User Support

May 2011

Anne Elixhauser, Ph.D. and Lauren M. Wier, M.P.H.



Introduction

Complications during pregnancy can pose a serious risk to both maternal and infant health, and are associated with various adverse outcomes, including miscarriage, hemorrhage, preterm labor, and low birth weight.¹ An objective of the U.S. Department of Health & Human Services' Healthy People 2020 is to reduce maternal illness and complications related to pregnancy during hospitalization for labor and delivery.²

This Statistical Brief presents data from the Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample (NIS) on pregnancy and childbirth hospitalizations with complicating conditions in 2008. All data are reported from the maternal perspective (i.e., reflecting the experience of the mother, not the newborn). For the purpose of this Brief, "complicating conditions" include all ICD-9-CM diagnosis codes that are in the section entitled "Complications of Pregnancy, Childbirth, and the Puerperium."³

This Brief presents information on hospital utilization and patient characteristics for the following types of hospital stays for:

• complicated pregnancy during which no delivery occurred ("non-delivery with complicating conditions"),
• delivery with complicated pregnancy or delivery ("delivery with complicating conditions"), and
• delivery without any mention of complicated pregnancy or delivery ("delivery without complicating conditions").

In addition, this report provides information on specific types of complicating conditions of pregnancy and delivery. All differences between estimates noted in the text are statistically significant at the 0.05 level or better.

Findings

There were 4,673,700 pregnancy and delivery hospital stays recorded in these hospital discharge data among females ages 15 to 44 years in 2008. As shown in table 1, there were 473,700 non-delivery maternal hospital stays with complicating conditions as a principal or secondary diagnosis. Among the 4.2 million deliveries in 2008, the vast majority (94.1 percent) listed some type of complicating condition.

Stays with pregnancy-related complicating conditions tended to be longer (2.9 days for non-delivery stays and 2.7 days for delivery stays) than delivery stays without complicating conditions (1.9 days). Maternal stays with complicating conditions were also about 50 percent more costly ($4,100 for non-delivery stays and $3,900 for delivery stays) than delivery stays without complications ($2,600). Maternal stays with pregnancy and delivery-related complicating conditions accounted for $17.4 billion, or nearly 5 percent of total hospital costs in the United States.

Discharge against medical advice was more common among non-delivery stays with complicating conditions (1.9 percent) compared to delivery stays with or without pregnancy-related complicating conditions (less than 0.1 percent). Among all women 18-44, less than 1 percent (0.9 percent) are discharged against medical advice (data not shown).

Rates and characteristics of complicating conditions, 2008
Table 2 shows the rates of complicating conditions among maternal stays. During an individual stay, multiple complicating conditions may be recorded; some may be more recorded as the principal diagnosis and some may be recorded as the secondary diagnosis. This table provides a complete accounting of all complicating conditions regardless of their severity.

Non-delivery stays
As shown in table 2, among non-delivery maternal stays, the following complicating conditions occurred at a rate of 100 or more for every 1,000 hospital stays:

• early or threatened labor (208 per 1,000 stays)
• infections of genitourinary tract (132 per 1,000 stays)
• hypertension including eclampsia and pre-eclampsia (113 per 1,000 stays)

The following complicating conditions occurred at a rate of 50-99 for every 1,000 hospital stays:

• anemia (99 per 1,000 stays)
• diabetes or abnormal glucose tolerance (82 per 1,000 stays)
• hyperemesis gravidarum (vomiting) (63 per 1,000 stays)
• poor fetal growth (60 per 1,000 stays)
• ectopic pregnancy (56 per 1,000 stays)
• advanced maternal age (56 per 1,000 stays)
• hemorrhage (52 per 1,000 stays)

Delivery stays
Among maternal stays with delivery, the following common complicating conditions occurred at a rate of 100 or more for every 1,000 deliveries:

• umbilical cord complications (233 per 1,000 stays)
• perineal lacerations (158 1st degree and 168 2nd degree lacerations per 1,000 stays)
• previous cesarean section (167 per 1,000 stays)
• abnormality in fetal heart rate or rhythm (148 per 1,000 stays)
• prolonged pregnancy (121 per 1,000 stays)
• polyhydramnios and problems of the amniotic cavity (117 per 1,000 stays)
• advanced maternal age (117 per 1,000 stays)
• anemia during pregnancy (112 per 1,000 stays)
• fetal distress and abnormal forces of labor (111 per 1,000 stays)

The following complicating conditions occurred at a rate of 50-99 for every 1,000 deliveries:

• hypertension including eclampsia and pre-eclampsia (94 per 1,000 stays)
• early or threatened labor (81 per 1,000 stays)
• malposition, malpresentation (80 per 1,000 stays)
• diabetes or abnormal glucose tolerance (68 per 1,000 stays)
• poor fetal growth (54 per 1,000 stays)
• fetopelvic disproportion (54 per 1,000 stays)

Patient characteristics of maternal hospitalizations
The average age for patients with complicating conditions was about 2 years older (27.2 years for non-delivery stays and 27.7 years for complicated delivery stays) than for patients delivering without complicating conditions (25.5 years). Figure 1 shows that patients 35 to 44 years accounted for 15 percent of maternal stays with complicating conditions (with or without delivery), but comprised only 1 percent of delivery stays without complicating conditions.

