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mortality in the second twin
S74 SMFM Abstracts 235
CESAREAN SECTION AND RISK OF UNEXPLAINED STILLBIRTH IN SUBSEQUENT PREGNANCY: THE UTAH STILLBIRTH DATABASE 1992-2002 CALLA HOLMGREN1, KJERSTI AAGAARD-TILLERY1, ROBERT SATTERFIELD2, SHAHEEN HOSSAIN3, YVETTE LACOURSIER4, T. PORTER1, MICHAEL VARNER1, 1University of Utah, Obstetrics and Gynecology, Salt Lake City, Utah, 2State of Utah, Department of Health, Salt Lake City, Utah, 3Utah Department of Health, Department of Health, Salt Lake City, Utah, 4University of Utah, Salt Lake City, Utah OBJECTIVE: It has been suggested that prior cesarean section (CS) increases the risk of unexplained stillbirth (SB) at term among singleton second births, when employing time-to-event analyses. We sought to assess the overall relative probability of SB in subsequent pregnancies among women with a prior CS. STUDY DESIGN: All Utah Stillbirth Certificates were reviewed from 1992 through 2002 and linked to subsequent Birth Certificates. After elimination of infants with anomalies, 1233 SBs were identified among Utah secundagravidas. A combined database was generated with a control study population of randomly identified multigravidas delivered of non-anomalous liveborns. Cases and controls were compared for potential confounding maternal characteristics. A logistic regression model with explanatory variables was employed. Odds ratios (OR) are reported with 95% CI. RESULTS: Of the women with SB, 9.8% were delivered by CS in a prior pregnancy, as compared with 15% of controls. In contrast to the findings of other investigators, in our multivariable model adjusting for maternal and gestational age we failed to demonstrate an increased probability of stillbirth in women with prior cesarean section(s) (OR 0.55, P ! .001 0.33-0.79 95% CI). Chronic hypertension, placental abruption, PPROM, cord prolapse, and hydramnios were dropped from this model to avoid colinearity. CONCLUSION: In our population, there does not appear to be an increased risk of stillbirth among women with prior cesarean section(s).
237
RISK OF STILLBIRTH WITH ADVANCING GESTATIONAL AGE AMONG PREGNANCIES COMPLICATED BY CHRONIC HYPERTENSION KJERSTI AAGAARD-TILLERY1, CALLA HOLMGREN1, YVETTE LACOURSIERE1, D. WARE BRANCH1, MICHAEL VARNER1, 1 University of Utah, Obstetrics and Gynecology, Salt Lake City, Utah OBJECTIVE: Utilizing a comprehensive stillbirth database from Utah, we observed an increased risk of stillbirths (SB) among women whose pregnancies are complicated by chronic hypertension (HTN). Given the long-standing recognition of risks of superimposed preeclampsia, placental abruption, and IUGR among these women, we hypothesized there might exist a gestational age threshold where risk of stillbirth in chronic hypertensives exceeded that among age-matched controls. STUDY DESIGN: Through the Utah Department of Health, we compiled a database of nonanomalous SB infants over the interval 1992-2002. A combined database was generated with randomly identified controls from Birth Certificates. Cox proportional hazard models were used in 3955 subjects to generate survival curves comparing pregnancies complicated by chronic HTN or gestational HTN to those of controls. Data is expressed as hazard ratios (HR) with 95% CI. RESULTS: In pregnancies complicated by chronic HTN, the survival curve diverged from that of controls at those gestational ages approaching term (HR 2.24 1.51, 3.32 95% CI; P ! .000). By contrast, pregnancies complicated by gestational HTN failed to demonstrate a significant aberration in the survival curve (HR 1.07 0.86, 1.33 95% CI; P = .543). CONCLUSION: We utilize survival curves generated from Cox proportional hazard models to demonstrate a divergent risk of stillbirth among pregnancies complicated by chronic HTN when compared with either gestational HTN or controls. Our data suggest that outcomes in such pregnancies might improve with induction prior to term. We speculate that their likely exists precise gestational age thresholds at which delivery is indicated in chronic hypertensives.
