Effects of intrauterine retention and postmortem interval on body weight following intrauterine death: implications for assessment of fetal growth restriction at autopsy

Autopsy-Based Growth Charts May under-Detect Fetal Growth Restriction at Autopsy

Background: Accurate identification of fetal growth restriction in fetal autopsy is critical for assessing causes of death. We examined the impact of using a chart derived from ultrasound measurements of healthy fetuses (World Health Organization fetal growth chart) versus a chart commonly used by pathologists (Archie et al.) derived from fetal autopsy-based populations in diagnosing small-for-gestational-age (SGA) birth in perinatal deaths. Study Design: We examined perinatal deaths that underwent autopsy at BC Women's Hospital, 2015-2021. Weight centiles were assigned using the ultrasound-based fetal growth chart for birthweight and autopsy-based growth chart for autopsy weight. Results: Among 352 fetuses, 30% were SGA based on the ultrasound-based fetal growth chart versus 17% using the autopsy-based growth chart (p < 0.001). Weight centiles were lower when using the ultrasound-based versus autopsy-based growth chart (median difference of 9 centiles [IQR 2, 20]). Conclusions: Autopsy-based growth charts may under-classify SGA status compared to ultrasound-based fetal growth charts.

Prevalence and risk of stillbirth according to biologic vulnerability phenotypes in the municipality of São Paulo, Brazil: A population-based cohort study

OBJECTIVE

To estimate the prevalence and risk of stillbirths by biologic vulnerability phenotypes in a cohort of pregnant women in the municipality of São Paulo, Brazil, 2017-2019.

METHODS

Retrospective population-based cohort study. Fetuses were assessed as small for gestational age (SGA), large for gestational age (LGA), adequate for gestational age (AGA), preterm (PT) as less than 37 weeks of gestation, non-PT (NPT) as 37 weeks of gestation or more, low birth weight (LBW) as less than 2500 g, and non-LBW (NLBW) as 2500 g or more. Relative risks (RR) with robust variance were estimated using Poisson regression.

RESULTS

In all 442 782 pregnancies, including 2321 (0.5%) stillbirths, were included. About 85% (n = 1983) of stillbirths had at least one characteristic of vulnerability, compared with 21% (n = 92524) of live births. Fetuses with all three markers of vulnerability had the highest adjusted RR of stillbirth-SGA + LBW + PT (RR 155.00; 95% confidence interval [CI] 136.29-176.30) and LGA + LBW + PT (RR 262.04; 95% CI 206.10-333.16) when compared with AGA + NLBW + NPT.

CONCLUSION

Our findings show that the simultaneous presence of prematurity, low birth weight, and abnormal intrauterine growth presented a higher risk of stillbirths. To accelerate progress towards reducing preventable stillbirths, one must identify the circumstances of greatest biologic vulnerability.

Stillbirths: Contribution of preterm birth and size-for-gestational age for 125.4 million total births from nationwide records in 13 countries, 2000-2020

OBJECTIVE

To examine the contribution of preterm birth and size-for-gestational age in stillbirths using six 'newborn types'.

DESIGN

Population-based multi-country analyses.

SETTING

Births collected through routine data systems in 13 countries.

SAMPLE

125 419 255 total births from 22+0 to 44+6 weeks' gestation identified from 2000 to 2020.

METHODS

We included 635 107 stillbirths from 22+0  weeks' gestation from 13 countries. We classified all births, including stillbirths, into six 'newborn types' based on gestational age information (preterm, PT, <37+0  weeks versus term, T, ≥37+0  weeks) and size-for-gestational age defined as small (SGA, <10th centile), appropriate (AGA, 10th-90th centiles) or large (LGA, >90th centile) for gestational age, according to the international newborn size for gestational age and sex INTERGROWTH-21st standards.

MAIN OUTCOME MEASURES

Distribution of stillbirths, stillbirth rates and rate ratios according to six newborn types.

RESULTS

635 107 (0.5%) of the 125 419 255 total births resulted in stillbirth after 22+0  weeks. Most stillbirths (74.3%) were preterm. Around 21.2% were SGA types (PT + SGA [16.2%], PT + AGA [48.3%], T + SGA [5.0%]) and 14.1% were LGA types (PT + LGA [9.9%], T + LGA [4.2%]). The median rate ratio (RR) for stillbirth was highest in PT + SGA babies (RR 81.1, interquartile range [IQR], 68.8-118.8) followed by PT + AGA (RR 25.0, IQR, 20.0-34.3), PT + LGA (RR 25.9, IQR, 13.8-28.7) and T + SGA (RR 5.6, IQR, 5.1-6.0) compared with T + AGA. Stillbirth rate ratios were similar for T + LGA versus T + AGA (RR 0.7, IQR, 0.7-1.1). At the population level, 25% of stillbirths were attributable to small-for-gestational-age.

CONCLUSIONS

In these high-quality data from high/middle income countries, almost three-quarters of stillbirths were born preterm and a fifth small-for-gestational age, with the highest stillbirth rates associated with the coexistence of preterm and SGA. Further analyses are needed to better understand patterns of gestation-specific risk in these populations, as well as patterns in lower-income contexts, especially those with higher rates of intrapartum stillbirth and SGA.

Stillbirth risk and smallness for gestational age according to Hadlock, INTERGROWTH-21st, WHO, and GROW fetal weight standards: analysis by maternal ethnicity and body mass index

BACKGROUND

Appropriate growth charts are essential for fetal surveillance, to confirm that growth is proceeding normally and to identify pregnancies that are at risk. Many stillbirths are avoidable through antenatal detection of the small-for-gestational-age fetus. In the absence of an international consensus on which growth chart to use, it is essential that clinical practice reflects outcome-based evidence.

OBJECTIVE

This study investigated the performance of 4 internationally used fetal weight standards and their ability to identify stillbirth risk in different ethnic and maternal size groups of a heterogeneous population.

STUDY DESIGN

We analyzed routinely collected maternity data from more than 2.2 million pregnancies. Three population-based fetal weight standards (Hadlock, Intergrowth-21st, and World Health Organization) were compared with the customized GROW standard that was adjusted for maternal height, weight, parity, and ethnic origin. Small-for-gestational-age birthweight and stillbirth risk were determined for the 2 largest ethnic groups in our population (British European and South Asian), in 5 body mass index categories, and in 4 maternal size groups with normal body mass index (18.5-25.0 kg/m2). The differences in trend between stillbirth and small-for-gestational-age rates were assessed using the Clogg z test, and differences between stillbirths and body mass index groups were assessed using the chi-square trend test.

