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.

Temporal changes in fetal death risk in pregnancies with preeclampsia: Does offspring birthweight matter? A population study

Objectives

To study the associations of preeclampsia with fetal death risk within percentiles of offspring birthweight, and whether these associations have changed during 1967–2014.

Study design

In this population study, we included all singleton pregnancies in the Medical Birth Registry of Norway during 1967–2014 (n = 2 607 199). Odds ratios (ORs) for fetal death associated with preeclampsia were estimated within percentiles of birthweight by applying logistic regression analyses. We estimated ORs for the study period as a whole, and for the years 1967–1983 and 1984–2014.

Results

During the study period as a whole, preeclampsia increased the risk of fetal death, OR 2.73 (95% CI 2.57–2.89), and the fetal death risk associated with preeclampsia differed across percentiles of offspring birthweight. The overall risk of fetal death decreased during our study period, and the decrease was most prominent in preeclamptic pregnancies with low offspring birthweight (<1 percentile). Thus, in recent years, the risk of fetal death in pregnancies with low offspring birthweight was lower in preeclamptic than in non-preeclamptic pregnancies, OR 0.22 (95% CI 0.12-0.41). Only in pregnancies with offspring birthweight within the 10–90 percentiles, the risk of fetal death associated with preeclampsia remained significantly increased throughout the study period.

Conclusions

The decline in fetal death risk was most prominent in preeclamptic pregnancies with low offspring birthweight. The introduction of a national screening program for preeclampsia in the 1980s, and identification of growth restricted offspring by fetal ultrasonography, may explain our findings.

Perinatal death and exposure to dental amalgam fillings during pregnancy in the population-based MoBa cohort

OBJECTIVES

The aim was to gain knowledge regarding the risk of perinatal death related to exposure to dental amalgam fillings in the mother.

DESIGN

Population-based observational cohort study.

SETTING

The Norwegian Mother and Child Cohort Study, a Norwegian birth cohort of children born in 1999-2008 conducted by the Norwegian Institute of Public Health.

PARTICIPANTS

72,038 pregnant women with data on the number of teeth filled with dental amalgam.

MAIN OUTCOME MEASURES

Data on perinatal death (stillbirth ≥ 22 weeks plus early neonatal death 0-7 days after birth) were obtained from the Medical Birth Registry of Norway.

RESULTS

The absolute risk of perinatal death ranged from 0.20% in women with no amalgam-filled teeth to 0.67% in women with 13 or more teeth filled with amalgam. Analyses including the number of teeth filled with amalgam as a continuous variable indicated an increased risk of perinatal death by increasing number of teeth filled with dental amalgam (crude OR 1.065, 95% CI 1.034 to 1.098, p<0.001). After adjustment for potential confounders (mothers' age, education, body mass index, parity, smoking during pregnancy, alcohol consumption during pregnancy) included as categorical variables, there was still an increased risk for perinatal death associated with increasing number of teeth filled with amalgam (ORadj 1.041, 95% CI 1.008 to 1.076, p = 0.015). By an increased exposure from 0 to 16 teeth filled with amalgam, the model predicted an almost doubled odds ratio (ORadj 1.915, 95% CI 1.12 to 3.28). In groups with 1 to 12 teeth filled with amalgam the adjusted odds ratios were slightly, but not significantly, increased. The group with the highest exposure (participants with 13 or more teeth filled with amalgam) had an adjusted OR of 2.34 (95% CI 1.27 to 4.32; p = 0.007).

CONCLUSION

The current findings suggest that the risk of perinatal death could increase in a dose-dependent way based on the mother's number of teeth filled with dental amalgam. However, we cannot exclude that the relatively modest odds ratios could be a result of residual confounding. Additional studies on the relationship between exposure to dental amalgam fillings during pregnancy and perinatal death are warranted.

