Lisa M. Koonin

Pregnancy-Related Mortality in the United States, 1991-1997

OBJECTIVE To describe trends in pregnancy-related mortality and risk factors for pregnancy-related deaths in the United States for the years 1991 through 1997. METHODS In collaboration with the American College of Obstetricians and Gynecologists and state health departments, the Pregnancy Mortality Surveillance System, part of the Division of Reproductive Health at the Centers for Disease Control and Prevention, has collected information on all reported pregnancy-related deaths occurring since 1979. Data include those present on death certificates and, when available, matching birth or fetal death certificates. Data are reviewed and coded by clinically experienced epidemiologists. The pregnancy-related mortality ratio was defined as pregnancy-related deaths per 100,000 live births. RESULTS The reported pregnancy-related mortality ratio increased from 10.3 in 1991 to 12.9 in 1997. An increased risk of pregnancy-related death was found for black women, older women, and women with no prenatal care. The leading causes of death were embolism, hemorrhage, and other medical conditions, although the percent of all pregnancy-related deaths caused by hemorrhage declined from 28% in the early 1980s to 18% in the current study period. CONCLUSION The reported pregnancy-related mortality ratio has increased, probably because of improved identification of pregnancy-related deaths. Black women continue to have an almost four-fold increased risk of pregnancy-related death, the greatest disparity among the maternal and child health indicators. Although review of pregnancy-related deaths by states remains an important public health function, such work must be expanded to identify factors that influence the survival of women with serious pregnancy complications.

Anesthesia-related Deaths during Obstetric Delivery in the United States, 1979–1990

Background Anesthesia‐related complications are the sixth leading cause of pregnancy‐related death in the United States. This study reports characteristics of anesthesia‐related deaths during obstetric delivery in the United States from 1979–1990. Methods Each state reports deaths that occur within 1 yr of delivery to the Centers for Disease Control and Prevention as part of the ongoing Pregnancy Mortality Surveillance. Maternal death certificates (with identifiers removed) matched with live birth or fetal death certificates when available from 1979–1990 were reviewed to identify deaths due to anesthesia, the cause of death, the procedure for delivery, and the type of anesthesia provided. Maternal mortality rates per million live births were calculated. Case fatality rates and risk ratios were computed to compare general to regional anesthesia for cesarean section deliveries. Results The anesthesia‐related maternal mortality rate decreased from 4.3 per million live births in the first triennium (1979–1981) to 1.7 per million in the last (1988–1990). The number of deaths involving general anesthesia have remained stable, but the number of regional anesthesia‐related deaths have decreased since 1984. The case‐fatality risk ratio for general anesthesia was 2.3 (95% confidence interval [CI], 1.9–2.9) times that for regional anesthesia before 1985, increasing to 16.7 (95% CI, 12.9–21.8) times that after 1985. Coclusions Most maternal deaths due to complications of anesthesia occurred during general anesthesia for cesarean section. Regional anesthesia is not without risk, primarily because of the toxicity of local anesthetics and excessively high regional blocks. The incidence of these deaths is decreasing, however, and deaths due to general anesthesia remain stable in number and hence account for an increased proportion of total deaths. Heightened awareness of the toxicity of local anesthetics and related improvements in technique may have contributed to a reduction in complications of regional anesthesia.

The epidemiology of placenta previa in the United States, 1979 through 1987

OBJECTIVE Placenta previa can cause serious, occasionally fatal complications for fetuses and mothers; however, data on its national incidence and sociodemographic risk factors have not been available. STUDY DESIGN We analyzed data from the National Hospital Discharge Survey for the years 1979 through 1987 and from the Retrospective Maternal Mortality Study (1979 through 1986). RESULTS We found that placenta previa complicated 4.8 per 1000 deliveries annually and was fatal in 0.03% of cases. Incidence rates remained stable among white women but increased among black and other minority women (p < 0.1). In addition, the risk of placenta previa was higher for black and other minority women than for white women (rate ratio 1.3, 95% confidence interval 1.0 to 1.7), and it was higher for women > or = 35 years old than for women <20 years old (rate ratio 4.7, 95% confidence interval 3.3 to 7.0). Women with placenta previa were at an increased risk of abruptio placentae (rate ratio 13.8), cesarean delivery (rate ratio 3.9), fetal malpresentation (rate ratio 2.8), and postpartum hemorrhage (rate ratio 1.7). CONCLUSION Our findings support the need for improved prenatal and intrapartum care to reduce the serious complications and deaths associated with placenta previa.

Public Response to Community Mitigation Measures for Pandemic Influenza

Results from a national survey indicated that most persons would follow public health officials’ guidelines.

