Trends in comorbidity, acuity, and maternal risk associated with preeclampsia across obstetric volume settings

OBJECTIVE

The objective of this study was to characterize morbidity, acuity, and maternal risks associated with preeclampsia across hospitals with varying obstetric volumes.

METHODS

This retrospective cohort analysis used a large administrative data source, the Perspective database, to characterize the risk for preeclampsia from 2006 to 2015. Hospitals were classified as having either low (≤1000), moderate (1001-2000), or high (≥2000) delivery volume. The primary outcomes included preeclampsia, antihypertensive administration, comorbidity, and related severe maternal morbidity. Severe maternal morbidity was estimated using criteria from the Centers for Disease Control and Prevention. Comorbidity was estimated using an obstetric comorbidity index. Univariable comparisons were made with Chi-squared test. Adjusted log linear regression models were fit to assess factors associated with severe morbidity with risk ratios with 95% confidence intervals as the measures of effect. Population weights were applied to create national estimates.

RESULTS

Of 36,985,729 deliveries included, 1,414,484 (3.8%) had a diagnosis of preeclampsia. Of these, 779,511 (2.1%) had mild, 171,109 (0.5%) superimposed, and 463,864 (1.3%) severe preeclampsia. The prevalence of mild, superimposed, and severe preeclampsia each increased over the study period with severe and superimposed preeclampsia as opposed to mild preeclampsia increasing the most proportionately (53.2 and 102.5 versus 10.8%, respectively). The use of antihypertensives used to treat severe range hypertension increased with use of intravenous labetalol increasing 31.5%, 43.2%, and 36.1% at low-, medium-, and high-volume hospitals. Comorbid risk also increased across hospital volume settings as did risk for severe maternal morbidity.

CONCLUSIONS

Preeclampsia is increasing across obstetric care settings with preeclamptic patients demonstrating increasing comorbid risk, increased risk for severe morbidity, and more frequent need for treatment of acute hypertension.

Maternal Depressive Symptoms, Perceived Stress, and Fetal Growth

OBJECTIVES

To determine whether longitudinal fetal growth is altered among pregnant women reporting greater perceived stress or more symptoms of depression.

METHODS

This analysis was based on a multicenter longitudinal study of fetal growth. Women were screened at gestational ages of 8 weeks to 13 weeks 6 days for low-risk status and underwent serial sonographic examinations. At each study visit during pregnancy, women were asked to complete the Cohen Perceived Stress Scale (PSS) and Edinburgh Postpartum Depression Survey (EPDS). Growth curves for estimated fetal weight and individual biometric parameters were created by using linear mixed models with cubic splines and compared on the basis of whether women scored 15 or higher on the PSS or 10 or higher on the EPDS either at the start of or at any time during pregnancy.

RESULTS

Of the 2334 women enrolled in the study, 2088 (89%) and 2108 (90%) completed the PSS and EPDS, respectively, at least once in all trimesters. The longitudinal growth curves of estimated fetal weight as well as all individual biometric parameters were similar (P > .05) regardless of whether the participants reported PSS of 15 or higher or EPDS of 10 or higher in the first trimester or whether these scores persisted throughout the pregnancy. Similarly, effect modification by race/ethnicity was not statistically significant for the biometric parameters under study (P > .05 for all race/ethnicity interactions).

CONCLUSIONS

More depressive symptoms and greater perceived stress, as quantified by the EPDS and the PSS, respectively, are not associated with alterations in fetal growth throughout gestation.

The role of maternal age in twin pregnancy outcomes

BACKGROUND

There are limited data on how maternal age is related to twin pregnancy outcomes.

OBJECTIVE

The purpose of this study was to assess the relationship between maternal age and risk for preterm birth, fetal death, and neonatal death in the setting of twin pregnancy.

STUDY DESIGN

This population-based study of US birth, fetal death, and period-linked birth-infant death files from 2007-2013 evaluated neonatal outcomes for twin pregnancies. Maternal age was categorized as 15-17, 18-24, 25-29, 30-34, 35-39, and ≥40 years of age. Twin live births and fetal death delivered at 20-42 weeks were included. Primary outcomes included preterm birth (<34 weeks and <37 weeks), fetal death, and neonatal death at <28 days of life. Analyses of preterm birth at <34 and <37 weeks were adjusted for demographic and medical factors, with maternal age modeled with the use of restricted spline transformations.

