518 Cervical colonization with genital mycoplasma,maternal serum anti-genital mycoplasmaantibodies, and preterm parturitionOffer Erez1, Ruthy Beer Weisel1, Sari Prutchi Sagiv4, Tal Rafaeli1,Ilan Levi3, Vered Klaitman1, Barak Aricha- Tamir1, AlonaKuzmina3, Limor Besser1, Orna Staretz-Chacham2, Iris Shoham1,Michela Quaranta5, Gershon Holcberg1, Moshe Mazor1

1Soroka University Medical Center, School of Medicine, Faculty of HealthSciences, Ben Gurion University of the Negev, Department of Obstetrics andGynecology, Beer Sheva, Israel, 2Soroka University Medical Center, School ofMedicine, Faculty of Health Sciences, Ben Gurion University of the Negev,Department of Neonatology, Beer Sheva, Israel, 3Soroka University MedicalCenter, Promyco Diagnostics, Beer Sheva, Israel, 4Clalit Health Services, MorResearch Applications, Tel Aviv, Israel, 5Policlinico GB Rossi AziendaOspedaliera, Obstetrics and Gynecology Departement, Verona, ItalyOBJECTIVE: Genital mycoplasmas (GM) are the most prevalent intra-amniotic microorganism in women with preterm parturition. In con-trast, the relationship between cervical colonization with these micro-organisms and preterm parturition is not well established. The aim ofthis study was to determine the association between maternal serumconcentrations of anti GM antibodies (AB) and spontaneous pretermdelivery (PTD).STUDY DESIGN: a prospective observational study was conducted in-cluding women with preterm parturition (n�131) and patients inlabor at term (n�22) as controls. Maternal serum AGM-AB weredetermined by the PROMYCO kit a novel immunoassay.RESULTS: There was a positive correlation between maternal serumAGM-AB during the episode of preterm parturition and at delivery(r�0.92, p�0.0001). Median maternal serum AGM-AB was higher inwomen with a positive GM cervical culture than in those with a neg-ative one (p�0.001). There was no correlation between gestationalage at sample collection and maternal serum AGM-AB concentra-tions. Women with preterm parturition who delivered preterm and apositive cervical GM culture had a higher rate of elevated AGM-AB(�75th percentile) than those with a sterile cervical culture (83.3% vs.41.5%, p�0.012). Among women with preterm labor and a positiveGM cervical culture, those who delivered preterm had a higher me-dian AGM-AB than those who delivered at term (p�0.042).CONCLUSION: Maternal cervical colonization with GM is associatedwith elevated serum AGM-AB concentrations. In the presence of cer-vical colonization with genital mycoplasma, maternal serum concen-trations of AGM-AB may assist in identifying those who will deliverpreterm following an episode of preterm parturition. This is impor-tant, since our observation might contribute to a better identificationof patients with cervical colonization with GM and preterm parturi-tion that may benefit from antimicrobial treatment.

519 Induction of labor has an independent protective effectfrom cesarean section in women with late preterm PROMGal Rodovsky3, Offer Erez1, Maayan Azran2, Moshe Mazor1,Ruthy Beer Weisel1, Daniella Landau4,Vered Klaitman1, Michela Quaranta5

1Soroka University Medical Center, School of Medicine, Faculty of HealthSciences, Ben Gurion University of the Negev, Department of Obstetrics andGynecology, Beer Sheva, Israel, 2School of Medicine, Faculty of HealthSciences, Ben Gurion University of the Negev, Department of Epidemiology,Beer Sheva, Israel, 3Faculty of Health Sciences, Ben Gurion University of theNegev, School of Medicine, Beer Sheva, Israel, 4Soroka University MedicalCenter, School of Medicine, Faculty of Health Sciences, Ben GurionUniversity of the Negev, Neonatology, Beer Sheva, Israel, 5Policlinico GBRossi Azienda Ospedaliera, Obstetrics and Gynecology Departement, Verona,ItalyOBJECTIVE: The management of late preterm prelabor rupture ofmembranes (PPROM), occurring from 34 to 36�6/7 weeks of gesta-tion, is under debate. The aims of this study were to determine in alarge population based study, the maternal and neonatal outcome

