William M. Callaghan

Pandemic 2009 Influenza A(H1N1) Virus Illness Among Pregnant Women in the United States

CONTEXT Early data on pandemic 2009 influenza A(H1N1) suggest pregnant women are at increased risk of hospitalization and death. OBJECTIVE To describe the severity of 2009 influenza A(H1N1) illness and the association with early antiviral treatment among pregnant women in the United States. DESIGN, SETTING, AND PATIENTS Surveillance of 2009 influenza A(H1N1) in pregnant women reported to the Centers for Disease Control and Prevention (CDC) with symptom onset from April through December 2009. MAIN OUTCOME MEASURES Severity of illness (hospitalizations, intensive care unit [ICU] admissions, and deaths) due to 2009 influenza A(H1N1) among pregnant women, stratified by timing of antiviral treatment and pregnancy trimester at symptom onset. RESULTS We received reports on 788 pregnant women in the United States with 2009 influenza A(H1N1) with symptom onset from April through August 2009. Among those, 30 died (5% of all reported 2009 influenza A[H1N1] influenza deaths in this period). Among 509 hospitalized women, 115 (22.6%) were admitted to an ICU. Pregnant women with treatment more than 4 days after symptom onset were more likely to be admitted to an ICU (56.9% vs 9.4%; relative risk [RR], 6.0; 95% confidence interval [CI], 3.5-10.6) than those treated within 2 days after symptom onset. Only 1 death occurred in a patient who received treatment within 2 days of symptom onset. Updating these data with the CDCs continued surveillance of ICU admissions and deaths among pregnant women with symptom onset through December 31, 2009, identified an additional 165 women for a total of 280 women who were admitted to ICUs, 56 of whom died. Among the deaths, 4 occurred in the first trimester (7.1%), 15 in the second (26.8%), and 36 in the third (64.3%); CONCLUSIONS Pregnant women had a disproportionately high risk of mortality due to 2009 influenza A(H1N1). Among pregnant women with 2009 influenza A(H1N1) influenza reported to the CDC, early antiviral treatment appeared to be associated with fewer admissions to an ICU and fewer deaths.

Pregnancy-Related Mortality in the United States, 1998 to 2005

OBJECTIVE: To estimate the risk of women dying from pregnancy complications in the United States and to examine the risk factors for and changes in the medical causes of these deaths. METHODS: De-identified copies of death certificates for women who died during or within 1 year of pregnancy and matching birth or fetal death certificates for 1998 through 2005 were received by the Pregnancy Mortality Surveillance System from the 50 states, New York City, and Washington, DC. Causes of death and factors associated with them were identified, and pregnancy-related mortality ratios (pregnancy-related deaths per 100,000 live births) were calculated. RESULTS: The aggregate pregnancy-related mortality ratio for the 8-year period was 14.5 per 100,000 live births, which is higher than any period in the previous 20 years of the Pregnancy Mortality Surveillance System. African-American women continued to have a three- to four-fold higher risk of pregnancy-related death. The proportion of deaths attributable to hemorrhage and hypertensive disorders declined from previous years, whereas the proportion from medical conditions, particularly cardiovascular, increased. Seven causes of death—hemorrhage, thrombotic pulmonary embolism, infection, hypertensive disorders of pregnancy, cardiomyopathy, cardiovascular conditions, and noncardiovascular medical conditions—each contributed 10% to 13% of deaths. CONCLUSION: The reasons for the reported increase in pregnancy-related mortality are unclear; possible factors include an increase in the risk of women dying, changed coding with the International Classification of Diseases, 10thRevision, and the addition by states of pregnancy checkboxes to the death certificate. State-based maternal death reviews and maternal quality collaboratives have the potential to identify deaths, review the factors associated with them, and take action on the findings. LEVEL OF EVIDENCE: III

Trends in postpartum hemorrhage in high resource countries: a review and recommendations from the International Postpartum Hemorrhage Collaborative Group

AbstractBackgroundPostpartum hemorrhage (PPH) is a major cause of maternal mortality and morbidity worldwide. Several recent publications have noted an increasing trend in incidence over time. The international PPH collaboration was convened to explore the observed trends and to set out actions to address the factors identified.MethodsWe reviewed available data sources on the incidence of PPH over time in Australia, Belgium, Canada, France, the United Kingdom and the USA. Where information was available, the incidence of PPH was stratified by cause.ResultsWe observed an increasing trend in PPH, using heterogeneous definitions, in Australia, Canada, the UK and the USA. The observed increase in PPH in Australia, Canada and the USA was limited solely to immediate/atonic PPH. We noted increasing rates of severe adverse outcomes due to hemorrhage in Australia, Canada, the UK and the USA.ConclusionKey Recommendations 1. Future revisions of the International Classification of Diseases should include separate codes for atonic PPH and PPH immediately following childbirth that is due to other causes. Also, additional codes are required for placenta accreta/percreta/increta.2. Definitions of PPH should be unified; further research is required to investigate how definitions are applied in practice to the coding of data.3. Additional improvement in the collection of data concerning PPH is required, specifically including a measure of severity.4. Further research is required to determine whether an increased rate of reported PPH is also observed in other countries, and to further investigate potential risk factors including increased duration of labor, obesity and changes in second and third stage management practice.5. Training should be provided to all staff involved in maternity care concerning assessment of blood loss and the monitoring of women after childbirth. This is key to reducing the severity of PPH and preventing any adverse outcomes.6. Clinicians should be more vigilant given the possibility that the frequency and severity of PPH has in fact increased. This applies particularly to small hospitals with relatively few deliveries where management protocols may not be defined adequately and drugs or equipment may not be on hand to deal with unexpected severe PPH.

