Racial and ethnic disparities in United States: stillbirth rates: trends, risk factors, and research needs

As with most adverse health outcomes, there has been long standing and persistent racial and ethnic disparity for stillbirth in the United States. In 2005, the stillbirth rate (fetal deaths ≥ 20 weeks' gestation per 1000 fetal deaths and live births) for non-Hispanic blacks was 11.13 compared with 4.79 for non-Hispanic whites. Rates were intermediate for American Indian or Alaska Natives (6.17) and Hispanics (5.44). There is racial disparity for both early (< 28 weeks' gestation) and late stillbirths. We review available data regarding risk factors for stillbirth with a focus on those factors that are more prevalent in certain racial/ethnic groups and those factors that appear to have a more profound effect in certain racial/ethnic groups. Although many factors, including genetics, environment, stress, social issues, access to and quality of medical care and behavior, contribute to racial disparity in stillbirth, the reasons for the disparity remain unclear. Knowledge gaps and recommendations for further research and interventions intended to reduce racial disparity in stillbirth are highlighted.     

死胎的预测及其高危人群的管理

死胎是各种高危因素下母体、胎儿、胎盘疾病的终末期结局。早中孕期联合母体病史、超声胎儿生长及子宫动脉多普勒血流评估、母体血清胎盘生长因子,对胎盘受损所致死胎的预测价值较高,但对足月死胎的预测价值有限。正确识别死胎的高危因素,加强高危人群的孕前及孕期管理,有效利用各种产前监护手段以及适时分娩,可降低死胎的发生率。     

Reducing stillbirths: screening and monitoring during pregnancy and labour

Background

Screening and monitoring in pregnancy are strategies used by healthcare providers to identify high-risk pregnancies so that they can provide more targeted and appropriate treatment and follow-up care, and to monitor fetal well-being in both low- and high-risk pregnancies. The use of many of these techniques is controversial and their ability to detect fetal compromise often unknown. Theoretically, appropriate management of maternal and fetal risk factors and complications that are detected in pregnancy and labour could prevent a large proportion of the world's 3.2 million estimated annual stillbirths, as well as minimise maternal and neonatal morbidity and mortality.

Methods

The fourth in a series of papers assessing the evidence base for prevention of stillbirths, this paper reviews available published evidence for the impact of 14 screening and monitoring interventions in pregnancy on stillbirth, including identification and management of high-risk pregnancies, advanced monitoring techniques, and monitoring of labour. Using broad and specific strategies to search PubMed and the Cochrane Library, we identified 221 relevant reviews and studies testing screening and monitoring interventions during the antenatal and intrapartum periods and reporting stillbirth or perinatal mortality as an outcome.

Results

We found a dearth of rigorous evidence of direct impact of any of these screening procedures and interventions on stillbirth incidence. Observational studies testing some interventions, including fetal movement monitoring and Doppler monitoring, showed some evidence of impact on stillbirths in selected high-risk populations, but require larger rigourous trials to confirm impact. Other interventions, such as amniotic fluid assessment for oligohydramnios, appear predictive of stillbirth risk, but studies are lacking which assess the impact on perinatal mortality of subsequent intervention based on test findings. Few rigorous studies of cardiotocography have reported stillbirth outcomes, but steep declines in stillbirth rates have been observed in high-income settings such as the U.S., where cardiotocography is used in conjunction with Caesarean section for fetal distress.

Conclusion

There are numerous research gaps and large, adequately controlled trials are still needed for most of the interventions we considered. The impact of monitoring interventions on stillbirth relies on use of effective and timely intervention should problems be detected. Numerous studies indicated that positive tests were associated with increased perinatal mortality, but while some tests had good sensitivity in detecting distress, false-positive rates were high for most tests, and questions remain about optimal timing, frequency, and implications of testing. Few studies included assessments of impact of subsequent intervention needed before recommending particular monitoring strategies as a means to decrease stillbirth incidence. In high-income countries such as the US, observational evidence suggests that widespread use of cardiotocography with Caesarean section for fetal distress has led to significant declines in stillbirth rates. Efforts to increase availability of Caesarean section in low-/middle-income countries should be coupled with intrapartum monitoring technologies where resources and provider skills permit.