Placenta and Umbilical Cord Cause in Antepartum Deaths

Stillbirth is a sudden and painful event for parents and obstetrical specialists as well. It is, therefore, of greatest importance to be able to give answers for the cause in order to plan a subsequent pregnancy. The aim of this retrospective study is to estimate the placental and umbilical cord cause of intrauterine death in relation to different gestational ages. The study took place on the Medical Birth Registry of Aretaieio Hospital, National and Kapodistrian University, Athens, Greece. We include a total of 19,283 pregnancies from 1998 to 2012. In this study period, 431 embryonic deaths occurred. The clinical history was documented on admission at delivery. Conditions thought to be associated with the intrauterine fetal death were recorded. Gestational age was calculated from the last menstrual period as well as with the three-trimester system. The autopsy, placenta and umbilical cord examination were performed by the same laboratory of pathology in Aretaieio University Hospital. We found that the majority of stillbirths occurred in the second trimester. We examined placenta and umbilical cord in all cases. The most frequent histologic abnormalities were those indicated placental vascular insufficiency. As far as the umbilical cord is concerned we found that the inflammatory disorder was the most common in antepartum deaths. A single umbilical artery was significantly related to gestational diabetes and congenital embryonic anomalies. Finally, our results showed steady declines in antepartum deaths during 1998-2012. As a result, we reached the conclusion that in order to reduce the fetal death rate, we have to insist on the autopsy of the placenta and umbilical cord in order to gain the appropriate information in counseling the parents.

Why babies die in unplanned out-of-institution births: an enquiry into perinatal deaths in Norway 1999-2013

Introduction

The aims were to describe causes of death associated with unplanned out‐of‐institution births, and to study whether they could be prevented.

Material and methods

Retrospective population‐based observational study based on data from the Medical Birth Registry of Norway and medical records. Between 1 January 1999 and 31 December 2013, 69 perinatal deaths among 6027 unplanned out‐of‐institution births, whether unplanned at home, during transportation, or unspecified, were selected for enquiry. Hospital records were investigated and cases classified according to Causes of Death and Associated Conditions.

Results

63 cases were reviewed. There were 25 (40%) antepartum deaths, 10 (16%) intrapartum deaths, and 24 neonatal (38%) deaths. Four cases were in the unknown death category (6%). Both gestational age and birthweight followed a bimodal distribution with modes at 24 and 38 weeks and 750 and 3400 g, respectively. The most common main cause of death was infection (n = 14, 22%), neonatal (n = 14, 22%, nine due to extreme prematurity) and placental (n = 12, 19%, seven placental abruptions). There were 86 associated conditions, most commonly perinatal (n = 32), placental (n = 15) and maternal (n = 14). Further classification revealed that the largest subgroup was associated perinatal conditions/sub‐optimal care, involving 25 cases (40%), most commonly due to sub‐optimal maternal use of available care (n = 14, 22%).

Conclusions

Infections, neonatal, and placental causes accounted for almost two‐thirds of perinatal mortality associated with unplanned out‐of‐institution births in Norway. Sub‐optimal maternal use of available care was found in more than one‐fifth of cases.

Intrauterine fetal death and risk of shoulder dystocia at delivery

INTRODUCTION

Vaginal delivery is recommended after intrauterine fetal death. However, little is known about the risk of shoulder dystocia in these deliveries. We studied whether intrauterine fetal death increases the risk of shoulder dystocia at delivery.

MATERIAL AND METHODS

In this population-based register study using the Medical Birth Registry of Norway, we included all singleton pregnancies with vaginal delivery of offspring in cephalic presentation in Norway during the period 1967-2012 (n = 2 266 118). Risk of shoulder dystocia was estimated as absolute risk (%) and odds ratio with 95% confidence interval. Adjustment was made for offspring birthweight (in grams). We performed sub-analyses within categories of birthweight (<4000 and ≥4000 g) and in pregnancies with maternal diabetes.

RESULTS

Shoulder dystocia occurred in 1.1% of pregnancies with intrauterine fetal death and in 0.8% of pregnancies without intrauterine fetal death (p < 0.0001) (crude odds ratio 1.5, 95% confidence interval 1.2-4.9). After adjustment for birthweight, the odds ratio was 5.9 (95% confidence interval 4.7-7.4). In pregnancies with birthweight ≥4000 g, shoulder dystocia occurred in 14.6% of pregnancies with intrauterine fetal death and in 2.8% of pregnancies without intrauterine fetal death (p < 0.001) (crude odds ratio 5.9, 95% confidence interval 4.5-7.9). In pregnancies with birthweight ≥4000 g and concurrent maternal diabetes, shoulder dystocia occurred in 57.1% of pregnancies with intrauterine fetal death and 9.6% of pregnancies without intrauterine fetal death (p < 0.001) (crude odds ratio 12.6, 95% confidence interval 5.9-26.9).