RESULTS

Stillbirth rates (per 1000) were higher in South Asian pregnancies (5.51) than British-European pregnancies (3.89) (P<.01) and increased in both groups with increasing body mass index (P<.01). Small-for-gestational-age rates were 2 to 3-fold higher for South Asian babies than British European babies according to the population-average standards (Hadlock: 26.2% vs 12.2%; Intergrowth-21st: 12.1% vs 4.9%; World Health Organization: 32.2% vs 16.0%) but were similar by the customized GROW standard (14.0% vs 13.6%). Despite the wide variation, each standard's small-for-gestation-age cases had increased stillbirth risk compared with non-small-for-gestation-age cases, with the magnitude of risk inversely proportional to the rate of cases defined as small for gestational age. All standards had similar stillbirth risk when the small-for-gestation-age rate was fixed at 10% by varying their respective thresholds for defining small for gestational age. When analyzed across body mass index subgroups, the small-for-gestation-age rate according to the GROW standard increased with increasing stillbirth rate, whereas small-for-gestation-age rates according to Hadlock, Intergrowth-21st, and World Health Organization fetal weight standards declined with increasing body mass index, showing a difference in trend (P<.01) to stillbirth rates across body mass index groups. In the normal body mass index subgroup, stillbirth rates showed little variation across maternal size groups; this trend was followed by GROW-based small-for-gestation-age rates, whereas small-for-gestation-age rates defined by each population-average standard declined with increasing maternal size.

CONCLUSION

Comparisons between population-average and customized fetal growth charts require examination of how well each standard identifies pregnancies at risk of adverse outcomes within subgroups of any heterogeneous population. In both ethnic groups studied, increasing maternal body mass index was accompanied by increasing stillbirth risk, and this trend was reflected in more pregnancies being identified as small for gestational age only by the customized standard. In contrast, small-for-gestation-age rates fell according to each population-average standard, thereby hiding the increased stillbirth risk associated with high maternal body mass index.

Maternal Hemoglobin A1c in the Third-Trimester May Underestimate Maternal Hyperglycemia and Its Impact on Offspring in Perinatal Demise Associated With Gestational Diabetes Mellitus: An Autopsy Case Series

INTRODUCTION

Gestational diabetes mellitus (GDM) is a common metabolic disorder linked to adverse pregnancy outcomes. Recent research indicates that HbA1c is reliable in detecting maternal glycemia during the first trimester but may underestimate glucose intolerance in the late second to third trimesters. Therefore, it is reasonable to hypothesize that mothers with GDM, despite apparently normal HbA1c levels in the third trimester, may give birth to infants displaying characteristic features often seen in infants of diabetic mothers with suboptimal glycemic control. This study aimed to describe a case series of autopsy cases involving stillborn or deceased neonates delivered in the third trimester to mothers diagnosed with GDM and having normal HbA1c levels at or around the time of delivery. The primary focus was on identifying and documenting the characteristic features commonly associated with "infants of diabetic mothers" with suboptimal glycemic control in this series of cases.

MATERIALS AND METHODS

We conducted a retrospective review of autopsy reports from our institution spanning 7.5 years. The study included cases that met the following criteria: (1) stillborn or infants who died in the early neonatal period, delivered in the third trimester; (2) mothers diagnosed with GDM; (3) normal maternal HbA1c levels of ≤6.1% at or around the time of delivery; (4) birthweight or femoral length exceeding the 90th percentile for gestational age; and (5) absence of genetic aberrations. We also examined these cases for other characteristic features associated with "infants of diabetic mothers."

RESULTS

Ten autopsy cases met our inclusion criteria, including 9 stillbirths and 1 neonatal death. Gestational age at delivery ranged from 32 to 39 weeks (mean: 35.7 weeks). Femoral length exceeded the 90th percentile in all cases, and 6 cases had birthweights above the 90th percentile. Puffy facies were observed in 6 cases. Among the 9 cases with complete autopsies including internal examination, 6 exhibited excess adipose tissue, 4 had cardiomegaly, and 3 showed pancreatic islet hyperplasia. Hypoxic-ischemic encephalopathy was detected in 7 cases. No structural abnormalities were noted.

DISCUSSION

Our findings demonstrated that fetuses and neonates born to mothers with apparently normal HbA1c levels in the third trimester could still display characteristic features commonly observed in infants of diabetic mothers with poor glycemic control, also known as "infants of diabetic mothers." This study underscores the potential of third-trimester maternal HbA1c measurements to underestimate maternal glycemia and its consequential impact on fetal development, as well as the subsequent manifestation of features of "infants of diabetic mothers."

Evidence of Placental Aging in Late SGA, Fetal Growth Restriction and Stillbirth-A Systematic Review

During pregnancy, the placenta undergoes a natural aging process, which is considered normal. However, it has been hypothesized that an abnormally accelerated and premature aging of the placenta may contribute to placenta-related health issues. Placental senescence has been linked to several obstetric complications, including abnormal fetal growth, preeclampsia, preterm birth, and stillbirth, with stillbirth being the most challenging. A systematic search was conducted on Pubmed, Embase, and Scopus databases. Twenty-two full-text articles were identified for the final synthesis. Of these, 15 presented original research and 7 presented narrative reviews. There is a paucity of evidence in the literature on the role of placental aging in late small for gestational age (SGA), fetal growth restriction (FGR), and stillbirth. For future research, guidelines for both planning and reporting research must be implemented. The inclusion criteria should include clear differentiation between early and late SGA and FGR. As for stillbirths, only those with no other known cause of stillbirth should be included in the studies. This means excluding stillbirths due to congenital defects, infections, placental abruption, and maternal conditions affecting feto-maternal hemodynamics.

Reduced fetal growth velocity and weight loss are associated with adverse perinatal outcome in fetuses at risk of growth restriction

BACKGROUND

Although fetal size is associated with adverse perinatal outcome, the relationship between fetal growth velocity and adverse perinatal outcome is unclear.

OBJECTIVE

This study aimed to evaluate the relationship between fetal growth velocity and signs of cerebral blood flow redistribution, and their association with birthweight and adverse perinatal outcome.

STUDY DESIGN

This study was a secondary analysis of the TRUFFLE-2 multicenter observational prospective feasibility study of fetuses at risk of fetal growth restriction between 32⁺⁰ and 36⁺⁶ weeks of gestation (n=856), evaluated by ultrasound biometry and umbilical and middle cerebral artery Doppler. Individual fetal growth velocity was calculated from the difference of birthweight and estimated fetal weight at 3, 2, and 1 week before delivery, and by linear regression of all available estimated fetal weight measurements. Fetal estimated weight and birthweight were expressed as absolute value and as multiple of the median for statistical calculation. The coefficients of the individual linear regression of estimated fetal weight measurements (growth velocity; g/wk) were plotted against the last umbilical-cerebral ratio with subclassification for perinatal outcome. The association of these measurements with adverse perinatal outcome was assessed. The adverse perinatal outcome was a composite of abnormal condition at birth or major neonatal morbidity.

RESULTS

Adverse perinatal outcome was more frequent among fetuses whose antenatal growth was <100 g/wk, irrespective of signs of cerebral blood flow redistribution. Infants with birthweight <0.65 multiple of the median were enrolled earlier, had the lowest fetal growth velocity, higher umbilical-cerebral ratio, and were more likely to have adverse perinatal outcome. A decreasing fetal growth velocity was observed in 163 (19%) women in whom the estimated fetal weight multiple of the median regression coefficient was <-0.025, and who had higher umbilical-cerebral ratio values and more frequent adverse perinatal outcome; 67 (41%; 8% of total group) of these women had negative growth velocity. Estimated fetal weight and umbilical-cerebral ratio at admission and fetal growth velocity combined by logistic regression had a higher association with adverse perinatal outcome than any of those parameters separately (relative risk, 3.3; 95% confidence interval, 2.3-4.8).

