Trends in the cause of late fetal death, 1982-2000

BACKGROUND: Progress in reducing late fetal deaths has slowed in recent years, despite changes in intrapartum and antepartum care. OBJECTIVES: To describe recent trends in cause-specific fetal death rates. DESIGN: Retrospective cohort study. SETTING: North of England. POPULATION/SAMPLE: 3,386 late fetal deaths (> or = 28 weeks of gestation and at least 500 g), occuring between 1982 and 2000. METHODS: Data on deaths were obtained from the Northern Perinatal Mortality Survey. Data on live births were obtained from national birth registration statistics. Rate ratios (RR) and 95% confidence intervals (CI) for fetal deaths in 1991-2000 compared with 1982-1990 were calculated. MAIN OUTCOME MEASURES: Cause-specific late fetal death rates per 10,000 total births. RESULTS: Mortality in singletons declined from 51.5 per 10,000 births in 1982-1990 to 42.0 in 1991-2000 (RR 0.82, 95% CI 0.76-0.87). There was a greater decline in multiples, from 197.9 to 128.0 per 10,000 (RR 0.65, 95% CI 0.51-0.83). In singletons, the largest reductions occurred in intrapartum-related deaths, and deaths due to congenital anomalies, antepartum haemorrhage and pre-eclampsia. There was little change in the rate of unexplained antepartum death occurring at term (RR 0.97, 95% CI 0.84-1.11) or preterm (RR 0.94, 95% CI 0.82-1.07), these accounting for about half of all late fetal deaths. Unexplained antepartum deaths declined in multiple births and in singletons of birthweight < 1500 g. CONCLUSIONS: While late fetal mortality due to many specific causes has declined, unexplained antepartum death rates have remained largely unchanged. Improved identification of deaths due to growth restriction and infection, which may otherwise be classified as unexplained, is important. Further investigation of the underlying aetiologies of genuinely unexplained deaths is needed.     

Expectant management of abruptio placentae before 35 weeks gestation

Forty-three patients with abruptio placentae before 35 weeks of pregnancy were managed expectantly with observation or with tocolytic therapy when contractions were present. Mean time to delivery was 12.4 days. Twenty-three patients were delivered within 1 week of admission. In the remaining 20 patients, the mean time to delivery was 26.8 days. There were no intrauterine deaths. In properly selected patients with preterm gestation and low-grade abruptio it is reasonable to defer delivery. These patients must be followed closely with antepartum fetal heart rate monitoring, serial hematologic and coagulation profiles, and serial sonograms when indicated.     

Risk factors for and perinatal mortality of abruptio placentae in patients hospitalised for early onset severe pre-eclampsia - a case controlled study.

We set out to determine which patients admitted for expectant management of early onset severe pre-eclampsia develop abruptio placentae and to compare the perinatal mortality rate of patients who developed abruptio placentae with those who did not have this complication. This was a case controlled study, using gestational age at delivery to select a control group for 69 patients who developed abruptio placentae. The only significant difference on admission was the higher uric acid levels in patients who developed abruptio placentae. Mean admission to delivery intervals were 11.9 and 8.8 days for the control and abruption groups respectively (P = 0.0083). Fifty-eight per cent of the babies in the abruptio placentae group developed late decelerations, as determined by fetal heart rate monitoring compared with 32% in the control group. Lactate dehydrogenase levels before delivery were significantly higher in the abruption group, but it only became elevated shortly before delivery and in the minority of cases. There were two intrauterine and four neonatal deaths in the abruption group and two neonatal deaths in the control group. Late decelerations detected by frequent fetal heart rate monitoring in patients with early onset severe pre-eclampsia is the only early warning of abruptio placentae.     

