Racial/ethnic trends in fetal mortality--United States, 1990-2000

Fetal deaths at > or =20 weeks' gestation account for 49% of all deaths that occur between the 20th week of pregnancy and the first year of life. Although the risk for fetal death has declined substantially since the 1950s, disparities in the risk for fetal death by race/ethnicity exist. One of the national health objectives for 2010 is to reduce deaths among fetuses of > or =20 weeks' gestation to 4.1 deaths per 1,000 live births plus fetal deaths for all racial/ethnic populations (objective no. 16-1a). To assess progress toward meeting this objective, CDC analyzed 1990-2000 data from the National Vital Statistics System (NVSS). The findings indicate substantial reductions in fetal deaths, primarily because of reductions in late fetal deaths (> or =28 weeks' gestation) compared with early fetal deaths (20-27 weeks' gestation). Despite these reductions, racial/ethnic disparities in fetal deaths persist, particularly among non-Hispanic blacks. Prevention strategies should recognize fetal deaths as a public health problem, improve fetal death surveillance and reporting, target etiologic research, and educate practitioners in identifying women at risk.     

Changes in rates of spontaneous fetal deaths reported in Upstate New York vital records by gestational age, 1968-78

Between 1968 and 1978, the rates for spontaneous deaths, recorded on Upstate New York fetal death certificates, that occurred after 28 or more weeks of gestation dropped 37 percent, and the rates for deaths that occurred at 20 to 27 completed weeks of gestation dropped 12 percent. However, the rates of reported spontaneous fetal deaths after 16 to 19 weeks gestation dropped only 4 percent. The rates for such deaths at 12-15 weeks of gestation increased by 21 percent and by 55 percent at less than 12 weeks of gestation. The decline in the late fetal death rate is probably attributable, at least in part, to medical and social advances during this period. The reported rise in early fetal deaths may be due, among other factors, to changes in reporting practices or to earlier deaths of conceptuses that formerly would have been lost after 20 weeks of gestation.     

Racial variation in spontaneous fetal deaths at 20 weeks or older in upstate New York, 1980-86.

The distribution of spontaneous fetal deaths (at age 20 weeks or more) by maternal race has received considerably less study than other adverse pregnancy outcomes. The purpose of this study was twofold--(a) to describe spontaneous fetal deaths among white, black, and American Indian women and (b) to determine if there was any variation by International Classification of Diseases, Ninth Revision (ICD-9) cause of death, gestational age at death, or maternal age at loss among these groups of mothers. Using the fetal death certificate registry maintained by the New York State Department of Health, 8,592 spontaneous fetal deaths at age 20 weeks or more were identified among upstate (exclusive of New York City) mothers between 1980 and 1986. By race it was 7,300 for white women, 1,257 for black women, and 27 for American Indian women. Spontaneous fetal death rates varied by maternal race as listed on vital records--black, 13.5 per 1,000 total births, white, 8.3, and American Indian, 8.1. The three leading causes of death (ICD-9,779, 762, and 761) did not vary by maternal race. Gestational age at death, imputed from last menstrual period, did vary by maternal race. Fetal deaths to white and black mothers were observed to occur most often between 24 weeks of pregnancy (39 percent) and 32 weeks (43 percent), while American Indian fetal deaths generally occurred later (more than 33 weeks) in pregnancy (41 percent). Most spontaneous fetal deaths occurred to mothers ages 20-29 regardless of race.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fetal and neonatal death from maternally acquired infection