     

Prediction and prevention of recurrent stillbirth

Stillbirth is one of the most common adverse pregnancy outcomes in the United States, occurring in one out of every 200 pregnancies. There is a paucity of information on the outcome of pregnancies after stillbirth. Prior stillbirth is associated with a twofold to 10-fold increased risk of stillbirth in the future pregnancy. The risk depends on the etiology of the prior stillbirth, presence of fetal growth restriction, gestational age of the prior stillbirth, and race. Categorization of the cause of the initial stillbirth will allow better estimates of individual recurrence risk and guide management. A history of stillbirth also increases the risk of other adverse pregnancy outcomes in the subsequent pregnancy such as placental abruption, cesarean delivery, preterm delivery, and low birth weight infants. Prospective studies have revealed an increased risk of stillbirth with low pregnancy-associated plasma protein A, elevated maternal serum alpha fetoprotein, abnormal uterine artery Doppler studies, and antiphospholipid antibodies. However, the positive predictive value of these factors individually is poor. Because fetal growth restriction is associated with almost half of all stillbirths, the correct diagnosis of fetal growth restriction is essential. The use of individualized or customized growth standards will improve prediction of adverse pregnancy outcome by distinguishing growth-restricted fetuses from constitutionally small, healthy fetuses. Antepartum fetal surveillance and fetal movement counting are also mainstays of poststillbirth pregnancy management.     

Stillbirth and fetal growth restriction

Objective: To confirm the role of fetal growth restriction (FGR) as a cause of stillbirth, and to compare diagnostic accuracy of customized fetal growth and population-based standards in identifying FGR within a pathological population of early and late stillbirths. Methods: Retrospective study on a cohort of 189 stillbirths occurred in single pregnancy between January 2006 and September 2011. Unexplained stillbirths, defined by Aberdeen-Wigglesworth and ReCoDe classifications, were evaluated on the basis of fetal birthweight with both Tuscany population and Gardosi customized standards. Unexplained stillbirths have been classified as early or late depending on the gestational age of occurrence. Results: Aberdeen-Wigglesworth classification, applied to the 189 cases of stillbirth, left 94 unexplained cases (49.7%), whereas the ReCoDe classification left only 40 (21%). By applying population standards to the 94 unexplained stillbirths we have identified 31 FGRs (33% of sample), while customized standards identified 54 FGRs (57%). Customised standards identified a larger number of FGRs with respect to population standards during the third trimester (i.e. 51% vs. 25% respectively) than in the second trimester (73% vs. 54% respectively) (p = 0.05). Conclusions: Customized standards have a higher diagnostic accuracy in identifying FGRs especially during the third trimester.     

Totgeburt und plötzlicher Kindstod

During the last 30 years the rate of stillbirths in industrial countries has remained nearly identical, while neonatal mortality und the incidence of the sudden infant death syndrome (SIDS) has declined significantly. This observation is in contrast to the decline of stillbirths due to placental insufficiency, maternal diabetes mellitus, preeclampsia, rhesus incompatibility and fetal aneuploidy. However, the incidence of unexplained stillbirths has increased. The decrease of the incidence of the sudden infant death syndrome proves that prevention of diseases of unknown origin is possible. Smoking, obesity and an excessive increase in body weight before pregnancy are modifiable risk factors for intrauterine stillbirth. The detection and treatment of diabetes mellitus, gestational diabetes and arterial hypertension are effective measures in pregnancy to reduce the risk for stillbirth. The induction of labor at term is also effective in the reduction of stillbirths, however, the burden of elective induction with all of the possible negative effects has to be balanced against the benefit of avoiding intrauterine deaths as approximately 300 labor inductions with the corresponding disadvantages, would be necessary to avoid 1 stillbirth.     