resulting from induction of labor vs. expectant management inwomen with late PPROM.STUDY DESIGN: This retrospective population based cohort study in-cluded the following groups of women with late PPROM: 1) sponta-neous delivery within 48 hours of admission (n�1237); 2) conserva-tive management (n�408); and 3) induction of labor within 48 hoursof admission (n�575). Maternal characteristics were collected from acomputerized database including all the deliveries at our medical cen-ter during the study period.RESULTS: 1) women in the induction group had a lower mean mater-nal age, median gravidity, and rate of previous preterm birth thanother study groups; 2) the median gestational age at delivery differsignificantly among the groups and the cesarean section (CS) rate wasthe lowest in those who had induction(p�0.001); 3) women who wereinduced had a lower incidence of clinical chorioamnionitis than in theexpectant group (p�0.001); 4) Induction by oxytocin was associatedwith a shorter median interval to delivery and hospitalization than inother methods (p�0.001 for both); 5) maternal parity (OR 2.5) was anindependent risk factor for chorioamnionitis; 6) an interval of morethan 1.5 days from PPROM to delivery had a sensitivity of 52.1% anda specificity of 72.7% for the development of chorioamnionitis (Areaunder the curve 0.641, p��0.01); and 6) induction of labor had anindependent protective effect against CS (OR 0.53) but not againstchorioamnionitis.CONCLUSION: In women with late preterm PROM: 1) induction of la-bor reduces the risk for CS by 46% without affecting the risk forchorioamnionitis; and 2) parity increases the risk for chorioamnioni-tis regardless of whether these patients were managed actively or con-servatively.

520 Severe and moderate thinness (prepregnancybody mass index <17) as risk factors forspontaneous preterm birthOgechi Agwu1, Jan Hart2, Barbra Fisher2, Nancy West3, RonaldGibbs2, Anne Lynch2

1Case Western Reserve University, School of Medicine, Cleveland, OH,2University of Colorado Denver, Obstetrics and Gynecology, Aurora, CO,3University of Colorado Denver, Colorado School of Public Health, Aurora,COOBJECTIVE: The prepregnancy body mass index (BMI, kg/m2) is one ofthe few modifiable risk factors for preterm birth (PTB). The objectiveof this study was to determine the relationship between WHO cate-gories of BMI and spontaneous preterm birth (SPTB).STUDY DESIGN: From our perinatal database (2005 - 2010), we ana-lyzed data on 11,967 women who delivered singleton births after ex-cluding women who had a medically indicated PTB or delivered � 20weeks. SPTB was defined as a PTB resulting from PPROM or sponta-neous preterm labor. We used the WHO international classification ofBMI (see figure). We analyzed the data using univariable and multi-variable logistic regression analysis, adjusting for maternal age, race/ethnicity, parity, cigarette smoking, history of PTB, chronic medicaldisease, uterine anomalies, cervical incompetence and infertility.RESULTS: SPTB accounted for 65% of all PTBs. The incidence of SPTBwas highest among women who had severe or moderate thinness, 28%and 22%, respectively. Compared to women with normal range BMI,the categories significantly associated with an increased risk of SPTBwere: severe thinness (AOR � 2.7, 95% CI � 1.3 to 5.8, P � 0.01) andmoderate thinness (AOR � 2.1, 95% CI 1.3 to 3.5, P � 0.003). We alsofound that obese class I was associated with a decreased risk (AOR �0.75, 95% CI � 0.60 to 0.93, P � 0.01).CONCLUSION: Women with BMI � 17 are more than twice as likely tohave SPTB compared to women with normal range BMI. Becausesevere and moderate thinness prior to pregnancy is potentially mod-ifiable, interventions for women in these categories to achieve ahealthy preconception weight should be evaluated.

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Supplement to JANUARY 2013 American Journal of Obstetrics & Gynecology S223