571 Trends in birth weight and ponderal index of pretermsingleton infants over 15 years at an urban tertiary centerKelly Gibson1, Thaddeus P. Waters2

1MetroHealth Medical Center-Case Western Reserve University, Divisionof Maternal Fetal Medicine, Department of Obstetrics and Gynecology,Cleveland, OH, 2MetroHealth Medical Center - Case Western ReserveUniversity, Division of Maternal Fetal Medicine, Departmentof Obstetrics and Gynecology, Cleveland, OHOBJECTIVE: To determine if there have been changes in birth weight(BW) and Ponderal Index (PI: gram/cm3) in preterm newbornsacross a fifteen year time period after controlling for populationchanges.STUDY DESIGN: This is a retrospective cohort analysis of data collectedwithin a perinatal database at an urban tertiary center. We includedliveborn singletons delivered between 28 0/7 and 36 6/7 weeks, andfrom 1/1995 to 12/2009. BW outliers (99th %ile for gestational age(GA) were excluded). Trends in BW and PI over time were evaluated.We divided the data into five year epochs. ANOVA, chi-squared, andlinear stepwise regression analyses were used as appropriate. Regres-sion analyses controlled for GA, maternal race, age, parity, smoking,BMI at delivery, diabetes (IDDM), hypertension (HTN), and deliveryindication.RESULTS: 5,132 infants were included. Mean BW (�118g), PI(�0.13g/cm3), and GA (�0.57wk) increased significantly over time(P�0.001 for each). Significant differences over time (p�0.001) werealso found for maternal age (�0.6yr), smoking (�7.0%), IDDM(�1.9%), nulliparity (�4.9%), PROM (�10.2%), and race (AfricanAmericans �7.4%), but not for BMI or HTN. Labor Inductions in-creased (�5.0%; p�0.001) while spontaneous preterm labor de-creased (�5.6%; p�0.001). In stepwise regression (R2 0.52; Table),GA was the most highly associated factor affecting BW, followed byIDDM, HTN, infant gender, smoking, parity, and PROM. Year ofdelivery and maternal BMI were not significant factors. Regarding PI,stepwise regression (R2 0.025, p�0.045) found GA, year of delivery,HTN, and IDDM to be significantly associated factors.CONCLUSION: Over fifteen years, BW and PI of singleton infants bornat 28-36 weeks GA have increased. The majority of this change isattributed to increased GA within this preterm cohort, and to changesin maternal social and medical demographic characteristics. PI, butnot BW, has increased over time after controlling for factors likely toimpact fetal growth.

572 Trends in severe obstetric morbidityNatalie Brooke Heath1, Sean Esplin2, ErickHenry2, Cindy Weng3, Michael Varner4

1University of Utah School of Medicine, Obstetrics and Gynecology, SLC,UT, 2Intermountain Healthcare, Maternal-Fetal Medicine, Salt LakeCity, UT, 3University of Utah, Biomedical Informatics, Salt LakeCity, UT, 4University of Utah Health Sciences Center,Obstetrics and Gynecology, Salt Lake City, UTOBJECTIVE: To identify the contemporary occurrence and temporaltrends of severe maternal morbidity in a large vertically integratedhealthcare system.STUDY DESIGN: The data warehouse of a large vertically integratedhealthcare system was searched for women delivering a singletonpregnancy delivered between July 2001 and December 2008. Severematernal morbidity was defined as one or more of the following: ICUadmission, cesarean hysterectomy, transfusion, uterine rupture, ec-lampsia, pulmonary embolism, cerebrovascular hemorrhage, intuba-tion, cardiomyopathy or readmission within 6 weeks of discharge.Cases were identified by ICD-9 discharge diagnoses. Maternal demo-graphic parameters, pregnancy outcome information and pre-exist-ing conditions were also analyzed using univariate and multivariatelogistic regression.RESULTS: 240,331 singleton births occurred during the study period.Severe maternal morbidity increased from 90.1 to 134.8 per 10,000deliveries over the study period and was driven primarily by increasedICU admissions and transfusions (Figure). Overall cesarean deliveryrates increased from 15.38% to 20.38%. However, rates of uterinerupture and pulmonary embolism decreased over the study period(Table). Each of the pre-existing medical conditions (chronic hyper-tension, chronic renal disease, diabetes and lupus) was associated withhaving a higher incidence of severe maternal morbidity. Women withpre-existing medical conditions were also more likely to be deliveredabdominally.CONCLUSION: The rate of severe maternal morbidity increased over thestudy period primarily due to increased ICU admission and transfu-sion rates. Cesarean delivery rates also increased over the study period,and the increased incidence of transfusion is associated with thistrend.

PosterSessionIV Epidemiology, Infectious Disease, Intrapartum Fetal Assessment, Operative Obstetrics, Obstetric Quality & Safety, Public Health-Global Health www.AJOG.org

S260 American Journal of Obstetrics & Gynecology Supplement to JANUARY 2012