RESULTS

A total of 955,882 twin live births from 2007-2013 were included in the analysis. Preterm birth rates at <34 and <37 weeks gestation were highest for women 15-17 years of age, decreased across subsequent maternal age categories, nadired for women 35-39 years old, and then increased slightly for women ≥40 years old. Risk for fetal death generally decreased across maternal age categories. Risk for fetal death was 39.9 per 1000 live births for women 15-17 years old, 24.2 for women 18-24 years old, 17.8 for women 25-29 years old, 16.4 for women 30-34 years old, 17.2 for women 35-39 years old, and 15.8 for women ≥40 years old. Risk for neonatal death at <28 days was highest for neonates born to women 15-17 years old (10.0 per 1,000 live births), decreased to 7.3 for women 18-24 years old and 5.5 for women 25-29 years old and ranged from 4.3-4.6 for all subsequent maternal age categories. In adjusted models, risk for preterm birth at <34-<37 weeks gestation was not elevated for women in their mid-to-late 30s; however, risk was elevated for women <20 years old and increased progressively with age for women in their 40s.

CONCLUSION

Although twin pregnancy is associated with increased risk for most adverse perinatal outcomes, this analysis did not find advanced maternal age to be an additional risk factor for fetal death and infant death. Preterm birth risk was relatively low for women in their late 30s. Risks for adverse outcomes were higher among younger women; further research is indicated to improve outcomes for this demographic group. It may be reasonable to counsel women in their 30s that their age is not a major additional risk factor for adverse obstetric outcomes in the setting of twin pregnancy.

Risk for postpartum hemorrhage, transfusion, and hemorrhage-related morbidity at low, moderate, and high volume hospitals

OBJECTIVE

The objective of this study was to characterize risk for and temporal trends in postpartum hemorrhage across hospitals with different delivery volumes.

STUDY DESIGN

This study used the Nationwide Inpatient Sample (NIS) to characterize risk for postpartum hemorrhage from 1998 to 2011. Hospitals were classified as having either low, moderate or high delivery volume (≤1000, 1001 to 2000, >2000 deliveries per year, respectively). The primary outcomes included postpartum hemorrhage, transfusion, and related severe maternal morbidity. Adjusted models were created to assess factors associated with hemorrhage and transfusion.

RESULTS

Of 55,140,088 deliveries included for analysis 1,512,212 (2.7%) had a diagnosis of postpartum hemorrhage and 361,081 (0.7%) received transfusion. Risk for morbidity and transfusion increased over the study period, while the rate of hemorrhage was stable ranging from 2.5 to 2.9%. After adjustment, hospital volume was not a major risk factor for transfusion or hemorrhage.

DISCUSSION

While obstetric volume does not appear to be a major risk factor for either transfusion or hemorrhage, given that transfusion and hemorrhage-related maternal morbidity are increasing across hospital volume categories, there is an urgent need to improve obstetrical care for postpartum hemorrhage. Those risk factors are able to discriminate women at increased risk supports routine use of hemorrhage risk assessment.

Severe maternal morbidity and comorbid risk in hospitals performing <1000 deliveries per year

BACKGROUND

While research has demonstrated increasing risk for severe maternal morbidity in the United States, risk at lower volume hospitals remains poorly characterized. More than half of all obstetric units in the United States perform <1000 deliveries per year and improving care at these hospitals may be critical to reducing risk nationwide.

OBJECTIVE

We sought to characterize maternal risk profiles and severe maternal morbidity at low-volume hospitals in the United States.

STUDY DESIGN

We used data from the Nationwide Inpatient Sample to evaluate trends in severe maternal morbidity and comorbid risk during delivery hospitalizations in the United States from 1998 through 2011. Comorbid maternal risk was estimated using a comorbidity index validated for obstetric patients. Severe maternal morbidity was defined as the presence of any 1 of 15 diagnoses representative of acute organ injury and critical illness.