CONCLUSION

In fetuses at risk of late preterm fetal growth restriction, reduced growth velocity is associated with an increased risk of adverse perinatal outcome, irrespective of signs of cerebral blood flow redistribution. Some fetuses showed negative growth velocity, suggesting catabolic metabolism.

Delivery characteristics in pregnancies with stillbirth: a retrospective case-control study from a tertiary teaching hospital

OBJECTIVES

We compared delivery characteristics and outcome of women with stillbirth to those with live birth.

METHODS

This was a retrospective case-control study from Helsinki University Hospital, Finland. The study population comprised 214 antepartum singleton stillbirths during 2003-2015. Two age-adjusted controls giving live birth in the same year at the same institution were chosen for each case from the Finnish Medical Birth Register. Delivery characteristics and adverse pregnancy outcomes were compared between the cases and controls, adjusted for gestational age.

RESULTS

Labor induction was more common (86.0 vs. 22.0%, p<0.001, gestational age adjusted odds ratio [aOR] 35.25, 95% confidence interval [CI] 12.37-100.45) and cesarean sections less frequent (9.3 vs. 28.7%, p<0.001, aOR 0.21, 95% CI 0.10-0.47) among women with stillbirth. Duration of labor was significantly shorter among the cases (first stage 240.0 min [115.0-365.0 min] vs. 412.5 min [251.0-574.0 min], p<0.001; second stage 8.0 min [0.0-16.0 min] vs. 15.0 min [4.0-26.0 min], p<0.001). Placental abruption was more common in pregnancies with stillbirth (15.0 vs. 0.9%, p<0.001, aOR 8.52, 95% CI 2.51-28.94) and blood transfusion was needed more often (10.7 vs. 4.4%, p=0.002, aOR 6.5, 95% CI 2.10-20.13). The rates of serious maternal complications were low.

CONCLUSIONS

Most women with stillbirth delivered vaginally without obstetric complications. The duration of labor was shorter in pregnancies with stillbirth but the risk for postpartum interventions and bleeding complications was higher compared to those with live birth.

Risk of Recurrent Stillbirth in Subsequent Pregnancies

OBJECTIVE

To compare the prospective risk of stillbirth between women with and without a stillbirth in their first pregnancy.

METHODS

We conducted a cohort study using perinatal data from Finland, Malta, and Scotland. Women who had at least two singleton deliveries were included. The exposed and unexposed cohorts comprised women with a stillbirth and live birth in their first pregnancy, respectively. The risk of stillbirth in any subsequent pregnancy was assessed using a Cox proportional hazards model. Time-to-event analyses were conducted to investigate whether first pregnancy outcome had an effect on time to or the number of pregnancies preceding subsequent stillbirth.

RESULTS

The pooled data set included 1,064,564 women, 6,288 (0.59%) with a stillbirth and 1,058,276 with a live birth in a first pregnancy. Compared with women with a live birth, women with a stillbirth in the first pregnancy were more likely to have a subsequent stillbirth (adjusted hazard ratio [aHR] 2.25, 95% CI 1.86-2.72). For women with more than two pregnancies, the difference in risk of subsequent stillbirth between the two groups increased with the number of subsequent pregnancies. Maternal age younger than 25 years or 40 years and older, smoking, low socioeconomic status, not having a partner, pre-existing diabetes, preeclampsia, placental abruption, or delivery of a growth-restricted neonate in a first pregnancy were independently associated with subsequent stillbirth. Compared with women with a live birth in the first pregnancy, women with a stillbirth were more likely to have another pregnancy within 1 year. The absolute risk of stillbirth in a subsequent pregnancy for women with stillbirth and live birth in a first pregnancy were 2.5% and 0.5%, respectively.

CONCLUSION

Compared with women with a live birth in a first pregnancy, women with a stillbirth have a higher risk of subsequent stillbirth irrespective of the number and sequence of the pregnancies. Despite high relative risk, the absolute risk of recurrence was low.

Reduced fetal growth velocity precedes antepartum fetal death

OBJECTIVES

To determine whether decreased fetal growth velocity precedes antepartum fetal death and to evaluate whether fetal growth velocity is a better predictor of antepartum fetal death compared to a single fetal biometric measurement at the last available ultrasound scan prior to diagnosis of demise.

METHODS

This was a retrospective, longitudinal study of 4285 singleton pregnancies in African-American women who underwent at least two fetal ultrasound examinations between 14 and 32 weeks of gestation and delivered a liveborn neonate (controls; n = 4262) or experienced antepartum fetal death (cases; n = 23). Fetal death was defined as death diagnosed at ≥ 20 weeks of gestation and confirmed by ultrasound examination. Exclusion criteria included congenital anomaly, birth at < 20 weeks of gestation, multiple gestation and intrapartum fetal death. The ultrasound examination performed at the time of fetal demise was not included in the analysis. Percentiles for estimated fetal weight (EFW) and individual biometric parameters were determined according to the Hadlock and Perinatology Research Branch/Eunice Kennedy Shriver National Institute of Child Health and Human Development (PRB/NICHD) fetal growth standards. Fetal growth velocity was defined as the slope of the regression line of the measurement percentiles as a function of gestational age based on two or more measurements in each pregnancy.

RESULTS

Cases had significantly lower growth velocities of EFW (P < 0.001) and of fetal head circumference, biparietal diameter, abdominal circumference and femur length (all P < 0.05) compared to controls, according to the PRB/NICHD and Hadlock growth standards. Fetuses with EFW growth velocity < 10^th percentile of the controls had a 9.4-fold and an 11.2-fold increased risk of antepartum death, based on the Hadlock and customized PRB/NICHD standards, respectively. At a 10% false-positive rate, the sensitivity of EFW growth velocity for predicting antepartum fetal death was 56.5%, compared to 26.1% for a single EFW percentile evaluation at the last available ultrasound examination, according to the customized PRB/NICHD standard.

CONCLUSIONS

Given that 74% of antepartum fetal death cases were not diagnosed as small-for-gestational age (EFW < 10^th percentile) at the last ultrasound examination when the fetuses were alive, alternative approaches are needed to improve detection of fetuses at risk of fetal death. Longitudinal sonographic evaluation to determine growth velocity doubles the sensitivity for prediction of antepartum fetal death compared to a single EFW measurement at the last available ultrasound examination, yet the performance is still suboptimal. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Consensus Definition of Fetal Growth Restriction in Intrauterine Fetal Death: A Delphi Procedure

CONTEXT.—

Fetal growth restriction is a risk factor for intrauterine fetal death. Currently, definitions of fetal growth restriction in stillborns are heterogeneous.

OBJECTIVES.—

To develop a consensus definition for fetal growth restriction retrospectively diagnosed at fetal autopsy in intrauterine fetal death.

DESIGN.—

A modified online Delphi survey in an international panel of experts in perinatal pathology, with feedback at group level and exclusion of nonresponders. The survey scoped all possible variables with an open question. Variables suggested by 2 or more experts were scored on a 5-point Likert scale. In subsequent rounds, inclusion of variables and thresholds were determined with a 70% level of agreement. In the final rounds, participants selected the consensus algorithm.

