Faculty Bibliography

INTRODUCTION:The rate of heparin-induced thrombocytopenia (HIT) on a population basis is unknown. The objective of this study was to characterize the risk for HIT during antepartum, delivery, and postpartum hospitalizations in the United States. MATERIALS AND METHODS:A large administrative database was used to determine the risk of HIT in hospitalized obstetric patients who received unfractionated heparin (UFH) or low molecular weight heparin (LMWH). Patients were presumed to have HIT if they were exposed to UFH or LMWH, received a diagnosis of HIT, and were administered a medication for the treatment of HIT including bivalirudin, argatroban, fondaparinux, or lepirudin. We queried severe complications of HIT including arterial thrombosis, limb amputation, heart failure, and death. RESULTS:We identified 66,468 antepartum hospitalizations, 66,741 delivery hospitalizations, and 16,325 postpartum readmissions where women received pharmacologic prophylaxis. Of these, 10 antepartum admissions, 1 delivery admission, and 14 postpartum readmissions involved a diagnosis of HIT with treatment of bivalirudin, argatroban, fondaparinux, or lepirudin. There were no deaths and no diagnoses of arterial thrombosis, limb amputation, heart failure, and death. CONCLUSION:Risk for HIT among hospitalized obstetric patients is low. In this cohort, no cases of death or severe complications were noted in relation to the diagnosis.

OBJECTIVE:This article evaluates trends in venous thromboembolism (VTE) prophylaxis during delivery hospitalizations in the United States. METHODS:We utilized an administrative database to determine if women hospitalized for vaginal or cesarean delivery received pharmacologic VTE prophylaxis, mechanical VTE prophylaxis, or both from January 2011 through March 2015. Mechanical prophylaxis included sequential compression devices, graduated compression stockings, and other pneumatic devices. Pharmacologic prophylaxis included unfractionated heparin, low molecular weight heparin, or fondaparinux. Probability of use of thromboprophylaxis for individual hospitals was estimated in an adjusted model. RESULTS: < 0.01). Of women undergoing vaginal delivery, 2.9% received prophylaxis. Delivery hospital was an important determinant of cesarean prophylaxis: in the adjusted model, one-third of hospitals used prophylaxis for less than 20% of deliveries, one-third of hospitals used prophylaxis for 20 to 80% of deliveries, and the final third of hospitals used prophylaxis in greater than 80% of deliveries. CONCLUSION:While many hospitals appear to be following best clinical practices, some do not provide routine cesarean VTE prophylaxis. Minimizing care quality variation may improve maternal safety.

BACKGROUND:Cesarean delivery has increased steadily in the United States over recent decades with significant downstream health consequences. The World Health Organization has endorsed the Robson 10-Group Classification System as a global standard to facilitate analysis and comparison of cesarean delivery rates. OBJECTIVE:Our objective was to apply the Robson 10-Group Classification System to a nationwide cohort in the United States over a 10-year period. STUDY DESIGN:This population-based analysis applied the Robson 10-Group Classification System to all births in the United States from 2005 through 2014, recorded in the 2003 revised birth certificate format. Over the study 10-year period, 27,044,217 deliveries met inclusion criteria. Five parameters (parity including previous cesarean, gestational age, labor onset, fetal presentation, and plurality), identifiable on presentation for delivery, were used to classify all women included into 1 of 10 groups. RESULTS:The overall cesarean rate was 31.6%. Group-3 births (singleton, term, cephalic multiparas in spontaneous labor) were most common, while group-5 births (those with a previous cesarean) accounted for the most cesarean deliveries increasing from 27% of all cesareans in 2005 through 2006 to >34% in 2013 through 2014. Breech pregnancies (groups 6 and 7) had cesarean rates >90%. Primiparous and multiparous women who had a prelabor cesarean (groups 2b and 4b) accounted for over one quarter of all cesarean deliveries. CONCLUSION:Women with a previous cesarean delivery represent an increasing proportion of cesarean deliveries. Use of the Robson criteria allows standardized comparisons of data and identifies clinical scenarios driving changes in cesarean rates. Hospitals and health organizations can use the Robson 10-Group Classification System to evaluate quality and processes associated with cesarean delivery.