236
DETERMINANTS OF PERINATAL MORBIDITY/MORTALITY IN THE SECOND TWIN ANTHONY ARMSON1, VIDIA PERSAD1, COLLEEN O’CONNELL2, K. S. JOSEPH2, DAVID YOUNG1, THOMAS BASKETT1, 1Dalhousie University, Obstetrics & Gynaecology, Halifax, Nova Scotia, Canada, 2Dalhousie University, Perinatal Epidemiology Research Unit, Halifax, Nova Scotia, Canada OBJECTIVE: To evaluate the rate and determinants of perinatal morbidity/ mortality of the second twin relative to the first twin. STUDY DESIGN: A retrospective cohort design was used to study all twin pregnancies in Nova Scotia from 1988-2002. Monoamniotic twins and twin pairs with major congenital anomaly or antepartum fetal death of either twin were excluded. The primary outcome was a composite measure of perinatal morbidity/mortality including birth asphyxia, severe respiratory distress, neonatal trauma or infection and perinatal death. A matched pair cohort technique was used to evaluate the risk of adverse perinatal outcomes of the second twin relative to the first twin. This comparison was examined within subcategories of potential risk factors including presentation, mode of delivery, chorionicity, birthweight discrepancy and interdelivery interval. RESULTS: Of 1542 twin pairs, the second twin was at a significantly greater risk of composite perinatal morbidity/mortality (RR 1.62, 95% CI 1.38-1.90, P ! .001) relative to the first twin. This increased risk was independent of presentation, chorionicity, birthweight discrepancy or interdelivery interval. The relationship remained significant within selected categories of gestational age (>37, 34-36, !34 wk). Among term twin pairs, the only protective factor for the second twin was delivery by elective C-section (RR 1.0,95% CI 0.14-7.0). In contrast, the risk of adverse outcome for the term second twin was significantly increased for planned vaginal delivery (P = .009) and emergency C-section (P = .06). Birth asphyxia and RDS were the major contributors to perinatal morbidity in the second twin. CONCLUSION: The second twin is at significant risk of perinatal morbidity/ mortality, relative to the first twin, independent of presentation, chorionicity, birthweight discrepancy or interdelivery interval. Elective C-section at term appears to improve perinatal outcome for the second twin.
238
MODES OF DELIVERY AND FACTORS ASSOCIATED WITH NON-ANOMALOUS STILLBIRTHS: THE UTAH STILLBIRTH DATABASE 1992-2002 KJERSTI AAGAARDTILLERY1, CALLA HOLMGREN1, ROBERT SATTERFIELD2, SHAHEEN HOSSAIN2, YVETTE LACOURSIERE1, MICHAEL VARNER1, 1University of Utah, Obstetrics and Gynecology, Salt Lake City, Utah, 2Utah Department of Health, Salt Lake City, Utah OBJECTIVE: We sought to characterize the mode of delivery and risk factors associated with stillborns (SB) delivered in Utah over the interval 1992-2002. STUDY DESIGN: Through the Utah Department of Health-Center for Health Data, we compiled a database of all SB infants over the interval 1992-2002 utilizing Stillbirth Certificates. After elimination of infants with major anomalies, 1586 SBs were identified. A combined database was generated with 2795 randomly identified controls utilizing Certificates of Live Births; similar elimination of anomalous infants yielded 2720 controls. The relative frequency of delivery mode was determined. In order to assess for risk factors associated with SB, logistic regression with nominal variables was employed. Odds ratios (OR) with 95% CI are reported. RESULTS: Stillborns were likely to be delivered vaginally (89.2%), unless confounded by a multiple gestation with potential for a surviving infant. Placental abruption, cord prolapse, and hydramnios increased probability of SB, while electronic fetal monitoring was found to be protective (Table). Among a comprehensive number of maternal risk factors and behaviors potentially associated with increased risk of SB, only chronic hypertension (HTN) was found to be statistically significant. CONCLUSION: Establishment of a large, comprehensive database from the Utah Department of Health has enabled us to formally assess the modes of delivery employed among SBs in our popluation. Moreover, we have utilized this database in a logistic regression model to explore maternal, fetal, and obstetrical risk factors associated with increased probability of SB. Risk of stillbirth