CONCLUSIONS

Intrauterine fetal death increased the risk of shoulder dystocia at delivery, and the absolute risk of shoulder dystocia was particularly high if offspring birthweight was high and the mother had diabetes.

Stillbirths: The Hidden Birth Asphyxia - US and Global Perspectives

Stillbirths are among the most common pregnancy-related adverse outcomes but are more common in low-income and middle-income countries than in high-income countries. In high-income countries, most stillbirths occur early in the preterm period, whereas in low-income and middle-income countries, most occur in term or in late preterm births. In low-income and middle-income countries, conditions, such as prolonged or obstructed labor, placental abruption, preeclampsia/eclampsia, fetal growth restriction, fetal distress, breech and other abnormal presentations, and multiple births, are associated with stillbirth. In high-income countries, placental abnormalities are the most common associations. Globally, fetal asphyxia is likely the most common final pathway to stillbirth.

The role of preterm placental calcification on assessing risks of stillbirth

INTRODUCTION

Stillbirth is an important issue in antenatal care and much remains unknown. This cohort study aims to explore the previously un-identified risk factor of third-trimester stillbirth to determine if Grade III preterm placental calcification (PPC) is associated with stillbirth.

METHODS

At a tertiary teaching hospital, obstetric ultrasonography was performed at 28 weeks' gestation to establish a diagnosis of PPC. Pregnancies with multifetal gestations, major fetal congenital anomalies, termination, cord accidents, apparent intrauterine infection, and antepartum complications were excluded.

RESULTS

15,122 eligible pregnancies were categorized as stillbirth (n = 99) and livebirth (n = 15,023) groups. Between these two groups, there were no significant differences in maternal age, BMI, and parity, but significant differences in smoking and in PPC (35.4% vs 6.3%, p < 0.001) were observed. The peak occurrence of stillbirths was at 30 and 37 weeks' gestation, with a bimodal distribution of 11 and 17 stillbirths, respectively. For pregnancies with or without PPC, the incidences of stillbirths per-1000-births were 35.9 and 4.5, respectively. Using Kaplan-Meier survival analysis, at 40 weeks' gestation the cumulative stillbirth risk for pregnancies with PPC was higher compared to those without PPC. Logistic regression revealed that after adjusting for the effects of smoking and demographic factors, the risk of stillbirth (adjusted OR:7.62; 95% CI:5.00-11.62) was much higher when PPC was present.

DISCUSSION

Grade III PPC is associated with a higher incidence of stillbirth, and identified an independent risk factor. Being a pathologic implication, it may precede this negative outcome and can serve as a warning sign or marker when noted on ultrasonography.

Stillbirth in an Anglophone minority of Canada

OBJECTIVES

We assessed trends in stillbirth over time for Francophones and Anglophones of Quebec, a large Canadian province with publically funded health care and an English-speaking minority.

METHODS

We calculated stillbirth rates for Francophones and Anglophones, and estimated hazard ratios (HR) by decade from 1981 to 2010, adjusting for maternal characteristics. We analyzed temporal trends by gestational interval and cause of fetal death.

RESULTS

Stillbirth rates decreased in Quebec during the three decades, due to improved rates in Francophones. Rates decreased for Anglophones in 1991-2000, but increased in 2001-2010 at term, during the second trimester, and for most causes of fetal death. In the 2000s, the hazard of stillbirth for Anglophones was nearly the same as the hazard for Francophones in the 1980s (HR 0.93, 95 % confidence interval 0.82, 1.05).

CONCLUSIONS

Stillbirth rates declined in both Francophones and Anglophones before the turn of the century, but increased thereafter for Anglophones, suggesting that linguistic inequalities in stillbirth may be emerging in Quebec. Linguistic status may be a useful marker for surveillance of inequalities in stillbirth.