BACKGROUND AND PURPOSE:Peripartum strokes during delivery admissions are rare but have high maternal morbidity. Infections have been proposed as a possible stroke trigger. We hypothesized that women who had infections diagnosed at the time of delivery admission would have higher risk of stroke during their delivery hospitalization. METHODS:We conducted a case-control study using state inpatient administrative databases for California (2007-2011), Florida (2009-2011), and New York (2009-2011). Women whose admission included a vaginal or cesarean delivery, with a new diagnosis of stroke during the admission, were considered cases and were randomly matched to 3 in-state controls by age/admission year and presence and severity of hypertensive disorders of pregnancy. The primary exposure of interest was infection of any type present on admission. Secondary exposures included race/ethnicity, payer status, delivery method, and known vascular risk factors such as chronic hypertension, diabetes mellitus, smoking, alcohol abuse, hypercoagulable states, coagulopathies, and renal disease. We used multivariable conditional logistic regression to estimate the odds ratios and 95% confidence intervals for the association of infections and known vascular risk factors with stroke risk. RESULTS:A total of 455 cases (mean age, 29.8), of whom 195 (42.9%) had hypertensive disorders of pregnancy, were matched with 1365 controls. Infection of any type present on admission increased the odds of stroke diagnosis during the admission (adjusted odds ratio, 1.74; 95% confidence interval, 1.29-2.35). Risk was higher for genitourinary infections (adjusted odds ratio, 2.56; 95% confidence interval, 1.25-5.24) and sepsis (adjusted odds ratio, 10.4; 95% confidence interval, 2.15-20.0). The association between infection and stroke during delivery admission did not differ by the presence of hypertensive disorders of pregnancy. CONCLUSIONS:Infections present on admission increased stroke risk during delivery admissions in women with and without hypertensive disorders of pregnancy. The results were driven by genitourinary infections and sepsis. Infections may be an underrecognized precipitant of peripartum stroke.

Severe maternal morbidity and mortality are often preventable and obstetric early warning systems that alert care providers of potential impending critical illness may improve maternal safety. While literature on outcomes and test characteristics of maternal early warning systems is evolving, there is limited guidance on implementation. Given current interest in early warning systems and their potential role in care, the 2017 Society for Maternal-Fetal Medicine (SMFM) Annual Meeting dedicated a session to exploring early warning implementation across a wide range of hospital settings. This manuscript reports on key points from this session. While implementation experiences varied based on factors specific to individual sites, common themes relevant to all hospitals presenting were identified. Successful implementation of early warnings systems requires administrative and leadership support, dedication of resources, improved coordination between nurses, providers, and ancillary staff, optimization of information technology, effective education, evaluation of and change in hospital culture and practices, and support in provider decision-making. Evolving data on outcomes on early warning systems suggest that maternal risk may be reduced. To effectively reduce maternal, risk early warning systems that capture deterioration from a broad range of conditions may be required in addition to bundles tailored to specific conditions such as hemorrhage, thromboembolism, and hypertension.

BACKGROUND:How race is associated with adverse outcomes in the setting of postpartum hemorrhage is not well characterized. OBJECTIVE:The objective of this study was to assess how race is associated with adverse maternal outcomes in the setting of postpartum hemorrhage. STUDY DESIGN:This retrospective cohort study utilized the National (Nationwide) Inpatient Sample (NIS) from the Agency for Healthcare Research and Quality for the years 2012-2014. Women aged 15-54 years with a diagnosis of postpartum hemorrhage were included. Race and ethnicity were categorized as non-Hispanic white, non-Hispanic black, Hispanic, Asian or Pacific Islander, Native American, other, and unknown. Overall risk for severe morbidity based on Centers for Disease Control and Prevention criteria was analyzed along with risk for specific outcomes such as disseminated intravascular coagulation, hysterectomy, transfusion, and maternal death. Risk for severe morbidity was stratified by comorbid risk and compared by race. Weights were applied to create population estimates. Log-linear regression models were created to assess risk for severe morbidity with risk ratios and associated 95% confidence intervals as measures of effect. RESULTS:A total of 360,370 women with postpartum hemorrhage from 2012 to 2014 were included in this analysis. Risk for severe morbidity was significantly higher among non-Hispanic black women (26.6%) than non-Hispanic white, Hispanic, or Asian or Pacific Islander women (20.7%, 22.5%, and 21.4%, respectively, P < .01). For non-Hispanic black compared with non-Hispanic white, Hispanic, and Asian or Pacific Islander women risk was higher for disseminated intravascular coagulation (8.4% vs 7.1%, 6.8%, and 6.8%, respectively, P < .01) and transfusion (19.4% vs 13.9%, 16.1%, and 15.8%, respectively, P < .01). Black women were also more likely than non-Hispanic white women to undergo hysterectomy (2.4% vs 1.9%, P < .01), although Asian or Pacific Islander women were at highest risk (2.9%). Adjusting for comorbidity, black women remained at higher risk for severe morbidity (P < .01). Risk for death for non-Hispanic black women was significantly higher than for nonblack women (121.8 per 100,000 deliveries, 95% confidence interval, 94.7-156.8 vs 24.1 per 100,000 deliveries, 95% confidence interval, 19.2-30.2, respectively, P < .01). CONCLUSION:Black women were at higher risk for severe morbidity and mortality associated with postpartum hemorrhage.

