1
65.8%, aOR 1.49, p0.01). No differences in contraction frequency or duration were noted between the groups. CONCLUSION: A significant proportion of both non-spontaneous and spontaneous labor at term results in SVD even when MVUs are less than adequate (200 MVU) in the second stage. Our findings of in- creased rates of contraction features previously considered abnormal in spontaneously laboring women highlights a need to re-examine the definitions of normal uterine activity. 316 Labor patterns in twin gestations Heidi Leftwich 1 , Mary Zaki 1 , Isabelle Wilkins 1 , Judith Hibbard 1 1 University of Illinois at Chicago, Obstetrics and Gynecology, Chicago, IL OBJECTIVE: To compare labor progression in twin versus singleton gestations. STUDY DESIGN: Retrospective review of the electronic database created by the Consortium on Safe Labor, reflecting labor and delivery infor- mation from 12 clinical centers (19 hospitals) 2002-2008. All women with twin gestations, cephalic presentation of presenting twin, gesta- tional age 34 weeks, with 2 cervical exams were included. Exclu- sion criteria were fetal anomalies or fetal demise. Singleton controls were selected by the same criteria. Categorical variables were analyzed by Chi square. Interval censored regression analysis was used to de- termine distribution for time of cervical dilation in centimeters, or “traverse times,” and controlled for birthweight (BW) of singleton and presenting twin. Repeated-measures analysis constructed mean labor curves by parity and number of fetuses. RESULTS: A total of 891 twin gestations met inclusion and exclusion criteria and were compared to 100,513 singleton controls. Twin ges- tations were more often older, Caucasian or African American, earlier gestational age, increased pre-pregnancy body mass index, and with lower BW. There was no difference in number of prior cesarean de- liveries, induction or augmentation of labor, or epidural use in the two groups. Median traverse times were increased at every centimeter in- terval in nulliparous twins, both without and with controlling for BW (p.01) (Table). For multiparas, statistically significant increase in traverse times for twin gestations was noted up to 7 centimeters re- gardless of BW (p.01); from 7-10 cm there were too few exams to evaluate. Labor curves demonstrate this same blunted labor pattern for nulliparous twin gestations, compared to singleton controls (Fig- ure). Multiparous labor curves revealed similar findings. CONCLUSION: We have demonstrated that twin gestations consistently have slower labor progression in both nulliparous and multiparous women compared to singletons, even when controlling for BW. Al- lowing longer time in labor for twin gestations is warranted. 317 Cesarean delivery once the fetal head station is already engaged: comparing data when station is evaluated clinically or non-invasively Jacky Nizard 1 , Shoshana Haberman 2 , Yves Ville 3 , Ron Gonen 4 , Yoav Paltieli 4 1 GH Pitié-Salpêtrière, Department of Obstetrics and Gynecology, Paris, France, 2 Maimonides Medical Center, Department of Obsteterisc & Gynecology, Brooklyn, NY, 3 Centre Hospitalo-Universitaire Necker-Enfants Malades, Department of Obstetrics and Gynecology, Paris, France, 4 Bnai Zion Medical Center, Department of Obstetrics and Gynecology, Haifa, Israel OBJECTIVE: Engagement of fetal head is defined as the crossing of the pelvic inlet by the larger diameter of the fetal head, defined as the BPD plane. Fetal head station can be evaluated clinically during transvagi- nal digital examination (TVDE) or using non-invasive ultrasound based devices such as the LaborPro system. The aim of this study is to analyze cases of cesarean deliveries once the fetal head is engaged according to the mode of evaluation of fetal head station. STUDY DESIGN: We performed a prospective observational study be- tween January 2009 to September 2011, in four centers in France (Paris), USA (New York), and Israel (Haifa). Total women 563 had a least one combination of fetal head station measurements with TVDE and LaborPro system, during the active phase of labor. 389 (69%) women delivered spontaneously, 90 (16%) with vacuum or forceps, and 84 (15%) by cesarean. Seven women (8% of cesarean deliveries) women had a cesarean delivery with a clinical or US evaluation con- sidering station to be more than engaged. Engagement was defined as clinical evaluation of fetal head below station 0, and head station of 0.5 or below for the LaborPro system. RESULTS: Using logistic regresion analysis, it was found that head sta- tion measured by the LaborPro system during active phase, was the only predictor of CS (P0.001, with OR0.56). Seven women were considered as having a fetal head station clearly passed engagement by Adjusted successful trial of labor (hours), singleton vs twin gestation *Adjusted for birthweight of singleton and presenting twin. Poster Session II Clinical Obstetrics, Diabetes, Labor, Medical-Surgical-Disease, Physiology/Endocrinology, Prematurity www.AJOG.org S142 American Journal of Obstetrics & Gynecology Supplement to JANUARY 2013
