Stillbirth evaluation: What tests are needed?

OBJECTIVE: We sought to investigate what aspects of the stillbirth evaluation are considered to be essential and what tests can potentially be eliminated. STUDY DESIGN: A retrospective analysis of 745 stillbirths occurring from January 1990 to December 1994 was conducted. A stillbirth was defined by an estimated gestational age >20 weeks' gestational age or fetal weight >500 gm. We attempted to arrive at an apparent cause for each stillbirth after evaluation of genetic or chromosomal abnormalities, obstetric history, maternal medical illnesses, laboratory tests, autopsy findings, and placental pathologic conditions. RESULTS: We found that the most important aspects of stillbirth evaluation were placental pathologic conditions and autopsy. When the placenta was examined, a significant abnormality was detected in 30% (160 of 529) of the cases. When autopsy was performed, only 31% of fetal deaths (142 of 462) were unexplained; however, when no autopsy was performed, 44% (125 of 283) were unexplained (p = 0.0002). The following laboratory evaluations that were routinely performed were found to yield little definitive information: antinuclear antibody testing, Kleihauer-Betke test, and screening for congenital infections (toxoplasmosis, other viruses, rubella, cytomegalovirus, and herpes simplex virus). Overall, 36% (267 of 745) of stillbirths still remained unexplained despite a thorough evaluation in most cases. CONCLUSION: The causes of stillbirth are many and varied, with a large proportion having no obvious cause. As this study demonstrates, certain laboratory tests can be eliminated in the workup of fetal death. In the evaluation of stillbirth a complete systematic method that incorporates placental pathologic conditions, as well as autopsy findings, should prove to be beneficial. (Am J Obstet Gynecol 1998;178:1121-5.)     

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.     

Placental Findings Contributing to Fetal Death, a Study of 120 Stillbirths between 23 and 40 Weeks Gestation

BackgroundIntrauterine fetal death is an agonizing, often unpredictable event. Autopsies of stillborn fetuses, including placentas, are performed to clarify the cause of death. Autopsy results are not always easily understood by the patients or their healthcare providers.ObjectiveTo evaluate placental causes of death in stillbirths based on autopsy and placental findings that are related to maternal underperfusion, fetal underperfusion, or inflammatory etiologies in hierarchical order.MethodsRetrospective review of 120 autopsy reports of singleton stillborn fetuses and placentas from 23 to 40 weeks of gestation.ResultsAmong the placental causes of death there were 54(51%) cases with direct cause or major contributor to death in the etiology of maternal vascular supply abnormalities, 28(26%) cases in the etiology of fetal vascular supply abnormalities and 13(12%) in the etiology of inflammatory lesions. Maternal vascular supply abnormalities were more common in preterm stillbirths and fetal vascular supply abnormalities were more common among term stillbirths. In 88% of stillbirths, the direct cause or a major contributor to death was found in the placentas. The incidence of unexplained death was 8%.ConclusionsPathological analysis of the placenta is essential for clarifying causes of stillbirths. Using specific simplified categories for abnormal placental findings may increase the benefits of the autopsy report.     

A New South Wales Population-based Study of Stillbirths Weighing 2,500 g or More

Summary: This paper describes factors associated with singleton stillbirths weighing 2,500 g or more, born in 1987 and reported to the NSW Midwives' Data Collection (MDC), a statewide perinatal data collection system. A total of 136 singleton stillbirths in this weight range were notified to the MDC, representing one-quarter of all singleton stillbirths in NSW. MDC records on these stillbirths were linked with perinatal death registrations for 125 of the 136. The death registrations indicated that fetal death occurred during labour in 20 cases, prior to the onset of labour in 98, and at an unknown time in the remaining 7 cases. Placental complications, including haemorrhage and functional abnormalities of the placenta, were the most frequent group of conditions associated with the stillbirths, being recorded as the underlying cause of death in 42 (34%) of the 125 cases. Cord complications (such as cord compression or cord around the neck) were given as the underlying cause of death in 30 cases (24%). The death certificate diagnosis was confirmed by autopsy in only 27 of the 125 cases (22%), although autopsies may have been done on a further 45 cases (36%). An adequate explanation of the cause appeared to be lacking for many of the fetal deaths. This highlights the importance of a thorough and systematic investigation of stillbirths. A list of standard investigations to be carried out following a stillbirth is proposed.     