BACKGROUND:Despite abruption's elusive etiology, knowledge of triggers that precede it by just a few days prior to delivery may help to understand the underpinnings of this acute obstetrical complication. We examine whether air pollution exposures immediately preceding delivery are associated with acute-onset abruptions. METHODS:We applied a bidirectional, time-stratified, case-crossover design to births with an abruption diagnosis in New York City, 2008-2014. We measured ambient fine particulate matter (PM2.5) and nitrogen dioxide (NO2). We fit distributed lag nonlinear models based on conditional logistic regression to evaluate individual exposure and cumulative exposures over lags 0-7 days before abruption, adjusted for temperature and relative humidity (similar lags to the main exposures). RESULTS:We identified 1,190 abruption cases. We observed increased odds of abruption for exposure to PM2.5 (per 10 μg/m) on lag day 3 (odds ratio [OR] 1.19, 95% confidence interval [CI] = 0.98, 1.43), lag day 4 (OR 1.21, 95% CI = 1.01, 1.46), and lag day 5 (OR 1.17, 95% CI = 1.03, 1.33). Similarly, the odds of abruption increased with exposure to NO2 (per 5 ppb) on lag day 3 (OR 1.16, 95% CI = 0.98, 1.37), lag day 4 (OR 1.19, 95% CI = 1.02, 1.39), and lag day 5 (OR 1.16, 95% CI = 1.05, 1.27). Exposures to PM2.5 and NO2 at other lags, or cumulative exposures, were not associated with abruption of acute onset. CONCLUSIONS:This case-crossover study showed evidence of an association between short-term ambient air pollution exposures and increased abruption risk of acute onset.

OBJECTIVE:To estimate whether the diagnosis of asthma is associated with the use of specific uterotonic and antihypertensive medications during delivery hospitalizations. METHODS:We used Perspective, an administrative database, to determine whether women hospitalized for delivery complicated by postpartum hemorrhage or preeclampsia received uterotonics and antihypertensive medications differentially based on the absence or presence of asthma from 2006 to 2015. Given that carboprost and intravenous (IV) labetalol may be associated with asthma exacerbation, adjusted models for receipt of these medications were created with adjusted risk ratios with 95% CIs as measures of effect. Risk for status asthmaticus based on receipt of carboprost and IV labetalol was analyzed. RESULTS:Over the study period, a total of 5,691,178 women were analyzed, of whom 239,915 (4.2%) had preeclampsia and 139,841 postpartum hemorrhage (2.5%). Carboprost was used less frequently in patients with asthma compared with patients with no asthma (11.4% vs 18.0%) in comparison with IV labetalol, which was used more commonly when a diagnosis of asthma was present (18.5% vs 16.7%). In unadjusted analysis, the presence of asthma was associated with a 37% decrease in likelihood of carboprost use and an 11% increase in likelihood of labetalol use. In adjusted analysis, the presence of asthma was associated with a 32% decrease in likelihood of carboprost use (adjusted risk ratio 0.68, 95% CI 0.62-0.74) compared with a 7% decrease in labetalol use (adjusted risk ratio 0.93, 95% CI 0.90-0.97). Risk for status asthmaticus was significantly increased with use of IV labetalol compared with other antihypertensive medications (6.5 vs 1.7/1,000 delivery hospitalizations, P<.01). CONCLUSION:There may be an opportunity to reduce use of β-blockers and carboprost among patients with asthma. Given their association with status asthmaticus, these drugs should be used cautiously in women with asthma.