Causes of late fetal death in New Zealand 1980-1999

BACKGROUND: In recent years there has been an emerging interest in sudden unexplained intrauterine death. Aims: To determine the major causes of late fetal death (LFD) in New Zealand during 1980-1999 and to document the proportion of deaths considered unexplained. In addition, to quantify the number of LFD undergoing post-mortem during this period. METHODS: Using the Office for National Statistics (UK) hierarchical classification system, all information available on death certificates was used to assign a single cause to LFD for the period 1980-1999. Trends were analysed using logistic regression and risk factor profiles established for each cause of death. Post-mortem rates and the characteristics of those failing to undergo post-mortem were analysed for the period 1989-1999. RESULTS: LFD rates declined from 60.1 per 10 000 in 1980-1981 to 30.5 in 1998-1999. The declines were not uniform across all causes, with intrapartum deaths declining 73%, congenital anomalies 70% and antepartum asphyxia 50%. In contrast, unspecified deaths increased 1%, and with the decline in other causes of death, also increased proportionally, from 10.8% of LFD in 1980-81 to 28.1% in 1998-1999. Post-mortem rates fell by 31% during 1989-1999, with Maori and Pacific babies and those in more deprived New Zealand Deprivation Index areas being significantly less likely to undergo post-mortem. CONCLUSIONS: While total LFD rates declined significantly during 1980-1999, rates of unspecified LFD remained static. Low post-mortem rates, however, suggest that many of these deaths may be uninvestigated rather than truly unexplained. Nevertheless, the persistence of a category of death which, to date, has failed to improve with advances in obstetric technology suggests that further measures are necessary if New Zealand's LFD rates are to continue to decline.     

Value of Cardiotoeography in Women with Antepartum Haemorrhage - Is It Too Late for Caesarean Section When the Cardiotocograph Shows Ominous Features?

Summary: Caesarean section is thought to be indicated by an ominous antepartum cardiotocograph (CTG). However, the fear remains that infants delivered for this indication in the presence of antepartum haemorrhage, especially when premature, are destined to have severe hypoxic neurological damage. We therefore reviewed our experience of cardiotoeography in women with antepartum haemorrhage (APH) from 1989 to 1992. There were 472 women with APH who had a CTG performed. Of them, 68 had abruptio placentae and 317 had an APH of undetermined cause. For the group with abruptio placentae, the perinatal mortality rate (PMR) was 230.7 per 1,000 when the CTG was abnormal, but only 18.2 per 1,000 if the CTG was normal (odds ratio 16.2, 95% confidence interval [CI] 1.53–171.9, p = 0.02). For APH of undetermined cause, the corresponding rates were 90.9 per 1,000 and 9.8 per 1,000 (odds ratio 10.1, 95% CI 0.96–105.8, p = 0.13). There were no perinatal losses in women with APH due to placenta praevia (87 cases).
There were 6 cases of critical fetal reserve identified on a CTG in women with abruptio or APH of undetermined cause. All were delivered by Caesarean section, with 4 surviving infants, 3 with normal neurological outcome and 1 lost to follow-up. There were 3 cases of APH resulting in an infant with cerebral palsy, all of whom had had a normal antepartum CTG. Our data suggest that cardiotoeography allows pregnancy to be safely prolonged in pregnancies complicated by abruptio placentae or APH of undetermined cause, and that Caesarean section is an appropriate form of delivery when the CTG becomes abnormal in these cases.     

Should older women have antepartum testing to prevent unexplained stillbirth?

OBJECTIVE: Older women are at an increased risk for unexplained stillbirth late in pregnancy. The purpose of this study was to compare 3 strategies for the prevention of unexplained fetal death in women aged 35 years and older. We compared usual care (no antepartum testing or induction before 41 weeks), weekly testing at 37 weeks with induction after a positive test, and no testing with induction at 41 weeks. METHOD: We used a Markov model to quantify the risks and benefits of each strategy in terms of the number of antepartum tests, inductions, and additional cesarean deliveries per fetal death averted. Probability data used in the model were derived from obstetrical databases and the literature. RESULTS: Without a strategy of antepartum surveillance between 37 and 41 weeks, women aged 35 years and older would experience 5.2 unexplained fetal deaths per 1,000 pregnancies. For nulliparous women 35 and older, weekly antepartum testing initiated at 37 weeks would avert 3.9 fetal deaths per 1,000 pregnancies but would require 863 antepartum tests, 71 inductions, and 14 additional cesarean deliveries per fetal death averted. A strategy of no testing but induction at 41 weeks would avert 0.9 fetal deaths per 1,000 pregnancies and require 469 inductions and 219 additional cesareans per fetal death averted. CONCLUSION: A strategy of antepartum testing in older women would reduce the number of unexplained stillbirths at term and would result in fewer inductions and cesareans per fetal death averted than a strategy of no antepartum testing but induction at 41 weeks.     

