Sublingual nitroglycerin versus placebo as a tocolytic for external cephalic version: a randomized controlled trial in parous women

Objective The purpose of this study was to evaluate the efficacy of sublingual nitroglycerin as a tocolytic agent for external cephalic version in parous women. Study design A double-blinded randomized controlled trial was performed. Patients with parity of ≥1 at 36 to 40 weeks of gestation who were eligible for external cephalic version were included. Patients were randomized to receive either two sublingual sprays of 400 μg of nitroglycerin or two sprays of placebo 3 minutes before the trial of external cephalic version. Rates of successful external cephalic version and side effects were compared between groups. Results Of 99 patients in the study, 50 patients received sublingual nitroglycerin, and 49 patients received placebo. There were no differences in maternal age, gestational age, estimated fetal weight, amniotic fluid index, and placental location between the two groups. The success rate of external cephalic version was 48% in the nitroglycerin group compared with 63% in the placebo group (P = .13). There was a higher incidence of headaches in the nitroglycerin group (42% vs 4%, P<.001). Conclusion Sublingual nitroglycerin was associated with a higher rate of headache and did not improve the rate of successful external cephalic version.