Biomedical subjects

David M Stamilio

Publications and source records attributed to David M Stamilio.

At least 19 recordsLinked to original sources

PubMed2006

Is vaginal birth after cesarean (VBAC) or elective repeat cesarean safer in women with a prior vaginal delivery?

OBJECTIVE: This study was undertaken to determine whether vaginal birth after cesarean (VBAC) or elective repeat cesarean delivery is safer overall for a woman with a prior vaginal delivery. STUDY DESIGN: This retrospective cohort study of pregnant women from 1996 to 2000 who had a prior cesarean delivery, was conducted in 17 centers. Trained nurses extracted historical and maternal outcome data on subjects by using standardized tools. This planned secondary analysis examined the subcohort that had also previously undergone a vaginal delivery, comparing those who underwent a VBAC trial with those who elected to have a repeat cesarean delivery. Outcomes included uterine rupture, bladder injury, fever, transfusion and a composite (uterine rupture, bladder injury, and artery laceration). We performed bivariate and multivariable analyses. RESULTS: Of 6619 patients with a prior cesarean delivery who had also had a prior vaginal delivery, 5041 patients attempted a VBAC delivery and 1578 had an elective cesarean delivery. Although there was no significant difference in uterine rupture or bladder injury between the two groups, women who underwent a VBAC attempt were less likely to experience the composite adverse maternal outcome, have a fever, or require a transfusion. CONCLUSION: Among VBAC candidates who have had a prior vaginal delivery, those who attempt a VBAC trial have decreased risk for overall major maternal morbidities, as well as maternal fever and transfusion requirement compared with women who elect repeat cesarean delivery. Physicians should make this more favorable benefit-risk ratio explicit when counseling this patient subpopulation on a trial of labor.

Adult↗

PubMed2006

Evaluating the thresholds of abnormal second trimester multiple marker screening tests associated with intra-uterine growth restriction.

Our objective was to evaluate the optimal thresholds for unexplained abnormal multiple marker screening (MMS) results that are associated with intrauterine growth restriction (IUGR). This was a case-control study from our perinatal database. MMS analyte levels (multiples of median [MoM]) of cases with IUGR (birthweight < 5th percentile for gestational age) were compared with a control group without IUGR. Pregnancies with fetal anomalies were excluded. Biochemical markers evaluated include alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3). Using receiver operating characteristic curves, the optimal thresholds of MMS (OTMs) associated with IUGR were determined. We identified 255 (12.3%) cases with IUGR and complete MMS records from the database. These were compared with 1785 controls without IUGR randomly selected from our perinatal database in a 1:7 ratio. The OTMs associated with IUGR were AFP > 2.0 MoM (odds ratio [OR] = 2.3; 95% confidence interval [CI], 1.4 to 3.7), hCG > 2.5 MoM (OR = 1.8; 95% CI, 1.1 to 3.2) and uE3 < 0.9 MoM (OR = 2.7; 95% CI, 2.0 to 3.7). The sensitivity, specificity, and positive and negative predictive values for predicting IUGR in the presence of at least one abnormal MMS were 46, 66, 11, and 90%, respectively. Elevated AFP > 2.0 MoM and hCG > 2.5 MoM were the most specific markers for MMS, with specificity of 94 and 95%, respectively. When all three analytes were abnormal, the specificity for predicting IUGR increased to 99%. Abnormal MMS results are associated with IUGR. As a screening tool for IUGR, the biochemical markers were associated with poor sensitivity. Elevated AFP and hCG, however, were highly specific in predicting IUGR. The provided thresholds could be useful in designing policies regarding women who would benefit most from sonographic screening for IUGR.

Adult↗

PubMed2006

Advanced maternal age is an independent risk factor for intrauterine growth restriction.