Hyperhomocysteinemia, pregnancy complications, and the timing of investigation

OBJECTIVE: To assess associations between vitamin-dependent homocysteine metabolism and vascular-related pregnancy complications by considering interval between delivery and postpartum investigation and maternal age. METHODS: Case-control study performed at the University Medical Center Nijmegen in the Netherlands. Patients had experienced pregnancy-induced hypertension (n = 37), preeclampsia (n = 144), hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome (n = 104), recurrent early pregnancy loss (n = 544), abruptio placentae (n = 135), intrauterine growth restriction (n = 144), or intrauterine fetal death (n = 104). Controls comprised 176 women with uncomplicated obstetric histories. Oral methionine loading tests and fasting vitamin profiles were performed more than 6 weeks after delivery. Odds ratios and 95% confidence intervals were calculated after logistic regression analysis. RESULTS: Hyperhomocysteinemia was associated with an approximately 2-fold to 3-fold increased risk for pregnancy-induced hypertension, abruptio placentae, and intrauterine growth restriction. Cobalamin deficiency was associated with HELLP syndrome, abruptio placentae, intrauterine growth restriction, and intrauterine fetal death. Pyridoxal 5-phosphate deficiency increased the risk for pregnancy-induced hypertension 4-fold. These associations lost their significance after adjustment for time interval and maternal age. High red cell folate was associated with a decreased risk for abruptio placentae and intrauterine growth restriction. An increased creatinine concentration was associated with pregnancy-induced hypertension, preeclampsia, HELLP syndrome, and abruptio placentae. CONCLUSION: Hyperhomocysteinemia and vitamin deficiencies are largely determined by the interval between delivery and postpartum investigation and by maternal age. Time interval and maternal age should be considered in the risk estimation for vascular-related pregnancy complications.     

A prospective study on the occurrence of autoantibodies in low-risk pregnancies

OBJECTIVE: This investigation was done to study the prevalence of anti-nuclear antibodies (ANA), anti-cardiolipin antibodies (aCL), and rheumatoid factor (RF), in presumed healthy women during their pregnancies. STUDY DESIGN: During an 18 month period blood samples were taken in the first, second and third trimester from 1200 pregnant women, representing a low-risk population. Clinical data on the pregnancy outcome were obtained by birth statistics after their deliveries. The diagnoses of preeclampsia, intrauterine growth retardation, fetal death, or abruptio placentae were stated in 57 of these women. An age- and parity-matched control group of 207 women with normal pregnancy outcome was drawn from the same low-risk population (n= 1200). A nonpregnant control group consisted of 157 women. The prevalence of ANA (immunofluorescence microscopy on HEp-2 cells), aCL-immunoglobulin G (enzyme-linked immunosorbent assay), and RF (latex agglutination test) in preeclampsia, intrauterine growth retardation, fetal death, or abruptio placentae were compared to the normal pregnancies, and to the nonpregnant controls. RESULTS: ANA occurred significantly more often (P<0.05) in pregnancies complicated by preeclampsia when compared to normal pregnancies. aCL occurred sparsely in normal as well as complicated pregnancies. RF was infrequently seen among all women in this study. CONCLUSION: An association was noted between the occurrence of ANA and preeclampsia. However, this association was too insensitive to use as a clinical tool.     