预防可避免死胎,重视死胎病因管理

全球死胎发生率差异较大的原因与死胎定义不一以及各地社会发展不均衡相关;以往研究发现,28周的死胎多与胎儿畸形、妊娠合并症相关;≥28周的死胎多与妊娠并发症有关,尤其胎儿生长受限;分娩过程的死胎,主要与临床监护、处置不当有关。针对不同死胎原因的管理,有望降低死胎发生率。     

Maternal medical disease: risk of antepartum fetal death

Although certain maternal medical conditions increase the risk of antepartum fetal death, improvements in medical and obstetric care have decreased the likelihood of stillbirth. This article examines the current stillbirth rates reported in pregnancies complicated by common medical diseases. The reported stillbirth rates are expressed as the number of stillbirths occurring at > or = 20 weeks of gestation per 1,000 births in patients with the condition. Overall, about 10% of all fetal deaths are related to maternal medical illnesses such as hypertension, diabetes, obesity, systemic lupus erythematosus, chronic renal disease, thyroid disorders, and cholestasis of pregnancy. The early recognition of maternal medical diseases provides an opportunity for increased surveillance and interventions that may lead to more favorable pregnancy outcomes.     

Intrapartum stillbirth in a Nigerian tertiary hospital setting

OBJECTIVE: To examine the nonmedical events contributing to intrapartum stillbirths in an African setting. METHODS: Retrospective analysis of the records of women who had intrapartum stillbirths at the University of Nigeria Teaching Hospital, Enugu, from January 1999 to December 2007. The events surrounding the delivery of these women were critically analyzed and statistically compared with those who had live births to determine the nonmedical factors contributing to the stillbirths. RESULTS: The overall stillbirth rate was 89 per 1000 births. The intrapartum stillbirth rate was 52.1 per 1000 births. Nonmedical factors contributing to stillbirths included delays in receiving appropriate management, inadequate intrapartum monitoring, inappropriate interventions, and wrong diagnosis. All 3 types of delay were significantly associated with intrapartum stillbirth (P=0.0001). CONCLUSION: Intrapartum stillbirth accounts for the majority of stillbirths in this setting. Avoidable delays, suboptimal intrapartum monitoring, and inappropriate interventions contribute to the majority of intrapartum stillbirths in Nigeria.     

Investigation and management of stillbirth

Stillbirth describes the delivery of a baby with no signs of life in relation to thresholds of either gestational age or birthweight. In the UK, a stillbirth is legally defined as the delivery of a baby at or after 24 weeks’ gestation or 500 g where gestation is unknown. A history of previous stillbirth remains one of the strongest risk factors for subsequent stillbirth and other adverse outcomes in a subsequent pregnancy. According to World Health Organization (WHO), there are nearly 2 million stillbirths globally every year. There is a drive to reduce the rate of stillbirths by 50% in England by 2025 and a global target of 12 or fewer stillbirths per 1000 total births in every country by 2030. The significant psychological burden placed on parents following a stillbirth and the associated increased risk of complications in subsequent pregnancies need appropriate management. This article covers the investigation and management of stillbirth reflecting current UK practice.     

Stillbirth after nonstress testing

The authors' experience with stillbirth within one week of a reactive nonstress test was reviewed to determine the reliability of this test in postdates patients and general high-risk patients. The corrected stillbirth rates were the same in both groups. Thirty-three percent of stillbirths in postdates patients occurred as early as 41.5 weeks' gestation. The cause of stillbirth in postdates patients was not clear even after careful autopsy. In the general high-risk group, 60% of stillbirths were due to an acute event with the remainder due to chronic fetal compromise that was not predicted by the nonstress test. Induction at 41.5 weeks' gestation or more comprehensive fetal surveillance than weekly nonstress testing are possible approaches to the management of postdates pregnancy, which need to be further studied.     

Suboptimal care in stillbirths - a retrospective audit study

BACKGROUND: Stillbirth rates have decreased radically over the last decades. One reason for this is improved perinatal care. The aim of this study was to explore whether sub-optimal factors in stillbirths were more frequent among non-western than western women. METHODS: Population-based perinatal audit of 356 stillbirths after gestational week 23, in 2 Norwegian counties during 1998-2003 (4.2 per 1,000 deliveries); of these 31% were born to non-western women. By audit, the stillbirths were attributed to optimal or sub-optimal care factors. Multivariate methods were used to analyse the data. RESULTS: Sub-optimal factors were identified in 37% of the deaths. When compared to western women, non-western women had an increased risk of stillbirth (OR: 2.2; 95% CI: 1.3-3.8), and an increased risk of sub-optimal care (OR: 2.4; 95% CI: 1.5-3.9). More often, non-western women received sub-optimal obstetric care (p<0.001), as e.g. failure to act on non-reassuring fetal status or incorrect assessment of labour progression. A common failure in antenatal care for both groups was unidentified or inadequate management of intrauterine growth restriction or decreased fetal movements. Non-western women were less prone to attend the program for antenatal care or to take the consequences of recommendations from health professionals. Inadequate communication was documented in 47% of non-western mothers; an interpreter was used in 29% of these cases. CONCLUSIONS: Non-western women constituted a risk group for sub-optimal care factors in stillbirths. Possibilities for improvements include a reduction of language barriers, better identification and management of growth restriction for both origin groups, and adequate intervention in complicated vaginal births; with increased vigilance towards non-western women.     