Infection is a potentially preventable cause of perinatal mortality but there is only limited epidemiological information on which to develop prophylactic guidelines. The aim of this study was to determine the population incidence of perinatal death from maternally acquired infection and to describe the responsible organisms and antibiotic sensitivities, and also the associated risk factors. Fetal and neonatal deaths from perinatal infection in the former Northern Health Region, United Kingdom, were identified for the years 1981-96 using data held by the Perinatal Mortality Survey, and the obstetric, paediatric and pathology case notes were reviewed. Maternally acquired bacterial infection of the baby was identified as responsible for 60 pre-delivery deaths and 142 post-delivery deaths among babies of 24 or more weeks gestation at birth between 1981 and 1996. There were 630,206 livebirths and 3,591 registered stillbirths in the survey area during this time. Bacterial infection was also considered the primary cause of death in 64 fetuses where delivery occurred at 20-23 weeks gestation between 1989 and 1996. Although group B streptococcus was the commonest single organism it was only responsible for 30% of all infectious deaths from 24 weeks gestation onwards. Ampicillin resistance was more common in the second half of the study. Infection remains an important cause of perinatal mortality but responsible organisms and antibiotic sensitivities have changed significantly over time. Although 80% of the post-delivery deaths would have received intrapartum antibiotics if current guidelines had been in place, the choice of antibiotics and identification of risk groups requires careful consideration.     

Influence of prenatal diagnosis and pregnancy termination of fetuses with birth defects on the perinatal mortality rate in Victoria, Australia

Historical data show that in Victoria birth defects have accounted for approximately 25% of all perinatal deaths. Terminations of pregnancies (TOPs) for birth defects occurring at > or =20 weeks gestation are included in the population-based perinatal data collection. These are classified as stillbirths or neonatal deaths. Some would have survived the perinatal period if no termination had taken place, and as a result they have the effect of increasing the perinatal mortality rate (PMR). Conversely, TOPs <20 weeks gestation, of fetuses with lethal birth defects that would have resulted in a perinatal death, are not included in the statistics and therefore reduce the PMR. The aim of this study was to examine the effect on the PMR of TOPs following the prenatal detection of birth defects, taking into account the severity or 'lethality' of the birth defects. Data on live births, stillbirths, neonatal deaths and TOPs carried out because of a birth defect were collected from the Victorian Birth Defects Register (BDR) for 1989-2000. Birth defects were categorised into three groups, according to the estimated likelihood of a baby with that condition dying in the perinatal period: a 'lethal' birth defect was one where there was >50% likelihood of death, 'possibly lethal' 15-50% and 'non-lethal' less than 15%. Based on these 'lethality' groups and associated assumptions about average survival rates beyond the neonatal period, the PMR was recalculated. TOPs for 'non-lethal' birth defects at > or =20 weeks gestation increased the PMR by 3.8%. TOPs for 'lethal' birth defects <20 weeks decreased the PMR by 14.4%. The net effect on the overall PMR from TOPs for birth defects was a 10.6% decrease.     

Perinatal mortality associated factors in a general hospital of Chiapas, Mexico

OBJECTIVE: To identify socioeconomic, gynecological-obstetric and fetal factors associated with perinatal mortality. METHODS: A matched case-control study was carried out. Cases were newborns (born live or dead) that were born and died between 28 weeks gestation and 7 days of life. Controls were live newborns between 28 weeks gestation and 7 days of life. A total of 99 cases and 197 controls were studied. Data were obtained from the corresponding medical charts. Statistical analysis was performed using Stata 6.0 software. RESULTS: Mean maternal age was 24.82 years and mean newborn age was 37.78 weeks gestation with an average birth weight of 2,760 grams. Factors associated with perinatal mortality were: father's occupation as a farmer (adjusted odds ratio (OR)=3.31; 95% CI=1.26-8.66); high obstetric risk index (adjusted OR=10.57; 95% CI=2.82-39.66), cesarean birth (adjusted OR=2.75; 95% CI=1.37-5.51), five or more prenatal visits (adjusted OR=4.43; 95% CI=1.86-10.54) and preterm fetal maturity indices (PEG, APG, GEG) (adjusted OR=9.20; 95% CI=4.39-19.25). CONCLUSIONS: The risk factors associated with perinatal mortality found in the study are consistent with the findings reported in the international literature. These results show that prevention and control measures should be implemented to identify at risk pregnant women in order to lower perinatal mortality.     

A comparative study of hospital fetal death records and Washington State fetal death certificates.

