Previous stillbirth, late preterm, and early-term birth

Subsequent pregnancies are emotionally traumatic for families with previous stillbirths. Such pregnancies have a 2- to 10-fold increase in the risk for stillbirth as well as an increased probability of other adverse obstetrical outcomes. These medical risks as well as anxiety on the part of families and care providers contribute to an increase in late preterm and early-term birth. However, delivery before 39 weeks' gestation has not been proven to reduce the risk of recurrent stillbirth or adverse pregnancy outcomes in women with previous stillbirths. This work reviews data regarding the optimal timing of delivery in subsequent pregnancies after previous stillbirth, as well as for patients at risk from stillbirth in general. Management recommendations from current data are presented and knowledge gaps are highlighted.     

Caesarean delivery and risk of stillbirth in subsequent pregnancy: a retrospective cohort study in an English population

OBJECTIVE: Two recent studies indicate an increased risk of stillbirth in the pregnancy that follows a pregnancy delivered by caesarean section. In this study, we report an analysis designed to test the hypothesis that delivery by caesarean section is a risk factor for explained or unexplained stillbirth in any subsequent pregnancy. We also report on the proportion of stillbirths in our study population, which may have been attributable to previous delivery by caesarean section. DESIGN: Retrospective cohort study. POPULATION: Linked statistical data set of 81 784 singleton deliveries registered in Oxfordshire and West Berkshire between 1968 and 1989. METHODS: The crude and adjusted hazard ratios for stillbirth in deliveries following a previous delivery by caesarean section, compared with no previous caesarean, were estimated using Cox regression. MAIN OUTCOME MEASURE: Stillbirth. RESULTS: The unadjusted hazard ratios for all, explained, and unexplained stillbirths were 1.54 (95% CI 1.04-2.29); 2.13 (1.22-3.72); and 1.19 (0.68-2.09), respectively. After adjustment for maternal age, parity, social class, previous adverse outcome of pregnancy, body mass indexand smoking the hazard ratios were 1.58 (0.95-2.63), 2.08 (1.00-4.31) and 1.24 (0.60-2.56). CONCLUSIONS: Pregnancies in women following a pregnancy delivered by caesarean section are at an increased risk of stillbirth. In our study, the risk appears to be mainly concentrated in the subgroup of explained stillbirths. However, there are sufficient inconsistencies in the developing literature about stillbirth risk that further research is needed.     

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。     

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。     

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.     

Heavy prenatal alcohol exposure and risk of stillbirth and preterm delivery

We prospectively identified 96 women consuming at least 4 drinks/day during pregnancy by screening 9628 pregnant women. In these women with heavy prenatal alcohol use, there were three stillbirths and one preterm delivery; 98 matched nondrinking women had no stillbirths and two preterm births. Preterm rates did not differ significantly. The stillbirth rate was higher in the exposed group (p?=?0.06). Additional investigation showed the stillbirth rate in the exposed population (3.1%) was significantly higher (p?=?0.019) than the reported Chilean population rate (0.45%). Our data suggest that heavy alcohol consumption may increase the risk for stillbirth but not preterm delivery.     