RESULTS

A total of 2,300,279 deliveries occurred at hospitals with annual delivery volume <1000, representing 20% of delivery hospitalizations overall. There were 7849 cases (0.34%) of severe morbidity in low-volume hospitals and this risk increased over the course of the study from 0.25% in 1998 through 1999 to 0.49% in 2010 through 2011 (P < .01). The risk in hospitals with ≥1000 deliveries increased from 0.35-0.62% during the same time periods. The proportion of patients with the lowest comorbidity decreased, while the proportion of patients with highest comorbidity increased the most. The risk of severe morbidity increased across all women including those with low comorbidity scores. Risk for severe morbidity associated with obstetric hemorrhage, infection, hypertensive diseases of pregnancy, and medical conditions all increased during the study period.

CONCLUSION

Our findings demonstrate increasing maternal risk at hospitals performing <1000 deliveries per year broadly distributed over the patient population. Rates of morbidity in centers with ≥1000 deliveries have also increased. These findings suggest that maternal safety improvements are necessary at all centers regardless of volume.

Hospital delivery volume, severe obstetrical morbidity, and failure to rescue

BACKGROUND

In the setting of persistently high risk for maternal death and severe obstetric morbidity, little is known about the relationship between hospital delivery volume and maternal outcomes.

OBJECTIVE

The objectives of this analysis were (1) to determine maternal risk for severe morbidity during delivery hospitalizations by hospital delivery volume in the United States and (2) to characterize, by hospital volume, the risk for death in the setting of severe obstetric morbidity, a concept known as failure to rescue.

STUDY DESIGN

This cohort study evaluated 50,433,539 delivery hospitalizations across the United States from 1998-2010. The main outcome measures were (1) severe morbidity that was defined as a composite of any 1 of 15 diagnoses that are representative of acute organ injury and critical illness and (2) failure to rescue that was defined as death in the setting of severe morbidity.

RESULTS

The prevalence of severe morbidity rose from 471.2-751.5 cases per 100,000 deliveries from 1998-2010, which was an increase of 59.5%. Failure to rescue was highest in 1998 (1.5%), decreased to 0.6% in 2007, and rose to 0.9% in 2010. In models that were adjusted for comorbid risk and hospital factors, both low and high annualized delivery volume were associated with increased risk for failure to rescue and severe morbidity. However, the relative importance of hospital volume for both outcomes compared with other factors was relatively small.

CONCLUSION

Although low-and high-delivery volume are associated with increased risk for both failure to rescue and severe maternal morbidity, other factors, in particular characteristics of individual centers, may be more important in the determination of outcomes.

Population-based risk for peripartum hysterectomy during low- and moderate-risk delivery hospitalizations

BACKGROUND

Postpartum hysterectomy is an obstetric procedure that carries significant maternal risk that is not well characterized by hospital volume.

OBJECTIVE

The objective of this study was to determine risk for peripartum hysterectomy for women at low and moderate risk for the procedure.

STUDY DESIGN

This population-based study used data from the Nationwide Inpatient Sample to characterize risk for peripartum hysterectomy. Women with a diagnosis of placenta accreta or prior cesarean and placenta previa were excluded. Obstetrical risk factors along with demographic and hospital factors were evaluated. Multivariable mixed-effects log-linear regression models were developed to determine adjusted risk. Based on these models receiver operating characteristic curves were plotted, and the area under the curve was determined to assess discrimination.

RESULTS

Peripartum hysterectomy occurred in 1 in 1913 deliveries. Risk factors associated with significant risk for hysterectomy included mode of delivery, stillbirth, placental abruption, fibroids, and antepartum hemorrhage. These factors retained their significance in adjusted models: the risk ratio for stillbirth was 3.44 (95% confidence interval, 2.94-4.02), abruption 2.98 (95% confidence interval, 2.52-3.20), fibroids 3.63 (95% confidence interval, 3.22-4.08), and antepartum hemorrhage 7.15 (95% confidence interval, 6.16-8.32). The area under the curve for the model was 0.833.

