411 SOFT TISSUE EFFECT ON THE INCIDENCE OF SHOULDER DYSTOCIA SHIRLEYP. WONG1, BENSON H. HARER1, GUILLERMO VALENZUELA2, 1Arrowhead RegionalMedical Center, Women’s Health, Colton, California, 2Arrowhead RegionalMedical Center, Colton, California

OBJECTIVE: It makes intuitive sense that an excess of soft tissue could resultin a reduction of the pelvic outlet and thus increase the incidence of expulsivedystocia. We decided to examine the correlation between maternal body massindex and the incidence of shoulder dystocia in patients delivered vaginallywhile controlling for fetal weight.

STUDY DESION: We obtained data from the department database, whichcollects data regarding prenatal care and delivery. The following informationwas obtained: age, medical or obstetrical complications, height, weight,newborn weight, complications at delivery, and Apgar scores. The inclusioncriteria for the study group was: singleton pregnancy, no previous cesareansection, non-medical complications, vaginal delivery, live birth, and birthweight O3,500 !4001 grams. The data was analyzed by Anova and Chi-square classified per BMI. Group 1 BMI %26, Group 2 O26%30, Group 3!30 !35, Group 4 R35.

RESULTS: A total of 15,664 patients with completed data, who deliveredbetween 1998 and 2004 were identified. A total of 4,218 cases met the estab-lished criteria. The parity, gestational age, gravidity, parity or race was notdifferent among the groups. The incidence of shoulder dystocia was between1.4 - 1.6c=o, without difference between the groups. For comparison; in ourpopulation the incidence in infants with birthweight ! 3,500 grams is 0.58c=o,while in diabetic patients it is 3.5c=o, a significant difference.

CONCLUSION: The present results suggest that soft tissue resistance doesnot present an extra barrier for vaginal delivery. Due to the large BMI of manyof the patients in the observational group, it is doubtful that the lack of effectof excess tissue is explained by the inability of the fetus to descend, which inturn may result in a cesarean delivery.

412 BOTH INNATE AND ADAPTIVE IMMUNITY MAY INDEPENDENTLY CAUSEDYSFUNCTIONAL CERVICAL RIPENING MANIFESTING AS INCOMPETENT CERVIX(IC) CARL P. WEINER1, KEUN-YOUNG LEE2, CATALIN S. BUHIMSCHI3, IRINAA. BUHIMSCHI4, 1University of Maryland at Baltimore, Physiology, Baltimore,Maryland, 2Kangnam Sacred Heart Hospital, Seoul, South Korea, 3Yale Uni-versity, Obstetrics/Gynecology & Reproductive Sciences, New Haven, Con-necticut, 4Yale University, Obstetrics/Gynecology, New Haven, Connecticut

OBJECTIVE: IC may result from dysfunctional cervical ripening via activa-tion of either the innate or adaptive immune pathways. Unaddressed is thefundamental issue of whether one pathway triggers the other, or whether theiractivation occurs along independent but intersecting lines. The object of thisstudy was to investigate that question.

STUDY DESIGN: IC was diagnosed in women (n=25) with cervicaldilationO2cm, intact bulging membranes between 15-24w, and no detectableuterine activity. Each woman had an amniocentesis to aid cerclage placement.36 women between 16-24w served as controls (amniocentesis for karyotype).All controls delivered normal infants O37w. Innate immune pathway activa-tion was identified in the amniotic fluid samples by presence or absence of4 proteins of the MR score (defensins/calgranulins) using mass spectrometrySELDI. Adaptive pathway activation was identified by an elevated IL-6(O11.4 pg/mL) (ELISA).

RESULTS: There were significant differences in the prevalence of abnor-mality rates between the two tests (p=0.05).12 (48%) women had either anabnormal MR Score, an elevated IL-6 or both. The IL-6 alone was abnormalin 20% (n=5), and the MR Score alone abnormal in 8% (n=2). No controlhad either an abnormal MR Score or an elevated IL-6 level.

CONCLUSION: Inflammation is present in about half the women whopresent for rescue cerclage. However, the relevant inciting inflammatorypathway may be either innate or adaptive. The results of this study breaksnew ground in our understanding of preterm birth associated with the clinicaldiagnosis of IC, and likely extends into idiopathic preterm labor associatedwith inflammation.