Reports on the association between advanced maternal age (AMA) and intrauterine growth restriction (IUGR) are conflicting. Our objective was to determine if AMA is an independent risk factor for IUGR. Our case-control study compared cases with IUGR (birthweight<10th percentile for gestational age) and a control group without IUGR. Gestational ages were all confirmed by ultrasound. The study included only singletons and fetal anomalies were excluded. Both groups were evaluated for maternal demographics and clinical risk factors. AMA was defined as maternal age>35 years. Univariate and multivariate analyses were used to examine associations. During the study period, there were 824 cases with IUGR meeting the inclusion criteria; these were compared with 1648 controls (no IUGR) randomly selected from the same population during the same study period. The significant factors associated with IUGR multivariate analyses were black race (odds ratio [OR], 22.4; 95% confidence interval [CI], 17.8 to 28); chronic hypertension (OR, 2.2; 95% CI, 1.5 to 3.2); pregestational diabetes (OR, 3.3; 95% CI, 1.6 to 7) illicit drug use (OR, 3.3; 95% CI, 2.2 to 5.2), and AMA (OR, 1.4; 95% CI, 1.1 to 1.8). There was a positive dose-response association between increasing maternal age and increasing risk for IUGR. At maternal age of 40 years or older, the OR and 95% CI for IUGR was 3.2 and 1.9 to 5.4, respectively. AMA is an independent risk factor for IUGR. Our findings suggest that screening for IUGR is indicated in women age 35 years or older.

Adolescent↗

PubMed2006

Safety and success of vaginal birth after cesarean delivery in patients with preeclampsia.

The objective of this study was to determine if preeclampsia (PRE) or gestational hypertension (GH) affects the rate of success of vaginal birth after cesarean delivery (VBAC), VBAC-related complications, or patient election to attempt VBAC. We performed a retrospective cohort study of all women who were offered VBAC from 1996 to 2000 in 17 community and university hospitals. Demographic, medical, and obstetric history, complications, treatment, and index pregnancy outcome information was collected on all patients in the database. Bivariate analysis and multivariable logistic regression were used to assess the independent association between GH and PRE and the rate of success of VBAC, VBAC-related complications, or patient election to attempt VBAC. A total of 25,005 patients were registered in the database. 13,706 (54.81%) attempted VBAC and 11,299 (45.19%) elected repeat cesarean delivery. After adjusting for confounding variables using multivariable logistic regression, patients with PRE were more likely to fail VBAC (relative risk [RR], 1.56; 95% CI, 1.22 to 2.00). Patients with GH were less likely to attempt VBAC (RR, 0.39; 95% CI, 0.34 to 0.46). A total of 304 (1.46%) patients had a uterine rupture. The VBAC group had a rupture rate of 0.93% and the elective cesarean group had a rupture rate of 0.04%. There was no difference in uterine rupture rates between the cohorts. Patients with gestational hypertension were less likely to attempt a VBAC. Patients with PRE, if they attempted a VBAC trial, had a higher VBAC failure rate. Patients with PRE or GH do not have increased uterine rupture rates. These findings can be used to improve mode of delivery counseling for VBAC candidate patients with preeclampsia.

Adult↗

PubMed2006

Should all pregnant diabetic women undergo a fetal echocardiography? A cost-effectiveness analysis comparing four screening strategies.

OBJECTIVE: To determine if a policy of universal fetal echocardiography for all pregnant diabetic women is cost-effective as a screening tool for congenital heart defects. STUDY DESIGN: Using a decision-analysis model, we compared the cost-effectiveness of four screening strategies: (1) none--no ultrasound is performed; (2) selective fetal echocardiography after abnormal detailed anatomic survey; (3) fetal echocardiography for only high hemoglobin A1C, and (4) universal fetal echocardiography for all diabetics. The sensitivity and specificity for each strategy were derived by literature search. The analysis was from a societal perspective using a willingness-to-pay threshold (50,000 dollars) and a theoretic cohort of 40,000 pregnant diabetics. Costs included costs of tests and the costs of complications and of raising a child with a cardiac defect. Outcomes were reported as cost per quality-adjusted life years (QALY) gained for each congenital heart defect prevented by each strategy and the number of congenital heart defects detected. One-way, multiway and probabilistic sensitivity analyses were performed. RESULTS: Compared with the other strategies, selective fetal echocardiography after abnormal detailed anatomic survey costs less per QALY gained for cardiac defect screening. Although universal fetal echocardiography was associated with a higher detection rate for cardiac defects, it was more costly. The sensitivity analyses revealed a robust model over a wide range of values. CONCLUSION: Under the baseline assumptions, selective fetal echocardiography after an abnormal detailed anatomic survey is more cost-effective compared with universal fetal echocardiography as a screening strategy for cardiac defects in pregnant diabetics.

Cost-Benefit Analysis↗

PubMed2006

Methods of clinical prediction.

