BP, but labetalol may offer a faster onset in IV form⁸. Similarly, a randomized study by Shekhar et al. highlighted better maternal tolerability with labetalol, although fetal outcomes did not differ significantly⁹. The 2011 WHO technical guidelines advocate for both medications as first-line options, depending on availability and physician familiarity¹⁰.

In developing countries like India, where maternal deaths due to preeclampsia are still unacceptably high, evaluating cost-effective and practical protocols for hypertensive emergencies becomes essential. This study compares the efficacy of intravenous labetalol and oral nifedipine in achieving rapid BP control in pregnant women presenting with hypertensive emergencies.

This is a Prospective, comparative, randomized study conducted in the Department of Obstetrics and Gynecology at a tertiary care hospital over 12 months.

Sample Size:

100 patients divided into:

·         Group A: 50 received intravenous labetalol

·         Group B: 50 received oral nifedipine

Inclusion Criteria:

·         Pregnant women aged 18–40 years

·         Gestational age > 28 weeks

·         Systolic BP ≥ 160 mmHg or diastolic BP ≥ 110 mmHg

·         No prior antihypertensive treatment

·         Singleton pregnancy

Exclusion Criteria:

·         Asthma or cardiac disease

·         Known allergy to labetalol or nifedipine

·         Fetal distress on admission

·         Chronic hypertension before pregnancy

Intervention Protocol:

·         Group A: IV labetalol 20 mg stat, repeated every 10–15 mins as needed (max 300 mg)

·         Group B: Oral nifedipine 10 mg capsule, repeated after 30 mins if needed (max 50 mg)

Monitoring Parameters:

·         Time to achieve target BP (<150/100 mmHg)

·         Number of doses required

·         Maternal side effects (nausea, hypotension, tachycardia)

·         Fetal heart rate changes

·         Mode of delivery and neonatal outcomes

Statistical Analysis:

Data analyzed using SPSS v25. Mean, SD, t-tests, and chi-square used. P < 0.05 was considered significant.

Table 1: Demographic Characteristics

Table 2: Time to Achieve Target BP

Table 3: Number of Doses Required

Table 4: Maternal Side Effects

Table 5: Fetal Heart Rate Changes

  Table 6: Maternal and Neonatal Outcome

Hypertensive emergencies during pregnancy, particularly in the third trimester, pose serious risks to both maternal and fetal well-being. Prompt, effective blood pressure control is crucial to prevent complications such as eclampsia, placental abruption, stroke, or fetal compromise. The current study compared two widely accepted first-line antihypertensives: intravenous labetalol and oral nifedipine, assessing their efficacy, onset of action, safety, and perinatal outcomes.

Our findings suggest that both agents are effective in lowering blood pressure in pregnant women presenting with severe hypertension; however, intravenous labetalol demonstrated a significantly faster onset of action, achieving target blood pressure within a mean of 25.1 minutes compared to 34.8 minutes for nifedipine (p < 0.01). This is consistent with the results reported by Magee et al. ¹¹, who noted a shorter time to control with IV labetalol. Similarly, Brown et al.¹² and Shekhar et al. 9 emphasized the quicker action of labetalol, attributing it to its combined alpha- and beta-adrenergic blockade that causes vasodilation without reflex tachycardia.

Despite the faster control achieved by labetalol, both drugs demonstrated comparable efficacy in sustaining blood pressure control, minimizing the need for repeated dosing in most patients. In our study, 56% of the labetalol group required only a single dose, whereas 42% did so in the nifedipine group. The requirement for three or more doses was higher in the nifedipine group, suggesting a potential need for closer follow-up when using oral agents.

The maternal side-effect profile also favored labetalol, with fewer complaints of palpitations and nausea. Notably, 10% of patients in the nifedipine group reported palpitations, a common adverse effect associated with dihydropyridine calcium channel blockers due to their vasodilatory action. These findings align with the results of Duley et al. ¹4 and Moodley et al.¹5, who observed higher incidences of maternal discomfort with oral nifedipine. Nonetheless, the overall side-effect profiles were acceptable in both groups, reaffirming their safety for use in acute settings.

Regarding fetal heart rate (FHR) changes, transient bradycardia and tachycardia were slightly more common in the nifedipine group (6% vs 2%), although these changes were self-limiting and not associated with adverse neonatal outcomes. These results mirror findings from Deka et al.¹6 and Belfort et al.¹7, who concluded that while both drugs may cause transient FHR alterations, neither is associated with sustained fetal compromise when used judiciously.

Perinatal outcomes, including Apgar scores, neonatal ICU admissions, and mode of delivery, were statistically comparable across both groups. Cesarean rates were slightly higher in the nifedipine group (30% vs. 28%), possibly reflecting physician preference rather than drug-related causes. Previous studies, including Magee et al. and Hall et al.18, 19 confirm that neither labetalol nor nifedipine adversely impacts delivery outcomes when administered appropriately.

One of the key strengths of our study is its prospective, randomized design and direct comparison of two first-line agents in real-time clinical settings. However, limitations include a relatively small sample size and single-center design, which may affect the generalizability of results.

Our findings reaffirm that both intravenous labetalol and oral nifedipine are effective and safe options for the management of hypertensive emergencies in pregnancy. However, the more rapid BP control and better maternal tolerability of labetalol may offer a clinical advantage in tertiary care centers where IV administration is feasible. Oral nifedipine remains an excellent choice in low-resource settings or where rapid IV access is unavailable. Further large-scale, multicentric trials may provide more definitive guidance on drug choice based on maternal-fetal outcomes

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