Hospital fetal death records were compared with Washington State fetal death certificates to ascertain the completeness of reporting. Washington State law requires reporting of all fetal deaths of 20 or more weeks gestation. For 16 hospitals reporting 603 fetal deaths, an additional 49 fetal deaths were identified in the mother's charts. The study documents underreporting, especially in the gestational ages closet to the 20-week age limitation where 71 per cent of the 48 unreported cases were 20 to 27 weeks gestation.     

Another look at the black-white gap in gestation-specific perinatal mortality.

In the US, black infants born near or at term experience higher mortality than white infants. To extend our understanding of black-white differences in the relative advantages of growth (measured by birthweight) for gestational age, we compared race-specific rates of perinatal mortality by deviation in grams from the median birthweight for four categories of gestation (35-36, 37-38, 39-41, and 42-43 weeks). We also used race-specific standards to examine the difference between the median birthweight and the optimum birthweight (i.e. birthweight with the lowest mortality). The data, which were derived from vital records for singletons delivered in the US from 1983-1984, comprised 24,626 fetal and neonatal deaths among 5,157,197 white infants and 5973 fetal and neonatal deaths among 926,678 black infants. At all deviations from the median birthweight, black infants had relatively better survival at 35-36 weeks of gestation. This advantage was reversed among infants with gestations of 39-41 and 42-43 weeks. The optimum birthweight for black infants with gestations greater than or equal to 37 weeks was closer to their median birthweight than was that for white infants. For black infants with gestations of 39-41 weeks, the optimum birthweight was 187g (95% confidence interval (CI): 150-234) greater than the median birthweight (3289g); for comparable white infants the optimum birthweight was 397g (95% CI: 366-431) greater than the median birthweight (3487g). To reduce the black-white gap in perinatal mortality, we need a better understanding of aetiological relations between gestation, growth, and mortality.     

Parental age difference and adverse perinatal outcomes in the United States

This study was undertaken to examine the relationship between paternal and maternal age differences and adverse perinatal outcomes in the United States. Data were obtained on singleton pregnancies delivering at >or=20 weeks gestation in the United States in 1995-97 from the National Center for Health Statistics data sets. Adverse perinatal outcomes that were evaluated included fetal death rate (>or=20 weeks), preterm delivery <37 weeks and small-for-gestational-age (SGA) births (birthweight <10th centile for gestational age and corrected for sex). Age difference was defined as paternal minus maternal age. The analysis included 8995274 pregnancies (11.3% blacks, 88.7% whites). An increase in fetal death rate, preterm delivery and SGA births was noted among white women who were older than their male partners. For black mothers older than their partners, there was an increase in fetal death rate when the women were <20 years old, but a decrease in fetal death rate when >35 years old. Neither rates of preterm delivery nor SGA births were increased much for black women with varying parental age differences. This demonstrates that race and maternal age both contribute to the effects of parental age difference on adverse perinatal outcomes.     

Fetal deaths in Mexican-American,black, and white non-Hispanic women seeking government-funded prenatal care

Hispanics of Mexican origin constitute the largest minority population in the Southwestern United States, yet little is known about their reproductive health. This study assessed ethnic differentials in fetal mortality at 20 or more weeks gestation and identified the social and behavioral predictors associated with this outcome among low-income Hispanic, black non-Hispanic and white non-Hispanic women. Records were used of 80,431 patients attending federally funded prenatal care clinics in California from 1984 through 1989. The fetal death rate per 1,000 liver births and fetal deaths was 7.8 for Hispanic, 8.4 for white non-Hispanic and 20.5 for black non-Hispanic women. These rates indicated favorable reproductive outcomes for Mexican Americans despite their social risk profile. An analysis of stillbirths by gestational age showed that Hispanic women stood a significantly lower risk of short-gestational stillbirths than non-Hispanics. In contrast, Hispanic women had a higher proportion of term stillbirths. Hispanic acculturation was a significant predictor of short-term gestation fetal deaths only. The inability to pay for health care was a strong predictor of fetal deaths for all ethnic groups, underscoring the need to ensure adequate access to maternity care for low-income women.This study was conducted under contract from the California Department of Health Services, Maternal and Child Health Branch, #90-11768. We appreciate the assistance and data support provided by Penelope Stephenson, Chief, Planning and Evaluation Section and the helpful comments provided by Dr. Rugmini Shah, Director, Maternal and Child Health Branch. The authors would also like to thank Connie Gee for her clerical support.     