As shown in table 1, Medicaid and private insurance were the most common expected payers for all maternity stays. For non-delivery stays with complicating conditions, Medicaid was the most common expected payer (45.5 percent), closely followed by private insurance (42.9 percent). Private insurance was the most common expected payer for delivery stays with complicating conditions (53.2 percent), followed by Medicaid (39.7 percent). About half of all delivery stays without complicating conditions of pregnancy were billed to Medicaid (50.5 percent), while 41.8 percent were billed to private insurance.

Hospitalization rates for non-delivery stays with complicating conditions and delivery stays (with and without complicating conditions) were highest in the poorest communities and declined with increasing income (figure 2). Across all three types of maternal stays, the rate of stays was higher for women living in large urban areas and rural areas (micropolitan and noncore) and lower for women living in medium and small metropolitan areas (figure 3).

Figure 4 shows the rates of pregnancy and childbirth stays with and without complicating conditions by region. Regional differences were not statistically significant for stays with complications (with or without delivery). Delivery stays without complications were lowest in the Northeast and highest in the South and West.

Data Source

The estimates in this Statistical Brief are based upon data from the 2008 HCUP Nationwide Inpatient Sample (NIS). Supplemental sources included data on regional population estimates from "Table 1: Annual Estimates of the Resident Population for the United States, Regions, States, and Puerto Rico: April 1, 2000 to July 1, 2009 (NST-EST2009-01)," Population Division, U.S. Census Bureau, Release date: December 2009 (https://www.census.gov/programs-surveys/popest/data/tables.html).

Definitions

Diagnoses, ICD-9-CM, and Clinical Classifications Software (CCS)
The principal diagnosis is that condition established after study to be chiefly responsible for the patient’s admission to the hospital. Secondary diagnoses are concomitant conditions that coexist at the time of admission or that develop during the stay.

ICD-9-CM is the International Classification of Diseases, Ninth Revision, Clinical Modification, which assigns numeric codes to diagnoses. There are about 13,600 ICD-9-CM diagnosis codes.

CCS categorizes ICD-9-CM diagnoses into a manageable number of clinically meaningful categories.⁴ This "clinical grouper" makes it easier to quickly understand patterns of diagnoses and procedures. For table 2, the Multi-Level CCS was used to examine more specific categories of conditions. The Multi-Level CCS is a hierarchical system that is defined using both single-level CCS groupings and ICD-9-CM codes.⁵

For this report, CCS codes 177-195 were used to identify complicating conditions of pregnancy and childbirth. Delivery stays were identified by ICD-9-CM diagnosis codes 640.0-676.9, where the fifth digit is 1 or 2, or ICD-9-CM 650. Maternal stays were identified as having an all-listed ICD-9-CM diagnosis code in the delivery range or an all-listed CCS code 177-195. All stays were limited to patients’ ages 15 to 44 years.

Types of hospitals included in HCUP
HCUP is based on data from community hospitals, defined as short-term, non-Federal, general and other hospitals, excluding hospital units of other institutions (e.g., prisons). HCUP data include OB-GYN, ENT, orthopedic, cancer, pediatric, public, and academic medical hospitals. Excluded are long-term care, rehabilitation, psychiatric, and alcoholism and chemical dependency hospitals. Please note, a discharge of this nature will be included in the NIS if it occurred in a community hospital.

Unit of analysis
The unit of analysis is the hospital discharge (i.e., the hospital stay), not a person or patient. This means that a person who is admitted to the hospital multiple times in one year will be counted each time as a separate "discharge" from the hospital.

Costs and charges
Total hospital charges were converted to costs using HCUP Cost-to-Charge Ratios based on hospital accounting reports from the Centers for Medicare and Medicaid Services (CMS).⁶ Costs will tend to reflect the actual costs of production, while charges represent what the hospital billed for the case. For each hospital, a hospital-wide cost-to-charge ratio is used because detailed charges are not available across all HCUP States. Hospital charges reflect the amount the hospital charged for the entire hospital stay and does not include professional (physician) fees. For the purposes of this Statistical Brief, costs are reported to the nearest hundred.