Characteristics and outcome of unplanned out-of-institution births in Norway from 1999 to 2013: a cross-sectional study

OBJECTIVE

To study the incidence, maternal characteristics and outcome of unplanned out-of-institution births (= unplanned births) in Norway.

DESIGN

Register-based cross-sectional study.

POPULATION

All births in Norway (n = 892 137) from 1999 to 2013 with gestational age ≥22 weeks.

METHODS

Analysis of data from the Medical Birth Registry of Norway from 1999 to 2013. Unplanned births (n = 6062) were compared with all other births (reference group).

RESULTS

The annual incidence rate of unplanned births was 6.8/1000 births and remained stable during the period of study. Young multiparous women residing in remote municipalities were at the highest risk of experiencing unplanned births. The unplanned birth group had higher perinatal mortality rate for the period, 11.4/1000 compared with 4.9/1000 for the reference group (incidence rate ratio 2.31, 95% confidence interval 1.82-2.93, p < 0.001). Annual perinatal mortality rate for unplanned births did not change significantly (p = 0.80) but declined on average by 3% per year in the reference group (p < 0.001). The unplanned birth group had a lower proportion of live births in all birthweight categories. Live born neonates with a birthweight of 750-999 g in the unplanned birth group had a more than five times higher mortality rate during the first week of life, compared with reference births in the same birthweight category.

CONCLUSIONS

Unplanned births are associated with adverse outcome. Excessive mortality is possibly caused by reduced availability of necessary medical interventions for vulnerable newborns out-of-hospital.

Trends and recurrence of stillbirths in NSW

OBJECTIVE

To examine the trend in stillbirth rates adjusted for the trends in the maternal risk profile, and to use local data to estimate the stillbirth recurrence risk.

METHODS

Linked hospital, birth and perinatal death review data were used to identify risk factors and stillbirths among women giving birth to singletons in NSW between 2001 and 2009. Logistic regression models were developed to predict stillbirth rates based on the changes in the maternal population.

RESULTS

Between 2001 and 2009 there were 3,449 stillbirths (4.4 per 1,000 births), with no significant change in rate overall (p=0.6) or across older gestational age categories (26-33 weeks p=0.67, ≥34 weeks p=0.36), and a slight increase at <26 weeks (p=0.01). However, when changes in the maternal population were taken into account, there was a significant increase in stillbirths at <26 weeks (p<0.001). Women with a stillbirth in a first pregnancy were at increased risk of stillbirth in their second pregnancy (4.3 95%CI 2.4-7.7).

CONCLUSION

There has been no decline in the stillbirth rate in NSW in recent years, which, at late gestations, may be accounted for by changes in the maternal population. At early gestations, there has been an increase in stillbirths where a decrease in rate may be expected based on the maternal population.

IMPLICATIONS

Further focus on addressing risk factors for stillbirths is needed to ensure continued progress is made in reducing stillbirths.

Identification of causes of stillbirth through autopsy and placental examination reports

The autopsy and placental histopathological examination results following fetal deaths were analyzed retrospectively in an attempt to explain the stillbirths that occurred from 1996 to 2010 at the Department of Obstetrics and Gynecology, University of Szeged. One hundred and forty fetal deaths were recorded in that period, i.e. a rate of 4.69 stillbirths per 1000 deliveries. The postmortem examination provided the exact cause of the fetal death in 57.9% of the cases. The most common causes were a placental insufficiency (46.9%) and an umbilical cord complication (25.9%). In the first half of the third trimester, a placental insufficiency predominated as the cause of stillbirth, whereas mainly umbilical cord complications occurred around term. In spite of the availability of the autopsy and histopathological examination results, the proportion of unexplained stillbirths in our sample was relatively high. A considerable proportion of stillbirth cases could probably be prevented by more effective screening of a placental insufficiency.

Stillbirth and infant death among generations of Pakistani immigrant descent: a population-based study

OBJECTIVE

To examine the risk of stillbirth and infant death among offspring of Pakistani-born and Norwegian-born women of Pakistani immigrant descent.