RESULTS.—

Fifty-two experts participated in the first round; 88% (46 of 52) completed all rounds. The consensus definition included antenatal clinical diagnosis of fetal growth restriction OR a birth weight lower than third percentile OR at least 5 of 10 contributory variables (risk factors in the clinical antenatal history: birth weight lower than 10th percentile, body weight at time of autopsy lower than 10th percentile, brain weight lower than 10th percentile, foot length lower than 10th percentile, liver weight lower than 10th percentile, placental weight lower than 10th percentile, brain weight to liver weight ratio higher than 4, placental weight to birth weight ratio higher than 90th percentile, histologic or gross features of placental insufficiency/malperfusion). There was no consensus on some aspects, including how to correct for interval between fetal death and delivery.

CONCLUSIONS.—

A consensus-based definition of fetal growth restriction in fetal death was determined with utility to improve management and outcomes of subsequent pregnancies.

Molecular Pathways of Cellular Senescence and Placental Aging in Late Fetal Growth Restriction and Stillbirth

Abnormally accelerated, premature placental senescence plays a crucial role in the genesis of pregnancy pathologies. Abnormal growth in the third trimester can present as small for gestational age fetuses or fetal growth restriction. One differs from the other by the presence of signs of placental insufficiency and the risk of stillbirth. The majority of stillbirths occur in normally grown fetuses and are classified as "unexplained", which often leads to conclusions that they were unpreventable. The main characteristic of aging is a gradual decline in the function of cells, tissues, and organs. These changes result in the accumulation of senescent cells in mitotic tissues. These cells begin the aging process that disrupts tissues' normal functions by affecting neighboring cells, degrading the extracellular matrix, and reducing tissues' regeneration capacity. Different degrees of abnormal placentation result in the severity of fetal growth restriction and its sequelae, including fetal death. This review aims to present the current knowledge and identify future research directions to understand better placental aging in late fetal growth restriction and unexplained stillbirth. We hypothesized that the final diagnosis of placental insufficiency can be made only using markers of placental senescence.

Customized birth-weight centiles and placenta-related fetal growth restriction

OBJECTIVE

The value of using customized birth-weight centiles to improve the diagnostic accuracy for fetal growth restriction (FGR), in comparison with using population-based charts, remains a matter of debate. One potential explanation for the conflicting data is that most studies used measures of perinatal mortality and morbidity as proxies for placenta-mediated FGR, many of which are not specific and may be confounded by other factors such as prematurity. The aim of this study was to compare the diagnostic accuracy of small-for-gestational age (SGA) at birth, defined according to customized vs population-based charts, for associated abnormal placental pathology.

METHODS

This was a secondary analysis of data from a prospective cohort study on risk factors for placenta-mediated complications and abnormal placental pathology in low-risk nulliparous women. All placentae were sent for detailed histopathological examination by two perinatal pathologists. The primary exposure was SGA, defined as birth weight < 10^th centile for gestational age using either a customized (SGA_cust ) or a population-based (SGA_pop ) birth-weight reference. The outcomes of interest were one of three types of abnormal placental pathology associated with FGR: maternal vascular malperfusion (MVM), chronic villitis and fetal vascular malperfusion (FVM). Adjusted relative risks (aRR) with 95% CIs were estimated using modified Poisson regression analysis, with adjustment for smoking, body mass index and aspirin treatment.

RESULTS

A total of 857 nulliparous women met the study criteria. The proportions of infants identified as SGA based on the customized and population-based charts were 12.6% (108/857) and 11.4% (98/857), respectively. A diagnosis of SGA using either customized or population-based charts was associated with an increased risk of any placental pathology (aRR, 3.04 (95% CI, 2.29-4.04) and 1.60 (95% CI, 1.10-2.31), respectively) and MVM pathology (aRR, 12.33 (95% CI, 6.60-23.03) and 5.29 (95% CI, 2.87-9.76), respectively). SGA_cust , but not SGA_pop , was also associated with an increased risk for chronic villitis (aRR, 1.85 (95% CI, 1.07-3.18)) and FVM pathology (aRR, 2.48 (95% CI, 1.25-4.93)). SGA_cust had a higher detection rate for any placental pathology (30.3% vs 17.1%; P < 0.001), MVM pathology (63.2% vs 39.5%; P = 0.003) and chronic villitis (20.8% vs 8.3%; P = 0.007) than did SGA_pop , for a similar false-positive rate. This was mainly the result of a higher detection rate for abnormal pathology in the white and East-Asian subgroups and a lower false-positive rate for abnormal pathology in the South-Asian subgroup by SGA_cust than by SGA_pop . In addition, pregnancies in the SGA_cust group, but not those in the SGA_pop group, were more likely to be complicated by preterm birth and a low 5-min Apgar score than were the corresponding non-SGA group.

CONCLUSION

These findings suggest that customized birth-weight centiles may be superior to population-based birth-weight centiles in detecting FGR that is due to underlying placental disease. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Obstetric and pediatric growth charts for the detection of late-onset fetal growth restriction and neonatal adverse outcomes

OBJECTIVES

Late-onset fetal growth restriction (FGR) has heterogeneous prenatal and postnatal diagnostic criteria. We compared the prenatal and postnatal diagnosis of late-onset FGR and their ability to predict adverse perinatal outcomes.

METHODS

Retrospective cohort study of 5442 consecutive singleton pregnancies that delivered beyond 34 + 0 weeks. Prenatal diagnosis of FGR was based on customized fetal growth standards and fetal Doppler while postnatal diagnosis was based on a birthweight <3rd percentile according to newborn charts (Olsen's charts and Intergrowth 21st century programme). Perinatal outcomes were analyzed depending on whether the diagnosis was prenatal, postnatal or both.

RESULTS

A total of 94 out of 5442 (1.7%) were diagnosed as late-onset FGR prenatally. Olsen's chart and Intergrowth 21st chart detected that 125/5442 (2.3%) and 106/5442 (2.0%) of infants had a birthweight <3rd percentile, respectively. These charts identified 35/94 (37.2%) and 40/94 (42.6%) of the newborns with a prenatal diagnosis of late-onset FGR. Prenatally diagnosed late-onset FGR infants were at a higher risk for hypoglycemia, jaundice and polycythemia. Both prenatally and postnatally diagnosed as late-onset FGR had a higher risk for respiratory distress syndrome when compared to non-FGR. The higher risks for intensive care admission and composite adverse outcomes were observed in those with a prenatal diagnosis of late-onset FGR that was confirmed after birth.

CONCLUSIONS

Current definitions of pre- and postnatal late-onset FGR do not match in more than half of cases. Infants with a prenatal or postnatal diagnosis of this condition have an increased risk of neonatal morbidity even if these diagnoses are not coincident.

Fetal weight change close to term is proportional to the birthweight percentile

OBJECTIVE

To investigate the relationship between the difference in estimated fetal weight and birthweight at or close to term, and in relation to Doppler parameters.

STUDY DESIGN

A cohort study of all term singleton pregnancies who underwent an ultrasound within two weeks of delivery after 36 weeks at one institution in one calendar year. When available, Doppler measurements of umbilical and middle cerebral artery pulsatility index were recorded. Data were analysed by Pearson rank correlation.

