progesterone (n¼14), PI 1.05 (CI 0.87-1.23), p¼0.004. However, there was no significant UtA PI difference for 17-OHPC (n¼16), PI 0.90 (CI 0.71-1.09), compared to referent at 18-24wks, p¼0.23. There were no differences observed in UtA PI between P4 (n¼8) and 17-OHPC (n¼11) compared to referent (n¼11) at 28-32wks, although sample size at visit 2 was below our calculated threshold. Study groups were similar with respect to race, BMI, smoking status. CONCLUSION: Vaginal progesterone in women with short cervix is associated with vascular relaxation and increased uterine blood flow at 18-24wks compared to women receiving no therapy. This vascular effect was not observed in those receiving systemic 17-OHPC for prior preterm birth. Increased blood flow to the uterus with sub-sequent improved local drug delivery may be a component of the mechanism by which vaginal P4 prevents preterm labor in women with short cervix. The differences in effects of P4 and 17-OHPC on uterine vascular flow support differences in their mechanisms of action, which warrant further investigation. OBJECTIVE: Progesterone supplementation can reduce rates of pre-term birth (PTB) via multiple mechanisms, including smooth muscle relaxation. Although most women who receive progesterone will deliver at term, a significant proportion still deliver prior to 37 weeks of gestation. Little is known regarding the effects of antenatal progesterone on labor outcomes in this cohort. Our objective was to assess the effect, if any, of antenatal 17-alpha hydroxyprogesterone caproate (17P) on labor outcomes among women delivering prior to term. STUDY DESIGN: This is a secondary analysis of a Maternal-Fetal Medicine Units Network prospective randomized, double-blind, placebo controlled trial of 17P for prevention of recurrent PTB. In the original study, women with a history of PTB carrying singleton gestations were randomized to weekly 17P or placebo from 16-20 weeks' gestation to 36 weeks' gestation, or delivery. For the current study, women delivering prior to 37 weeks were identified for analysis. Between-group comparisons were made for labor out-comes, using Student's t-test or chi-square test; p<0.05 was considered significant. RESULTS: 195 women delivering at less than 37 weeks of gestation were included in the analysis; 111 received 17P and 84 received placebo. Baseline demographic characteristics including maternal age, parity, and body mass index (BMI) are presented; only BMI differed between groups (Table). The mean interval between the final injection and delivery, and the gestational age at delivery were also similar between groups (Table). When analyzing labor charac-teristics, there was no significant difference in duration of labor (10.82 vs. 9.56 hours, p¼0.37330), duration of ruptured membranes (11.83 vs. 30.56 hours, p¼0.1030), or need for labor induction (12.61% vs. 14.29%, p¼ 0.7336) between those receiving 17P and those receiving placebo. CONCLUSION: In this cohort of women with a history of PTB, weekly antenatal 17P was not associated with differences in labor charac-teristics among women delivering prior to term.
Gonthier, C., Estellat, C., Alfaiate, T., Schmitz, T., Oury, J.-F., Mandelbrot, L., … AZRIA, E. (2016). 547: Impact of maternal deprivation on prenatal care utilization: the PreCARE cohort study. American Journal of Obstetrics and Gynecology, 214(1), S294–S295. https://doi.org/10.1016/j.ajog.2015.10.591