Reclassification of unexplained stillbirths using clinical practice guidelines

Background: Twenty-eight per cent of stillbirths in Australia remain unexplained. A clinical practice guideline (CPG) produced by the Perinatal Society of Australia and New Zealand (PSANZ) Perinatal Mortality Special Interest Group is in use to assist clinicians in the investigation and audit of perinatal deaths.
Aims: To describe in a tertiary hospital using the PSANZ stillbirth investigation guidelines: (i) the distribution and classification of stillbirths, and (ii) the compliance with suggested stillbirth core investigations.
Methods: Retrospective cohort of all stillbirths delivered between November 2005 and March 2008. Stillbirths were defined as no sign of life on delivery at ≥ 20 weeks gestation or 400 g birthweight if gestation is unknown. Data were collected via the hospital Perinatal Mortality Audit Committee (PMAC). Cause of death was classified by the PSANZ Perinatal Death Classification.
Results: There were 86 stillbirths (rate 7.2 per 1000 births). The percentage of unexplained stillbirths was 34% and 13% before and after CPG investigations, respectively. Unexplained stillbirths had the highest compliance with the recommended investigations. The initial cause of death documented on the death certificate was changed by the PMAC in 19 cases. The investigations most likely to prompt a change in the cause of death classification were autopsy and placental pathology.
Conclusions: The percentage of unexplained stillbirths is lower than the national average in a hospital using the Perinatal Mortality Audit Guidelines. However, overall compliance is low, suggesting a targeted approach to investigation is used by clinicians despite a policy that aims to be non-selective. Autopsy and placental examination are the most useful investigations in assisting formal classification of cause of death.     

Work-up of stillbirth: a review of the evidence

Despite improvements in antenatal and intrapartum care, stillbirth, defined as in utero fetal death at 20 weeks of gestation or greater, remains an important, largely unstudied, and poignant problem in obstetrics. More than 26,000 stillbirths were reported in the United States in 2001. Although several conditions have been linked to stillbirth, it is difficult to define the precise etiology in many cases. This paper reviews known and suspected causes of stillbirth including genetic abnormalities, infection, fetal-maternal hemorrhage, and a variety of medical conditions in the mother. The proportion of stillbirths that have a diagnostic explanation is higher in centers that conduct a defined and systematic evaluation. The evidence for recommended diagnostic tests for stillbirth are discussed. The ongoing work of the National Institute of Child Health and Human Development Stillbirth Collaborative Research Network, a consortium of 5 academic centers in the United States that are studying the scope and causes of stillbirth, is presented.     

Stillbirth: is it preventable?

In the UK stillbirth, describes the death of a baby before birth after 24 completed weeks of pregnancy. The rate has decreased in the UK over recent years but at a slower pace than other similar high-income countries. The association of certain risk factors (including maternal age, previous poor obstetric outcome, smoking and obesity) is clearly documented, though only a number of these factors can be modified. Use of interventions including the ‘Saving Babies Lives’ Care Bundle focussing on smoking cessation, assessment for small for gestational age (SGA) babies, educating women regarding reduced fetal movements and effective fetal monitoring during labour aim to reduce both antenatal and intrapartum stillbirth. As yet, it remains difficult to predict which pregnancies are at greatest risk of stillbirth but with further research, ongoing improvements in antenatal and intrapartum care, and improved patient education, it is anticipated that the incidence in the UK can be substantially reduced.     

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.     

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.     

Prospective risk of stillbirth.

Some fraction of any cohort of fetuses alive at a given gestational age will ultimately die before birth. The residual prospective risk of stillbirth as a function of gestational age was calculated from records of the New York City Department of Health covering 370,051 reported births between 1987-1989, including 2454 stillbirths. In the general population, the prospective risk of stillbirth at 26 weeks was one in 150 and, because the time distributions of live births and stillbirths were not proportionate, the risk changed with gestational age. By 40 weeks' gestation, it was one in 475, rising progressively thereafter to one in 375 at 43 weeks. The prospective risk of stillbirth was elevated in certain ethnic groups and increased significantly with advanced maternal age, multiple gestation, and lack of prenatal care. The prospective risk of stillbirth is an important consideration in decisions regarding timing of delivery.     

Prospective risk of stillbirth in multiple-gestation pregnancies: a population-based analysis

OBJECTIVE: To evaluate the prospective risk of stillbirth in multiple gestations. METHODS: We conducted a retrospective analysis of birth notifications and infant mortality records relating to all multiple gestations to residents in a predefined health district. The incidence of live births and stillbirths was used to calculate the prospective risk of stillbirth at each week of gestation. RESULTS: The risk of stillbirth in multiple gestations increased from 1:3333 at 28 weeks' gestation to 1:69 at 39 or more weeks' gestation. The stillbirth risk in multiple gestations at 39 weeks surpassed that of postterm singleton pregnancies (1:526). CONCLUSION: Multiple gestations at 37-38 weeks have a risk of stillbirth equivalent to that of postterm singleton pregnancy. Because multiple gestations rarely proceed beyond 39 weeks, and because stillbirth risk increases several-fold beyond this stage, elective delivery might be justified at this gestational age.     

