Nicole Marshall

Vaginal birth after cesarean: New insights on maternal and neonatal outcomes

OBJECTIVE: To systematically review the evidence about maternal and neonatal outcomes relating to vaginal birth after cesarean (VBAC). DATA SOURCES: Relevant studies were identified from multiple searches of MEDLINE, DARE, and the Cochrane databases (1980 to September 2009) and from recent systematic reviews, reference lists, reviews, editorials, Web sites, and experts. METHODS OF STUDY SELECTION: Inclusion criteria limited studies to the English-language and human studies conducted in the United States and developed countries specifically evaluating birth after previous cesarean delivery. Studies focusing on high-risk maternal or neonatal conditions, including breech vaginal delivery, or fewer than 10 patients were excluded. Poor-quality studies were not included in analyses. TABULATION, INTEGRATION, AND RESULTS: We identified 3,134 citations and reviewed 963 articles for inclusion; 203 articles met the inclusion criteria and were quality rated. Overall rates of maternal harms were low for both trial of labor and elective repeat cesarean delivery. Although rare in both elective repeat cesarean delivery and trial of labor, maternal mortality was significantly increased for elective repeat cesarean delivery at 0.013% compared with 0.004% for trial of labor. The rates of maternal hysterectomy, hemorrhage, and transfusions did not differ significantly between trial of labor and elective repeat cesarean delivery. The rate of uterine rupture for all women with prior cesarean was 0.30%, and the risk was significantly increased for trial of labor (0.47% compared with 0.03% for elective repeat cesarean delivery). Perinatal mortality was also significantly increased for trial of labor (0.13% compared with 0.05% for elective repeat cesarean delivery). CONCLUSION: Overall the best evidence suggests that VBAC is a reasonable choice for the majority of women. Adverse outcomes were rare for both elective repeat cesarean delivery and trial of labor. Definitive studies are lacking to identify patients who are at greatest risk for adverse outcomes.

Impact of multiple cesarean deliveries on maternal morbidity: a systematic review

OBJECTIVE The purpose of this study was to determine the impact of increasing numbers of cesarean deliveries on maternal morbidity. This study was performed for the 2010 National Institutes of Health Consensus Development Conference on Vaginal Birth After Cesarean: New Insights. STUDY DESIGN We conducted a systematic review and metaanalysis of observational studies. RESULTS Twenty-one studies (2,282,922 deliveries) were included. The rate of hysterectomy, blood transfusions, adhesions, and surgical injury all increased with increasing number of cesarean deliveries. The incidence of placenta previa increased from 10/1000 deliveries with 1 previous cesarean delivery to 28/1000 with ≥3 cesarean deliveries. Compared with women with previa and no previous cesarean delivery, women with previa and ≥3 cesarean deliveries had a statistically significant increased risk of accreta (3.3-4% vs 50-67%), hysterectomy (0.7-4% vs 50-67%), and composite maternal morbidity (15% vs 83%; odds ratio, 33.6; 95% confidence interval, 14.6-77.4). CONCLUSION Serious maternal morbidity progressively increased as the number of previous cesarean deliveries increased.

Maternal superobesity and perinatal outcomes

OBJECTIVE The purpose of this study was to determine the effect of maternal superobesity (body mass index [BMI], ≥ 50 kg/m(2)) compared with morbid obesity (BMI, 40-49.9 kg/m(2)) or obesity (BMI, 30-39.9 kg/m(2)) on perinatal outcomes. STUDY DESIGN We conducted a retrospective cohort study of birth records that were linked to hospital discharge data for all liveborn singleton term infants who were born to obese Missouri residents from 2000-2006. We excluded major congenital anomalies and women with diabetes mellitus or chronic hypertension. RESULTS There were 64,272 births that met the study criteria, which included 1185 superobese mothers (1.8%). Superobese women were significantly more likely than obese women to have preeclampsia (adjusted relative risk [aRR], 1.7; 95% confidence interval [CI], 1.4-2.1), macrosomia (aRR, 1.8; 95% CI, 1.3-2.5), and cesarean delivery (aRR, 1.8; 95% CI, 1.5-2.1). Almost one-half of all superobese women (49.1%) delivered by cesarean section, and 33.8% of superobese nulliparous women underwent scheduled primary cesarean delivery. CONCLUSION Women with a BMI of ≥ 50 kg/m(2) are at significantly increased risk for perinatal complications compared with obese women with a lower BMI.

Obesity in pregnancy: a big problem and getting bigger.

Obesity has increased dramatically in the United States over the last several decades, with approximately 40% of women now considered overweight or obese. Obesity has been shown to be associated with poor pregnancy outcomes, including increased rates of cesarean delivery, preeclampsia, gestational diabetes, fetal macrosomia, stillbirth, and postterm pregnancy. In this review, we discuss the association of obesity with maternal, fetal, and pregnancy outcomes as well as the recommendations for care of the obese gravida. Target Audience: Obstetricians and gynecologists and family physicians Learning Objectives: After completing the CME activity, physicians should be better able to describe the maternal, neonatal, and intrapartum complications associated with obesity in pregnancy and implement additional changes to prenatal care appropriate for the obese gravida.

New Insights on Vaginal Birth After Cesarean: Can It Be Predicted?

