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

Trends and outcomes for deliveries with hypertensive disorders of pregnancy from 2000 to 2018: A repeated cross-sectional study

OBJECTIVE

To analyse trends, risk factors, and outcomes related to hypertensive disorders of pregnancy (HDP).

DESIGN

Repeated cross-sectional.

SETTING

US delivery hospitalisations.

POPULATION

Delivery hospitalisations in the 2000-2018 National Inpatient Sample.

METHODS

US hospital delivery hospitalisations with HDP were analysed. Several trends were analysed: (i) the proportion of deliveries by year with HDP, (ii) the proportion of deliveries with HDP risk factors and (iii) adverse outcomes associated with HDP including maternal stroke, acute renal failure and acute liver injury. Risk ratios were determined using regression models with HDP as the exposure of interest.

MAIN OUTCOME MEASURES

Prevalence of HDP, risk factors for HDP and associated adverse outcomes.

RESULTS

Of 73.1 million delivery hospitalisations, 7.7% had an associated diagnosis of HDP. Over the study period, HDP doubled from 6.0% of deliveries in 2000 to 12.0% in 2018. The proportion of deliveries with risk factors for HDP increased from 9.6% in 2000 to 24.6% in 2018. In adjusted models, HDP were associated with increased stroke (aRR [adjusted risk ratio] 15.9, 95% CI 14.8-17.1), acute renal failure (aRR 13.8, 95% CI 13.5-14.2) and acute liver injury (aRR 1.2, 95% CI 1.2-1.3). Among deliveries with HDP, acute renal failure and acute liver injury increased; in comparison, stroke decreased.

CONCLUSION

Hypertensive disorders of pregnancy increased in the setting of risk factors for HDP becoming more common, whereas stroke decreased.

TWEETABLE ABSTRACT

While hypertensive disorders of pregnancy increased from 2000 to 2018, stroke appears to be decreasing.

The causal effect of delivery volume on severe maternal morbidity: an instrumental variable analysis in Sichuan, China

Objective

Findings regarding the association between delivery volume and maternal health outcomes are mixed, most of which explored their correlation. This study aims to demonstrate the causal effect of delivery volume on severe maternal morbidity (SMM) in China.

Methods

We analysed all women giving birth in the densely populated Sichuan province with 83 million residents in China, during the fourth quarters of each of 4 years (from 2016 to 2019). The routinely collected discharge data, the health institutional annual report data and road network data were used for analysis. The maternal health outcome was measured by SMM. Instrumental variable (IV) methods were applied for estimation, while the surrounding average number of delivery cases per institution was used as the instrument.

Results

The study included 4545 institution-years of data from 1456 distinct institutions with delivery services, reflecting 810 049 associated delivery cases. The average SMM rate was approximately 33.08 per 1000 deliveries during 2016 and 2019. More than 86% of delivery services were provided by a third of the institutions with the highest delivery volume (≥143 delivery cases quarterly). In contrast, less than 2% of delivery services were offered by a third of the institutions with the lowest delivery volume (<19 delivery cases quarterly). After adjusting the confounders in the IV-logistic models, the average marginal effect of per 1000 cases in delivery volume was −0.162 (95% CI −0.169 to –0.155), while the adjusted OR of delivery volume was 0.005 (95% CI 0.004 to 0.006).

Conclusion

Increased delivery volume has great potential to improve maternal health outcomes, while the centralisation of delivery services might facilitate maternal health promotion in China. Our study also provides implications for other developing countries confronted with similar challenges to China.

Trends in Venous Thromboembolism and Associated Risk Factors During Delivery Hospitalizations From 2000 to 2018

OBJECTIVE

To characterize trends in and risk factors for venous thromboembolism (VTE) during delivery hospitalizations in the United States.

METHODS

The 2000-2018 National Inpatient Sample was used for this repeated cross-sectional analysis. Venous thromboembolism (including deep vein thrombosis [DVT] and pulmonary embolism) during delivery hospitalizations for women aged 15 to 54 years was determined by year. Temporal trends in VTE were characterized using joinpoint regression with estimates presented as the average annual percent change. Temporal trends in common VTE risk factors were also analyzed. The proportion of vaginal and cesarean deliveries by year that had VTE risk factors was determined, and average annual percent changes with 95% CIs were calculated. The relationship between risk factors and the likelihood of VTE events was determined with adjusted and unadjusted logistic regression models.