The ability to predict clinical outcomes is of great importance to physicians and patients alike. Accordingly, multiple different methods have been used in an effort to accurately predict these outcomes. These methods include the development of scoring systems based on univariable and multivariable analysis, as well as models involving the use of neural network, nomograms, and classification and regression trees. The principles of these types of methods, as well as their advantages and disadvantages will be presented.

Forecasting↗

PubMed2006

Can uterine rupture in patients attempting vaginal birth after cesarean delivery be predicted?

OBJECTIVE: This study was undertaken to use multivariable methods to develop clinical predictive models for the occurrence of uterine rupture by using both antepartum and early intrapartum factors. STUDY DESIGN: This was a planned secondary analysis from a multicenter case-control study of uterine rupture among women attempting vaginal birth after cesarean (VBAC) delivery. Multivariable methods were used to develop 2 separate clinical predictive indices--one that used only prelabor factors and the other that used both prelabor and early labor factors. These indices were also assessed with the use of Receiver operating characteristic curves. RESULTS: We identified 134 cases of uterine rupture and 665 noncases. No single individual factor is sufficiently sensitive or specific for clinical prediction of uterine rupture. Likewise, the 2 clinical predictive indices were neither sufficiently sensitive nor specific for clinical use (receiver operating characteristic curve [area under the curve] 0.67 and 0.70, respectively). CONCLUSION: Uterine rupture cannot be predicted with either individual or combinations of clinical factors. This has important clinical and medical-legal implications.

Adult↗

PubMed2006

17alpha-hydroxyprogesterone caproate for the prevention of preterm delivery: A cost-effectiveness analysis.

OBJECTIVE: To evaluate whether the use of 17alpha-hydroxyprogesterone caproate for the prevention of recurrent preterm deliveries is cost-effective. METHODS: Using decision-analysis modeling, we compared the cost-effectiveness of using 17alpha-hydroxyprogesterone caproate in four subgroups: 1) Prior preterm deliveries less than 32 weeks; 2) prior preterm deliveries 32-37 weeks; 3) prior term delivery; and 4) no prior delivery. Each subgroup was compared with a "no treatment" group. Costs included those for 17alpha-hydroxyprogesterone caproate, hospital admissions, and complications from preterm deliveries. The main outcome measures include cost per quality-adjusted life-year gained and the number of preterm deliveries prevented. Secondary outcomes include neonatal complications prevented. One-way and multiway sensitivity analyses were performed. RESULTS: The use of 17alpha-hydroxyprogesterone caproate for the prevention of preterm deliveries result in cost-savings in women with prior preterm deliveries less than 32 weeks and 32-37 weeks. The sensitivity analyses revealed the model to be robust over a wide range of values for evaluated variables. CONCLUSION: Within our baseline assumptions, 17alpha-hydroxyprogesterone caproate was associated with cost-savings when used for the prevention of preterm deliveries in women with prior preterm deliveries.

17 alpha-Hydroxyprogesterone Caproate↗

PubMed2005

Obstetric outcomes in women with two prior cesarean deliveries: is vaginal birth after cesarean delivery a viable option?

OBJECTIVE: This study was undertaken to compare clinical outcomes in women with 1 versus 2 prior cesarean deliveries who attempt vaginal birth after cesarean delivery (VBAC) and also to compare clinical outcomes of women with 2 prior cesarean deliveries who attempt VBAC or opt for a repeat cesarean delivery. STUDY DESIGN: We performed a secondary analysis of a retrospective cohort study, in which the medical records of more than 25,000 women with a prior cesarean delivery from 16 community and tertiary care hospitals were reviewed by trained nurse abstractors. Information on demographics, obstetric history, medical and social history, and the outcomes of the index pregnancy was obtained. Comparisons of obstetric outcomes were made between women with 1 versus 2 prior cesarean deliveries, and also between women with 2 prior cesarean deliveries who opt for VBAC attempt versus elective repeat cesarean delivery. Both bivariate and multivariate techniques were used for these comparisons. RESULTS: The records of 20,175 women with one previous cesarean section and 3,970 with 2 prior cesarean sections were reviewed. The rate of VBAC success was similar in women with a single prior cesarean delivery (75.5%) compared with those with 2 prior cesarean deliveries (74.6%), though the odds of major morbidity were higher in those with 2 prior cesarean deliveries (adjusted odd ratio[OR] = 1.61 95% CI 1.11-2.33). Among women with 2 prior cesarean deliveries, those who opt for a VBAC attempt had higher odds of major complications compared with those who opt for elective repeat cesarean delivery (adjusted OR = 2.26, 95% CI 1.17-4.37). CONCLUSION: The likelihood of major complications is higher with a VBAC attempt in women with 2 prior cesarean deliveries compared with those with a single prior cesarean delivery. In women with 2 prior cesarean deliveries, while major complications are increased in those who attempt VBAC relative to elective repeat cesarean delivery, the absolute risk of major complications remains low.