Stillbirths in Western Australia 1980–1983: Influence of Race, Residence and Place of Birth

All stillbirths in Western Australia from 1980-83 weighing 1,000 g and over were identified from perinatal death certificates, and their causes and demographic correlates described. The stillbirth rate was 4.91 per 1,000 total births; nearly 65% were antepartum, 25% intrapartum and in 10% the time of death was unknown. The cause of death of most stillbirths was unknown (52%) or associated with lethal congenital malformations (13%), antepartum haemorrhage (12%) or maternal hypertension (8%). Whilst Aboriginal women had much higher stillbirth rates (10.80) than non-Aboriginal women (4.57), their patterns of time and causes of death were similar. Both antepartum and intrapartum stillbirth rates were much higher at low birth-weights and low gestational ages in both racial groups. Women living in rural areas who delivered in the metropolitan area had much higher antepartum (11.02) and intrapartum (3.31) stillbirth rates than either rural women delivering in rural areas (1.89 and 1.34) or metropolitan women delivering in the metropolitan area (2.72, 0.98). This reflects the transfer of rural high risk pregnant women or those with fetal death in utero, for delivery in metropolitan specialist hospitals.     

Alloimmunization in twin pregnancies

Among 7052 patients studied between 1976 and 1982 in a collaborative project on antepartum fetal heart rate monitoring, 337 patients had a previous stillbirth as a reason for testing. Overall a previous stillbirth history significantly increased the risk of having a positive result on a contraction stress test, primarily among hypertensive patients. Patients with a previous stillbirth also had a significantly higher incidence of respiratory distress syndrome in their neonates attributable to premature intervention for maternal indications (primarily among hypertensive women and patients with clinical intrauterine growth retardation). Low Apgar scores were found to be significantly increased in diabetics with previous stillbirths primarily due to neonates with congenital malformations. Premature intervention by labor induction or cesarean section was more common among patients with a previous stillbirth for both maternal indications and abnormal antepartum fetal heart rate studies. Previous stillbirth would appear therefore to be a significant risk factor primarily when associated with a diagnosis of hypertension or clinical intrauterine growth retardation.     

彩色多普勒超声在预测死胎中的作用

死胎是指妊娠大于23+6周、无生命迹象的胎儿,是围产儿死亡的主要原因之一,产前有效预测死胎,对降低围产儿死亡率具有重大意义。利用彩色多普勒超声监测不同孕期母体子宫动脉血流参数,特别是妊娠中期子宫动脉搏动指数(PI)对与子痫前期、胎盘早剥、小于胎龄儿(SGA)相关的死胎预测有重要意义;监测胎儿各项多普勒血流参数,如脐动脉、大脑中动脉、静脉导管、腹内脐静脉等,能够反映胎儿宫内缺氧状况,提高胎儿窘迫的诊断率;联合监测母体及胎儿各项血流参数,全面评估胎儿宫内缺氧程度并及时干预,可避免死胎的发生。     

Incidence of stillbirth and perinatal mortality and their associated factors among women delivering at Harare Maternity Hospital, Zimbabwe: a cross-sectional retrospective analysis