The Contribution of Preterm Birth to Infant Mortality Rates in the United States

OBJECTIVE. Although two thirds of infant deaths in the United States occur among infants born preterm (<37 weeks of gestation), only 17% of infant deaths are classified as being attributable to preterm birth with the standard classification of leading causes of death. To address this apparent discrepancy, we sought to estimate more accurately the contribution of preterm birth to infant mortality rates in the United States. METHODS. We identified the top 20 leading causes of infant death in 2002 in the US linked birth/infant death file. The role of preterm birth for each cause was assessed by determining the proportion of infants who were born preterm for each cause of death and by considering the biological connection between preterm birth and the specific cause of death. RESULTS. Of 27970 records in the linked birth/infant death file for 2002, the 20 leading causes accounted for 22273 deaths (80% of all infant deaths). Among infant deaths attributable to the 20 leading causes, we classified 9596 infant deaths (34.3% of all infant deaths) as attributable to preterm birth. Ninety-five percent of those deaths occurred among infants who were born at <32 weeks of gestation and weighed <1500 g, and two thirds of those deaths occurred during the first 24 hours of life. CONCLUSIONS. On the basis of this evaluation, preterm birth is the most frequent cause of infant death in the United States, accounting for at least one third of infant deaths in 2002. The extreme prematurity of most of the infants and their short survival indicate that reducing infant mortality rates requires a comprehensive agenda to identify, to test, and to implement effective strategies for the prevention of preterm birth.

Trends in Pre-pregnancy Obesity in Nine States, 1993-2003

Objective: Pre‐pregnancy obesity poses risks to both pregnant women and their infants. This study used a large population‐based data source to examine trends, from 1993 through 2003, in the prevalence of pre‐pregnancy obesity among women who delivered live infants.

Maternal obesity and risk of cesarean delivery: a meta‐analysis

Despite numerous studies reporting an increased risk of cesarean delivery among overweight or obese compared with normal weight women, the magnitude of the association remains uncertain. Therefore, we conducted a meta‐analysis of the current literature to provide a quantitative estimate of this association. We identified studies from three sources: (i) a PubMed search of relevant articles published between January 1980 and September 2005; (ii) reference lists of publications selected from the search; and (iii) reference lists of review articles published between 2000 and 2005. We included cohort designed studies that reported obesity measures reflecting pregnancy body mass, had a normal weight comparison group, and presented data allowing a quantitative measurement of risk. We used a Bayesian random effects model to perform the meta‐analysis and meta‐regression. Thirty‐three studies were included. The unadjusted odd ratios of a cesarean delivery were 1.46 [95% confidence interval (CI): 1.34–1.60], 2.05 (95% CI: 1.86–2.27) and 2.89 (95% CI: 2.28–3.79) among overweight, obese and severely obese women, respectively, compared with normal weight pregnant women. The meta‐regression found no evidence that these estimates were affected by selected study characteristics. Our findings provide a quantitative estimate of the risk of cesarean delivery associated with high maternal body mass.

Pregnancy-related mortality in the United States, 2006-2010

OBJECTIVE: To update national population-level pregnancy-related mortality estimates and examine characteristics and causes of pregnancy-related deaths in the United States during 2006–2010. METHODS: We used data from the Pregnancy Mortality Surveillance System and calculated pregnancy-related mortality ratios by year and age group for four race–ethnicity groups: non-Hispanic white, non-Hispanic black, Hispanic, and other. We examined causes of pregnancy-related deaths by pregnancy outcome during 2006–2010 and compared causes of pregnancy-related deaths since 1987. RESULTS: The 2006–2010 pregnancy-related mortality ratio was 16.0 deaths per 100,000 live births (20,959,533 total live births). Specific race–ethnicity pregnancy-related mortality ratios were 12.0, 38.9, 11.7, and 14.2 deaths per 100,000 live births for non-Hispanic white, non-Hispanic black, Hispanic, and other race women, respectively. Pregnancy-related mortality ratios increased with maternal age for all women and within all age groups, non-Hispanic black women had the highest risk of dying from pregnancy complications. Over time, the contribution to pregnancy-related deaths of hemorrhage, hypertensive disorders of pregnancy, embolism, and anesthesia complications continued to decline, whereas the contribution of cardiovascular conditions and infection increased. Seven of 10 categories of causes of death each contributed from 9.4% to 14.6% of all 2006–2010 pregnancy-related deaths; cardiovascular conditions ranked first. CONCLUSION: Relative to previous years, during 2006–2010, the U.S. pregnancy-related mortality ratio increased as did the contribution of cardiovascular conditions and infection to pregnancy-related mortality. Although the identification of pregnancy-related deaths may be improving in the United States, the increasing contribution of chronic diseases to pregnancy-related mortality suggests a change in risk profile of the birthing population. LEVEL OF EVIDENCE: II