Systematic multidisciplinary approach to reporting perinatal mortality: Lessons from a five-year regional review

Background:  Because of differences in reporting criteria throughout the world, comparing perinatal mortality rates and identifying areas of concern can be complicated and imprecise.
Aims:  To detail the systematic approach to reporting perinatal deaths and to identify any significant differences in outcomes in the Australian Capital Territory (ACT).
Methods:  Review of perinatal deaths from 2001 to 2005 in the ACT using the Australian and New Zealand Antecedent Classification of Perinatal Mortality (ANZACPM) and the Australian and New Zealand Neonatal Death Classification (ANZNDC) systems.
Results:  ACT residents' perinatal mortality rate was 10.6 per 1000 total births, fetal death rate 7.5 per 1000 total births and neonatal death rate 3.2 per 1000 live births. The three leading antecedent causes of perinatal death were congenital anomalies, spontaneous preterm birth and unexplained antepartum death. The three leading causes of neonatal death were extreme prematurity, cardiorespiratory disorders and congenital anomalies. Multiple births attributed to 20% (65 of 321) of perinatal deaths. Perinatal autopsy was performed in 50% of cases, but in only 64% of unexplained antepartum deaths.
Conclusions:  Causes of perinatal death for the ACT and surrounding New South Wales region are similar to other states using this classification system. The following are considered important lessons to promote accurate perinatal mortality reporting: (i) a universal reporting system for Australia utilising a multidisciplinary team; (ii) a high perinatal autopsy rate, especially in the critical area of antepartum death with no identifiable cause; and (iii) standardised definitions for avoidability. Attention to these areas may prompt further research and changes in practice to further reduce perinatal mortality.     

Restricted fetal growth in sudden intrauterine unexplained death

BACKGROUND: Unexplained antepartum stillbirth is a common cause of perinatal death, and identifying the fetus at risk is a challenge for obstetric practice. Intrauterine growth restriction (IUGR) is associated with a variety of adverse perinatal outcomes, but reports on its impact on unexplained stillbirths by population-based birthweight standards have been varying, including both unexplained and unexplored stillbirths. AIM: We have studied IUGR, assessed by individually adjusted fetal weight standards, in antepartum deaths that remained unexplained despite thorough postmortem investigations. METHODS: Antenatal health cards from a complete population-based 10-year material of 76 validated sudden intrauterine unexplained deaths were compared to those of 582 randomly selected liveborn controls. Birthweight <10th percentile of the individualized standard adjusted for gestational age, maternal height, weight, parity, ethnicity, and fetal gender was defined as growth restriction. RESULTS: 52% of unexplained stillbirths were growth restricted, with a mean gestational age at death of 35.1 weeks. Suboptimal growth was the most important fetal determinant for sudden intrauterine unexplained death (odds ratio 7.0, 95% confidence interval 3.3-15.1). Concurrent maternal overweight or obesity, high age, and low education further increase the risk. Overweight and obesity increase the risk irrespective of fetal growth, and while high maternal age increases the risk of the normal weight fetus, it is not associated to growth restriction as a precursor of sudden intrauterine unexplained death. CONCLUSIONS: IUGR is an important risk factor of sudden intrauterine unexplained death, and this should be excluded in pregnancies with any other risk factor for sudden intrauterine unexplained death.     

Fetal demise following negative contraction stress tests

The contraction stress test (CST) has become widely used to assess antepartum fetal well-being over the past 5 years. A summary of 14 reports in the literature revealed seven fetal deaths in 1739 patients within 1 week of a negative CST, an incidence of 0.4%. This prompted an investigation of our results for comparison. During the period January 1, 1975, to February 28, 1977, 746 patients underwent 1119 CSTs. Seven fetal deaths occurred in 680 patients within 1 week of a negative CST, an incidence of 1.0%. Although maternal conditions associated with fetal demise within 1 week of a negative CST include diabetes mellitus, prolonged pregnancy, chronic hypertension, and pre-eclampsia, fetal death in most instances resulted from factors other than uteroplacental insufficiency (UPI). Conditions commonly associated with fetal demise following a negative CST were umbilical cord accidents, severe congenital anomalies, and abruptio placentae. The low incidence of fetal death after a negative CST supports continued use of the CST in evaluation of high-risk pregnancies.     

Unexplained fetal death: Are women with a history of fetal loss at higher risk?

