B

Current obstetric-anesthesia guidelines favor phenylephrine as first-line treatment for maternal hypotension because it reliably restores blood pressure with less fetal acidosis and fewer maternal side-effects than ephedrine; hence it is considered the vasopressor of choice during pregnancy, particularly for cesarean delivery under neuraxial anesthesia [Cooper, 2012, PMID 22473212; Loubert, 2012, PMID 22528166].