Adult↗

PubMed2005

Maternal complications with vaginal birth after cesarean delivery: a multicenter study.

OBJECTIVE: This study was undertaken to determine incidence and risk factors for uterine rupture in women attempting vaginal birth after cesarean delivery (VBAC) in a wide range of hospital settings. STUDY DESIGN: We performed a case-control study nested within a cohort of women who have had a prior cesarean to determine the incidence and risk factors for uterine rupture in women attempting VBAC. RESULTS: The incidence rate of uterine rupture in those who attempt VBAC was 9.8 per 1000. A prior vaginal delivery was associated with a lower risk of uterine rupture (adjusted odds ratio [OR] = 0.40, 95% CI 0.20-0.81). Although prostaglandins alone were not associated with uterine rupture, sequential use of prostaglandin and pitocin was associated with uterine rupture (adjusted OR = 3.07, 95% CI 0.98-9.88). CONCLUSION: Women with a prior cesarean should be offered VBAC, and women with a prior cesarean and prior vaginal delivery should be encouraged to VBAC. Although other studies have suggested that prostaglandins should be avoided, we suggest that inductions requiring sequential agents be avoided.

Adult↗

PubMed2005

Is fetal gender associated with adverse perinatal outcome in intrauterine growth restriction (IUGR)?

OBJECTIVE: The purpose of this study was to determine if there is a difference in perinatal outcome by gender among growth-restricted fetuses. STUDY DESIGN: This was a retrospective cohort study of intrauterine growth restriction (IUGR) singleton pregnancies over a 5-year period. Clinical outcomes compared by gender included preterm delivery, perinatal mortality (PNM), respiratory distress syndrome (RDS), grade 3 or 4 intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), and periventricular leukomalacia (PVL). Statistical analysis included bivariate and multivariable techniques. RESULTS: Seven hundred and twenty-seven singleton pregnancies with IUGR were identified. Three hundred and forty-six (47.6%) were males. Birth weight was similar between the groups. After adjusting for maternal demographics, medical history, gestational age, mode of delivery, and antenatal corticosteroids, adverse perinatal outcomes were similar between the groups. Severity of outcomes was also similar between males and females (P = .66). CONCLUSION: Male fetuses with IUGR have similar outcomes when compared with female IUGR fetuses. Gender does not play a role in perinatal outcome in the setting of fetal growth restriction.

Female↗

PubMed2005

Vaginal birth after cesarean (VBAC) attempt in twin pregnancies: is it safe?

OBJECTIVE: The purpose of this study was to compare the rate of vaginal birth after cesarean (VBAC) attempt, VBAC failure, and major maternal adverse outcomes in women with a previous cesarean with twin or singleton pregnancies. STUDY DESIGN: This was a multicenter retrospective cohort study between the years 1996 and 2000. Subjects were identified by ICD-9 code. Trained research nurses collected medical record data on the outcome of VBAC attempts, and clinical outcomes, including uterine rupture and major operative injuries. We used bivariate and multivariable techniques to assess the association between twins and the outcomes. RESULTS: Of 25,005 patients with at least 1 previous cesarean, there were 535 twin pregnancies and 24,307 singleton pregnancies. Compared with patients with singleton gestations, patients with twins were less likely to attempt a VBAC (adjusted odds ratio [AOR] 0.3, 95% CI 0.2-0.4), but no more likely to have a VBAC failure (AOR 1.1, 95% CI 0.8-1.6), a uterine rupture (AOR 1.2, 95% CI 0.3-4.6), or a major maternal morbidity (AOR 1.6, 95% CI 0.7-3.7). CONCLUSION: Women with twin gestations are less likely to attempt a VBAC, but they are no more likely to fail a VBAC trial or experience a major morbid event compared with women with singleton gestations.