Antenatal booking and perinatal mortality in Scotland 1972-1982

Data from Scottish maternity hospital discharge returns (SMR2) were analysed to determine the relationship between gestational age at antenatal booking and perinatal mortality during 1972-82, controlling for maternal age, parity, socioeconomic and marital status. Maternal youth, multiparity and unmarried status were independently associated with both a high perinatal mortality and a low proportion of maternities booked before 17 weeks gestation. However, among primiparae and mothers aged 30 years or more relatively high perinatal mortality rates were associated with high proportions booking early for antenatal care. Socioeconomic status amongst married women, independent of age and parity, influenced perinatal mortality but had little effect on booking behaviour. Between 1972-75 and 1980-82, there was a general increase in the proportion of maternities booked before 17 weeks gestation, but no significant difference was found between the standardized perinatal mortality rates for pregnancies booked before and after 17 weeks gestation. More detailed analysis for different gestational ages at booking during 1980-82 revealed no trend of increasing risk with later booking. Despite technological advances, antenatal care during the first half of pregnancy is unlikely to have made a substantial contribution to the fall in perinatal mortality over this period.     

Perinatal mortality attributable to complications of childbirth in Matlab, Bangladesh

Very few population-based studies of perinatal mortality in developing countries have examined the role of intrapartum risk factors. In the present study, the proportion of perinatal deaths that are attributable to complications during childbirth in Matlab, Bangladesh, was assessed using community-based data from a home-based programme led by professional midwives between 1987 and 1993. Complications during labour and delivery--such as prolonged or obstructed labour, abnormal fetal position, and hypertensive diseases of pregnancy--increased the risk of perinatal mortality fivefold and accounted for 30% of perinatal deaths. Premature labour, which occurred in 20% of pregnancies, accounted for 27% of perinatal mortality. Better care by qualified staff during delivery and improved care of newborns should substantially reduce perinatal mortality in this study population.     

Placental abruption and perinatal mortality in the United States

Placental abruption is an uncommon obstetric complication associated with high perinatal mortality rates. The authors explored the associations of abruption with fetal growth restriction, preterm delivery, and perinatal survival. The study was based on 7,508,655 singleton births delivered in 1995 and 1996 in the United States. Abruption was recorded in 6.5 per 1,000 births. Perinatal mortality was 119 per 1,000 births with abruption compared with 8.2 per 1,000 among all other births. The high mortality with abruption was due, in part, to its strong association with preterm delivery; 55% of the excess perinatal deaths with abruption were due to early delivery. Furthermore, babies in the lowest centile of weight (<1% adjusted for gestational age) were almost nine times as likely to be born with abruption than those in the heaviest (> or =90%) birth weight centiles. This relative risk progressively declined with higher birth weight centiles. After controlling for fetal growth restriction and early delivery, the high risk of perinatal death associated with abruption persisted. Even babies born at 40 weeks of gestation and birth weight of 3,500-3,999 g (where mortality was lowest) had a 25-fold higher mortality with abruption. The link between fetal growth restriction and abruption suggests that the origins of abruption lie at least in midpregnancy and perhaps even earlier.     

Seasonal patterns in perinatal mortality and preterm delivery

An investigation of possible seasonal patterns in preterm delivery and perinatal mortality utilized linked birth, infant death, and fetal death records from Minnesota for the years 1967-1973. Data included over 400,000 white singleton live births and stillbirths of 29 or more weeks completed gestation. Composite monthly cohorts of ongoing pregnancies were constructed for each month of the year and the probability of a preterm delivery and/or perinatal death was estimated. A statistically significant increase in the probability of a preterm delivery or perinatal death occurred during July, August, and September. The probability of a preterm delivery ranged from a low of 55 per 1000 pregnancies at risk in April to a high of over 59 per 1000 in July and August. In addition, although each assigned cause of death group showed a similar pattern, perinatal deaths due to infection in the mother or fetus showed a standardized mortality ratio of 65 in May and 155 in August and September, while the ratios of all other causes combined ranged from 94 to 108. Fetal deaths reported as having occurred before labor began showed a seasonal pattern nearly identical with that for all perinatal deaths, while those occurring during labor showed no seasonal pattern. The findings are consistent with published evidence that environmental factors likely involving ascending infections may play a larger role in preterm delivery and perinatal mortality than has been generally recognized.     

