Secondary analysis of the use of transdermal nitroglycerin for preterm labor.

Author(s): Smith GN, Guo Y, Wen SW, Walker MC

Affiliation(s): Department of Obstetrics and Gynecology, Queen's Perinatal Research Unit, Kingston General Hospital, Queen's University, Kingston, ON, Canada. gns@queensu.ca.

Publication date & source: 2010-12, Am J Obstet Gynecol., 203(6):565.e1-6.

Publication type: Comparative Study; Randomized Controlled Trial; Research Support, Non-U.S. Gov't

OBJECTIVE: This secondary analysis of a randomized placebo-controlled trial was to hypothesize on mechanisms for the improved neonatal outcomes with the use of nitroglycerin (GTN) for preterm labor. STUDY DESIGN: Women in the original trial who delivered at term were excluded. A composite of severe neonatal outcomes, gestational age at delivery, and corticosteroid use in addition to Kaplan-Meier survival analysis to assess time from randomization to delivery were examined. RESULTS: A decrease in composite neonatal outcome (relative risk, 0.21; 95% confidence interval, 0.05-0.81; P = .018) with GTN (n = 39) compared with placebo (n = 38) was primarily due to a 23 day prolongation of pregnancy (P = .019) and a trend (P = .04) toward completing a course of corticosteroids in the subgroup randomized prior to 28 weeks' gestation. CONCLUSION: We hypothesize that GTN has a gestational age-dependent reduction in neonatal outcomes as a result of pregnancy prolongation and corticosteroid administration. Copyright (c) 2010 Mosby, Inc. All rights reserved.