413 PLACENTA PREVIA & THE ATTRIBUTABLE RISK OF PRETERM DELIVERY MARYA G.ZLATNIK1, YVONNE CHENG1, MARY NORTON1, VIRGINIA WINN1, MARI-PAULE THIET1, AARON B. CAUGHEY1, 1University of California, San Francisco,Obstetrics, Gynecology and Reproductive Sciences, San Francisco, California

OBJECTIVE: To quantify the maternal & neonatal morbidities associated withplacenta previa& to quantify the risk of pretermdelivery at eachweek until 37weeks.

STUDY DESIGN: A retrospective cohort study was conducted of all singletonbirths delivered at UCSF between 1976 & 2001, excluding transports. Primaryoutcomes included preterm delivery (PTD) prior to 28 & 32 weeks, 5-minuteApgar scores!7, postpartum hemorrhage (PPH), blood transfusion, low birthweight (LBW), & small for gestational age (SGA). Multivariate analyses wereperformed controlling for maternal ethnicity, BMI, age, parity, diabetes, &preeclampsia. Survival curves were generated for deliveries at less than 37weeks.

RESULTS: Among the 38,533 women, 230 women had previas (0.6%).Previa was significantly associated with PTD prior to 28 weeks (3.5% vs 1.3%)& PTD prior to 32 weeks (11.7% vs 2.5%). Previa was associated with LBW(32% vs 7.0%), but not SGA (5.7% vs 7.4%). Previa was associated with low5-minute Apgar scores (!7: 7.8% vs 3.8%). Patients with previa were morelikely to be experience PPH (59.7% vs. 36.1%), & to receive a bloodtransfusion (11.8% vs 2.7%). All comparisons were statistically significantwith p! 0.001 & remained so in multivariate analysis. Kaplan-Meier survivalcurves (figure) demonstrate the cumulative risk of preterm delivery at eachweek from 24 to 37 weeks (p! 0.001).

CONCLUSION: We found that the diagnosis of placenta previa is associatedwith an increased risk of maternal & neonatal complications, including PTD(both before 28 & 32 weeks), PPH, blood transfusion, low 5-minute Apgar, &LBW. These gestational age-specific outcomes can be used to counsel womenwith a placenta previa prospectively.

414 THE MFMU CESAREAN REGISTRY: IMPACT OF TIME OF DAY ON CESAREANCOMPLICATIONS JENNIFER BAILIT1, 1for the NICHD MFMU Network, Be-thesda, Maryland

OBJECTIVE: Studies suggest that sleep deprivation adversely affects perfor-mance.Wehypothesized that cesarean delivery (CD) complicationswould bemorefrequent during thenight shift (11p-7a), andevaluatedmorbidities bydelivery shift.

STUDY DESIGN: 18,964 term women undergoing an unscheduled CD in 13centers from 1999-2000 within a prospective observational study were in-cluded. Maternal/neonatal morbidities and time from decision to CD wereevaluated by time of delivery (7a-3p, 3p-11p, 11p-7a). A composite of maternalmorbidities (Table 1 & 20 others) was evaluated by logistic regressioncontrolling for potentially confounding factors.

RESULTS: No differences in maternal morbidities were seen by time ofdelivery (TABLE 1). Controlling for age, race, insurance, cardiac disease,preeclampsia, diabetes, prior incision type, and PNC, shift of delivery had noimpact on maternal morbidity (11p-7a OR 0.9 [95% CI 0.81-1.0]). NICUadmissions were slightly increased at night but neonatal complications werenot. (TABLE 2). Time from decision to delivery for emergent CDs was longer(26,29,31 min, p!0.0001) during evening and night shifts.

CONCLUSION: Maternal and neonatal complications of CD do not increasewith delivery during the night shift.

Table 1 Maternal complications by shift

Complication 7a-3p% 3p-11p% 11p-7a% p value

Transfx 2.6 2.2 2.6 .22Cystotomy .3 .3 .3 .94Bowel inj .1 .1 0 .20Ureteral inj .1 .1 0 .14Endometritis 10 9.2 9.6 .30Wound inf .6 .7 .6 .62Hematoma .3 .2 .2 .33Ileus .9 .8 .8 .94C-hyst .4 .3 .3 .4Readmit 1.6 1.5 1.6 .81Composite 15.9 14.6 15.1 .1

Table 2 Neonatal complications by shift

Complication 7a-3p% 3p-11p% 11p-7a% p value

Ph !7.0 2.5 1.9 2.4 .18Laceration .7 .8 .8 .82NICU 19.3 19.1 20.9 .02Seizure .3 .3 .5 .12Death .3 .2 .2 .36!2500gr 2.9 3.3 3.4 .25

S122 SMFM Abstracts