Urban-rural location
Urban-rural location is one of six categories as defined by the National Center for Health Statistics:

• Large Central Metropolitan: Central counties of metropolitan areas with a population of 1 million or greater
• Large Fringe Metropolitan: Fringe counties of counties of metropolitan areas with a population of 1 million or greater
• Medium Metropolitan: Counties in metro area of 250,000-999,999 population
• Small Metropolitan: Counties in metro areas of 50,000-249,999 population
• Micropolitan: Micropolitan counties, i.e. a non-metropolitan county with an area of 10,000 or more population
• Non-core: Non-metropolitan and non-micropolitan counties

In this report, medium and small metropolitan were combined into one category and micropolitan and non-core were combined and labeled "rural."

Median community-level income
Median community-level income is the median household income of the patient’s ZIP Code of residence. The cut-offs for the quartile designation are determined using ZIP Code demographic data obtained from Claritas. The income quartile is missing for homeless and foreign patients.

Payer
Payer is the expected primary payer for the hospital stay. To make coding uniform across all HCUP data sources, payer combines detailed categories into more general groups:

• Medicare includes fee-for-service and managed care Medicare patients.
• Medicaid includes fee-for-service and managed care Medicaid patients. Patients covered by the State Children's Health Insurance Program (SCHIP) may be included here. Because most state data do not identify SCHIP patients specifically, it is not possible to present this information separately.
• Private insurance includes Blue Cross, commercial carriers, and private HMOs and PPOs.
• Other includes Workers’ Compensation, TRICARE/CHAMPUS, CHAMPVA, Title V, and other government programs.
• Uninsured includes an insurance status of "self-pay" and "no charge."

When more than one payer is listed for a hospital discharge, the first-listed payer is used.

Region
Region is one of the four regions defined by the U.S. Census Bureau:

• Northeast: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, and Pennsylvania
• Midwest: Ohio, Indiana, Illinois, Michigan, Wisconsin, Minnesota, Iowa, Missouri, North Dakota, South Dakota, Nebraska, and Kansas
• South: Delaware, Maryland, District of Columbia, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida, Kentucky, Tennessee, Alabama, Mississippi, Arkansas, Louisiana, Oklahoma, and Texas
• West: Montana, Idaho, Wyoming, Colorado, New Mexico, Arizona, Utah, Nevada, Washington, Oregon, California, Alaska, and Hawaii

Discharge status
Discharge status indicates the disposition of the patient at discharge from the hospital, and includes the following six categories: routine (to home), transfer to another short-term hospital, other transfers (including skilled nursing facility, intermediate care, and another type of facility such as a nursing home), home healthcare, against medical advice (AMA), or died in the hospital.

About HCUP

HCUP is a family of powerful healthcare databases, software tools, and products for advancing research. Sponsored by the Agency for Healthcare Research and Quality (AHRQ), HCUP includes the largest all-payer encounter-level collection of longitudinal healthcare data (inpatient, ambulatory surgery, and emergency department) in the United States, beginning in 1988. HCUP is a Federal-State-Industry Partnership that brings together the data collection efforts of many organizations—such as State data organizations, hospital associations, private data organizations, and the Federal government—to create a national information resource.

HCUP would not be possible without the contributions of the following data collection Partners from across the United States:

Arizona Department of Health Services
Arkansas Department of Health
California Office of Statewide Health Planning and Development
Colorado Hospital Association
Connecticut Hospital Association
Florida Agency for Health Care Administration
Georgia Hospital Association
Hawaii Health Information Corporation
Illinois Department of Public Health
Indiana Hospital Association
Iowa Hospital Association
Kansas Hospital Association
Kentucky Cabinet for Health and Family Services
Louisiana Department of Health and Hospitals
Maine Health Data Organization
Maryland Health Services Cost Review Commission
Massachusetts Division of Health Care Finance and Policy
Michigan Health & Hospital Association
Minnesota Hospital Association
Missouri Hospital Industry Data Institute
Montana MHA — An Association of Montana Health Care Providers
Nebraska Hospital Association
Nevada Department of Health and Human Services
New Hampshire Department of Health & Human Services
New Jersey Department of Health and Senior Services
New Mexico Health Policy Commission
New York State Department of Health
North Carolina Department of Health and Human Services
Ohio Hospital Association
Oklahoma State Department of Health
Oregon Association of Hospitals and Health Systems
Pennsylvania Health Care Cost Containment Council
Rhode Island Department of Health
South Carolina State Budget & Control Board
South Dakota Association of Healthcare Organizations
Tennessee Hospital Association
Texas Department of State Health Services
Utah Department of Health
Vermont Association of Hospitals and Health Systems
Virginia Health Information
Washington State Department of Health
West Virginia Health Care Authority
Wisconsin Department of Health Services
Wyoming Hospital Association

About the NIS

The HCUP Nationwide Inpatient Sample (NIS) is a nationwide database of hospital inpatient stays. The NIS is nationally representative of all community hospitals (i.e., short-term, non-Federal, non-rehabilitation hospitals). The NIS is a sample of hospitals and includes all patients from each hospital, regardless of payer. It is drawn from a sampling frame that contains hospitals comprising about 95 percent of all discharges in the United States. The vast size of the NIS allows the study of topics at both the national and regional levels for specific subgroups of patients. In addition, NIS data are standardized across years to facilitate ease of use.