RESULTS

Of 73,109,789 delivery hospitalizations, 48,546 VTE events occurred (6.6/10,000 deliveries), including 37,312 DVT diagnoses and 12,487 pulmonary embolism diagnoses. Rates increased significantly for vaginal (average annual percent change 2.5%, 95% CI 1.5-3.5%) but not for cesarean delivery hospitalizations (average annual percent change 0.3%, 95% CI -1.0 to 1.6%) over the study period. Pulmonary embolism increased for both vaginal delivery (average annual percent change 8.7%, 95% CI 6.0-11.5%) and cesarean delivery (average annual percent change 4.9%, 95% CI 3.6-6.2%). The proportion of cesarean deliveries with at least one VTE risk factor increased from 27.2% in 2000 to 43.6% in 2018 (average annual percent change 2.6%, 95% CI 2.2-3.1%) and for vaginal deliveries, from 17.7% to 31.4% (average annual percent change 3.4%, 95% CI 2.3-4.4%). The 5.9% of deliveries with at least two VTE risk factor diagnoses accounted for 25.4% of VTE diagnoses. Factors with the highest VTE risk included transfusion (adjusted odds ratio [aOR] 4.1, 95% CI 3.7-4.5), infection (aOR 5.8, 95% CI 5.3-6.3), history of VTE (aOR 7.2, 95% CI 6.2-8.4), and thrombophilias (aOR 9.6, 95% CI 8.5-11.0).

CONCLUSION

Both risk factors for VTE and rate of pulmonary embolism increased over the study period. Deep vein thrombosis increased during vaginal delivery hospitalizations but not during cesarean delivery hospitalizations.

Obstetric venous thromboembolism prophylaxis, risk factors and outcomes

PURPOSE OF REVIEW

Risk factors for obstetric venous thromboembolism (VTE), a leading cause of maternal mortality in the United States, are increasing on a population basis. This review provides the obstetrician with an update of current issues related to obstetric VTE risk, prophylaxis, outcomes, anaesthesia considerations and future research opportunities.

RECENT FINDINGS

Obstetric VTE affects approximately 1 per 1000 pregnancies and accounts consistently for 9-10% of maternal deaths in the United States. In industrialized countries, risk factors for VTE, including overweight/obesity, caesarean delivery and obstetrical complications such postpartum haemorrhage and infection continue to increase. VTE prophylaxis is central to reducing maternal mortality. However, recommendations for prophylaxis from leadership societies vary widely. In the UK, maternal mortality risk from VTE has decreased significantly in the setting of broader heparin prophylaxis. In the United States where mechanical VTE prophylaxis is used more commonly, mortality risk has remained constant.

SUMMARY

Obstetric VTE is a leading cause of maternal mortality in the United States. The incidence of risk factors for obstetric VTE continues to increase. Currently, recommendations for obstetric VTE prophylaxis vary substantially. Opportunities for research in this area exist to optimize prophylaxis and improve maternal outcomes.

Expert review: prevention of obstetrical venous thromboembolism

Venous thromboembolism represents a persistent proportionate cause of maternal mortality in the United States accounting for 9% to 10% of maternal deaths. Given that overall maternal mortality rose >40% since the late 1990s, it is likely that absolute venous thromboembolism mortality risk increased as well. This persistent risk may be secondary to increases in broad population-based risk factors for venous thromboembolism such as obesity and cesarean delivery. Widespread adoption of perioperative cesarean mechanical thromboprophylaxis is associated with reduced risk for venous thromboembolism events but has not been sufficient to reduce mortality. Experts agree that improved clinical care is required to reduce risk as it is unlikely that trends in venous thromboembolism risk factors will reverse course anytime soon. Experts further agree that improving prophylaxis and prevention may provide the largest benefit. However, how to best improve prophylaxis is highly controversial with both experts and guidelines in disagreement. In the United Kingdom, mortality risk decreased substantially following the 2004 recommendations for broader heparin prophylaxis without evidence of increased mortality risk from hemorrhage. A key clinical question in the United States is whether heparin prophylaxis should be expanded to patients hospitalized for cesarean delivery or an antepartum indication. Some experts, including us, support expanded heparin prophylaxis. Evidence supporting heparin prophylaxis includes (1) demonstration of safety and efficacy in the United Kingdom, (2) that mechanical prophylaxis-the primary alternative to heparin-has major limitations outside the immediate perioperative setting, and (3) that hospitalized cesarean and antepartum patients are at high relative risk of events. Experts against broader heparin prophylaxis cite concerns related to safety, efficacy, and cost. This expert review focused on whether heparin prophylaxis should be routinely used during antepartum hospitalizations and after cesarean delivery. First, we review the differences in major society guidelines. Second, we review arguments for and against broader heparin prophylaxis. Third, we discuss what future research may be most likely to further inform best practices. Fourth, we review practical clinical considerations with heparin prophylaxis, including access to neuraxial anesthesia. Given the best available data, we concluded that expanding heparin prophylaxis represents a modest intervention with the potential to meaningfully reduce venous thromboembolism mortality.