Adult↗

PubMed2005

Maternal and fetal tuberous sclerosis complicating pregnancy: a case report and overview of the literature.

Tuberous sclerosis complex (TSC) is an autosomal-dominant phakomatosis that can result in cardiac and central nervous system lesions and may adversely impact fetal and maternal health. We report a case of a 19-year-old primagravida with TSC whose pregnancy was complicated by preeclampsia, preterm labor, and fetal demise. The fetus, also affected with TSC, was diagnosed with a cardiac rhabdomyoma on ultrasound at 24 gestational weeks and intracranial tubers on fetal magnetic resonance imaging at 26 gestational weeks. Hydrops fetalis developed in the 30th gestational week. Fetal demise occurred during induction of labor. A systematic review of the medical literature was conducted. Our objective was to quantify maternal and fetal morbidity and mortality associated with TSC. We identified 36 additional cases of fetal TSC with cardiac rhabdomyoma diagnosed prenatally. Including our case, we also identified 23 pregnancies (17 mothers) complicated by maternal TSC. Rates of complications are calculated. We conclude that pregnancies complicated by maternal or fetal TSC deserve careful vigilance. Although benign histologically, cardiac rhabdomyomas can result in fetal morbidity and mortality.

Adult↗

PubMed2005

Perinatal outcomes in growth-restricted twins compared with age-matched growth-restricted singletons.

The objective of this study was to compare the perinatal outcomes in growth-restricted (IUGR) twins with a matched group of IUGR singletons. We performed a retrospective cohort study evaluating the perinatal outcomes in IUGR twins matched for gestational age at delivery to the next four IUGR singletons (1:4) in our perinatal database. The perinatal outcomes evaluated included rates of uncorrected perinatal mortality (PMR), admission to the neonatal intensive care unit (NICU), respiratory distress syndrome, grades 3 or 4 intraventricular hemorrhage, necrotizing enterocolitis, periventricular leukomalacia, and length of NICU stay. A cohort of twins with IUGR were matched with a cohort of IUGR singletons and compared for perinatal outcomes. A p value < 0.05 was considered significant. During the study period, we identified 99 IUGR twins meeting our inclusion criteria. These were matched with 396 singletons with IUGR. The mean gestational age at delivery for the twins was 34 +/- 3.8 weeks and 35 +/- 3.5 weeks for the singletons ( p = 0.11). The PMR in twins was significantly higher than in singletons (OR, 2.2; 95% confidence interval, 1.1 to 5.7). Perinatal morbidity was similarly significantly higher in IUGR twins. Compared with age-matched singletons, twins with IUGR have higher perinatal mortality and morbidity rates.

Adult↗

PubMed2005

The effect of prematurity on vaginal birth after cesarean delivery: success and maternal morbidity.

OBJECTIVE: We sought to compare vaginal birth after cesarean (VBAC) success and uterine rupture rates between preterm and term gestations in women with a history of one prior cesarean delivery. Our hypothesis was that preterm women undergoing VBAC were more likely to be successful and have a lower rate of complications than term women undergoing VBAC. METHODS: We reviewed medical records of women with a history of a cesarean delivery who either attempted a VBAC or underwent a repeat cesarean delivery from 1995 through 2000 in 17 community and university hospitals. We collected information on demographics, medical and obstetric history, complications, and outcome of the index pregnancy. The primary analysis was limited to women with singleton gestations and one prior cesarean delivery. Statistical analysis consisted of bivariate and multivariable techniques. RESULTS: Among the 20,156 patients with one prior cesarean delivery, 12,463 (61%) attempted a VBAC. Mean gestational ages for the term and preterm women were 39.2 weeks and 33.9 weeks of gestation, respectively. The VBAC success rates for the term and preterm groups were 74% and 82%, respectively (P < .001). Multivariable analysis showed that the VBAC success was higher (adjusted odds ratio 1.54, 95% confidence interval 1.27-1.86) in preterm gestations. A decreased risk of rupture among preterm gestations was suggested in these results (adjusted odds ratio 0.28, 95% confidence interval 0.07-1.17; P = .08). CONCLUSION: Preterm patients undergoing a VBAC have higher success rates when compared with term patients undergoing a VBAC. Preterm patients undergoing VBAC may have lower uterine rupture rates.

Cesarean Section, Repeat↗

PubMed2005

A cost-effectiveness analysis of prenatal screening strategies for Down syndrome.