For More Information

For more information about HCUP, visit http://www.hcup-us.ahrq.gov.

For additional HCUP statistics, visit HCUPnet, our interactive query system, at www.hcup.ahrq.gov.

For information on other hospitalizations in the U.S., download HCUP Facts and Figures: Statistics on Hospital-based Care in the United States in 2008, located at http://www.hcup-us.ahrq.gov/reports.jsp.

For a detailed description of HCUP, more information on the design of the NIS, and methods to calculate estimates, please refer to the following publications:

Steiner, C., Elixhauser, A., Schnaier, J. The Healthcare Cost and Utilization Project: An Overview. Effective Clinical Practice 5(3):143–51, 2002.

Introduction to the HCUP Nationwide Inpatient Sample, 2008. Online. May 2010. Agency for Healthcare Research and Quality. http://hcup-us.ahrq.gov/db/nation/nis/NIS_2008_INTRODUCTION.pdf

Houchens, R., Elixhauser, A. Final Report on Calculating Nationwide Inpatient Sample (NIS) Variances, 2001. HCUP Methods Series Report #2003-2. Online. June 2005 (revised June 6, 2005). U.S. Agency for Healthcare Research and Quality. http://www.hcup-us.ahrq.gov/reports/methods/2003_02.pdf.

Suggested Citation

Elixhauser, A. (AHRQ) and Wier, L.M. (Thomson Reuters). Complicating Conditions of Pregnancy and Childbirth, 2008. HCUP Statistical Brief #113. May 2011. Agency for Healthcare Research and Quality, Rockville, MD. http://www.hcup-us.ahrq.gov/reports/statbriefs/sb113.pdf.

Acknowledgments

The authors would like to acknowledge Minya Sheng (Thomson Reuters) for programming assistance.

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AHRQ welcomes questions and comments from readers of this publication who are interested in obtaining more information about access, cost, use, financing, and quality of healthcare in the United States. We also invite you to tell us how you are using this Statistical Brief and other HCUP data and tools, and to share suggestions on how HCUP products might be enhanced to further meet your needs. Please e-mail us at hcup@ahrq.gov or send a letter to the address below:

Irene Fraser, Ph.D., Director
Center for Delivery, Organization, and Markets
Agency for Healthcare Research and Quality
540 Gaither Road
Rockville, MD 20850



¹ American Pregnancy Association, Pregnancy Complications. http://www.americanpregnancy.org/pregnancycomplications/
² U.S. Department of Health & Human Services, Maternal, Infant, and Child Health. http://www.healthypeople.gov/2020/topics-objectives/topic/maternal-infant-and-child-health/objectives
³ This classification of pregnancy complications is more inclusive than those diagnoses considered complications by Diagnostic Related Group (DRG) codes. Depending on the DRG assignment, an ICD-9-CM pregnancy or delivery complication code may not be considered a complication. For example, the following ICD-9-CM codes all fall into DRG 775 –"Vaginal delivery without complicating diagnoses" but are listed as complications based on ICD-9-CM codes:
64311-hyperemesis gravidarum with metabolic disturbance
64321-late vomiting of pregnancy
64622-renal disease not otherwise specified
64661-genitourinary infection
64831-drug dependence
64881-abnormal glucose tolerance
65221-breech presentation
⁴ HCUP CCS. Healthcare Cost and Utilization Project (HCUP). December 2009. U.S. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/toolssoftware/ccs/ccs.jsp.
⁵ Elixhauser A., Steiner C., Palmer L. Clinical Classifications Software (CCS), 2011. U.S. Agency for Healthcare Research and Quality. Available: http://www.hcup-us.ahrq.gov/toolssoftware/ccs/CCSUsersGuide.pdf .
⁶ HCUP Cost-to-Charge Ratio Files (CCR). Healthcare Cost and Utilization Project (HCUP). 2001–2008. U.S. Agency for Healthcare Research and Quality, Rockville, MD. www.hcup-us.ahrq.gov/db/state/costtocharge.jsp.