Placental mitochondrial function as a driver of angiogenesis and placental dysfunction

The placenta is a highly vascularized and complex foetal organ that performs various tasks, crucial to a healthy pregnancy. Its dysfunction leads to complications such as stillbirth, preeclampsia, and intrauterine growth restriction. The specific cause of placental dysfunction remains unknown. Recently, the role of mitochondrial function and mitochondrial adaptations in the context of angiogenesis and placental dysfunction is getting more attention. The required energy for placental remodelling, nutrient transport, hormone synthesis, and the reactive oxygen species leads to oxidative stress, stemming from mitochondria. Mitochondria adapt to environmental changes and have been shown to adjust their oxygen and nutrient use to best support placental angiogenesis and foetal development. Angiogenesis is the process by which blood vessels form and is essential for the delivery of nutrients to the body. This process is regulated by different factors, pro-angiogenic factors and anti-angiogenic factors, such as sFlt-1. Increased circulating sFlt-1 levels have been linked to different preeclamptic phenotypes. One of many effects of increased sFlt-1 levels, is the dysregulation of mitochondrial function. This review covers mitochondrial adaptations during placentation, the importance of the anti-angiogenic factor sFlt-1in placental dysfunction and its role in the dysregulation of mitochondrial function.

A scoping review of severe maternal morbidity: describing risk factors and methodological approaches to inform population-based surveillance

Background

Current interest in using severe maternal morbidity (SMM) as a quality indicator for maternal healthcare will require the development of a standardized method for estimating hospital or regional SMM rates that includes adjustment and/or stratification for risk factors.

Objective

To perform a scoping review to identify methodological considerations and potential covariates for risk adjustment for delivery-associated SMM.

Search methods

Following the guidelines for Preferred Reporting Items for Systematic Reviews and Meta-analyses Extension for Scoping Reviews, systematic searches were conducted with the entire PubMed and EMBASE electronic databases to identify publications using the key term “severe maternal morbidity.”

Selection criteria

Included studies required population-based cohort data and testing or adjustment of risk factors for SMM occurring during the delivery admission. Descriptive studies and those using surveillance-based data collection methods were excluded.

Data collection and analysis

Information was extracted into a pre-defined database. Study design and eligibility, overall quality and results, SMM definitions, and patient-, hospital-, and community-level risk factors and their definitions were assessed.

Main results

Eligibility criteria were met by 81 studies. Methodological approaches were heterogeneous and study results could not be combined quantitatively because of wide variability in data sources, study designs, eligibility criteria, definitions of SMM, and risk-factor selection and definitions. Of the 180 potential risk factors identified, 41 were categorized as pre-existing conditions (e.g., chronic hypertension), 22 as obstetrical conditions (e.g., multiple gestation), 22 as intrapartum conditions (e.g., delivery route), 15 as non-clinical variables (e.g., insurance type), 58 as hospital-level variables (e.g., delivery volume), and 22 as community-level variables (e.g., neighborhood poverty).

Conclusions

The development of a risk adjustment strategy that will allow for SMM comparisons across hospitals or regions will require harmonization regarding: a) the standardization of the SMM definition; b) the data sources and population used; and c) the selection and definition of risk factors of interest.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40748-020-00123-1.

Estimating the obstetric co-morbidity burden using administrative data: The impact of the pregnancy-related assessment window

BACKGROUND

Despite increased research using large administrative databases to identify determinants of maternal morbidity and mortality, the extent to which these databases capture obstetric co-morbidities is unknown.