Aims: To identify factors, including the loss of a previous pregnancy before 20 weeks gestation, which are associated with increased risk of singleton antepartum unexplained fetal death (UFD) in Western Australia (WA) using information recorded in routine data collections.
Methods: All fetal deaths in WA from 1990 to 1999 that underwent thorough post-mortem investigations were classified using the Perinatal Society of Australia and New Zealand Perinatal Death Classification System. All UFDs were selected as cases and unmatched controls were randomly drawn from all live births in WA occurring during the study period. Demographic and clinical information on cases and controls was obtained from the WA Midwives' Notification System. Multivariable logistic regression was carried out to determine the independent effect of risk factors and calculate odds ratios.
Results: Almost one quarter (22%) of stillbirths were unexplained. Primigravid and primiparous women with a history of pregnancy loss before 20 weeks were at higher risk of UFD than multiparous women who had not experienced any loss. Women with a history of fetal death (after 20 weeks) had the highest risk of UFD.
Conclusion: The current practice of closely monitoring pregnant women with a history of fetal loss or death should continue as this study suggests they may have a higher risk of poor obstetric outcome. Larger studies are needed to confirm the association between previous pregnancy loss and UFD.     

Diabetes in pregnancy: a population-based study of incidence, referral for care, and perinatal mortality

During 1979 and 1980 in Washington State, 260 infants (live births plus fetal deaths greater than or equal to 20 weeks' gestation) were born to women with preexisting diabetes mellitus, the equivalent to a population-based incidence of 2.1 per 1000 total births. One quarter of these women had non-insulin-dependent diabetes prior to pregnancy. The perinatal mortality rate for all infants of diabetic mothers in this series was 108 per 1000, which was eight times the state perinatal mortality rate. Only 45% of births occurred in the five tertiary centers in the state, whereas 39% occurred in hospitals that had fewer than six deliveries per year complicated by overt diabetes. The mortality rate was slightly, but not significantly, lower among infants born in referral hospitals than among those born in primary-level hospitals. Congenital malformations accounted for 43% of the 28 perinatal deaths, and fetal losses between 20 and 27 weeks' gestation accounted for another 21%. During the 2-year study period there were only three cases in which antepartum care in nonspecialty centers may have contributed to a perinatal loss.     

Determinants of unexplained antepartum fetal deaths

OBJECTIVE: To assess fetal, maternal, and pregnancy-related determinants of unexplained antepartum fetal death. METHODS: We conducted a hospital-based cohort study of 84,294 births weighing 500 g or more from 1961-1974 and 1978-1996. Unexplained fetal deaths were defined as fetal deaths occurring before labor without evidence of significant fetal, maternal, or placental pathology. RESULTS: One hundred ninety-six unexplained antepartum fetal deaths accounted for 27.2% of 721 total fetal deaths. Two thirds of the unexplained fetal deaths occurred after 35 weeks' gestation. The following factors were independently associated with unexplained fetal death: maternal prepregnancy weight greater than 68 kg (adjusted odds ratio [OR] 2.9; 95% confidence interval [CI] 1.85, 4.68), birth weight ratio (defined as ratio of birth weight to mean weight for gestational age) between 0.75 and 0.85 (OR 2.77; 95% CI 1.48, 5.18) or over 1.15 (OR 2.36; 95% CI 1.26, 4.44), fewer than four antenatal visits in women whose fetuses died at 37 weeks or later (OR 2.21; 95% CI 1.08, 4.52), primiparity (OR 1.74; 95% CI 1.26, 2.40), parity of three or more (OR 2.01; 95% CI 1.26, 3.20), low socioeconomic status (OR 1.59; 95% CI 1.14, 2.22), cord loops (OR 1.75; 95% CI 1.04, 2.97) and, for the 1978-1996 period only, maternal age 40 years or more (OR 3.69; 95% CI 1.28, 10.58). Trimester of first antenatal visit, low maternal weight, postdate pregnancy, fetal-to-placental weight ratio, fetal sex, previous fetal death, previous abortion, cigarette smoking, and alcohol use were not significantly associated with unexplained fetal death. CONCLUSION: In this study, we identified several factors associated with an increased risk of unexplained fetal death.     

