Ectopic Pregnancy Surveillance

Sally F. Dorfman, M.D., M.S.H.S.A.

Pregnancy Epidemiology Branch (Formerly Abortion Surveillance Branch)

Division of Reproductive Health (Formerly Family Planning Evaluation Division) Center for Health Promotion and Educationšlf8å

Introduction

Ectopic pregnancy is an important cause of maternal mortality in the United States. However, no comprehensive national statistics on ectopic pregnancies have been obtained in routinely collected data. This report summarizes data on ectopic pregnancy among females 15-44 years of age, documenting the estimated number and characteristics of females discharged from hospitals after treatment for ectopic pregnancy and describing the characteristics of females who died from this condition.

Methods

The numbers of ectopic pregnancies reported are estimates based on a systematic sample of medical records for a representative sample of hospitals in the United States, the data having been collected by the National Center for Health Statistics (NCHS) as part of the ongoing National Hospital Discharge Survey. The rates for ectopic pregnancy are also estimates calculated using data prepared by the U.S. Bureau of the Census and NCHS. Data on deaths from ectopic pregnancy are based on U.S. mortality statistics provided by NCHS. Results

In the period 1970-1978, approximately 261,600 females ages 15-44 were discharged from United States hospitals with a diagnosis of ectopic pregnancy. For every 1,000 reported pregnancies during that period, an estimated 7.1 were ectopic. The number of reported ectopic pregnancies steadily increased from 17,800 in 1970 to 42,400 in 1978 (Table 1). The ectopic pregnancy rate also increased each year, regardless of which of three denominators (female population ages 15-44, live births, or reported pregnancies) was used. For each denominator, the rate more than doubled in the period 1970-1978.

In this same period, over half the ectopic pregnancies occurred among females ages 25-34; over 70% occurred among white females, although the rates were consistently higher for black females. The ectopic pregnancy rates increased with age when live births or reported pregnancies were used as denominators. Because older females are less likely than younger females to become pregnant, rates decreased for the oldest group (35-44) when the female population was used as the denominator.

The greatest number of ectopic pregnancies occurred among females in the South, but ectopic pregnancy rates were slightly higher for those in the Northeast. Previously noted variations with regard to age and race held true for each region. Although over 70% of ectopic pregnancies occurred among currently married females, the ectopic pregnancy rates were highest for previously married females. The average length of hospital stay for ectopic pregnancy decreased from 7.2 days in 1970 to 5.9 days in 1978 and averaged 6.5 days for the period 1970-1978.

Although 437 females died because of ectopic pregnancy in the period 1970-1978, the mortality rate declined during this period from 3.5 to 0.9 deaths per 1,000 ectopic pregnancies (Figure 1). This trend was generally true for each age group. However, for each age group and region, the ectopic pregnancy mortality rates for black females were higher than those for white females. Mortality rates by month ranged from 0.9 (April) to 2.3 (January), with an overall rate of 1.7 deaths per 1,000 ectopic pregnancies.

Discussion

The incidence and rates of ectopic pregnancies in the United States increased more than twofold in the period 1970-1978. The risk of this condition increased with age and was higher for black females than for white females. Mortality rates for black females remained consistently higher than those for white females in every age group and geographic region.

The estimated national numbers of ectopic pregnancies in this report are low because they do not include females admitted to federally operated hospitals, such as Armed Forces and Public Health Service hospitals. Furthermore, ectopic pregnancies may not be diagnosed and may therefore be underreported, although presumably most cases are eventually seen in hospitals.

At the same time, the reported pregnancies used as denominators are also underestimates because the numbers of spontaneous abortions, illegal abortions, and still births are excluded (no accurate data on these three outcomes are available). In addition, the numbers of legal abortions included in this denominator are based on data reported to CDC and are approximately 18% less than those ascertained by the Alan Guttmacher Institute. Therefore, the ectopic pregnancy rates based on reported pregnancies are likely to be overestimates.

The most striking aspect of the ectopic-pregnancy mortality rates, other than the overall decline over time, is the variation by race. These racial differences persist over time for different age groups and regions. Black females are not only at higher risk of having an ectopic pregnancy but are also at higher risk of dying if they have an ectopic pregnancy.

Technologic changes have probably decreased the risk of death from this condition. Progressively more sensitive pregnancy tests, ultrasound examination, and laparoscopy have contributed to a higher likelihood of accurately diagnosing an ectopic pregnancy and diagnosing it earlier. Greater awareness of ectopic pregnancies on the part of females and health-care providers has also probably contributed to a heightened likelihood of obtaining an accurate diagnosis of ectopic pregnancy. Shorter stays for treatment of ectopic pregnancy may have resulted from earlier intervention and less extensive treatment for unruptured ectopic pregnancies. Selected Bibliography Cates W Jr, Ory HW. IUD complications: infection, death and ectopic pregnancy. In: Moghissi KS, ed. Controversies in contraception. Baltimore: Williams & Wilkins, 1979:187-201. CDC. Fatal ectopic pregnancy after sterilization or abortion--New York, California. MMWR 1977;26:75. CDC. Follow-up on ectopic pregnancy following sterilization. MMWR 1977;26:154-9. Cheng MCE, Wong YM, Rochat RW, Ratnam SS. Sterilization failures in Singapore: an examination of ligation techniques and failure rates. Stud Fam Plann 1977;8:109-15. Curran JW. Economic consequences of pelvic inflammatory disease in the United States. Am J Obstet Gynecol 1980;138:848-51. Grimes DA, Geary FH Jr, Hatcher RA. Rh immunoglobulin utilization after ectopic pregnancy. Am J Obstet Gynecol 1981;140:246-9. Ory HW and the Women's Health Study. Ectopic pregnancy and intrauterine contraceptive devices: new perspectives. Obstet Gynecol 1981;57:137-44. Rochat RW. Maternal and perinatal mortality statistics. In: Aladjem S, ed. Obstetrical practice. St. Louis: C.V. Mosby, 1980:264-78. Rubin GL, Cates W Jr, Gold J, Rochat RW, Tyler CW Jr. Fatal ectopic pregnancy after attempted legally induced abortion. JAMA 1980;244:1705-8. Rubin GL, Peterson HB, Dorfman SF, et al. Ectopic pregnancy in the United States, 1970-1978. JAMA (in press). St. John RK, Brown ST, Tyler CW Jr. Pelvic inflammatory disease, 1980. Am J Obstet Gynecol 1980;138:845-7.

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