Abruption Cord prolapse Hydramnios Chronic HTN EFM
OR
95% CI
P value
8.67 4.05 2.58 3.46 0.06
4.92, 1.16, 1.31, 1.13, 0.05,
.000 .029 .006 .029 .000
15.27 14.20 5.11 10.49 0.08
CESAREAN SECTION AND RISK OF UNEXPLAINED STILLBIRTH IN SUBSEQUENT PREGNANCY: THE UTAH STILLBIRTH DATABASE 1992-2002 CALLA HOLMGREN1, KJERSTI AAGAARD-TILLERY1, ROBERT SATTERFIELD2, SHAHEEN HOSSAIN3, YVETTE LACOURSIER4, T. PORTER1, MICHAEL VARNER1, 1University of Utah, Obstetrics and Gynecology, Salt Lake City, Utah, 2State of Utah, Department of Health, Salt Lake City, Utah, 3Utah Department of Health, Department of Health, Salt Lake City, Utah, 4University of Utah, Salt Lake City, Utah OBJECTIVE: It has been suggested that prior cesarean section (CS) increases the risk of unexplained stillbirth (SB) at term among singleton second births, when employing time-to-event analyses. We sought to assess the overall relative probability of SB in subsequent pregnancies among women with a prior CS. STUDY DESIGN: All Utah Stillbirth Certificates were reviewed from 1992 through 2002 and linked to subsequent Birth Certificates. After elimination of infants with anomalies, 1233 SBs were identified among Utah secundagravidas. A combined database was generated with a control study population of randomly identified multigravidas delivered of non-anomalous liveborns. Cases and controls were compared for potential confounding maternal characteristics. A logistic regression model with explanatory variables was employed. Odds ratios (OR) are reported with 95% CI. RESULTS: Of the women with SB, 9.8% were delivered by CS in a prior pregnancy, as compared with 15% of controls. In contrast to the findings of other investigators, in our multivariable model adjusting for maternal and gestational age we failed to demonstrate an increased probability of stillbirth in women with prior cesarean section(s) (OR 0.55, P ! .001 0.33-0.79 95% CI). Chronic hypertension, placental abruption, PPROM, cord prolapse, and hydramnios were dropped from this model to avoid colinearity. CONCLUSION: In our population, there does not appear to be an increased risk of stillbirth among women with prior cesarean section(s).
237
RISK OF STILLBIRTH WITH ADVANCING GESTATIONAL AGE AMONG PREGNANCIES COMPLICATED BY CHRONIC HYPERTENSION KJERSTI AAGAARD-TILLERY1, CALLA HOLMGREN1, YVETTE LACOURSIERE1, D. WARE BRANCH1, MICHAEL VARNER1, 1 University of Utah, Obstetrics and Gynecology, Salt Lake City, Utah OBJECTIVE: Utilizing a comprehensive stillbirth database from Utah, we observed an increased risk of stillbirths (SB) among women whose pregnancies are complicated by chronic hypertension (HTN). Given the long-standing recognition of risks of superimposed preeclampsia, placental abruption, and IUGR among these women, we hypothesized there might exist a gestational age threshold where risk of stillbirth in chronic hypertensives exceeded that among age-matched controls. STUDY DESIGN: Through the Utah Department of Health, we compiled a database of nonanomalous SB infants over the interval 1992-2002. A combined database was generated with randomly identified controls from Birth Certificates. Cox proportional hazard models were used in 3955 subjects to generate survival curves comparing pregnancies complicated by chronic HTN or gestational HTN to those of controls. Data is expressed as hazard ratios (HR) with 95% CI. RESULTS: In pregnancies complicated by chronic HTN, the survival curve diverged from that of controls at those gestational ages approaching term (HR 2.24 1.51, 3.32 95% CI; P ! .000). By contrast, pregnancies complicated by gestational HTN failed to demonstrate a significant aberration in the survival curve (HR 1.07 0.86, 1.33 95% CI; P = .543). CONCLUSION: We utilize survival curves generated from Cox proportional hazard models to demonstrate a divergent risk of stillbirth among pregnancies complicated by chronic HTN when compared with either gestational HTN or controls. Our data suggest that outcomes in such pregnancies might improve with induction prior to term. We speculate that their likely exists precise gestational age thresholds at which delivery is indicated in chronic hypertensives.