Tubal sterilization in the United States, 1994-1996

CONTEXT Although the number and rate of tubal sterilizations, the settings in which they are performed and the characteristics of women obtaining sterilization procedures provide important information on contraceptive practice and trends in the United States, such data have not been collected and tabulated for manyyears. METHODS Information on tubal sterilizations from the National Hospital Discharge Survey and the National Survey of Ambulatory Surgery was analyzed to estimate the number and characteristics of women having a tubal sterilization procedure in the United States during the period 1994-1996 and the resulting rates of tubal sterilization. These results were compared with those of previous studies to examine trends in clinical setting, in the timing of the procedure and in patient characteristics. RESULTS In 1994-1996, more than two million tubal sterilizations were performed, for an average annual rate of 1 1.5 per 1,000 women; half were performed postpartum and half were interval procedures (i. e., were unrelated by timing to a pregnancy). All postpartum procedures were performed during inpatient hospital stays, while 96% of interval procedures were outpatient procedures. Postpartum sterilization rates were higher than interval sterilization rates among women 20-29 years of age; interval sterilization procedures were more common than postpartum procedures at ages 35-49. Sterilization rates were highest in the South. For postpartum procedures, private insurance was the expectedprimary source of payment for 48% and Medicaid was expected to pay for 41 %; for interval sterilization procedures, private insurance was the expected primary source of payment for 68% and Medicaid for 24%. CONCLUSIONS Outpatient tubal sterilizations andprocedures using laparoscopy have increased substantially since the last comprehensive analysis of tubal sterilization in 1987, an indication of the effect of technical advances on the provision of this service. Continued surveillance of both inpatient and outpatient procedures is necessary to monitor the role of tubal sterilization in contraceptive practice.

The Decline in US Teen Pregnancy Rates, 1990–1995

Objectives. Estimate pregnancy, abortion, and birth rates for 1990 to 1995 for all teens, sexually experienced teens, and sexually active teens. Design. Retrospective analysis of national data on pregnancies, abortions, and births. Participants. US women aged 15 to 19 years. Outcome Measures. Annual pregnancy, abortion, and birth rates for 1990 to 1995 for women aged 15 to 19 years, with and without adjustments for sexual experience (ever had intercourse), and sexual activity (had intercourse within last 3 months). Results. Approximately 40% of women aged 15 to 19 years were sexually active in 1995. Teen pregnancy rates were constant from 1990 to 1991. From 1991 to 1995, the annual pregnancy rate for women aged 15 to 19 years decreased by 13% to 83.6 per 1000. The percentage of teen pregnancies that ended in induced abortions decreased yearly; thus, the abortion rate decreased more than the birth rate (21% vs 9%). From 1988 to 1995, the proportion of sexually experienced teens decreased nonsignificantly. Conclusions. After a 9% rise from 1985 to 1990, teen pregnancy rates reached a turning point in 1991 and are now declining. Physicians should counsel their adolescent patients about responsible sexual behavior, including abstinence and proper use of regular and emergency contraception.

Novel framework for assessing epidemiologic effects of influenza epidemics and pandemics.

Organizing and prioritizing data collection may lead to informed assessment and guide decision making.

Characteristics of U.S. women having abortions, 1987.

In 1987, as in earlier years, women having abortions were predominantly white (65 percent), younger than 25 (59 percent), and unmarried (82 percent). A majority had no previous live births (53 percent), and most had no previous abortions (58 percent). About half the abortions were performed before nine weeks of gestation, and 97 percent were curettage procedures, usually suction curettage. Comparisons with 1980 data reveal a six percent decline in the U.S. abortion rate after changes in age, race and marital status within the population are controlled for; however, the decline occurred only among the white population and not among minority races. Among teenagers aged 15-19, the abortion rate declined slightly for whites and increased for minorities. The rate also increased among women younger than age 15.

Vasectomy in the United States, 1991 and 1995

OBJECTIVES This study sought to assess whether the controversy surrounding publications linking vasectomy and prostate cancer has had an effect on vasectomy acceptance and practice in the United States. METHODS National probability surveys of urology, general surgery, and family practices were undertaken in 1992 and 1996. RESULTS Estimates of the total number of vasectomies performed, population rate, and proportion of practices performing vasectomy were not significantly different in 1991 and 1995. CONCLUSIONS This study provides no solid evidence that the recent controversy over prostate cancer has influenced vasectomy acceptance or practice in the United States. However, the use of vasectomy appears to have leveled off in the 1990s.

School Closure to Reduce Influenza Transmission

We agree with Koonin and Cetron (1) that early application of any intervention during an influenza epidemic or pandemic is critical in maximizing population health benefits. Further, the longer an intervention is sustained, the greater the likely benefit. Whether surveillance data can inform public health interventions may depend on the timeliness of the data as well as the length of the epidemic. In tropical and subtropical settings, influenza tends to circulate longer. Although duration of the epidemic could enable delayed interventions a chance of success, social distancing interventions may need to be sustained to ensure that the epidemic does not revive when the intervention period ends. One important study not mentioned by Koonin and Cetron is a natural experiment in France where the staggering of school holiday periods in different regions enabled Cauchemez et al. to estimate that school holidays prevent 16%–18% of seasonal influenza cases (2). In contrast to our study of a single school closure event in response to 1 seasonal outbreak, the French study considered preplanned holiday periods spanning many years. Although pandemic plans often describe action to be taken depending on features in the epidemic curve (e.g., the acceleration interval as the upslope of the epidemic curve), we would argue that more focus should be given to underlying transmission dynamics. In our analysis of the effect of school closures in Hong Kong, we used a simple statistical technique (3) to estimate the underlying reproductive number. Changes in the epidemic curve may lag behind changes in the underlying transmission dynamics by at least 1 serial interval, as has previously been shown for severe acute respiratory syndrome (3–5). Public health practitioners must be encouraged to use these methods routinely. Finally, we concur that a multipronged, targeted, layered approach will likely provide the best mitigation strategy in the event of a pandemic. However, we caution against conflating good public health practice of “pulling out all the stops” in the event of a pandemic with good scientific practice of evaluating the independent effect of school closures, which was the object of our article.