CONCLUSION

Peripartum hysterectomy is a relatively common event that hospitals providing routine obstetric care should be prepared to manage. That specific risk factors are highly associated with risk for hysterectomy supports routine use of hemorrhage risk-assessment tools. However, given that a significant proportion of hysterectomies will be unpredictable, the availability of rapid transfusion protocols may be necessary for hospitals to safely manage these cases.

Proposed diagnostic criteria for the case definition of amniotic fluid embolism in research studies

Amniotic fluid embolism is a leading cause of maternal mortality in developed countries. Our understanding of risk factors, diagnosis, treatment, and prognosis is hampered by a lack of uniform clinical case definition; neither histologic nor laboratory findings have been identified unique to this condition. Amniotic fluid embolism is often overdiagnosed in critically ill peripartum women, particularly when an element of coagulopathy is involved. Previously proposed case definitions for amniotic fluid embolism are nonspecific, and when viewed through the eyes of individuals with experience in critical care obstetrics, would include women with a number of medical conditions much more common than amniotic fluid embolism. We convened a working group under the auspices of a committee of the Society for Maternal-Fetal Medicine and the Amniotic Fluid Embolism Foundation whose task was to develop uniform diagnostic criteria for the research reporting of amniotic fluid embolism. These criteria rely on the presence of the classic triad of hemodynamic and respiratory compromise accompanied by strictly defined disseminated intravascular coagulopathy. It is anticipated that limiting research reports involving amniotic fluid embolism to women who meet these criteria will enhance the validity of published data and assist in the identification of risk factors, effective treatments, and possibly useful biomarkers for this condition. A registry has been established in conjunction with the Perinatal Research Branch of the Eunice Kennedy Shriver National Institute of Child Health and Human Development to collect both clinical information and laboratory specimens of women with suspected amniotic fluid embolism in the hopes of identifying unique biomarkers of this condition.

Gastroschisis: epidemiology and mode of delivery, 2005-2013

BACKGROUND

Gastroschisis is a severe congenital anomaly the etiology of which is unknown. Research evidence supports attempted vaginal delivery for pregnancies complicated by gastroschisis in the absence of obstetric indications for cesarean delivery.

OBJECTIVE

The objectives of the study evaluating pregnancies complicated by gastroschisis were to determine the proportion of women undergoing planned cesarean vs attempted vaginal delivery and to provide up-to-date epidemiology on the risk factors associated with this anomaly.

STUDY DESIGN

This population-based study of US natality records from 2005 through 2013 evaluated pregnancies complicated by gastroschisis. Women were classified based on whether they attempted vaginal delivery or underwent a planned cesarean (n = 24,836,777). Obstetrical, medical, and demographic characteristics were evaluated. Multivariable log-linear regression models were developed to determine the factors associated with the mode of delivery. Factors associated with the occurrence of the anomaly were also evaluated in log-linear models.

RESULTS

Of 5985 pregnancies with gastroschisis, 63.5% (n = 3800) attempted vaginal delivery and 36.5% (n = 2185) underwent a planned cesarean delivery. The rate of attempted vaginal delivery increased from 59.7% in 2005 to 68.8% in 2013. Earlier gestational age and Hispanic ethnicity were associated with lower rates of attempted vaginal delivery. Factors associated with the occurrence of gastroschisis included young age, smoking, high educational attainment, and being married. Protective factors included chronic hypertension, black race, and obesity. The incidence of gastroschisis was 3.1 per 10,000 pregnancies and did not increase during the study period.

CONCLUSION

Attempted vaginal delivery is becoming increasingly prevalent for women with a pregnancy complicated by gastroschisis. Recommendations from the research literature findings may be diffusing into clinical practice. A significant proportion of women with this anomaly still deliver by planned cesarean, suggesting further reduction of surgical delivery for this anomaly is possible.

Dichorionic twin trajectories: the NICHD Fetal Growth Studies

BACKGROUND

Systematic evaluation and estimation of growth trajectories in twins require ultrasound measurements across gestation that are performed in controlled clinical settings. Currently, there are few such data for contemporary populations. There is also controversy about whether twin fetal growth should be evaluated with the use of the same benchmarks as singleton growth.