Cytogenetic Studies in Perinatal Death

Following tissue culture cytogenetic studies were performed on tissue obtained from 136 fetuses who died in the perinatal period (98 stillbirths and 38 neonatal deaths). The gestational age of the stillbirths was evenly distributed between 20 and 40 weeks (1 was 42 weeks) while 74% of the neonatal deaths were term babies. Analyzable metaphases were obtained in 45 stillbirth specimens (46%) and 32 neonatal specimens (84%). Abnormal karyotypes were identified in 7 of the stillbirths (15.5%) and 8 of the neonatal deaths (25%) and all these were from babies with congenital anomalies identified at autopsy. Time delays were crucial to the success of culture from stillbirths, but specimens obtained from neonatal deaths could be grown successfully up to 3 days after death. Generally the placenta was more viable than other tissues, including skin, cartilage and muscle. Whereas growth was obtained in 69% of fresh unexplained stillbirths, no tissue from the macerated stillbirths grew. This is a group which may have a high abnormality rate. We recommend that if fetal assessment during pregnancy suggests a compromised fetus and there are no maternal factors to account for this, an amniocentesis be performed.     

Review of Stillbirth in a Canadian Tertiary Care Centre

ObjectiveBecause literature on stillbirth in Canada and its related factors is scarce, the objective of this study was to determine the causes of stillbirth in a Canadian tertiary care centre and to identify the risk factors present in these deliveries.MethodsThe charts of 180 stillbirth deliveries with a gestational age greater than or equal to 20 weeks or a birth weight greater than or equal to 500 g between 2011 and 2016 were reviewed. Information collected from maternal charts included maternal demographics, known risk factors for stillbirth during pregnancy, delivery parameters, and pathologic examination (Canadian Task Force Classification III).ResultsThe autopsy rate was 42.5%, placental pathology rate was 100%, and karyotype was completed in 20.2% of the reviewed cases. Often, the cause of stillbirth was unexplained (43.2%). The most common causes were preterm birth (9.8%) and abruption (9.3%). The most common risk factors in this population were maternal obesity (37.6%), late prenatal care (35.0%), and maternal smoking (22.4%).ConclusionMost stillbirths were unexplained in this Canadian tertiary care centre, and the rates of autopsy and karyotype were low. Identified risk factors present in this population may contribute to the significantly higher rate of stillbirth in this centre compared with the provincial rate.     

Etiology of stillbirth at term: a 10-year cohort study

Objective. To examine etiological factors contributing to cases of intrauterine fetal demise in term pregnancies over a 10-year period.

Methods. This was a retrospective cohort analysis of 29 908 term (37⁺⁰ to 41⁺⁶ weeks gestation) infants delivering in a single tertiary-referral university institution over the 10-year period from 1996 to 2005. Cases of stillbirth were identified from a computerized hospital database, and pathological, clinical, and biochemical data were reviewed for all cases. Trends were analyzed using the Cusick test for trend. Categorical data were analyzed using the Fisher's exact test, with the 5% level considered significant.

Results. The incidence of intrauterine fetal demise at term was 1.8 per 1000 at-risk pregnancies. There was no significant downward trend in the rate of term stillbirth between 1996 and 2005 (p = 0.0808). Stillbirths were unexplained in 51% of cases, although in many cases a possible etiological factor was identified but not necessarily proven. There was a significant downward trend in the incidence of unexplained term stillbirths at our institution over the 10-year study period (p = 0.0105). Placental/cord factors accounted for 25% of term stillbirths and did not decrease significantly over the study period (p = 0.0953). Almost 50% of term stillbirths occurred in women who registered late or had no antenatal care. However, suboptimal antenatal care was not predictive of differences in either acceptance of perinatal postmortem or successful identification of stillbirth etiology.

Conclusions. The incidence of stillbirth at term is 2 per 1000 term pregnancies and has not changed significantly in the past 10 years. Almost 50% of term stillbirths occurred in women with suboptimal antenatal care. More than half of cases are unexplained, often resulting from an incomplete diagnostic work-up. Despite this, there has been a significant downward trend in the rates of unexplained stillbirth at term. It is imperative that a complete diagnostic work-up is performed in cases of term stillbirth, to minimize the incidence of unexplained stillbirth.     