RESULTS

Of 8517 eligible deliveries, 885 women had an ultrasound scan within 2 weeks of delivery. Mean daily differences between estimated fetal weight and birth weight were: those born <10th percentile lost 26 g per day (95 % CI -36 to -16), 10-50th percentile gained 7 g per day (95 % CI -2 to 15), 50th-90th percentile gained 27 g per day (95 % CI 19-35) and >90th percentile gained 48 g per day (95 % CI 32-64). There was a negative correlation between umbilical: middle cerebral artery pulsatility index and the change in weight per day (n = 348, p = 0.001, r = 0.17).

CONCLUSIONS

Difference in the estimated fetal weight and birthweight, expressed as grams growth per day, is proportional to the birthweight percentile. Fetuses with a birthweight >10th percentile gain weight, while those with a birthweight <10th percentile apparently decline in weight between their final ultrasound estimated fetal weight and delivery. In babies with the smallest or apparent negative weight gain there was an association with Doppler parameters that signified hypoxia indicating fetal growth at term may be restricted by impaired placental function. Estimated fetal weight may be a poor predictor of birthweight for reasons other than ultrasound or algorithmic error.

Preventing term stillbirth: benefits and limitations of using fetal growth reference charts

PURPOSE OF REVIEW

This review examines the variation in clinical practice with regards to ultrasound estimation of fetal weight, as well as calculation of fetal weight centiles.

RECENT FINDINGS

Placental dysfunction is associated with fetal smallness from intrauterine malnutrition as well as fetal disability and even stillbirth from hypoxemia. Although estimating fetal weight can be done accurately, the issue of which fetal weight centile chart should be used continues to be a contentious topic. The arguments against local fetal growth charts based on national borders and customization for variables known to be associated with disease are substantial. As for other human diseases such as hypertension and diabetes, there is a rationale for the use of an international fetal growth reference standard. Irrespective of the choice of fetal growth reference standard, a significant limitation of small for gestational age (SGA) detection programs to prevent stillbirth is that the majority of stillborn infants at term were not SGA at the time of demise.

SUMMARY

Placental dysfunction can present with SGA from malnutrition and/or stillbirth from hypoxemia depending on the gestational age of onset. Emerging data show that at term, fetal Doppler arterial redistribution is associated more strongly with perinatal death than fetal size. Properly conducted trials of the role for maternal characteristics, fetal size, placental biomarkers, and Doppler assessing fetal well-being are required urgently.

The etiology of stillbirth over 30 years: A cross-sectional study in a tertiary referral unit

INTRODUCTION

Stillbirth remains an often unpredictable and devastating pregnancy outcome, and despite thorough investigation, the number of stillbirths attributable to unexplained causes remains high. Placental examination has become increasingly important where access to perinatal autopsy is limited. We aimed to examine the causes of stillbirth in normally formed infants over 30 years and whether a declining autopsy rate has affected our ability to determine a cause for stillbirths.

MATERIAL AND METHODS

All cases of normally formed singleton infants weighing ≥500 g that died prior to the onset of labor from 1989 to 2018 were examined. Trends for specific causes and uptake of perinatal autopsy were analyzed individually.

RESULTS

In all, 229 641 infants were delivered, with 840 stillbirths giving a rate of 3.66/1000. The rate of stillbirth declined from 4.84/1000 in 1989 to 2.51 in 2018 (P < .001). There was no difference in the rate of stillbirth between nulliparous and multiparous women (4.25 vs 3.66 per 1000, P = .026). Deaths from placental abruption fell (1.13/1000 in 1989 to 0 in 2018, P < .001) and the relative contribution of placental abruption to the incidence of stillbirth also fell, from 23.3% (7/30) in 1989 to 0.0% (0/19) in 2018 (P < .001). Stillbirth attributed to infection remained static (0.31/1000 in 1989 to 0.13 in 2018, P = .131), while a specific causal organism was found in 79.2% (42/53) of cases. Unexplained stillbirths decreased from 2.58/1000 (16/6200) in 1989 to 0.13 (1/7581) in 2018 (P < .001) despite a fall in the uptake of perinatal autopsy (96.7% [29/30] in 1989 to 36.8% (7/19) in 2018; P < .001). Placental disease emerged as a significant cause of stillbirth from 2004 onwards (89.5% [17/19] in 2018).

CONCLUSIONS

The present analysis is one of the largest single-center studies on stillbirth published to date. Stillbirth rates have fallen across the study period across parity. A decrease in deaths secondary to placental abruption contributed largely to this. Infection-related deaths are static; however, in one-fifth of cases a causative organism was not found. Despite a decreasing autopsy rate, the number of unexplained stillbirths continues to fall as the importance of placental pathology is increasingly recognized.

Identification of the optimal growth chart and threshold for the prediction of antepartum stillbirth

PURPOSE

To evaluate the effect of the choice growth chart and threshold used to define small for gestational age (SGA) on the predictive value of SGA for placenta-related or unexplained antepartum stillbirth.

METHODS

A retrospective cohort study of all women with a singleton pregnancy who gave birth > 24 week gestation in a single center (2000-2016). The exposure of interest was SGA, defined as birth weight < 10th or < 25th centile according to three fetal growth charts (Hadlock et al., Radiology 181:129-133, 1991; intergrowth-21st (IG21), WHO 2017, and a Canadian birthweight-based reference-Kramer et al., Pediatrics 108:E35, 2001). The outcome of interest was antepartum stillbirth due to placental dysfunction or unknown etiology. Cases of stillbirth attributed to other specific etiologies were excluded.

RESULTS

A total of 49,458 women were included in the cohort. There were 103 (0.21%) cases of stillbirth due to placental dysfunction or unknown etiology. For cases in the early stillbirth cluster (≤ 30 weeks), the detection rate was high and was similar for the three ultrasound-based fetal growth charts of Hadlock, IG21, and WHO (range 83.3-87.0%). In contrast, the detection rate of SGA for cases in the late stillbirth cluster (> 30 weeks) was low, being highest for WHO and Hadlock (36.7% and 34.7%, respectively), and lowest for IG21 (18.4%). Using a threshold of the 25th centile increased the detection rate for stillbirth by approximately 15-20% compared with that achieved by the 10th centile cutoff.

CONCLUSION

At > 30 week gestation, the Hadlock or WHO fetal growth charts provided the best balance between detection rate and false positive rate for stillbirth.

Stillbirth at term: Does size really matter?

Placental dysfunction has a deleterious influence on fetal size and is associated with higher rates of perinatal morbidity and mortality. This association underpins the strategy of fetal size evaluation as a mechanism to identify placental dysfunction and prevent stillbirth. The optimal method of routine detection of small for gestational age (SGA) remains to be clarified with choices between estimation of symphyseal-fundal height versus routine third-trimester ultrasound, various formulae for fetal weight estimation by ultrasound, and the variable use of national, customized, or international fetal growth references. In addition to these controversies, the strategy for detecting SGA is further undermined by data demonstrating that the relationship between fetal size and adverse outcome weakens significantly with advancing gestation such that near term, the majority of stillbirths and adverse perinatal outcomes occur in normally sized fetuses. The use of maternal serum biochemical and Doppler parameters near term appears to be superior to fetal size in the identification of fetuses compromised by placental dysfunction and at increased risk of damage or demise. Multiparameter models and predictive algorithms using maternal risk factors, and biochemical and Doppler parameters have been developed, but need to be prospectively validated to demonstrate their effectiveness.