OBJECTIVES

Our objective was to define the trajectory of fetal growth in dichorionic twins empirically using longitudinal 2-dimensional ultrasonography and to compare the fetal growth trajectories for dichorionic twins with those based on a growth standard that was developed by our group for singletons.

STUDY DESIGN

A prospective cohort of 171 women with twin gestations was recruited from 8 US sites from 2012-2013. After an initial sonogram at 11 weeks 0 days-13 weeks 6 days of gestation during which dichorionicity was confirmed, women were assigned randomly to 1 of 2 serial ultrasonography schedules. Growth curves and percentiles were estimated with the use of linear mixed models with cubic splines. Percentiles were compared statistically at each gestational week between the twins and 1731 singletons, after adjustment for maternal age, race/ethnicity, height, weight, parity, employment, marital status, insurance, income, education, and infant sex. Linear mixed models were used to test for overall differences between the twin and singleton trajectories with the use of likelihood ratio tests of interaction terms between spline mean structure terms and twin-singleton indicator variables. Singleton standards were weighted to correspond to the distribution of maternal race in twins. For those ultrasound measurements in which there were significant global tests for differences between twins and singletons, we tested for week-specific differences using Wald tests that were computed at each gestational age. In a separate analysis, we evaluated the degree of reclassification in small for gestational age, which was defined as <10th percentile that would be introduced if fetal growth estimation for twins was based on an unweighted singleton standard.

RESULTS

Women underwent a median of 5 ultrasound scans. The 50th percentile abdominal circumference and estimated fetal weight trajectories of twin fetuses diverged significantly beginning at 32 weeks of gestation; biparietal diameter in twins was smaller from 34-36 weeks of gestation. There were no differences in head circumference or femur length. The mean head circumference/abdominal circumference ratio was progressively larger for twins compared with singletons beginning at 33 weeks of gestation, which indicated a comparatively asymmetric growth pattern. At 35 weeks of gestation, the average gestational age at delivery for twins, the estimated fetal weights for the 10th, 50th, and 90th percentiles were 1960, 2376, and 2879 g for dichorionic twins, respectively, and 2180, 2567, and 3022 g for the singletons, respectively. At 32 weeks of gestation, the initial week when the mean estimated fetal weight for twins was smaller than that of singletons, 34% of twins would be classified as small for gestational age with the use of a singleton, non-Hispanic white standard. By 35 weeks of gestation, 38% of twins would be classified as small for gestational age.

CONCLUSION

The comparatively asymmetric growth pattern in twin gestations, initially evident at 32 weeks of gestation, is consistent with the concept that the intrauterine environment becomes constrained in its ability to sustain growth in twin fetuses. Near term, nearly 40% of twins would be classified as small for gestational age based on a singleton growth standard.

Ultrasound Quality Assurance for Singletons in the National Institute of Child Health and Human Development Fetal Growth Studies

OBJECTIVES

To report on the ultrasound quality assurance program for the National Institute of Child Health and Human Development Fetal Growth Studies and describe both its advantages and generalizability.

METHODS

After training on an ultrasound system and software, research sonographers were expected to capture blank (unmeasured) images in triplicate for crown-rump length, biparietal diameter, head circumference, abdominal circumference, and femur length. A primary expert sonographer was designated and validated. A 5% sample (n = 740 of 14,785 scans) was randomly selected in 3 distinct rounds from within strata of maternal body mass index (round 1 only), gestational age, and research site. Unmeasured images were extracted from selected scans and measured with the ultrasound software by an expert sonographer. Correlations and coefficients of variation (CVs) were calculated, and the within-measurement standard deviation (ie, technical error of the measurement), was calculated.

RESULTS

The reliability between the site sonographers and the expert was high, with correlations exceeding 0.99 for all dimensions in all rounds. The CV % values showed low variability, with the percentage differences being less than 2%, except for abdominal circumference in rounds 2 and 3, in which it averaged about 3%. Correlations remained high (>0.90) with increasing fetal size; there was a monotonic increase in technical errors of the measurement but without a corresponding increase in the CV %.

CONCLUSIONS

Using rigorous procedures for training sonographers, coupled with quality assurance oversight, we determined that the measurements acquired longitudinally for singletons are both accurate and reliable for establishment of an ultrasound standard for fetal growth.