Improvement in infant and perinatal mortality in the United States, 1965--1973: I. Priorities for intervention

Changes in United States infant and perinatal mortality in the period 1965--1973 were examined by race, age at death or length of gestation, and degree of urbanization. The decline of postneonatal mortality rates was greater than the declines of fetal and neonatal mortality rates. Other-than white infant and fetal mortality rates improved more than the white rates, except in the first day of life. Postneonatal mortality rates improved more in rural than in urban areas, while neonatal and perinatal mortality rates improved more in urban areas than in rural. These improvements in mortality rates have occurred at the same time as changes in medical techniques and the organization and availability of health services, improvements in economic conditions and standards of living, and changes in the demographic characteristics of the child-bearing population of the United States. Each of these changes was in a direction expected to have a favorable effect on infant and perinatal mortality. Nevertheless, the improvement of infant mortality rates has not changed the relative position of the United States in comparison with other countries. Programs to improve infant and perinatal mortality can use the data in this study to define high priority target groups using a method based on the size of the problem in the target group, the severity of the problem, and the amount and direction of change.     

A proportional hazards model with time-dependent covariates and time-varying effects for analysis of fetal and infant death

Birth-weight- and gestational-age-specific perinatal mortality curves intersect when compared by race and maternal smoking. The authors propose a new measure to replace fetal and infant mortality and an analytic strategy to assess the effects of risk factors on this outcome. They used 1998 data for US Blacks and Whites. Age-specific post-last menstrual period (LMP) mortality rate was defined as the proportion of deaths (stillbirth, perinatal death, or infant death) at a given age post-LMP. The authors used extended Cox regression with time-varying covariates and hazard ratios to model the effects of race and smoking on post-LMP mortality. Perinatal mortality rates (conventional calculation) for Blacks and Whites showed the expected crossover. However, analyses of post-LMP mortality showed no crossover. For the Black-White comparison, a hazard ratio of 1.72 (95% confidence interval: 1.67, 1.77) was obtained. The hazard was higher for smokers than for nonsmokers, but the hazard ratio increased from 1.09 (95% confidence interval: 0.98, 1.22) at 22 weeks to 1.82 (95% confidence interval: 1.72, 1.92) at 40 weeks. The hazard ratio associated with birth was also time dependent: higher than 1 for preterm gestation and lower than 1 for term gestation. The increasing adverse effect of smoking with gestational age suggests an accumulating effect of smoking on mortality. Modeling post-LMP mortality eliminates the crossover paradox for race and maternal smoking in a single statistical model.     

Postdatism -- a perinatal problem?

It has been traditionally accepted that maternal and fetal complications are at their lowest levels 37-42 weeks into gestation. 20% of pregnancies completed after 42 weeks gestation are thought to be affected by the postmaturity syndrome of uteroplacental insufficiency resulting in oligohydramnios, meconium passage, loss of fetal subcutaneous tissue, fetal asphyxia, and fetal death. Some workers, however, have also found that pregnancies completed between 40 and 42 weeks carry significant risk. The authors explored this question in a case-control study of 464 women seen at the Mahatma Gandhi Institute of Medical Sciences in Maharashtra, India. The cases of postdatism occurred in the absence of any other medical or obstetric problem. The operative delivery rate increased significantly among these patients compared to deliveries between 39 and 40 weeks. There was neither significant asphyxia nor perinatal loss in term completed normal patients. Asphyxia and perinatal mortality did, however, occur with postdatism. The authors note the likely role of oligohydramnios combined with placental dysfunction.