DESIGN

Population-based study linking the Medical Birth Registry of Norway to immigration data from Statistics Norway.

SETTING

Norway.

POPULATION

Births to women of Pakistani immigrant descent classified as Pakistani-born (n = 8814) or Norwegian-born (n = 1801), and to the host population of Norwegian descent (n = 712 430) from 1995 to 2010.

METHODS

The relative risk of stillbirth and infant death by country of descent and birth was estimated by odds ratios with 95% confidence intervals (95% CI) using logistic regression.

MAIN OUTCOME MEASURES

Stillbirth and infant death.

RESULTS

Risk of stillbirth was highest in the Pakistani-born group (7.4/1000, 95% CI 5.7-9.4) followed by the Norwegian-born group (5.0/1000, 95% CI 1.7-8.3) and finally the host population (3.5/1000, 95% CI 3.3-3.6). Relative to the host population, risk of stillbirth was higher in both Pakistani-born (odds ratios 2.8, 95% CI 2.2-3.6) and Norwegian-born (odds ratios 2.2, 95% CI 1.1-4.2) groups, after adjustment for year of birth, age, parity and residence. For infant death, absolute risks were 6.9/1000 (95% CI 5.2-8.8), 5.6/1000 (95% CI 2.7-10.2), and 2.9/1000 (95% CI 2.7-3.0), with adjusted odds ratios of 2.8 (95% CI 2.1-3.7) and 2.4 (95% CI 1.3-4.6), respectively.

CONCLUSIONS

An elevated risk of stillbirth and infant death persists across generations of Pakistani immigrant descent living in Norway. While translating into few excess deaths, the elevated risks should be taken into account by obstetric and pediatric care providers.

Maternal education and risk of offspring death; changing patterns from 16 weeks of gestation until one year after birth

BACKGROUND

The social disparity in perinatal mortality may vary by the age of the offspring. We studied offspring mortality from pregnancy week 16 until 1 year after birth by maternal educational level.

METHODS

We included all births in Norwegian women during the years 1999-2004 (n = 297 663). The Medical Birth Registry of Norway was linked to the Norwegian Education Registry to obtain individual information on maternal education at the time of delivery. Information on infant mortality was obtained by linkage to the Norwegian Central Person Registry.

RESULTS

In pregnancy weeks 37 through 43 and in the first week after birth, there was little difference in offspring mortality by maternal education. Before pregnancy week 37, the excess offspring mortality associated with compulsory school only was >60% using university/college education as the reference. During the 2nd through 12th month after birth, the excess mortality was 132% in offspring of mothers with compulsory school only.

CONCLUSION

The social disparity in offspring mortality was lowest in pregnancies at term and in the first week after birth. In this period, all women living in Norway and their infants use the public health care service extensively. Our results may suggest that health care that is equally available to all citizens, reduces social disparities in mortality.

Changes in fetal and neonatal mortality during 40 years by offspring sex: a national registry-based study in Norway

Background

There has been a considerable decline in fetal and neonatal mortality in the Western world. The authors hypothesized that this decline has been largest for boys, since boys have a higher risk of fetal and neonatal death.

Methods

The authors used data from the Medical Birth Registry about all births in Norway to study changes during 1967–2005 in mortality for boys and girls from the 23rd week of pregnancy until one month after birth. Absolute and relative yearly changes in fetal and neonatal death rates were estimated separately for boys and girls.

Results

From 1967 to 2005, the average annual reduction in the overall death rate was greater for boys: 0.47 per 1000 boys (95% CI: 0.45, 0.48) and 0.37 per 1000 girls (95% CI: 0.35, 0.39). These estimates were not affected by adjustments made for changes over time in maternal characteristics. The convergence in death rates by sex was strongest for the first week after birth: average annual reduction in the early neonatal death rate was 0.24 per 1000 boys (95% CI: 0.23, 0.25) and 0.17 per 1000 girls (95% CI: 0.16, 0.18). The death rates for boys and girls also converged during pregnancy and from one week to one month after birth. The relative reduction in death rates was quite similar for boys and girls: the overall death rate fell annually by 4.4% (95% CI: 4.3, 4.6%) for boys and by 4.2% (95% CI: 4.0, 4.4%) for girls.