Clinicopathological evaluation of 59 cases of fetal death

OBJECTIVE: The purpose of this study has been assessing the determinants of stillbirth among the newborns of the Verona University Obstetrics Department. MATERIALS AND METHODS: A total of 59 stillbirth cases, observed between January 2000 and June 2006, were retrospectively studied. WHO definition for stillbirth was adopted as the inclusion criterion. Clinical files, feto-maternal laboratory data, feto-placental pathology findings as well as delivery mode and circumstances were all systematically reviewed. RESULTS: The 59 observed cases correspond to an incidence of 9.8 stillbirths/year, which, considering the institutional delivery rate, correspond to 5.4 cases per 1000 births. Frequent relevant conditions associated with stillbirth were intrauterine growth restriction (15.2%), congenital fetal anomalies (13.5%), various maternal diseases (21.0%); no cause of fetal demise could be found in 10/59 (17.0%) cases, which were classified as unexplained. Most deliveries were successfully induced with prostaglandins except 11 cases (19.0%) which required a C-section due to severe maternal conditions associated with the fetal loss. CONCLUSION: Thorough investigation of each individual stillbirth case, by means of an integrated study protocol, along with the Pathologist's close collaboration, allows identification of a likely cause in the majority of cases. Better knowledge of unexpected fetal loss is the premise for better parental counselling and for prevention of recurrences.     

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.     

Stillbirth: a review.

Stillbirth occurs in nearly 1% of all births in the USA, and is one of the most common but least studied adverse pregnancy outcomes. The many risk factors for and causes of stillbirth are presented. Over the past several decades, the rate of stillbirth has been substantially reduced, with the reduction most apparent in those stillbirths previously occurring at term and/or in labor. Reductions have occurred because of reductions in risk factors (i.e. prevention of Rh disease and better control of diabetes), better antepartum monitoring of those with risk factors followed by early delivery for those fetuses found to be at risk (i.e. growth restriction, maternal pre-eclampsia), better intrapartum fetal monitoring, increases in Cesarean section for those at risk, and early detection of congenital anomalies followed by termination prior to the time that these early fetal deaths are classified as stillbirths. Finally, the value of using fetal autopsy and placental examination to determine the cause of death accurately, both for research purposes and for patient counseling in future pregnancies, is explored.     

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.     

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.     

The possible role of intrauterine infections in unexplained second trimester abortions and macerated stillbirths: a study from a single center.

OBJECTIVE: To investigate the role of intrauterine infections in unexplained second trimester abortions and stillbirths. STUDY DESIGN: Histopathologic and microbiologic evidence of intrauterine infection in the placentas, fetal membranes and fetal lung tissues of 18 unexplained second trimester abortions and macerated stillbirth cases as well as the placentas and fetal membranes of 10 healthy term neonates were investigated in a prospective study conducted in Ankara University School of Medicine, Turkey. RESULTS: Histopathologic chorioamnionitis and placental culture positivity rates in the study and control groups were 64.7 vs 0%. Bacteria were recovered from 90.9% of placentas and 36.4% of fetal lungs of the cases with histopathologic chorioamnionitis. Intrauterine infection was found in 66.7% of the whole study group, in 85.7% of the unexplained second trimester abortions, and in 54.5% of the macerated stillbirths. CONCLUSION: Intrauterine infection may be an important factor in unexplained stillbirths and second trimester abortions in centers where pregnancy follow-ups lack evaluation for asymptomatic infection.     

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.     

Value of perinatal autopsy

OBJECTIVE: To determine how often a perinatal autopsy identified the cause of death, and how frequently this information changed recurrence risk estimates or altered parental counseling. METHODS: We reviewed all autopsies of fetal stillbirths and briefly viable neonates performed by one perinatal pathologist at the University of Alabama Hospital from 1992 to 1994. RESULTS: Four hundred sixteen fetal and early neonatal deaths occurred at our hospital from January 1, 1992, to June 1, 1994. Consent for an autopsy examination was granted for 139 of these (33%), and all autopsies were performed by a single perinatal pathologist. Abnormalities likely to be the cause of death were identified in 130 of 139 cases (94%). Ninety-one subjects did not have structural anomalies: In 14 cases autopsy revealed previously unsuspected pathology that altered parental counseling; in 68 cases autopsy findings were consistent with the clinical obstetrical diagnosis; and in nine cases the cause of death could not be identified. Forty-eight subjects were anomalous. Thirty-seven of these (79%) had been evaluated by antenatal ultrasonography, and autopsy identified additional abnormalities in 51% (19 of 37). In the 11 deaths evaluated neonatally, a previously unsuspected diagnosis likely to be the cause of death was identified in three. Overall, autopsy findings changed recurrence risk estimates and/or parental counseling in 36 of 139 cases (26%). CONCLUSION: The cause of fetal or perinatal death was determined by autopsy in 94% of cases in our series. Counseling and recurrence risk estimates were altered by autopsy findings in 26%.     

