Rates of Cesarean Delivery -- United States, 1993

The rate of cesarean delivery in the United States is among the highest for developed nations (1). Because increased risks for maternal death and morbidity and perinatal morbidity are associated with cesarean delivery, a national health objective for the year 2000 is to reduce the overall rate of cesarean delivery to less than or equal to 15.0 per 100 deliveries (1987 baseline: 24.4 per 100 deliveries) (objective 14.8) (2) -- a level last observed in 1978 (3). This report uses data from CDC's National Hospital Discharge Survey (NHDS) to characterize cesarean deliveries during 1993, compares these rates with rates for 1970-1992, and assesses progress toward the national health objective for the year 2000.

Since 1965, NHDS has collected data annually on discharges from short-stay, nonfederal hospitals. For 1993, medical and demographic information were abstracted from a sample of 235,411 inpatients discharged from the 466 participating hospitals. In this analysis, data about the number of cesareans and vaginal births after a previous cesarean (VBAC) are based on weighted national estimates from the NHDS sample of approximately 27,000 (11.5%) women discharged after delivery. The estimated numbers of live births by type of delivery were calculated by applying cesarean rates from the NHDS to the number of live births from national vital registration data. Stated differences in this report are significant at the 95% confidence level.

In 1993, of the estimated 4,039,000 live births, approximately 585,000 (14.5%) were primary cesareans, 336,000 (8.3%) repeat cesareans, 115,000 (2.9%) VBACs, and 3,003,000 (74.4%) other vaginal deliveries. The overall rate of cesarean delivery in 1993 was 22.8 per 100 deliveries, the lowest rate since 1985 but approximately four times the rate in 1970 (5.5) Table_1. The primary cesarean rate (i.e., number of first cesareans per 100 deliveries to women who had no previous cesarean) for 1993 (16.3) also was the lowest rate since 1985 but approximately four times the rate in 1970 (4.2). Declines in the overall and primary cesarean delivery rates from the mid-1980s to 1993 were not statistically significant. In 1993, of the women who had a previous cesarean birth, approximately one fourth gave birth vaginally (VBAC rate: 25.4); the VBAC rate in 1993 more than doubled from 1988 (12.6).

In 1993, the overall rate of cesarean delivery differed by region, maternal age, hospital size and ownership, and expected source of payment Table_2. Rates were higher in the South *, for mothers aged greater than or equal to 30 years (especially those aged greater than or equal to 35 years), for hospitals containing less than 100 beds, for proprietary hospitals, and for mothers with Blue Cross/Blue Shield ** or other private insurance.

The rate of cesarean delivery varied by the complications of pregnancy or delivery that preceded the cesarean. Rates were highest for women who had fetopelvic disproportion (98.5 per 100 deliveries) or failed induction of labor (94.3). Common medical complications were breech presentation (rate: 87.1); history of previous cesarean (74.6); antepartum hemorrhage, abruptio placenta, and placenta previa (64.1); obstructed labor (63.5); and multiple gestation (57.8). In 1993, of all women who had a cesarean, 36.5% had a previous cesarean delivery, 17.4% had an abnormal labor, and 17.0% had fetopelvic disproportion. Of all women who delivered, 11.2% had a previous cesarean, 8.7% each had abnormal labor or uterine inertia, and 7.6% were anemic. Reported by: Natality, Marriage, and Divorce Statistics Br, Div of Vital Statistics, National Center for Health Statistics, CDC.

Editorial Note

Editorial Note: The findings in this report indicate that the overall and primary cesarean rates have remained relatively stable since the mid-1980s. Although the VBAC rate increased twofold during 1988-1993, the anticipated reduction in the overall rate of cesarean delivery was offset by trends among women giving birth that are associated with higher risk for cesarean delivery (i.e., increases in maternal age at birth and in first order and plural births {4}). In particular, maternal age is an independent risk factor for cesarean delivery even after adjustments for other potential confounding factors (e.g., race, education, and complications of labor and delivery) (5).

In this study, rates of cesarean delivery were analyzed separately by region, hospital size and ownership, and expected source of payment; therefore, simultaneous effects of the other variables could not be analyzed. For example, the study could not assess whether the higher rates of cesarean delivery in small hospitals (i.e., less than 100 beds) reflected the increased likelihood of proprietary ownership of these hospitals.

