359: Crown-rump length discordance and adverse pregnancy outcomes in dichorionic twins

Lorie Harper, Aaron B Caughey, Anthony Odibo, Kimberly Roehl, Qiuhong Zhao, Alison Cahill Washington University in St. Louis, Department of Obstetrics and Gynecology, St. Louis, MO, Oregon Health & Science University, Department of Obstetrics and Gynecology, Portland, OR OBJECTIVE: Knowledge of the normal progress of labor enables obstetricians both to actively manage labor and to diagnose protraction and arrest. Unfortunately, little information is available regarding the progress of labor in patients who are induced. Our objective was to compare the normal labor progress of women whose labor was induced to that of women who labor spontaneously. STUDY DESIGN: A retrospective cohort study of all consecutive women admitted for labor 37.0 weeks’ gestation from 2004-2008 who reached the second stage of labor. Detailed information was collected on maternal demographics, labor progress, medications used during labor, and neonatal outcomes. Women whose labor was induced were compared to women who labored spontaneously. Women with augmented labor were excluded from this analysis. Results were stratified by parity. Univariate and multivariate analyses were performed; interval censored regression was used to estimate the median time spent to progress 1-cm in dilation and the total time from 4-10-cm dilation by parity. RESULTS: Of 5,388 women in the cohort, 3668 were included in this analysis: 2021 spontaneous labor and 1647 induced. After adjusting for race, obesity, macrosomia and Bishop score, induced subjects had a significantly longer total time in labor than subjects who labored spontaneously (median (95th percentile) in hours for nulliparas: 5.5 (17.4) induced vs 3.8 (12.1) spontaneous, for multiparas 4.4 (17.0) induced vs 2.4 (9.2) spontaneous) . However, median time to progress 1-cm dilation in active labor ( 6-cm) was similar in induced and spontaneous labor. The time to progress 1-cm dilation in latent labor ( 6-cm) was significantly longer in induced versus spontaneous laboring subjects. CONCLUSION: The latent phase of labor is significantly longer in induced labor compared to spontaneous labor, though the active phase of labor ( 6-cm) is similar between the two groups. Arrest diagnoses before 6-cm in women undergoing induction should be considered carefully, but expectations for labor progression after 6-cm should be similar to women laboring spontaneously. 359 Crown-rump length discordance and adverse pregnancy outcomes in dichorionic twins Lorie Harper, Kimberly Roehl, Anthony Odibo, Alison Cahill Washington University in St. Louis, Department of Obstetrics and Gynecology, St. Louis, MO OBJECTIVE: Growth discordance in twin pregnancy is considered a risk factor for adverse perinatal outcomes. However, data is conflicting regarding the significance of first trimester growth discordance. Our objective was to determine the association of first trimester growth discordance and adverse pregnancy outcomes in dichorionic twin pregnancies. STUDY DESIGN: A retrospective cohort study of all consecutive women with dichorionic twin pregnancies undergoing ultrasound between 7-14 weeks gestation at a single tertiary center. Study groups were defined by the presence of 11% crown-rump length (CRL) discordance, based on the definition in published literature, calculated as the CRL difference between twins divided by the larger CRL. Pregnancies were excluded if one twin was demised at initial ultrasound or if a termination was performed. Dedicated research nurses identified outcomes prospectively. Primary outcomes were 20 week loss of either fetus (SAB), fetal anomaly, and fetal demise after 20 weeks (stillbirth). Secondary outcomes included growth restriction (IUGR), defined as growth 10% on the Alexander growth standard, admission to the neonatal intensive care unit (NICU), and preterm delivery 34 weeks. RESULTS: Of 805 dichorionic twin pregnancies undergoing first trimester ultrasound, 610 met the inclusion criteria; 86 of whom had 11% CRL discordance. Of these, 9 (10.5%) had a SAB (risk ratio (RR) 7.8, 95% confidence interval (CI) 3.0-20.5). In the surviving pregnancies, an increased risk of fetal anomalies was seen (27.3% vs Poster Session II Diabetes, Labor, Medical-Surgical-Disease, Obstetric Quality & Safety, Prematurity, Ultrasound-Imaging www.AJOG.org