Antenatal detection of fetal growth restriction and risk of stillbirth: population-based case-control study

OBJECTIVES

Antenatal surveillance of intrauterine growth aims to detect growth-restricted fetuses (FGR), which face increased risk of stillbirth. Improving their detection could be an effective strategy for prevention of stillbirth. The French REPERE study was conducted to estimate the association between antenatal detection of FGR and risk of stillbirth.

METHODS

REPERE is a case-control study performed in three French districts with a combined total of approximately 30 000 births annually. Cases were singleton small-for-gestational-age (SGA) stillbirths ≥ 24 weeks' gestation and without severe congenital anomaly, between 2012 and 2014, identified using a population-based stillbirth registry; controls were live births fulfilling the same inclusion criteria over a 9-week period from 7 April to 8 June 2014. Data were extracted by trained investigators from medical records and ultrasound reports. SGA was defined as birth weight < 10^th percentile of French customized standards. FGR was defined by the presence of at least one of seven predefined parameters (suspected FGR mentioned in medical records or in ultrasound report, suspected faltering growth mentioned in an ultrasound report, documented abdominal circumference or estimated fetal weight < 10^th percentile, referral for additional ultrasound examination to monitor growth or abnormal umbilical artery Doppler). We used logistic regression to estimate crude and adjusted odds ratios (ORs) for the association between detection of FGR and risk of stillbirth. Included covariables were parity, maternal medical history, vascular complications during pregnancy and birth-weight percentile, which are known to be associated with risk of detection of FGR and of stillbirth.

RESULTS

During the study period, there were 92 182 births ≥ 22 weeks' gestation, including 669 stillbirths, of which 79 were singleton SGA stillbirths ≥ 24 weeks and without severe congenital anomaly. Of these cases, 44.3% (35/79) had FGR detected, compared with a detection rate of 36.2% in controls (154/426). The crude OR expressing the association between detection of FGR and risk of stillbirth was 1.4 (95% CI, 0.9-2.3) and the OR adjusted for parity, presence of risk factors for FGR, presence of vascular disorder and birth-weight percentile was 0.6 (95% CI, 0.3-1.0). Among deliveries ≥ 28 weeks, detection rates were 38.3% vs 36.0% for cases and controls, with an adjusted OR of 0.5 (95% CI, 0.2-1.0).

CONCLUSION

Antenatal detection of FGR was protective against stillbirth, but over 40% of stillbirths among SGA fetuses occurred despite detection of FGR, pointing to the need to improve management following detection. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

An evaluation of the potential to improve perinatal outcomes by improving antenatal detection of small for gestational age babies in Scotland: a retrospective population cohort study

Background: Small for gestational age (SGA) babies are at high risk of perinatal mortality. We aimed to determine the potential to reduce perinatal mortality by improving antenatal detection of SGA babies in Scotland. Methods: We conducted a retrospective population study of all singleton SGA babies born in the 15 Consultant-led maternity units in Scotland in a 3-month period (1st Dec 2014 to 28th Feb 2015 inclusive).  Demographic and pregnancy outcome data were extracted from Scottish birth records for all pregnancies; case note review was performed for all SGA cases [defined as birthweight less than the 10th centile for their gestational age at delivery as defined by the appropriate sex-specific UK-WHO Child Growth Standards]. Results: The SGA rate in Scotland was 5.5% (673/12218; 95% confidence interval [CI] 5.1, 5.9) and 27.6% (186/673; 95% CI 24.3, 31.2) of SGA cases were identified prior to delivery. SGA was associated with 18.2% (12/66; 95% CI [10.1%, 30.0%) of all perinatal deaths. The majority (10/12, 83.3%) of SGA babies who died had been identified as SGA in the antenatal period. There was no difference in perinatal mortality whether SGA was detected or not (5.4% [10/186; 95% CI 2.8, 10.0] in the SGA detected group vs 0.4% [2/487 [95% CI 0.3, 2.2] in the non-detected group after adjusting for risk factors for SGA, gestation at delivery and birthweight centile (Adjusted odds ratio [AOR] 0.85 [95% CI 0.5, 1.5], p=0.556). Conclusions: Despite only around a quarter of SGA babies being identified antenatally, the potential to reduce perinatal mortality in the Scottish population by improving SGA detection is limited. Only a minority of perinatal deaths occurred in SGA babies; and in the majority of these SGA was detected antenatally.

Maceration determines diagnostic yield of fetal and neonatal whole body post-mortem ultrasound

OBJECTIVES

To determine factors in nondiagnostic fetal and neonatal post-mortem ultrasound (PMUS) examinations.

METHODS

All fetal and neonatal PMUS examinations were included over a 5-year study period (2014-2019). Nondiagnostic image quality by body parts (brain, spine, thorax, cardiac, and abdomen) was recorded and correlated with patient variables. Descriptive statistics and logistic regression analyses were performed to identify significant factors for nondiagnostic studies.

RESULTS

Two hundred sixty-five PMUS examinations were included, with median gestational age of 22 weeks (12-42 wk), post-mortem weight of 363 g (16-4033 g), and post-mortem interval of 8 days (0-39 d). Diagnostic imaging quality was achieved for 178/265 (67.2%) studies. It was high for abdominal (263/265, 99.2%), thoracic (264/265, 99.6%), and spine (265/265, 100%) but lower for brain (210/265, 79.2%) and cardiac imaging (213/265, 80.4%). Maceration was the best overall predictor for nondiagnostic imaging quality (P < .0001). Post-mortem fetal weight was positively associated with cardiac (P = .0133) and negatively associated with brain imaging quality (P = .0002). Post-mortem interval was not a significant predictor.

CONCLUSIONS

Fetal maceration was the best predictor for nondiagnostic PMUS, particularly for brain and heart. Fetuses with marked maceration and suspected cardiac or brain anomalies should be prioritised for post-mortem MRI.

Clinical significance of cerebroplacental ratio

PURPOSE OF REVIEW

Two-thirds of the pregnancies complicated by stillbirth demonstrate growth restriction. Identification of the foetus at risk of growth restriction is essential to reduce the risk of stillbirth. The aim of this review is to critically appraise the current evidence regarding clinical utility of cerebroplacental ratio (CPR) in antenatal surveillance.

RECENT FINDINGS

The CPR has emerged as an assessment tool for foetuses at increased risk of growth disorders. CPR is a better predictor of adverse events compared with middle-cerebral artery or umbilical artery Doppler alone. The predictive value of CPR for adverse perinatal outcomes is better for suspected small-for-gestational age foetuses compared with appropriate-for-gestational age (AGA) foetuses. CPR could be useful for the risk stratification of small-for-gestational age foetuses to determine the timing of delivery and also to calculate the risk of intrapartum compromise or prolonged admission to the neonatal care unit. Although there are many proposed cut-offs for an abnormal CPR value, evidence is currently lacking to suggest the use of one cut-off over another. CPR appears to be associated with increased risk of intrapartum foetal compromise, abnormal growth velocity, and lower birthweight in AGA foetuses as well. Moreover, birthweight differences are better explained with CPR compared to other factors such as ethnicity. However, the role of CPR in predicting adverse perinatal outcomes such as acidosis or low Apgar scores in AGA foetuses is yet to be determined.

SUMMARY

CPR appears to be a useful surrogate of suboptimal foetal growth and intrauterine hypoxia and it is associated with a variety of perinatal adverse events.