OBJECTIVE: To evaluate existing vaginal birth after cesarean (VBAC) screening tools and to identify additional factors that may predict VBAC or failed trial of labor. DATA SOURCES: Relevant studies were identified through MEDLINE, Database of Abstracts of Reviews of Effectiveness, and the Cochrane databases (1980-September 2009), and from recent systematic reviews, reference lists, reviews, editorials, web sites, and experts. METHODS OF STUDY SELECTION: Inclusion criteria limited studies to those of humans, written in English, studies conducted in the United States and developed countries, and those rated good or fair quality by the U.S. Preventive Services Task Force criteria. Studies of individual predictors were combined using a random effects model when the estimated odds ratios were comparable across included studies. TABULATION, INTEGRATION, AND RESULTS: We identified 3,134 citations and reviewed 963 papers, of which 203 met inclusion criteria and were quality-rated. Twenty-eight provided evidence on predictors of VBAC and 16 presented information on scored models for predicting VBAC (or failed trial of labor). Six of the 11 scored models for predicting VBAC (or failed trial of labor) were validated by separated dataset, cross-validation, or both. Whereas accuracy remained high across all models for predicting VBAC, with predictive values ranging from 88% to 95%, accuracy for predicting failed trial of labor was low, ranging from 33% to 58%. Individual predictors including Hispanic ethnicity, African-American race, advanced maternal age, no previous vaginal birth history, birth weight heavier than 4 kg, and use of either augmentation or induction were all associated with reduced likelihood of VBAC. CONCLUSION: Current scored models provide reasonable predictability for VBAC, but none provides consistent ability to identify women at risk for failed trial of labor. A scoring model is needed that incorporates known antepartum factors and can be adjusted for current obstetric factors and labor patterns if induction or augmentation is needed. This would allow women and clinicians to better determine individuals most likely to require repeat cesarean delivery.

Pregnancy Risks Associated with Obesity

Obesity has increased dramatically in the United States over the last several decades, with approximately 40% of pregnant women now considered overweight or obese. Obesity has been shown to be associated with numerous poor pregnancy outcomes, including increased rates of preeclampsia, gestational diabetes, fetal macrosomia, stillbirth, postterm pregnancy, and increased rates of cesarean delivery. Many of these complications have been found to increase even further with increasing body mass index in a dose-response fashion. In this review, the association of obesity with maternal, fetal, and pregnancy outcomes is discussed as are the recommendations for caring for the obese gravida.

Delivery after prior cesarean: maternal morbidity and mortality.

Nearly 1 in 3 pregnant women in the United States undergo cesarean. This trend is contrary to the national goal of decreasing cesarean delivery in low-risk women. The decline in vaginal birth after cesarean (VBAC) contributes to the continual increase in cesarean deliveries. Prior cesarean delivery is the most common indication for cesarean and accounts for more than one-third of all cesareans. The appropriate use and safety of cesarean and VBAC are of concern not only at the individual patient and clinician level but they also have far-reaching public health and policy implications at the national level.

Maternal obesity alters immune cell frequencies and responses in umbilical cord blood samples

Maternal obesity is one of the several key factors thought to modulate neonatal immune system development. Data from murine studies demonstrate worse outcomes in models of infection, autoimmunity, and allergic sensitization in offspring of obese dams. In humans, children born to obese mothers are at increased risk for asthma. These findings suggest a dysregulation of immune function in the children of obese mothers; however, the underlying mechanisms remain poorly understood. The aim of this study was to examine the relationship between maternal body weight and the human neonatal immune system.

The placenta is the center of the chronic disease universe

Over the past quarter century it has become clear that adult onset chronic diseases like heart disease and type 2 diabetes have their roots in early development. The report by David Barker and colleagues showing an inverse relationship between birthweight and mortality from ischemic heart disease was the first clear-cut demonstration of fetal programming. Because fetal growth depends upon the placental capacity to transport nutrients from maternal blood, it has been a suspected causative agent since the original Barker reports. Epidemiological studies have shown that placental size and shape have powerful associations with offspring disease. More recent studies have shown that maternal phenotypic characteristics, such as body mass index and height, interact with placental size and shape to predict disease with much more precision than does birthweight alone. For example, among people in the Helsinki Birth Cohort, who were born during 1924–1944, the risk for acquiring colorectal cancer increased as the placental surface became longer and more oval. Among people in whom the difference between the length and breadth of the surface exceeded 6 cm, the hazard ratio for the cancer was 2.3 (95% CI 1.2–4.7, p=0.003) compared with those in whom there was no difference. Among Finnish men, the hazard ratio for coronary heart disease was 1.07 (1.02–1.13, P =0.01) per 1% increase in the placental weight/birthweight ratio. Thus, it appears that the ratio of birthweight to placental weight, known as placental efficiency, predicts cardiovascular risk as well. Babies born with placentas at the extremes of efficiency are more vulnerable for adult onset chronic diseases. Recent evidence suggests that placental growth patterns are sex specific. Boys’ placentas are, in general, more efficient than those made by girls. Another recent discovery is that the size, shape and efficiencies of the placenta can change over years of time with very narrow confidence limits. This suggests that the growth of the placenta within a population of women is strongly affected by their nutritional environment. Even though it is known that an individual placenta can expand to improve its nutrient acquisition capacity in the first 2/3rd of gestation, the mechanisms by which placentas grow in response to a specific nutritional environment are not known. Discovering those mechanisms is the task of the current generation of scientists. While it may seem obvious that good nutrition is highly important for women who are pregnant because it supports optimal placentation and fetal development, more research is needed to determine the mechanisms by which maternal nutrition, placenta growth and fetal health are related.

Obesity, pregnancy complications, and birth outcomes

Obesity is an increasingly common complication of pregnancy with over half of all women in the United States starting pregnancy overweight or obese. Obese women face unique physiological changes during pregnancy, and these women and their neonates are at increased risk for perinatal morbidity and mortality. In this review, we discuss physiological alterations in obese pregnant women and examine obesity-related antepartum, intrapartum, and postpartum complications along with management options.