BACKGROUND: Death of an infant in utero or at birth has always been a devastating experience for the mother and of concern in clinical practice. Infant mortality remains a challenge in the care of pregnant women worldwide, but particularly for developing countries and the need to understand contributory factors is crucial for addressing appropriate perinatal health. METHODS: Using information available in obstetric records for all deliveries (17,072 births) at Harare Maternity Hospital, Zimbabwe, we conducted a cross-sectional retrospective analysis of a one-year data, (1997-1998) to assess demographic and obstetric risk factors for stillbirth and early neonatal death. We estimated risk of stillbirth and early neonatal death for each potential risk factor. RESULTS: The annual frequency of stillbirth was 56 per 1,000 total births. Women delivering stillbirths and early neonatal deaths were less likely to receive prenatal care (adjusted relative risk [RR] = 2.54; 95% confidence intervals [CI] 2.19-2.94 and RR = 2.52; 95% CI 1.63-3.91), which for combined stillbirths and early neonatal deaths increased with increasing gestational age (Hazard Ratio [HR] = 3.98, HR = 7.49 at 28 and 40 weeks of gestation, respectively). Rural residence was associated with risk of infant dying in utero, (RR = 1.33; 95% CI 1.12-1.59), and the risk of death increased with increasing gestational age (HR = 1.04, HR = 1.69, at 28 and 40 weeks of gestation, respectively). Older maternal age was associated with risk of death (HR = 1.50; 95% CI 1.21-1.84). Stillbirths were less likely to be delivered by Cesarean section (RR = 0.64; 95% CI 0.51-0.79), but more likely to be delivered as breech (RR = 4.65; 95% CI 3.88-5.57, as were early neonatal deaths (RR = 3.38; 95% CI 1.64-6.96). CONCLUSION: The frequency of stillbirth, especially macerated, is high, 27 per 1000 total births. Early prenatal care could help reduce perinatal death linking the woman to the health care system, increasing the probability that she would seek timely emergency care that would reduce the likelihood of death of her infant in utero. Improved quality of obstetric care during labor and delivery may help reduce the number of fresh stillbirths and early neonatal deaths.     

Reducing stillbirths: prevention and management of medical disorders and infections during pregnancy

Background

An estimated two-thirds of the world's 3.2 million stillbirths occur antenatally, prior to labour, and are often overlooked in policy and programs. Poorly recognised, untreated or inadequately treated maternal infections such as syphilis and malaria, and maternal conditions including hypertensive disorders, are known risk factors for stillbirth.

Methods

We undertook a systematic review of the evidence for 16 antenatal interventions with the potential to prevent stillbirths. We searched a range of sources including PubMed and the Cochrane Library. For interventions with prior Cochrane reviews, we conducted additional meta-analyses including eligible newer randomised controlled trials following the Cochrane protocol. We focused on interventions deliverable at the community level in low-/middle-income countries, where the burden of stillbirths is greatest.

Results

Few of the studies we included reported stillbirth as an outcome; most that did were underpowered to assess this outcome. While Cochrane reviews or meta-analyses were available for many interventions, few focused on stillbirth or perinatal mortality as outcomes, and evidence was frequently conflicting. Several interventions showed clear evidence of impact on stillbirths, including heparin therapy for certain maternal indications; syphilis screening and treatment; and insecticide-treated bed nets for prevention of malaria. Other interventions, such as management of obstetric intrahepatic cholestasis, maternal anti-helminthic treatment, and intermittent preventive treatment of malaria, showed promising impact on stillbirth rates but require confirmatory studies. Several interventions reduced known risk factors for stillbirth (e.g., anti-hypertensive drugs for chronic hypertension), yet failed to show statistically significant impact on stillbirth or perinatal mortality rates. Periodontal disease emerged as a clear risk factor for stillbirth but no interventions have reduced stillbirth rates.

Conclusion

Evidence for some newly recognised risk factors for stillbirth, including periodontal disease, suggests the need for large, appropriately designed randomised trials to test whether intervention can minimise these risks and prevent stillbirths. Existing evidence strongly supports infection control measures, including syphilis screening and treatment and malaria prophylaxis in endemic areas, for preventing antepartum stillbirths. These interventions should be incorporated into antenatal care programs based on attributable risks and burden of disease.