First Birth Cesarean and Risk of Antepartum Fetal Death in a Subsequent Pregnancy

Introduction: To examine the relationship between first birth by cesarean and antepartum fetal death in a subsequent pregnancy in a large, hospital‐based population. Methods : Data for this retrospective cohort study were taken from a database of all women who gave birth at Brigham and Women's Hospital during 4 waves of data collection beginning in 1994 and ending in 2002. We calculated the risk of antepartum fetal death in the subsequent pregnancy for women whose first birth was by cesarean compared to women with a vaginal first birth. Survival analysis was used to examine the influence of gestational age at birth. Results: Of 10,996 women who met inclusion criteria, 22% (n = 2450) had first births by cesarean, and 78% (n = 8546) had vaginal first births. The risk of antepartum fetal death in the subsequent pregnancy for women whose first birth was by cesarean was significantly greater than the risk for women whose first birth was vaginal (odds ratio 2.6; 95% confidence interval, 1.1‐6.2). The relationship between first birth cesarean and antepartum fetal death in a subsequent pregnancy differed by gestational age at birth, with no excess risk among women with a previous cesarean birth who gave birth before 34 weeks’ gestation but with a substantially increased risk for women who gave birth at 34 or more weeks’ gestation (unadjusted hazard ratio = 5.6; 95% confidence interval, 1.6‐19.8). Hazard ratio estimates for the association remained significant in bivariate models when adjusted for maternal height, weight, age, hypertension, and diabetes. Discussion: In these data, first birth by cesarean was associated with an increased risk of antepartum fetal death in a subsequent pregnancy. Our findings suggest that antepartum fetal deaths in subsequent pregnancies might be prevented by avoiding primary cesarean birth.     

Unexplained antepartum fetal deaths: what are the determinants?

Objective The objective was to assess fetal, antenatal, and pregnancy determinants of unexplained antepartum fetal death.Methods This is a hospital-based cohort study of 34,394 births weighing 500 g or more from January 1995 to December 2002. Unexplained fetal deaths were defined as fetal deaths occurring before labor, without evidence of significant fetal, maternal or placental pathology.Results Ninety-eight unexplained antepartum fetal deaths accounted for 27.2% of 360 total fetal deaths. Two-thirds of these deaths occurred after 36 weeks gestation. The following factors are independently associated with unexplained fetal deaths: primiparity (OR 1.74; 95% CI 1.21, 2.86); parity of five or more (OR 1.19; 95% CI 1.26, 3.26); low socioeconomic status (OR 1.22; 95% CI 1.14, 2.86); maternal age 40 years or more (OR 3.62; 95% CI 1.22, 4.52); maternal age of 18 years or less (OR 1.79; 95% CI 0.82, 2.89); maternal prepregnancy weight greater than 70 kg (OR 2.20; 95% CI 1.85, 3.68); fewer than three antenatal visits in women whose fetuses died at 31 weeks or more (OR 1.11; 95% CI 1.08, 2.48); birth weight ratio (defined as ratio of birth weight to mean birth weight for gestational age) between 0.85 and 0.94 (OR 1.77; 95% CI 1.28, 4.18) or over 1.45 (OR 2.92; 95% CI 1.75, 3.21); trimester of first antenatal visit. Previous fetal death, previous abortion, cigarette smoking, fetal sex, low maternal weight, fetal-to-placenta weight, and post date pregnancy were not significantly associated with unexplained fetal deaths.Conclusion Several factors were identified that are associated with an increased risk of unexplained fetal deaths.     

