The American College of Obstetricians and Gynecologists has added nifedipine as a first-line treatment for acute-onset severe hypertension during pregnancy and the postpartum period in an updated opinion from its Committee on Obstetric Practice.

The update, released on Jan. 22, points to studies showing that women who received oral nifedipine had their blood pressure lowered more quickly than with either intravenous labetalol or hydralazine – the traditional first-line treatments – and had a significant increase in urine output. Concerns about neuromuscular blockade and severe hypotension with the use of nifedipine and magnesium sulphate were not borne out in a large review, the committee members wrote, but they advised careful monitoring since both drugs are calcium antagonists.

The committee opinion includes model order sets for the use of labetalol, hydralazine, and nifedipine for the initial management of acute onset severe hypertension in women who are pregnant or post partum with preeclampsia or eclampsia ( Obstet. Gynecol. 2015;125:521-5) .

While all three medications are appropriate in treating hypertensive emergencies during pregnancy, each drug has adverse effects.

For instance, parenteral hydralazine can increase the risk of maternal hypotension. Parenteral labetalol may cause neonatal bradycardia and should be avoided in women with asthma, heart disease, or heart failure. Nifedipine has been associated with increased maternal heart rate and overshoot hypotension.

“Patients may respond to one drug and not another,” the committee noted.

The ACOG committee also called for standardized clinical guidelines for the management of patients with preeclampsia and eclampsia.

“With the advent of pregnancy hypertension guidelines in the United Kingdom, care of maternity patients with preeclampsia or eclampsia improved significantly and maternal mortality rates decreased because of a reduction in cerebral and respiratory complications,” they wrote. “Individuals and institutions should have mechanisms in place to initiate the prompt administration of medication when a patient presents with a hypertensive emergency.”

The committee recommended checklists as one tool to help standardize the use of guidelines.