OBJECTIVE:To clarify how race is associated with adverse maternal outcomes and risk for women aged 40 years or older. METHODS:This retrospective cohort study used the Nationwide Inpatient Sample for the years 1998-2014. Women aged 40-54 years were included. Race and ethnicity were categorized as non-Hispanic white, non-Hispanic black, Hispanic, Asian or Pacific Islander, Native American, other, and unknown. Temporal trends in severe maternal morbidity and overall comorbid risk by race in women aged 40 years or older were evaluated as were common pregnancy complications including preeclampsia, gestational diabetes, and cesarean delivery. Adjusted models were created to assess factors associated with severe morbidity. RESULTS:A total of 1,724,694 deliveries were included in this analysis. Severe maternal morbidity increased over the study period from 1.6% in 1998-2000 to 3.0% from 2013 to 2014. Black women had the highest rates of severe morbidity at both the beginning (2.4% in 1998-2000) and the end (4.9% in 2013-2014) of the study period. During this same period, comorbid risk based on medical conditions and other factors increased overall and individually by race. Black women also experienced the absolute largest increase from 1998-2003 to 2010-2014 in risk for acute renal failure, disseminated intravascular coagulation, transfusion, and hysterectomy. Pregnancy complications including preeclampsia, cesarean delivery, and gestational diabetes were more common at the end compared with the beginning of the study for black, white, and Hispanic women. The adjusted risk ratio for overall severe morbidity for black compared with white race was 1.81 (95% CI 1.76-1.87). Black women had a substantially higher risk of death than white women (risk ratio 4.71, 95% CI 3.36-6.61), and Hispanic women had more than twice the risk of death (risk ratio 2.13, 95% CI 1.48-3.07) as white women. CONCLUSION:Although black women older than 40 years were at increased risk for adverse outcomes and severe morbidity, this differential was of smaller magnitude than reported mortality risk.

BACKGROUND:There are limited data on when postpartum readmissions for thromboembolism occur after delivery hospitalizations on a population basis in the United States. OBJECTIVE:We sought to characterize risk factors for and timing of postpartum venous thromboembolism readmission after delivery hospitalization discharge. STUDY DESIGN:The Healthcare Cost and Utilization Project Nationwide Readmissions Database for calendar years 2013 and 2014 was used to perform a retrospective cohort study evaluating risk for readmission for venous thromboembolism within 60 days of discharge from a delivery hospitalization. Risks for deep vein thrombosis and pulmonary embolism were individually assessed. Obstetric, medical, demographic, and hospital factors associated with postpartum readmission for venous thromboembolism were analyzed. Risk was characterized as odds ratios with 95% confidence intervals. Both unadjusted and adjusted analyses were performed. Adjusted analyses included relevant obstetric, medical, demographic, and hospital factors within logistic regression models. RESULTS:From Jan. 1 through Oct. 31 in 2013 and 2014, 6,269,641 delivery hospitalizations were included in the analysis. In all, 2975 cases of readmission for any venous thromboembolism were identified (4.7 per 10,000 delivery hospitalizations) including 1170 cases of deep vein thrombosis and 1805 cases of pulmonary embolism. In all, 69.6% of readmissions for any venous thromboembolism occurred within the first 20 days of discharge vs 22.3% and 8.0% at 21-40 and 41-60 days after discharge. Median times to readmission were 12.7, 14.0, and 11.7 days for venous thromboembolism, deep vein thrombosis, and pulmonary embolism, respectively. Women readmitted for any venous thromboembolism were more likely to have a history of venous thromboembolism (4.2% vs 0.3%, P < .01), to have had a cesarean delivery (54.4% vs 32.4%, P < .01), to have a thrombophilia (1.8% vs 0.4%, P < .01), to have had a longer delivery hospitalization of >3 days for vaginal delivery and >4 days for cesarean (18.0% vs 6.6%, P < .01), to have been diagnosed with gestational hypertension or preeclampsia (19.7% vs 8.2%, P < .01), and to have had postpartum hemorrhage with transfusion (2.6% vs 0.5%, P < .01). These factors retained significance in adjusted models. History of venous thromboembolism and hemorrhage with transfusion were associated with the largest odds of readmission (odds ratio, 9.5; 95% confidence interval, 6.6-13.6, and odds ratio, 3.6; 95% confidence interval, 2.4-5.5, respectively). Other factors associated with increased odds included thrombophilia (odds ratio, 2.0; 95% confidence interval, 1.2-3.5), cesarean delivery (odds ratio, 2.0; 95% confidence interval, 1.8-2.3), longer delivery hospitalization (odds ratio, 1.8; 95% confidence interval, 1.5-2.2), and preeclampsia or gestational hypertension (odds ratio, 2.0; 95% confidence interval, 1.6-2.4). CONCLUSION:While the majority of events occurred within 20 days of discharge, risk factors other than thrombophilia and prior venous thromboembolism were generally associated with modestly increased odds of events, and only a small proportion of readmissions occurred among women with thrombophilia and prior events. Our data demonstrate both the challenging nature and urgent need for further research to determine which clinical practices and interventions may reduce risk for venous thromboembolism readmissions on a population basis.