RESULTS: A total of eighty women were recruited for this study (37 inthe treatment groop & 43 to the control group). Characteristics ofparticipants were similar between the groups. We found that the oddsof entering active phase of labor within 12 hours of administration ofintervention was 3 times higher among women receiving castor oilcompared to women receiving placebo (p�0.034). Further adjust-ment for parity and age augmented these findings (Odds ratio�3.94,p�0.017). Additionally, Kaplan-Meier analysis following up partici-pants 48 hours postadministration of treatment demonstrated thatwomen receiving castor oil were likely to enter the active phase oflabor somewhat faster than controls (p�0.077) (Figure). Thus, thismay suggest that the potential effect of castor oil on induction of labormay extend beyond the first 12 hours of its administration. No differ-ences between the two groups were found in labor complications andneonatal outcomes (table 1).CONCLUSION: In this trial we have shown, for the first time in a RCT,that castor oil is a safe and effective substance for induction of labor inpost-date pregnancies. Its safety profile, even in an out-patient set-up,adds to its value as a reliable “natural” modality to induce labor.

149 Evaluation of the 2009 Institute of Medicine weight gainin pregnancy guidelines in overweight and obese womenRoxane Holt1, Kenneth Leveno1, Don McIntire1, Jeanne Sheffield1

1University of Texas Southwestern Medical Center,Obstetrics and Gynecology, Dallas, TXOBJECTIVE: To evaluate the 2009 Institute of Medicine weight gain inpregnancy guidelines for overweight (BMI 25-29.9) and obese (BMI� 30) women.STUDY DESIGN: Retrospective cohort study from a single institutioninvolving a primarily indigent population. From January 1, 2002 toApril 30, 2011, women presenting with a BMI recorded in the 1sttrimester and a subsequent delivery weight were included. The study

cohort included singleton infants, excluding preexisting maternal hy-pertension. Overweight and obese women were compared to womenwith a normal BMI (18.5-24.9) using three categories of weight gain(weight gain under, within, and above the recommended guidelines).Standard methods were used for statistical analysis.RESULTS: During the study period, 16,428 overweight women wereidentified: 2,625 gained below, 6,156 gained within, and 7,647 gainedabove the guidelines. In addition, 11,607 obese women were included:2,120 gained below, 3,840 gained within, and 5,647 gained above theguidelines. Overweight and obese women gaining less than the rec-ommended weight gain had significant adverse outcomes includingPTB 4000g, and �90%), and cesarean delivery for labor dystocia.Overweight and obese women gaining above the recommendedweight gain guidelines were found to have fewer preterm births(4,000g and �90%), labor induction, cesarean delivery, chorioam-nionitis, ICN admissions, preeclampsia, and 3rd and 4th degree lac-erations.CONCLUSION: The multiple disadvantages of weight gain above or be-low the guidelines in overweight and obese women far exceed thebenefits of weight gain outside these Institute of Medicine recommen-dations.

150 When is the optimal time todeliver dichorionic diamniotic twins?Sarah Little1, Teresa N. Sparks2, Rachel Pilliod3,Brian Shaffer3, Aaron B. Caughey3, Anjali Kaimal41Brigham and Women’s Hospital and Harvard Medical School,Division of Maternal Fetal Medicine, Dept of Ob/Gyn, Boston, MA,2Brigham & Women’s/Massachusetts General Hospital, Obstetricsand Gynecology, Boston, MA, 3Oregon Health & Science University,Department of Obstetrics and Gynecology, Portland, OR, 4MassachusettsGeneral Hospital and Harvard Medical School, Obstetrics andGynecology, Division of Maternal-Fetal Medicine, Boston, MAOBJECTIVE: Determining the appropriate timing of delivery of a twingestation involves balancing the risk of complications such as intra-uterine fetal demise (IUFD) which are known to increase with advanc-ing gestational age against the potential morbidity of late preterm andearly term birth. We sought to use decision analysis to estimate theoptimal gestational age for elective delivery of uncomplicated dicho-rionic, diamniotic twin gestations.STUDY DESIGN: We created a decision analytic model to compare theoutcomes of elective delivery at 34, 35, 36, 37, 38 or 39 weeks in atheoretical cohort of uncomplicated dichorionic, diamniotic twinpregnancies. Strategies involving expectant management until a latergestational age accounted for the probabilities of spontaneous deliv-ery, indicated delivery, and IUFD during each successive week of ges-tation. Gestational age associated risks of neonatal complications in-cluding minor learning disability, major morbidity, and perinataldeath were assessed. Baseline assumptions were derived from the lit-erature. Total quality-adjusted life years (QALYs) were calculated,accounting for both neonatal and maternal utilities. Sensitivity anal-yses were conducted to evaluate the impact of baseline assumptionson model outcomes.RESULTS: Earlier gestational ages were associated with increased mi-nor and major neonatal morbidity while overall perinatal mortalitynadired at 36 weeks (see table). Balancing these outcomes, the optimaldelivery strategy was expectant management until 38 weeks, whichmaximized the total QALYs. Our results were most sensitive to theprobability of IUFD. Expectant management until 38 weeks remainedthe optimal strategy as long as the probability of IUFD in each gesta-tional week was less than 1.77 times the rate assumed in the base caseanalysis.CONCLUSION: Weighing the risks of IUFD against the neonatal mor-bidity and mortality from iatrogenic prematurity, we found that theideal gestational age at which to deliver dichorionic diamniotic twinsis 38 weeks.