Mechanisms of death in structurally normal stillbirths

Objectives To investigate mechanisms of in utero death in normally formed fetuses by measuring amniotic fluid (AF) biomarkers for hypoxia (erythropoietin [EPO]), myocardial damage (cardiac troponin I [cTnI]) and brain injury (glial fibrillary acidic protein [GFAP]), correlated with risk factors for fetal death and placental histopathology. Methods This retrospective, observational cohort study included intrauterine deaths with transabdominal amniocentesis prior to induction of labor. Women with a normal pregnancy and an indicated amniocentesis at term were randomly selected as controls. AF was assayed for EPO, cTnI and GFAP using commercial immunoassays. Placental histopathology was reviewed, and CD15-immunohistochemistry was used. Analyte concentrations >90th centile for controls were considered "raised". Raised AF EPO, AF cTnI and AF GFAP concentrations were considered evidence of hypoxia, myocardial and brain injury, respectively. Results There were 60 cases and 60 controls. Hypoxia was present in 88% (53/60), myocardial damage in 70% (42/60) and brain injury in 45% (27/60) of fetal deaths. Hypoxic fetuses had evidence of myocardial injury, brain injury or both in 77% (41/53), 49% (26/53) and 13% (7/53) of cases, respectively. Histopathological evidence for placental dysfunction was found in 74% (43/58) of these cases. Conclusion Hypoxia, secondary to placental dysfunction, was found to be the mechanism of death in the majority of fetal deaths among structurally normal fetuses. Ninety-one percent of hypoxic fetal deaths sustained brain, myocardial or both brain and myocardial injuries in utero. Hypoxic myocardial injury was an attributable mechanism of death in 70% of the cases. Non-hypoxic cases may be caused by cardiac arrhythmia secondary to a cardiac conduction defect.

Is it possible to predict late antepartum stillbirth by means of cerebroplacental ratio and maternal characteristics?

Objective: To examine the potential value of fetal ultrasound and maternal characteristics in the prediction of antepartum stillbirth after 32 weeks' gestation.Methods: This was a retrospective multicenter study in Spain. In 29 pregnancies, umbilical artery pulsatility index (UA PI), middle cerebral artery pulsatility index (MCA PI), cerebroplacental ratio (CPR), estimated fetal weight (EFW), and maternal characteristics were recorded within 15 days prior to a stillbirth. The values of UA PI, MCA PI, and CPR were converted into multiples of the normal median (MoM) for gestational age and the EFW was expressed as percentile according to a Spanish reference range for gestational age. Data from the 29 pregnancies with stillbirths and 2298 control pregnancies resulting in livebirths were compared and multivariate logistic regression analysis was used to determine significant predictors of stillbirth.Results: The only significant predictor of stillbirth was CPR (OR = 0.161, 95% confidence interval [CI] 0.035, 0.654; p = .014); the area under the receiver operating characteristics curve was 0.663 (95% CI 0.545, 0.782) and the detection rate (DR) was 32.14% at a 10% false-positive rate (FPR). In addition, when we included MCA and UA PI MoM instead of CPR, only MCA PI MoM was significant (OR = 0.104, 95% confidence interval [CI] 0.013, 0.735; p = .029), with similar prediction abilities (area under the curve (AUC) 0.645, DR 28.6%, FPR 10%).Conclusions: The CPR and MCA PI are predictors of late stillbirth but the performance of prediction is poor.

Perinatal loss at term: role of uteroplacental and fetal Doppler assessment

OBJECTIVE

To examine the associations of uterine artery (UtA) Doppler indices and cerebroplacental ratio (CPR) with perinatal outcome at term.

METHODS

This was a retrospective cohort study conducted at a tertiary referral center that included all singleton pregnancies undergoing ultrasound assessment in the third trimester that subsequently delivered at term. Fetal biometry and Doppler assessment, including that of the umbilical artery (UA), fetal middle cerebral artery (MCA) and UtA, were recorded. Data were corrected for gestational age, and CPR was calculated as the ratio of MCA pulsatility index (PI) to UA-PI. Logistic regression analysis was conducted to examine for independent predictors of adverse perinatal outcome.

RESULTS

The study included 7013 pregnancies, 12 of which were complicated by perinatal death. When compared with pregnancies resulting in perinatal survival, pregnancies complicated by perinatal death had a significantly higher proportion of small-for-gestational-age infants (25.0% vs 5%; P = 0.001) and a higher incidence of low (< 5^th centile) CPR (16.7% vs 4.5%; P = 0.041). A subgroup analysis comparing 1527 low-risk pregnancies that resulted in fetal survival with pregnancies complicated by perinatal death demonstrated that UtA-PI multiples of the median (MoM), CPR < 5^th centile and estimated fetal weight (EFW) centile were all associated significantly with the risk of perinatal death at term (all P < 0.05). After adjusting for confounding variables, only EFW centile (odds ratio (OR) 0.96 (95% CI, 0.93-0.99); P = 0.003) and UtA-PI MoM (OR 13.10 (95%CI, 1.95-87.89); P = 0.008) remained independent predictors of perinatal death in the low-risk cohort.

CONCLUSION

High UtA-PI at term is associated independently with an increased risk of adverse perinatal outcome, regardless of fetal size. These results suggest that perinatal mortality at term is related not only to EFW and fetal redistribution (CPR), but also to indices of uterine perfusion. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Small for gestational age and perinatal mortality at term: An audit in a Dutch national cohort study

OBJECTIVE

To assess the underlying risk factors for perinatal mortality in term born small for gestational age infants.

STUDY DESIGN

We performed a population based nationwide cohort study in the Netherlands of 465,532 term born infants from January 2010 to January 2013. Logistic regression analyses were performed. Also audit results were studied for detailed care information.

RESULTS

We studied 162 small for gestational age infants who died in the perinatal period. Risk factors were: gestational age at 37completed weeks (adjusted Odds Ratio (aOR) 2.6, 95% Confidence Interval (CI) 1.6-4.3), male gender (aOR 1.4, 95% CI 1.01-1.9), South Asian ethnicity (aOR 3.6, 95% CI 1.6-8.4), African (aOR 3.5, 95% CI 1.9-6.5) and other non-Western ethnicity (aOR 1.9, CI 1.2-3.1). At 37 completed weeks gestation audit results showed that 26% of the women smoked, 91% were boys and in all but one case death occurred before birth. In 61% of all deceased SGA infants born at 37 completed weeks gestation referral from primary care by independent midwives to the obstetrician took place because of antepartum death before labor.

CONCLUSIONS

Gestational age of 37 completed weeks, male gender, South Asian, African or other non-Western ethnicity and smoking are associated with perinatal mortality in SGA infants. These risk factors concern the complete term population starting at 37 weeks or even earlier. Therefore, it is of utmost importance to develop accurate diagnostic tests to screen for SGA before 36 weeks gestation to prevent perinatal mortality at term in SGA infants.