236
DETERMINANTS OF PERINATAL MORBIDITY/MORTALITY IN THE SECOND TWIN ANTHONY ARMSON1, VIDIA PERSAD1, COLLEEN O’CONNELL2, K. S. JOSEPH2, DAVID YOUNG1, THOMAS BASKETT1, 1Dalhousie University, Obstetrics & Gynaecology, Halifax, Nova Scotia, Canada, 2Dalhousie University, Perinatal Epidemiology Research Unit, Halifax, Nova Scotia, Canada OBJECTIVE: To evaluate the rate and determinants of perinatal morbidity/ mortality of the second twin relative to the first twin. STUDY DESIGN: A retrospective cohort design was used to study all twin pregnancies in Nova Scotia from 1988-2002. Monoamniotic twins and twin pairs with major congenital anomaly or antepartum fetal death of either twin were excluded. The primary outcome was a composite measure of perinatal morbidity/mortality including birth asphyxia, severe respiratory distress, neonatal trauma or infection and perinatal death. A matched pair cohort technique was used to evaluate the risk of adverse perinatal outcomes of the second twin relative to the first twin. This comparison was examined within subcategories of potential risk factors including presentation, mode of delivery, chorionicity, birthweight discrepancy and interdelivery interval. RESULTS: Of 1542 twin pairs, the second twin was at a significantly greater risk of composite perinatal morbidity/mortality (RR 1.62, 95% CI 1.38-1.90, P ! .001) relative to the first twin. This increased risk was independent of presentation, chorionicity, birthweight discrepancy or interdelivery interval. The relationship remained significant within selected categories of gestational age (>37, 34-36, !34 wk). Among term twin pairs, the only protective factor for the second twin was delivery by elective C-section (RR 1.0,95% CI 0.14-7.0). In contrast, the risk of adverse outcome for the term second twin was significantly increased for planned vaginal delivery (P = .009) and emergency C-section (P = .06). Birth asphyxia and RDS were the major contributors to perinatal morbidity in the second twin. CONCLUSION: The second twin is at significant risk of perinatal morbidity/ mortality, relative to the first twin, independent of presentation, chorionicity, birthweight discrepancy or interdelivery interval. Elective C-section at term appears to improve perinatal outcome for the second twin.
238
MODES OF DELIVERY AND FACTORS ASSOCIATED WITH NON-ANOMALOUS STILLBIRTHS: THE UTAH STILLBIRTH DATABASE 1992-2002 KJERSTI AAGAARDTILLERY1, CALLA HOLMGREN1, ROBERT SATTERFIELD2, SHAHEEN HOSSAIN2, YVETTE LACOURSIERE1, MICHAEL VARNER1, 1University of Utah, Obstetrics and Gynecology, Salt Lake City, Utah, 2Utah Department of Health, Salt Lake City, Utah OBJECTIVE: We sought to characterize the mode of delivery and risk factors associated with stillborns (SB) delivered in Utah over the interval 1992-2002. STUDY DESIGN: Through the Utah Department of Health-Center for Health Data, we compiled a database of all SB infants over the interval 1992-2002 utilizing Stillbirth Certificates. After elimination of infants with major anomalies, 1586 SBs were identified. A combined database was generated with 2795 randomly identified controls utilizing Certificates of Live Births; similar elimination of anomalous infants yielded 2720 controls. The relative frequency of delivery mode was determined. In order to assess for risk factors associated with SB, logistic regression with nominal variables was employed. Odds ratios (OR) with 95% CI are reported. RESULTS: Stillborns were likely to be delivered vaginally (89.2%), unless confounded by a multiple gestation with potential for a surviving infant. Placental abruption, cord prolapse, and hydramnios increased probability of SB, while electronic fetal monitoring was found to be protective (Table). Among a comprehensive number of maternal risk factors and behaviors potentially associated with increased risk of SB, only chronic hypertension (HTN) was found to be statistically significant. CONCLUSION: Establishment of a large, comprehensive database from the Utah Department of Health has enabled us to formally assess the modes of delivery employed among SBs in our popluation. Moreover, we have utilized this database in a logistic regression model to explore maternal, fetal, and obstetrical risk factors associated with increased probability of SB. Risk of stillbirth
Abruption Cord prolapse Hydramnios Chronic HTN EFM
OR
95% CI
P value
8.67 4.05 2.58 3.46 0.06
4.92, 1.16, 1.31, 1.13, 0.05,
.000 .029 .006 .029 .000
15.27 14.20 5.11 10.49 0.08