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.     

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。     

Understanding perinatal mortality

The term perinatal death is used to describe antepartum and intrapartum stillbirths, and early neonatal deaths. At term, intrapartum stillbirth and neonatal death are collectively referred to as delivery related perinatal death, and the incidence in nulliparous and multiparous women is approximately one in 1000 and one in 2000 births, respectively. Associated factors include advanced maternal age, small for gestational age, fetal macrosomia, breech labour and previous caesarean delivery. The impact of obstetric interventions in labour on delivery related perinatal death, including rising rates of caesarean delivery, is complex and unclear. The incidence of overall perinatal death is falling mainly as a result of improvements in the management of premature neonates and from decreased deaths secondary to intrapartum anoxia at term. This review will provide an overview of perinatal mortality with a particular emphasis on delivery related perinatal death at term.     

Major risk factors for stillbirth in different trimesters of pregnancy—A systematic review

Stillbirth remains an event that has an important impact on global health issues. Different levels of health care between countries suggest that the stillbirth rate may be one of the indicators of the quality of a country's medical system. In this review, major risk factors for stillbirth will be discussed, especially in different trimesters of pregnancy. Early identification of risk factors for stillbirth and appropriate antenatal management may reduce preventable stillbirths and improve general outcomes of pregnancy.     

Life-table analysis of the risk of perinatal death at term and post term in singleton pregnancies

OBJECTIVE: This study was undertaken to estimate the cumulative risk of perinatal death associated with delivery at each gestational week both at term and post term. STUDY DESIGN: The numbers of antepartum stillbirths, intrapartum stillbirths, neonatal deaths, and surviving neonates delivered at between 37 and 43 weeks' gestation in Scotland, 1985-1996, were obtained from national databases (n = 700,878) after exclusion of multiple pregnancies and deaths caused by congenital abnormality. The numbers of deaths at each gestational week were related to appropriate denominators: antepartum stillbirths were related to ongoing pregnancies, intrapartum stillbirths were related to all births (excluding antepartum stillbirths), and neonatal deaths were related to live births. The cumulative probability of perinatal death associated with delivery at each gestational week was estimated by means of life-table analysis. RESULTS: The gestational week of delivery associated with the lowest cumulative risk of perinatal death was 38 weeks' gestation, whereas the perinatal mortality rate was lowest at 41 weeks' gestation. The risk of death increased more sharply among primigravid women after 38 weeks' gestation because of a greater risk of antepartum stillbirth. The relationships between risk of death and gestational age were similar for the periods 1985-1990 and 1991-1996. CONCLUSION: Delivery at 38 weeks' gestation was associated with the lowest risk of perinatal death.     

预防死胎的临床监测方法

我国界定死胎为妊娠20周后临产前的胎儿死亡称为死胎。死胎发生率的高低直接影响围产儿死亡率,而后者是评估一个国家和地区医疗质量的敏感指标。临床上死胎发生前后常有迹可循。正确识别高危因素,加强孕期管理,有效利用检测手段是预防死胎发生,提高产科质量的关键。     

New indications for antepartum testing: making the case for antepartum surveillance or timed delivery for women of advanced maternal age

Maternal age is an independent risk factor for stillbirth; a moderate number of these occur in normally formed babies near term. For a woman 40 years of age or older giving birth, her risk of having a chromosomal anomaly is 1/66. What is not appreciated is that even without medical risk factors, her risk of having a stillbirth after 37 weeks of gestation is 1/116. This article reviews the risks and benefits of the strategy of antepartum testing and timed delivery and discusses the limitations of the available data in this field.