     

Analysis of intrauterine fetal demise—A hospital-based study in Taiwan over a decade

ObjectiveTo identify timing-specified risk factors for stillbirth, in order to help physicians to reduce preventable factors and stillbirths, and improve general outcomes of pregnancy.Materials and MethodsA retrospective analysis was performed of births registered in our hospital, a medical center in Taiwan, between September 1, 1999 and December 31, 2011. We collected basic characteristics from the medical records, including maternal and fetal conditions. All stillbirths were divided into two groups according to gestational age: the second trimester group and the third trimester group. Comparisons were made between these groups.ResultsThere were a total of 12,290 births and 121 stillbirths during our study period. The 121 stillbirths were divided into two groups: 67/121 (55.4%) were in the second trimester group and 54/121 (44.6%) were in the third trimester group. The overall incidence for intrauterine fetal demise was 0.98% (121/12,290). The increased risks in the third trimester stillbirths, as compared with the second trimester group, were significantly associated with males born, increased maternal body mass index (BMI) at delivery, habitual cigarette smoking, previous history of intrauterine fetal demise, and diabetic or hypertensive pregnancies. Unexplained causes (29.85%) were the most common causes of second trimester intrauterine fetal demise and the most common cause of third trimester intrauterine fetal demise was umbilical cord pathology (33.33%).ConclusionManagement of any pregnant patient remains a challenge. Identifying upstream and cost-effective solutions will improve these pregnancy outcomes.     

Risk factors for antepartum and intrapartum stillbirth: a population-based study

To examine disparities in risk factors for stillbirths and its occurrence in the antepartum versus intrapartum periods. A population-based, cross-sectional study using data on women that delivered singleton births between 20 and 43 weeks in Missouri (1989-1997) was conducted (n = 626,883). Hazard ratios and 95% confidence intervals were derived from regression models and population attributable fractions were estimated to examine the impact of risk factors on stillbirth. Among African Americans, risks of antepartum and intrapartum stillbirth were 5.6 and 1.1 per 1,000 singleton births, respectively; risks among whites were 3.4 and 0.5 per 1,000 births, respectively. Maternal age > or = 35 years, lack of prenatal care, prepregnancy body mass index (BMI) > or = 30 kg/m2, and prior preterm or small-for-gestational age birth were significantly associated with increased risk for antepartum stillbirth among whites, but not African Americans. BMI < or = 18.5 kg/m2 was associated with antepartum and intrapartum stillbirth among African Americans, but not whites. The presence of any congenital anomaly, abruption, and cord complications were associated with antepartum stillbirth in both races. Premature rupture of membranes was associated with intrapartum stillbirth among whites and African Americans, but intrapartum fever was associated with intrapartum stillbirth among African Americans. These risk factors were implicated in 54.9% and 19.7% of antepartum and intrapartum stillbirths, respectively, among African American women, and in a respective 46.6% and 11.9% among white women. Considerable heterogeneity in risk factors between antepartum and intrapartum stillbirths is evident. Knowledge on timing of stillbirth specific risk factors may help clinicians in decreasing antepartum and intrapartum stillbirth risks through monitoring and timely intervention.     

Stillbirth in developing countries: a review of causes,risk factors and prevention strategies

Objective. To understand the rates, causes and risk factors for stillbirth in developing countries as well as the strategies that have been evaluated to reduce stillbirth.

Methods. We searched the English literature for 2003–2008 for all articles related to stillbirth and perinatal mortality in developing countries and reviewed all related publications.

Results. Despite the large number of stillbirths worldwide, the topic of stillbirths in developing countries has received very little research, programmatic or policy attention. In many developing countries, almost half of the deliveries occur at home, and under-reporting of stillbirths is a significant problem. Reliable data about rates and causes are unavailable in many areas of the world. Nevertheless, of the estimated 3.2 million stillbirths that occur yearly world-wide, the vast majority occur in developing countries. Rates in many developing countries are 10-fold greater or more than in developed countries. There is not a standard international classification system that defines cause of death, nor is there agreement about the lower limits of birthweight or gestational age that define stillbirth, making comparisons of causes of stillbirth or rates over time or between sites problematic. From available data, prolonged and obstructed labour, pre-eclampsia and various infections, all without adequate treatment, appear to account for the majority of stillbirths in developing countries. Identification and treatment of maternal syphilis has been effective in reducing stillbirth risk, as has improvements in access to emergency obstetrical services and particularly caesarean section.

Conclusions. Further research is needed to understand the causes and the best preventive strategies for stillbirth specific to geographic areas. However, based on current data, better access to appropriate obstetric care, particularly during labour and delivery and better screening and treatment of syphilis should reduce developing country stillbirth rates dramatically.