Triggers, bundles, protocols, and checklists--what every maternal care provider needs to know

The rise in maternal morbidity and mortality has resulted in national and international attention at optimally organizing systems and teams for pregnancy care. Given that maternal morbidity and mortality can occur unpredictably in any obstetric setting, specialists in general obstetrics and gynecology along with other primary maternal care providers should be integrally involved in efforts to improve the safety of obstetric care delivery. Quality improvement initiatives remain vital to meeting this goal. The evidence-based utilization of triggers, bundles, protocols, and checklists can aid in timely diagnosis and treatment to prevent or limit the severity of morbidity as well as facilitate interdisciplinary, patient-centered care. The purpose of this document is to summarize the pertinent elements from this forum to assist primary maternal care providers in their utilization and implementation of these safety tools.

Maternal mortality in New York--Looking back, looking forward

New York City was ahead of its time in recognizing the issue of maternal death and the need for proper statistics. New York has also documented since the 1950s the enormous public health challenge of racial disparities in maternal mortality. This paper addresses the history of the first Safe Motherhood Initiative (SMI), a voluntary program in New York State to review reported cases of maternal deaths in hospitals. Review teams found that timely recognition and intervention in patients with serious morbidity could have prevented many of the deaths reviewed. Unfortunately the program was defunded by New York State. The paper then focuses on the revitalization of the SMI in 2013 to establish three safety bundles across the state to be used in the recognition and treatment of obstetric hemorrhage, severe hypertension in pregnancy, and the prevention of venous thromboembolism; and their introduction into 118 hospitals across the state. The paper concludes with a look to the future of the coordinated efforts needed by various organizations involved in women's healthcare in New York City and State to achieve the goal of a review of all maternal deaths in the state by a multidisciplinary team in a timely manner so that appropriate feedback to the clinical team can be given and care can be modified and improved as needed. It is the authors' opinion that we owe this type of review to the women of New York who entrust their care to us.

Venous thromboembolism bundle: Risk assessment and prophylaxis for obstetric patients

While venous thromboembolism (VTE) is a leading cause of severe maternal morbidity and mortality, maternal death from VTE is amenable to prevention. Thromboprophylaxis is the most readily implementable means of systematically reducing the maternal death rate, and protocols that identify at-risk women have led to a significant reduction in maternal deaths from VTE. Strategies to prevent VTE require minimal resources. A multidisciplinary working group convened as part of American Congress of Obstetricians and Gynecologists' District II Safe Motherhood Initiative reviewed research evidence and major society thromboprophylaxis guidelines and identified clinical strategies to reduce maternal VTE risk. This review provides recommendations for VTE prophylaxis and describes suggested clinical strategies for office and hospital-based implementation.

Detection and confirmation of serum lipid biomarkers for preeclampsia using direct infusion mass spectrometry

Despite substantial research, the early diagnosis of preeclampsia remains elusive. Lipids are now recognized to be involved in regulation and pathophysiology of some disease. Shotgun lipidomic studies were undertaken to determine whether serum lipid biomarkers exist that predict preeclampsia later in the same in pregnancy. A discovery study was performed using sera collected at 12-14 weeks pregnancy from 27 controls with uncomplicated pregnancies and 29 cases that later developed preeclampsia. Lipids were extracted and analyzed by direct infusion into a TOF mass spectrometer. MS signals, demonstrating apparent differences were selected, their abundances determined, and statistical differences tested. Statistically significant lipid markers were reevaluated in a second confirmatory study having 43 controls and 37 preeclampsia cases. Multi-marker combinations were developed using those lipid biomarkers confirmed in the second study. The initial study detected 45 potential preeclampsia markers. Of these, 23 markers continued to be statistically significant in the second confirmatory set. Most of these markers, representing several lipid classes, were chemically characterized, typically providing lipid class and potential molecular components using MS(2) Several multi-marker panels with areas under the curve >0.85 and high predictive values were developed. Developed panels of serum lipidomic biomarkers appear to be able to identify most women at risk for preeclampsia in a given pregnancy at 12-14 weeks gestation.