OBJECTIVE

To evaluate the impact that the time window used to assess obstetric co-morbidities has on the completeness of ascertainment of those co-morbidities.

METHODS

We conducted a five-year analysis of inpatient hospitalisations of pregnant women from 2010-2014 using the Nationwide Readmissions Database. For each woman, using discharge diagnoses, we identified 24 conditions used to create the Obstetric Comorbidity Index. Using various assessment windows for capturing obstetric co-morbidities, including the delivery hospitalisation only and all weekly windows from 7 to 280 days, we calculated the frequency and rate of each co-morbidity and the degree of underascertainment of the co-morbidity. Under each scenario, and for each co-morbidity, we also calculated the all-cause, 30-day readmission rate.

RESULTS

There were over 3 million delivery hospitalisations from 2010 to 2014 included in this analysis. Compared with a full 280-day window, assessment of obstetric co-morbidities using only diagnoses made during the delivery hospitalisation would result in failing to identify over 35% of cases of chronic renal disease, 28.5% cases in which alcohol abuse was documented during pregnancy, and 23.1% of women with pulmonary hypertension. For seven other co-morbidities, at least 1 in 20 women with that condition would have been missed with exclusive reliance on the delivery hospitalisation for co-morbidity diagnoses. Not only would reliance on delivery hospitalisations have resulted in missed cases of co-morbidities, but for many conditions, estimates of readmission rates for women with obstetric co-morbidities would have been underestimated.

CONCLUSIONS

An increasing proportion of maternal and child health research is based on large administrative databases. This study provides data that facilitate the assessment of the degree to which important obstetric co-morbidities may be underascertained when using these databases.

Gene expression of four targets in situ of the first trimester maternal-fetoplacental interface

EPAS1, FSTL3, IGFBP1, and SEMA3C were localized to determine whether expression is decidual, trophoblastic, or both in the human first trimester maternal-fetoplacental interface. Identified on global genome-wide microarray analysis of chorionic villus sampling tissues in preclinical preeclampsia, these targets were predicted to interact by bioinformatics pathways analysis. In situ hybridization (ISH) with mRNA of each gene was conducted in 10 cases of archived first trimester termination tissues. Randomly selected areas of cells by tissue type yielded the relative proportion of cells expressing mRNA signal in decidual and fetoplacental sites. Data were analyzed using Shapiro-Wilk and Kruskal-Wallis tests (p ≤ .05). The average gestational age was 10.2 weeks. Expression signal for each gene differed by cell type (p < .001). FSTL3 expression was 17 times higher in cells of anchoring columns than areas of decidua without ISH signal. SEMA3C was three times higher in cells of anchoring columns than in decidua. EPAS1 was 1.31 times higher in cells of anchoring columns than in areas of decidua. IGFBP1 was 20 times higher in some decidua versus cells in anchoring columns or villous trophoblast. While all targets were expressed by both maternal and fetoplacental cells, our localizations identified which compartment had relatively higher expression of each gene.

Putting the "M" back in maternal-fetal medicine: A 5-year report card on a collaborative effort to address maternal morbidity and mortality in the United States

The Centers for Disease Control and Prevention have demonstrated continuous increased risk for maternal mortality and severe morbidity with racial disparities among non-Hispanic black women an important contributing factor. More than 50,000 women experienced severe maternal morbidity in 2014, with a mortality rate of 18.0 per 100,000, higher than in many other developed countries. In 2012, the first "Putting the 'M' back in Maternal-Fetal Medicine" session was held at the Society for Maternal-Fetal Medicine's (SMFM) Annual Meeting. With the realization that rising risk for severe maternal morbidity and mortality required action, the "M in MFM" meeting identified the following urgent needs: (i) to enhance education and training in maternal care for maternal-fetal medicine (MFM) fellows; (ii) to improve the medical care and management of pregnant women across the country; and (iii) to address critical research gaps in maternal medicine. Since that first meeting, a broad collaborative effort has made a number of major steps forward, including the proliferation of maternal mortality review committees, advances in research, increasing educational focus on maternal critical care, and development of comprehensive clinical strategies to reduce maternal risk. Five years later, the 2017 M in MFM meeting served as a "report card" looking back at progress made but also looking forward to what needs to be done over the next 5 years, given that too many mothers still experience preventable harm and adverse outcomes.