OBJECTIVE: To evaluate which Down syndrome screening strategy is the most cost-effective. METHODS: Using decision-analysis modeling, we compared the cost-effectiveness of 9 screening strategies for Down syndrome: 1) no screening, 2) first-trimester nuchal translucency (NT) only, 3) first-trimester combined NT and serum screen, 4) first-trimester serum only, 5) quadruple screen, 6) integrated screening, 7) sequential screening, 8) integrated serum only, or 9) maternal age. Costs included cost of tests and resources used for raising a child with Down syndrome. One-way and multiway sensitivity analyses were performed for all model variables. The main outcome measures were cost per Down syndrome case detected, rate of delivering a liveborn neonate with Down syndrome, and rate of diagnostic procedure-related pregnancy loss for each strategy. RESULTS: Sequential screening detected more Down syndrome cases compared with the other strategies, but it had a higher procedure-related loss rate. Integrated serum screening was the most cost-effective strategy. Sensitivity analyses revealed the model to be robust over a wide range of values for the variables. The addition of the cost of genetic sonogram to the second-trimester strategies resulted in first-trimester combined screening becoming the most cost-effective strategy. CONCLUSION: Within our baseline assumptions, integrated serum screening was the most cost-effective screening strategy for Down syndrome. If the cost of nuchal translucency is less than dollars 57 or when genetic sonogram is included in the second-trimester strategies, first-trimester combined screening became the most cost-effective strategy. LEVEL OF EVIDENCE: III.

Adult↗

PubMed2005

Thromboprophylaxis after cesarean delivery: a decision analysis.

OBJECTIVE: To compare 4 strategies for managing patients after cesarean delivery. METHODS: Using decision analysis, we compared universal subcutaneous (SC) heparin prophylaxis, heparin prophylaxis only for patients with a genetic thrombophilia, use of pneumatic compression stockings (PCS), and no thromboprophylaxis. Outcomes included heparin-induced thrombocytopenia (HIT), HIT-related thrombosis, major maternal bleeding, and venous thromboembolism (VTE). RESULTS: Use of PCS was the strategy with the lowest number of adverse events. With heparin prophylaxis, 13 cases of HIT-induced thrombosis and hemorrhage would occur per VTE prevented. When heparin prophylaxis is administered only to thrombophilia-positive women, 1.2 cases of HIT-induced thrombosis and bleeding would occur per VTE prevented. In sensitivity analyses, the model was stable across virtually all variable ranges. CONCLUSION: Use of PCS after cesarean delivery is the strategy with the lowest number of adverse events. Universal prophylaxis with SC heparin is associated with an excess risk of HIT-induced thrombosis and bleeding per VTE prevented compared with PCS use. Until future studies are completed, postcesarean thromboprophylaxis with PCS should be used if the clinician elects to provide prophylaxis.

Bandages↗

PubMed2005

Safety and efficacy of vaginal birth after cesarean attempts at or beyond 40 weeks of gestation.

OBJECTIVE: To compare rates of vaginal birth after cesarean (VBAC) failure and major complications in women attempting VBAC before and after the estimated date of delivery (EDD) METHODS: This was a 5-year retrospective cohort study in 17 university and community hospitals of women with at least 1 prior cesarean delivery. Women who attempted VBAC before the EDD were compared with those at or beyond 40 weeks of gestation. Logistic regression analyses were performed to assess the relationship between delivery beyond the EDD and VBAC failure or complication rate. RESULTS: A total of 11,587 women in the cohort attempted VBAC. Women past 40 weeks of gestation were more likely to have a failed VBAC. After controlling for confounders, the increased risk of a failed VBAC beyond 40 weeks remained significant (31.3% compared with 22.2%, odds ratio 1.36, 95% confidence interval 1.24-1.50). The risk of uterine rupture (1.1% compared with 1.0%) or overall morbidity (2.7% compared with 2.1%) was not significantly increased in the women attempting VBAC beyond the EDD. When the cohort was defined as 41 weeks or more of gestation, the risk of a failed VBAC was again significantly increased (35.4% compared with 24.3%, odds ratio 1.35, 95% confidence interval 1.20-1.53), but the risk of uterine rupture or overall morbidity was not increased. CONCLUSION: Women beyond 40 weeks of gestation can safely attempt VBAC, although the risk of VBAC failure is increased.

Adult↗