The overall cesarean delivery rate is directly associated with the primary cesarean rate and the VBAC rate. Therefore, in addition to establishing year 2000 national health objective 14.8 to assist in monitoring trends in the overall cesarean delivery rate, two more specific objectives were established to monitor trends in primary cesarean and VBAC rates. The objectives are to reduce the primary cesarean delivery rate to less than or equal to 12.0 per 100 deliveries (1987 baseline: 17.4 per 100 deliveries) (objective 14.8a) and to increase the number of VBACs to greater than or equal to 35.0 per 100 women who had a previous cesarean (objective 14.8b) (2). If the VBAC rate continues to increase at the rate observed during 1988-1993, the national health objective may be met by the year 2000; however, the most recent data indicate the rate stabilized during 1991-1993. Even with a VBAC rate of 35.0, the primary rate must decline by nearly half (to 8.4) to achieve the year 2000 target rate for overall cesarean deliveries (15.0). Based on the stability of the primary cesarean delivery rates during 1985-1993, the overall cesarean rate probably will not decline to meet the objective by the year 2000.

In many countries with demographic profiles similar to the United States, cesarean rates are less than or equal to 15.0 per 100 deliveries (1). Strategies to achieve this rate in the United States will require the widespread use of four obstetrical practices that have been successful in reducing cesarean delivery rates in many hospitals: 1) active management of labor; 2) public dissemination of physician-specific cesarean delivery rates to increase public awareness of differences in practices; 3) implementation of standardized protocols for repeat cesareans, dystocia, and fetal distress; and 4) establishment of reduction of the rate as an institutional priority (6-8).

References

1. Notzon FC. International differences in the use of obstetric interventions. JAMA 1990;263:3286-91.

2. Public Health Service. Healthy people 2000: national health promotion and disease prevention objectives -- full report, with commentary. Washington, DC: US Department of Health and Human Services, Public Health Service, 1991; DHHS publication no. (PHS)91-50212.

3. CDC. Rates of cesarean delivery -- United States, 1991. MMWR 1993;42:285-9.

4. Ventura SJ, Martin JA, Taffel SM, et al. Advance report of final natality statistics, 1992. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1994. (Monthly vital statistics report; vol 43, no. 4, suppl).

5. Peipert JF, Bracken M. Maternal age: an independent risk factor for cesarean delivery. Obstet Gynecol 1993;81:200-5.

6. Sanchez-Ramos L, Kaunitz AM, Peterson HB, et al. Reducing cesarean section rates at a teaching hospital. Am J Obstet Gynecol 1990;163:1081-8.

7. Socol ML, Garcia PM, Peaceman AM, Dooley SL. Reducing cesarean births at a primarily private university hospital. Am J Obstet Gynecol 1993;168:1748-58.

8. Myers SA, Gleicher N. A successful program to lower cesarean-section rates. N Engl J Med 1988;319:1511-6.

* South=Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, and West Virginia 

** Use of trade names and commercial sources is for identification only and does not imply endorsement by the Public Health Service or the U.S. Department of Health and Human Services.