Poster Session I Clinical Obstetrics, Medical-Surgical-Disease, Neonatology, Physiology-Endocrinology www.AJOG.org

S78 American Journal of Obstetrics & Gynecology Supplement to JANUARY 2012

151 The accuracy of noninvasive hemoglobinassessment in an obstetric populationSharon Cooley1, Marie Bourke2, RogerMcMorrow3, Fionnuala McAuliffe4

1Rotunda Hospital, Obstetrics and Gynecology, Dublin, Ireland,2National Maternity Hospital, UCD School of Medicine and MedicalSciences, Dublin 2, Ireland, 3National Maternity Hospital, Departmentof Anaesthesia, Dublin 2, Ireland, 4UCD Obstetrics and Gynaecology,School of Medicine and Medical Science, Dublin, IrelandOBJECTIVE: To validate continuous and non-invasive hemoglobin as-sessment in an obstetric setting, and to compare the values with tra-ditional laboratory measurements of hemoglobin.STUDY DESIGN: Ethical approval was obtained and participants wererecruited from the antenatal clinic of the National Maternity Hospitalat the time of phlebotomy for their standard antenatal laboratoryhemoglobin estimation. Hemoglobin was measured using the SysmexXE-2100 automated haematology analyser (Sysmex Corporation,Sysmex Europe GmbH, Norderstedt, Germany). The SpHb Pulse Co-Oximeter was calibrated and the probe attached to the index finger ofthe patients hand. The mean of three non-invasive measurements ofhemoglobin was recorded over 5 minutes. Maternal age, gestation,medical history, medications, body mass index and blood pressurewere also recorded. Data analysis was undertaken using the StatisticalPackage for the Social Sciences (SPSS), Version 15.0. Bland Altmanplots were used to determine acceptability of the new non-invasivetest as a replacement for invasive testing in a clinical setting.RESULTS: In total 125 women were recruited and two women wereexcluded as their laboratory hemoglobin tests had to be repeated dueto sampling error. The mean maternal age of the participants was 31.7years. The mean gestation was 20.8 (8.6) weeks. Laboratory hemoglo-bin values ranged from 8.8 to 15.1 g/dL with a mean of 12.1 (1.0) g/dL.The range for the SpHb Pulse Co-Oximeter assessment was 9.1 to15.8g/dL with a mean of 12.6 (1.3) g/dL. The Bland Altman plot for thetwo tests (Figure) illustrates the acceptable accuracy of haemoglobinassessment with the noninvasive method.CONCLUSION: Non-invasive hemoglobin measurement proved accu-rate compared to traditional hemoglobin testing and may offer a rapidcheap acceptable alternative to invasive testing in obstetric clinicalscenarios.

152 Perinatal outcome of induction of labor comparedwith expectant management for term twin pregnancySoo Hyeon Moon1, Eun-Na Kim2,Seung Chul Kim1, Jong Kwan Jun3

1Pusan National University School of Medicine, Departmentof Obstetrics and Gynecology, Busan, Korea, 2Seoul NationalUniversity College of Medicine, Obstetrics and Gynecology,Seoul, Korea, 3Seoul National University College of Medicine,Department of Obstetrics and Gynecology, Seoul, KoreaOBJECTIVE: It was reported that maternal complications such as cesar-ean section rate, chorioamnionitis, and uterine atony are increased ininduction of labor in singleton pregnancies. The purpose of this studywas to evaluate the risk of induction of labor in term twin pregnancy.STUDY DESIGN: We conducted a retrospective study of 479 term twinpregnancies between January 1999 and June 2011. Perinatal outcomesof induction of labor for term twin pregnancies (n�377) were com-pared with term twin pregnancies with spontaneous labor (n�102).Outcome criteria are cesarean section rate, chorioamnionitis, uterineatony, Apgar score at 5 minutes, umbilical artery pH �7.2, and therate of NICU admission.RESULTS: The average gestational age at delivery in the inductiongroup was significantly later than that in the expectant managementgroup (38.25 �- 0.69, 37.94 �- 0.72 weeks, p�0,001). There were nosignificant differences in maternal and neonatal outcome between thetwo groups (Table).CONCLUSION: In the term twin pregnancy, induction of labor does notincrease the maternal and neonatal complication. For the term twinpregnant women suffering from overdistended uterus, induction oflabor is a reasonable approach without additional maternal and neo-natal risk.

www.AJOG.org Clinical Obstetrics, Medical-Surgical-Disease, Neonatology, Physiology-Endocrinology Poster Session I

Supplement to JANUARY 2012 American Journal of Obstetrics & Gynecology S79