Examining the link between placental pathology, growth restriction, and stillbirth

Stillbirth, often defined as death of a fetus ≥20 weeks of gestation, is emotionally devastating for families and caregivers. It is often associated with fetal growth restriction (FGR). Indeed, FGR or small-for-gestational age fetus (SGA) is a major risk factor for stillbirth. In rare cases, this is due to genetic abnormalities or infections. However, in most cases, it is linked to placental insufficiency. This may be due to abnormal placental development or placental damage, thereby resulting in decreased blood flow, oxygen, and nutrients to the fetus. Several placental histological abnormalities are associated with stillbirth, FGR, or both. Most involve vascular abnormalities but some are inflammatory lesions. This paper reviews evidence regarding the relationships between placental function and pathology, FGR, and stillbirth. Issues with clinical relevance, knowledge gaps, and areas for further research are highlighted.

Reduced fetal movements and cerebroplacental ratio: evidence for worsening fetal hypoxemia

OBJECTIVE

To investigate the fetal cerebroplacental ratio (CPR) in women presenting with reduced fetal movements (RFM).

METHODS

This was a retrospective cohort study of data collected over an 8-year period at a fetal medicine unit at a tertiary referral center. The cohort comprised 4500 singleton pregnancies presenting with RFM at or after 36 weeks' gestation and 1527 control pregnancies at a similar gestational age without RFM. Fetal biometry and Doppler parameters were recorded and converted into centiles and multiples of the median (MoM). CPR was defined as the ratio between the fetal middle cerebral artery (MCA) pulsatility index (PI) and the umbilical artery (UA) PI. Subgroup analysis for fetal size and for single vs multiple episodes of RFM was performed.

RESULTS

Compared with controls, pregnancies with RFM had lower MCA-PI MoM (median, 0.95 vs 0.97; P < 0.001) and CPR MoM (median, 0.97 vs 0.99; P = 0.018). Compared with women presenting with single episodes of RFM, pregnancies with multiple episodes (≥ 2 episodes) had lower CPR MoM (median, 0.94 vs 0.98; P = 0.003). On subgroup analysis for fetal size, compared with controls, appropriate-for-gestational-age fetuses in the RFM group had lower MCA-PI MoM (median, 0.96 vs 0.97; P = 0.003) and higher rate of CPR below the 5^th centile (5.3% vs 3.6%; P = 0.015). Logistic regression analysis demonstrated an association of risk of recurrent RFM with maternal age (OR, 0.96; 95% CI, 0.93-0.99), non-Caucasian ethnicity (OR, 0.72; 95% CI, 0.53-0.97), estimated fetal weight centile (OR, 1.01; 95% CI, 1.00-1.02) and CPR MoM (OR, 0.24; 95% CI, 0.12-0.47).

CONCLUSION

Pregnancies complicated by multiple episodes of RFM show significantly lower CPR MoM and MCA-PI MoM compared with those with single episodes and controls. This is likely to be due to worsening fetal hypoxemia in women presenting with recurrent RFM. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Fetal and neonatal outcomes of preterm infants born before 32 weeks of gestation according to antenatal vs postnatal assessments of restricted growth

BACKGROUND

Fetal growth restriction is defined using ultrasound parameters during pregnancy or as a low birthweight for gestational age after birth, but these definitions are not always concordant.

OBJECTIVE

The purpose of this study was to investigate fetal and neonatal outcomes based on antenatal vs postnatal assessments of growth restriction.

STUDY DESIGN

From the EPIPAGE 2 population-based prospective study of very preterm births in France in 2011, we included 2919 singleton nonanomalous infants 24-31 weeks gestational age. We constituted 4 groups based on whether the infant was suspected with fetal growth restriction during pregnancy and/or was small for gestational age with a birthweight <10th percentile of intrauterine norms by sex: 1) suspected with fetal growth restriction/small for gestational age 2) not suspected with fetal growth restriction/small for gestational age 3) suspected with fetal growth restriction/not small for gestational age and 4) not suspected with fetal growth restriction/not small for gestational age. We estimated relative risks of perinatal mortality and morbidity for these groups adjusting for maternal and neonatal characteristics.

RESULTS

We found that 22.2% of infants were suspected with fetal growth restriction/small for gestational age, that 11.4% infants were not suspected with fetal growth restriction/small for gestational age, that 3.0% infants were suspected with fetal growth restriction/not small for gestational age, and that 63.4% infants were not suspected with fetal growth restriction/not small for gestational age. Compared with infants who were not suspected with fetal growth restriction/not small-for-gestational-age infants, small-for-gestational-age infants suspected and not suspected with fetal growth restriction had higher risks of stillbirth or termination of pregnancy (adjusted relative risk, 2.0 [95% confidence interval, 1.6-2.5] and adjusted relative risk, 2.8 [95% confidence interval, 2.2-3.4], respectively), in-hospital death (adjusted relative risk, 2.8 [95% confidence interval, 2.0-3.7] and adjusted relative risk, 2.0 [95% confidence interval, 1.5-2.8], respectively), and bronchopulmonary dysplasia (adjusted relative risk, 1.3 [95% confidence interval, 1.2-1.4] and adjusted relative risk, 1.3 [95% confidence interval, 1.1-1.4], respectively), but not severe brain lesions. Risks were not increased for infants suspected with fetal growth restriction but not small-for-gestational-age.

CONCLUSION

Antenatal and postnatal assessments of fetal growth restriction were not concordant for 14% of very preterm infants. In these cases, birthweight appears to be the more relevant parameter for the identification of infants with higher risks of adverse short-term outcomes.

Stillbirth and intrauterine fetal death: factors affecting determination of cause of death at autopsy

OBJECTIVES

There have been several attempts to classify cause of death (CoD) in stillbirth; however, all such systems are subjective, allowing for observer bias and making comparisons between systems challenging. This study aimed to examine factors relating to determination of CoD using a large dataset from two specialist centers in which observer bias had been reduced by classifying findings objectively and assigning CoD based on predetermined criteria.

METHODS

Detailed autopsy reports from intrauterine deaths in the second and third trimesters during 2005-2013 were reviewed and findings entered into a specially designed database, in which CoD was assigned using predefined objective criteria. Data regarding CoD categories and factors affecting determination of CoD were examined.

RESULTS

There were 1064 intrauterine deaths, including 246 early intrauterine fetal deaths (IUFD) (< 20 weeks), 179 late IUFDs (20-23 weeks) and 639 stillbirths (≥ 24 weeks' gestation). Overall, around 40% (n = 412) had a clear CoD identified, whilst around 60% (n = 652) were classified as 'unexplained', including around half with identified risk factors or lesions of uncertain significance, with the remaining half (n = 292 (45%)) being entirely unexplained. A stepwise increase in the proportion of unexplained deaths was observed with increasing maceration. Black and Asian women had significantly greater proportions of deaths due to ascending infection, whilst women aged over 40 years had significantly increased placenta-related CoDs. There was no significant difference in CoD distribution according to maternal body mass index or with increasing postmortem interval. Around half of those with an identifiable CoD could be identified from clinical review and external fetal examination or imaging, with most of the remainder being determined following placental examination.

CONCLUSIONS

Based on objective criteria, many intrauterine deaths throughout gestation remain unexplained despite autopsy examination. The rate of unexplained death varies from around 30% to 60% depending on interpretation of the significance of features. CoD determination is dependent on both the classification system used and subjective interpretation, such that variation in the proportion of 'unexplained' cases is based largely on speculation regarding mechanisms of death. Novel methods to determine objectively the mechanism of death at postmortem examination are required. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.