Unexplained elevated maternal serum alpha-fetoprotein and/or human chorionic gonadotropin and the risk of adverse outcomes

OBJECTIVE: The study was undertaken to determine the risks of adverse obstetric outcomes in pregnant women with unexplained elevations of maternal serum alpha-fetoprotein (MSAFP) and/or human chorionic gonadotropin (hCG) and to determine whether these risks vary by prepregnancy risk status. STUDY DESIGN: All women who underwent double-marker screening (MSAFP+hCG) between 1994 and 2000 and were delivered of an infant in Nova Scotia, Canada, during this period were identified from a hospital serum screening database and a provincial perinatal database. Patients with inaccurate dating, major structural anomalies, or chromosomal abnormalities were excluded. The primary outcomes studied were preeclampsia, abruptio placentae, fetal growth restriction, fetal death, and preterm birth. Women with medical or previous obstetric complications were designated high risk. Logistic regression, controlling for confounding factors, was used to estimate the relative risks (RRs) and 95% CI for elevated levels of MSAFP and/or hCG and each of the outcomes. RESULTS: Among the 14,374 women who met the study criteria, 5,789 were designated high risk. Except for abruptio placentae, unexplained elevated MSAFP or elevated hCG levels were independently associated with all the outcomes in both high- and low-risk women. Elevated screening values were associated with increased risk of abruptio placentae among low-risk women only. Particularly large RRs were seen for fetal death in both high- and low-risk women (RR=4.9, 95% CI 2.7-8.7 for elevated MSAFP or hCG in high- and low-risk women combined). CONCLUSION: Unexplained elevated levels of MSAFP and/or hCG are associated with an increased risk of most pregnancy complications. Increased antenatal surveillance of these patients is important regardless of prepregnancy risk status.     

Risk factors for sudden intrauterine unexplained death: epidemiologic characteristics of singleton cases in Oslo, Norway, 1986-1995

OBJECTIVE: The epidemiologic characteristics of unexplained stillbirths are largely unknown or unreliable. We define sudden intrauterine unexplained death as a death that occurs antepartum and results in a stillbirth for which there is no explanation despite postmortem examinations, and we present risk factors for this type of stillbirth in singleton gestations.Study Design: Singleton antepartum stillbirths (n = 291) and live births (n = 582) in Oslo were included and compared with national data (n = 2025 and n = 575,572, respectively). Explained stillbirths (n = 165) and live births in Oslo served as controls for the cases of sudden intrauterine unexplained death (n = 76) in multiple logistic regression analyses. RESULTS: One fourth of stillbirths remain unexplained. The risk of sudden intrauterine unexplained death (1/1000) increased with gestational age, high maternal age, high cigarette use, low education, and overweight or obesity. Primiparity and previous stillbirths or spontaneous abortions were not associated with sudden intrauterine unexplained death. CONCLUSIONS: Risk factors for sudden intrauterine unexplained death are identifiable by basic antenatal care. Adding unexplored stillbirths to the unexplained ones conceals several risk factors and underlines the necessity of a definition that includes thorough postmortem examinations.     

Causes of stillbirth: an analysis of 77 cases

OBJECTIVE: To devise preventive measures for stillbirths, which account for more than 70% of perinatal deaths in Japan. METHODS: We retrospectively reviewed the medical records of 77 women with singleton pregnancies who gave birth to stillborn infants at > or = 30 weeks between 1979 and 1996 at our hospital. RESULTS: Major malformations were present in 21 (27%) of 77 infants, including 11 infants with anencephaly. Two infants (2.6%) were severely hydropic. Preeclampsia preceded the stillbirth and might have been an indirect cause of stillbirth in 21 (39%) of 54 women whose infants had normal formations. The cause of stillbirth in 33 non-preeclamptic women was unclear in 15 (28%), abruptio placentae in 9, fetal growth retardation in 3, the HELLP syndrome in 3, chorioamnionitis in 2, and cord accident in 1. Abruptio placentae also occurred in 9 of 21 preeclamptic patients. Thus, abruptio placentae was responsible for 18 (33%) of 54 stillborn infants with a grossly normal appearance. An autopsy was performed on only 13 (24%) of 54 infants with grossly normal appearance and did not provide new information relating to deaths. CONCLUSIONS: The causes of stillbirth were many and varied, with a large proportion having no obvious cause, although autopsies were underused. Increased monitoring for women with preeclampsia and early diagnosis and prompt delivery for women with abruptio placentae might be helpful in reducing the number of stillbirths.