Conclusions

During the period 1967–2005, the absolute reduction in fetal and neonatal death rates was greatest for boys. The relative reduction in mortality was about the same for both sexes, but the absolute reduction was greatest for boys since the mortality for boys began at a higher level. The convergence of death rates was not due to changes in the composition of mothers, suggesting that convergence has been caused by technological progress.

Hypertensive disorders in pregnancy and fetal death at different gestational lengths: a population study of 2 121 371 pregnancies

OBJECTIVE

To compare the proportion of offspring that was stillborn in pregnancies with pre-eclampsia, gestational hypertension or chronic hypertension with those in normotensive pregnancies.

DESIGN

Register-based observational study.

SETTING

The Medical Birth Registry of Norway.

POPULATION

All singleton births after 20 completed weeks of gestation in Norway from 1967 to 2006 (n = 2 121 371).

METHODS

The proportion of stillborn offspring was estimated in normotensive pregnancies, and in pregnancies with pre-eclampsia, gestational and chronic hypertension at different gestational lengths. In addition, changes in the proportions of stillborn offspring by maternal hypertensive disorder from 1967-1986 to 1987-2006 were estimated.

MAIN OUTCOME MEASURES

Fetal death.

RESULTS

The prevalence of hypertensive disorders in pregnancy was 4.7%. In total, 17 933 fetal deaths occurred and 9.2% of these were in hypertensive pregnancies. In normotensive pregnancies, 0.8% (16 290/2 022 400) experienced fetal death. This was true for 1.9% (1170/62 261) of the pregnancies with pre-eclampsia, 1.2% (390/32 068) with gestational hypertension and 1.8% (83/4642) with chronic hypertension. There was a 44% overall reduction in fetal death rate from 1967-1986 to 1987-2006. The largest decline was in women with pre-eclampsia (80% reduction). In women with gestational hypertension and chronic hypertension, the overall reductions in fetal death rates were 49% and 57%, respectively, comparable with the 41% decline in normotensive pregnancies.

CONCLUSIONS

In our nationwide study during 1967-2006, the risk of fetal death among women with hypertensive disorders in pregnancy has been greatly reduced, especially among pre-eclamptic women at term. The risk of fetal death among women with gestational or chronic hypertension has also decreased, but in a different manner.

Resilience of the human fetal lung following stillbirth: potential relevance for pulmonary regenerative medicine

Recent advances in pulmonary regenerative medicine have increased the demand for alveolar epithelial progenitor cells. Fetal lung tissues from spontaneous pregnancy losses may represent a neglected, yet ethically and societally acceptable source of alveolar epithelial cells. The aim of this study was to determine the regenerative capacity of fetal lungs obtained from second trimester stillbirths. Lung tissues were harvested from 11 stillborn fetuses (13 to 22 weeks' gestation) at postdelivery intervals ranging from 10 to 41 hours and grafted to the renal subcapsular space of immune-suppressed rats to provide optimal growth conditions. Histology, epithelial and alveolar type II cell proliferation, and surfactant protein-C mRNA expression were studied in preimplantation lung tissues and in xenografts at posttransplantation week 2. All xenografts displayed advanced architectural maturation compared with their respective preimplantation tissues, regardless of gestational age and postdelivery interval. The proliferative activity of the grafts was significantly higher than that of the preimplantation tissues (mean Ki-67 labeling index 26.7%±7.7% versus 14.7%±10.5%; P<.01). The proliferative activity of grafts obtained after a long (>36 hours) postdelivery interval was significantly higher than that of the corresponding preimplantation tissue, and equivalent to that of grafts obtained after a short postdelivery interval (<14 hours). The regenerative capacity of fetal lung tissue was greater at younger (13 to 17 weeks) than at older (19 to 22 weeks) gestational ages. The presence of inflammation/chorioamnionitis did not appear to affect graft regeneration. All grafts studied displayed robust surfactant protein-C mRNA expression. In conclusion, fetal lung tissues from second trimester stillbirths can regain their inherent high regenerative potential following short-term culture, even if harvested more than 36 hours after delivery.