TABLE 1.  Number of live births; estimated rate of cesarean deliveries, by type; estimated number and percentage of cesarean
deliveries, by type; and estimated number and rate of vaginal births after a previous cesarean delivery, by year -- United
States, selected years, 1970--1993
=============================================================================================================================
                                                           Cesarean deliveries *
                                                           ---------------------                 Vaginal birth
                             Cesarean rate                          Repeat +              after a previous cesarean
            No. live     ---------------------                    -----------             --------------------------
Year         births &    Primary @  Overall **     No. primary &  No. &  (%)    Total&      No. * &        Rate ++
-----------------------------------------------------------------------------------------------------------------------------
1993          4039 &&      16.3       22.8              585       336  (36.5)    921        115            25.4
1992          4084         16.8       23.6              605       359  (37.2)    964        119            25.1
1991          4111         17.1       23.5              628       338  (35.0)    966        108            24.2
1990          4158         16.8       23.5              626       351  (35.9)    977         90            20.4
1989          4041         17.1       23.8              620       342  (35.6)    962         78            18.5
1988          3910         17.5       24.7              615       351  (36.3)    966         50            12.6
1987          3809         17.4       24.4              601       328  (35.3)    929         36             9.8
1986          3757         17.4       24.1              595       310  (34.3)    905         29             8.5
1985          3761         16.3       22.7              559       295  (34.6)    854         21             6.6
1980          3612         12.1       16.5              418       178  (29.9)    596          6 @@          3.4 @@
1975          3144          7.8       10.4              238        89  (27.1)    327          2 @@          2.0 @@
1970          3731          4.2        5.5              153        52  (25.2)    205          1 @@          2.2 @@
-----------------------------------------------------------------------------------------------------------------------------
 * Estimated by applying cesarean rates derived from the National Hospital Discharge Survey to the number of live births
   from national vital registration data.
 + Proportion of all cesareans that are repeat cesareans; standard error does not exceed 1.8% for any year.
 & In thousands.
 @ Number of first cesareans per 100 deliveries to women who had no previous cesarean delivery; standard error does not
   exceed 1.1% for any year.
** Number of cesarean deliveries per 100 deliveries; standard error does not exceed 1.5% for any year.
++ Number of women who had a vaginal birth after a previous cesarean delivery per 100 deliveries to women who had a previous
   cesarean delivery; standard error does not exceed 1.3% for any year.
&& Provisional data.
@@ Number does not meet standards of reliability or precision because the weighted numerator is <10,000 deliveries.
============================================================================================================================= 

TABLE 2. Estimated overall and primary cesarean rates, * by region, age of mother,
hospital size and ownership, and expected source of payment -- United States, 1993
============================================================================================
                              Estimated overall cesarean  Estimated primary cesarean
                              --------------------------  --------------------------
Category                         Rate           (SE +)       Rate           (SE)
--------------------------------------------------------------------------------------------
Region &
  Northeast                      23.4           (0.9)        17.4          (0.8)
  Midwest                        20.8           (1.1)        14.4          (1.1)
  South                          25.9           (0.9)        18.6          (0.8)
  West                           19.3           (1.6)        13.7          (1.5)

Age (yrs) of mother
     <20                         15.6           (0.8)        14.0          (0.8)
   20-24                         19.9           (0.6)        15.1          (0.6)
   25-29                         23.0           (0.6)        16.1          (0.6)
   30-34                         26.3           (0.7)        17.1          (0.7)
    >=35                         30.3           (1.1)        21.9          (1.1)

Hospital size (no. beds)
      <100                       25.4           (1.0)        17.9          (0.9)
   100-299                       21.9           (0.6)        15.5          (0.6)
   300-499                       22.6           (0.9)        16.2          (0.8)
     >=500                       22.2           (1.3)        16.9          (1.2)

Hospital ownership
  Nonprofit                      22.0           (0.5)        15.8          (0.5)
  State and local government     20.5           (1.1)        14.0          (1.1)
  Proprietary                    29.0           (1.2)        20.7          (1.1)

Expected source of payment
  Blue Cross/Blue Shield@        26.7           (3.2)        18.6          (0.7)
  Other private insurance        25.7           (1.6)        18.7          (0.8)
  Medicaid                       19.5           (1.0)        13.8          (0.9)
  Other government sources       24.5           (4.0)        16.8          (0.6)
  Self                           16.1           (2.4)        12.1          (0.8)
  Other                          21.9           (3.1)        14.4          (0.8)

Total                            22.8           (0.4)        16.3          (0.4)
--------------------------------------------------------------------------------------------
* Overall=number of cesarean deliveries per 100 deliveries; primary=number of first
  cesareans per 100 deliveries to women who did not have a previous cesarean.
+ Standard error.
& Northeast=Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York,
  Pennsylvania, Rhode Island, and Vermont; Midwest=Illinois, Indiana, Iowa, Kansas,
  Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, Wisconsin,
  and Wyoming; South=Alabama, Arkansas, Delaware, District of Columbia, Florida,
  Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South
  Carolina, Tennessee, Texas, Virginia, and West Virginia; West=Alaska, Arizona,
  California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, and
  Washington.
@ Use of trade names and commercial sources is for identification only and does not imply
  endorsement by the Public Health Service or the U.S. Department of Health and Human
  Services.
===========================================================================================

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