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.     

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.     

Challenges in classification and assignment of causes of stillbirths in low- and lower middle-income countries

Stillbirths account for 2.6 million deaths annually. 98% occur in low- and lower middle-income countries. Accurate classification of stillbirths in low-resource settings is challenged by poor pregnancy dating and infrequent access to electronic heart rate monitoring for both the newborn and fetus. In these settings, liveborn infants may be misclassified as stillbirths, and stillbirths may be misclassified as miscarriages. Causation is available for only 3% of stillbirths globally due to the absence of registration systems. In low-resource settings where culture and autopsy are infrequently available, clinical course is used to assign cause of stillbirth. This method may miss rare or subtle causes, as well as those with non-specific clinical presentations. Verbal autopsy is another technique for assigning cause of stillbirth when objective medical data are limited. This method requires family engagement and physician attribution of cause. As interventions to reduce stillbirths in LMICs are increasingly implemented, attention to accurate classification and assignment of causes of stillbirth are critical to charting progress.     

A case-control study of unexplained antepartum stillbirths.

OBJECTIVE: To ascertain factors that will identify women who are at increased risk of unexplained antepartum stillbirth. DESIGN: Matched case-control study. The cases and controls were initially analysed as a whole group and again after dichotomizing into those of low birthweight (< 2500 g) and those of normal birthweight (> or = 2500 g). SETTING: Western Australia 1980-1983. SUBJECTS: Unexplained antepartum stillbirths of > or = 1000 g birthweight (cases) and liveborn infants individually matched for year of birth, plurality, sex and birthweight of infant and race of mother (controls). RESULTS: The case pregnancies had more polyhydramnios (OR 10.83, 95% CI 2.41-48.69) and cord problems (OR 6.57 95% CI 1.36-31.75) than the controls but, paradoxically, other obstetric and medical complications were less common in the cases. The association with polyhydramnios persisted when the analysis was confined to those with low birthweight. With normal birthweight fetal distress was more frequent in the cases (OR 3.65 95% CI 1.36-9.80) but there were few other differences. CONCLUSIONS: The clinical and diagnostic systems currently in use are unable to identify many fetuses at risk of death. Decreases in the rate of unexplained antepartum stillbirths await the discovery of new preventable causes, or of innovations in clinical or laboratory aspects of obstetric care.     

Intrauterine infection may be a major cause of stillbirth in Sweden

AIM OF THE STUDY: To investigate intrauterine infection as a cause for unexplained stillbirth. METHODS: Chorioamnionitis was studied in a material of stillbirths (117 subjects from the years 1985-1994) from a region in the south Sweden. Control material (126 alive and healthy newborns and with healthy mothers) was gathered from the same region. RESULTS: Chorioamnionitis was a common diagnosis both with stillbirths and 'healthy' deliveries (82 and 68%, respectively). Extension of the inflammation to decidua basalis was seven times more common among stillbirths than among controls (odds ratio 7.2, confidence interval 2.8-21.9). The most common bacteria found at cultures were Escherichia coli, Coagulase negative staphylococcus, Enterococcus faecalis and group B Streptococcus. The risk for stillbirth was doubled if both inflammation and bacteria were present (odds ratio 2.3, confidence interval 0.92-5.8). Meconium discharge was more common among stillbirths than controls (odds ratio=4.7, confidence interval 1.7-14). There were no differences in any respect regarding macerated and non-macerated stillbirths. Our findings are similar to the results from studies in developing countries except for the higher incidence of stillbirths in such countries. CONCLUSIONS: Thus, a large part of otherwise unexplained stillbirths might be due to ascending infections.