Severe Maternal Morbidity Among Delivery and Postpartum Hospitalizations in the United States

OBJECTIVES: To propose a new standard for monitoring severe maternal morbidity, update previous estimates of severe maternal morbidity during both delivery and postpartum hospitalizations, and estimate trends in these events in the United States between 1998 and 2009. METHODS: Delivery and postpartum hospitalizations were identified in the Nationwide Inpatient Sample for the period 1998–2009. International Classification of Diseases, 9th Revision codes indicating severe complications were used to identify hospitalizations with severe maternal morbidity and related in-hospital mortality. Trends were reported using 2-year increments of data. RESULTS: Severe morbidity rates for delivery and postpartum hospitalizations for the 2008–2009 period were 129 and 29, respectively, for every 10,000 delivery hospitalizations. Compared with the 1998–1999 period, severe maternal morbidity increased by 75% and 114% for delivery and postpartum hospitalizations, respectively. We found increasing rates of blood transfusion, acute renal failure, shock, acute myocardial infarction, respiratory distress syndrome, aneurysms, and cardiac surgery during delivery hospitalizations. Moreover, during the study period, rates of postpartum hospitalization with 13 of the 25 severe complications examined more than doubled, and the overall mortality during postpartum hospitalizations increased by 66% (P<.05). CONCLUSIONS: Severe maternal morbidity currently affects approximately 52,000 women during their delivery hospitalizations and, based on current trends, this burden is expected to increase. Clinical review of identified cases of severe maternal morbidity can provide an opportunity to identify points of intervention for quality improvement in maternal care. LEVEL OF EVIDENCE: III

Trends in postpartum hemorrhage: United States, 1994–2006

OBJECTIVE The purpose of this study was to estimate the incidence of postpartum hemorrhage (PPH) in the United States and to assess trends. STUDY DESIGN Population-based data from the 1994-2006 National Inpatient Sample were used to identify women who were hospitalized with postpartum hemorrhage. Data for each year were plotted, and trends were assessed. Multivariable logistic regression was used in an attempt to explain the difference in PPH incidence between 1994 and 2006. RESULTS PPH increased 26% between 1994 and 2006 from 2.3% (n = 85,954) to 2.9% (n = 124,708; P < .001). The increase primarily was due to an increase in uterine atony, from 1.6% (n = 58,597) to 2.4% (n = 99,904; P < .001). The increase in PPH could not be explained by changes in rates of cesarean delivery, vaginal birth after cesarean delivery, maternal age, multiple birth, hypertension, or diabetes mellitus. CONCLUSION Population-based surveillance data signal an apparent increase in PPH caused by uterine atony. More nuanced clinical data are needed to understand the factors that are associated with this trend.

Hypertensive disorders and severe obstetric morbidity in the United States.

OBJECTIVE: To examine trends in the rates of hypertensive disorders in pregnancy and compare the rates of severe obstetric complications for delivery hospitalizations with and without hypertensive disorders. METHODS: We performed a cross-sectional study using the 1998–2006 Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project. Logistic regressions and population-attributable fractions were used to examine the effect of hypertensive disorders on severe complications. RESULTS: The overall prevalence of hypertensive disorders among delivery hospitalizations increased significantly from 67.2 per 1,000 deliveries in 1998 to 81.4 per 1,000 deliveries in 2006. Compared with hospitalizations without any hypertensive disorders, the risk of severe obstetric complications ranged from 3.3 to 34.8 for hospitalizations with eclampsia/severe preeclampsia and from 1.4 to 2.2 for gestational hypertension. The prevalence of hospitalizations with eclampsia/severe preeclampsia increased moderately from 9.4 to 12.4 per 1,000 deliveries (P for linear trend <0.001) during the period of study. However, these hospitalizations were associated with 38% of hospitalizations with acute renal failure and 19% or more of hospitalizations with ventilation, disseminated intravascular coagulation syndrome, pulmonary edema, puerperal cerebrovascular disorders, and respiratory distress syndrome. Overall, hospitalizations with hypertensive disorders were associated with 57% of hospitalizations with acute renal failure, 27% of hospitalizations with disseminated intravascular coagulation syndrome, and 30% or more of hospitalizations with ventilation, pulmonary edema, puerperal cerebrovascular disorders, and respiratory distress syndrome. CONCLUSION: The number of delivery hospitalizations in the United States with hypertensive disorders in pregnancy is increasing, and these hospitalizations are associated with a substantial burden of severe obstetric morbidity. LEVEL OF EVIDENCE: III