Umbilical cord accidents: human studies

Morphometric Evaluation of Human Placental and Umbilical Cord for Neonatal Indices: A Cross-Sectional Study

BACKGROUND

In India, there is only limited data on studies related to umbilical cord and placental indices in newborn infants. The present study was undertaken to evaluate the morphometric analysis of placental and umbilical cord indices and their association with length, weight, and head size in newborns.

MATERIALS AND METHODS

This was a longitudinal cross-sectional study conducted on placentas and fetal measures from 245 women who gave birth during the study period. The placental variables, umbilical cord indices, and neonatal indices were measured. The association between the parameters was done using Pearson's correlation, and p<0.05 was considered statistically significant.  Results: The placental weight (p=0.01) and placental volume (p=0.01) showed a significant positive correlation with newborn weight. The mean placental diameter was 16.32 ± 1.54 cm, and there was no significant correlation between placental diameter and infant weight (p=0.232), length (p=0.658), or head circumference (0.842). In addition, there was a significant association between placental diameter, placental volume (p=0.000), and placental weight (p=0.000). There was a significant positive correlation (p<0.05) between ponderable index and birth weight, length, and head circumference.

CONCLUSION

Placental weight and newborn weight were significantly associated in this study. The length of the umbilical cord was found to be related to placental weight. So, placental measurements are reliable indicators for the assessment of fetal wellbeing.

Single umbilical artery and risk of congenital malformation: population-based study in Norway

OBJECTIVES

Single umbilical artery (SUA) is associated with congenital malformations in most organ systems, but reported findings have not been consistent. While it has been suggested that genetic and persisting environmental factors influence the development of SUA, it is not known whether there is an increased risk of recurrence in a subsequent pregnancy of the same woman. The aims of this study were to investigate the occurrence of, and risk factors for, SUA in Norway, to assess its association with congenital malformations and trisomies 13, 18 and 21 and to study the risk of recurrence of SUA in subsequent pregnancies.

METHODS

This was a population-based study of all (n = 918 933) singleton pregnancies of > 16 weeks' gestation recorded in the Medical Birth Registry of Norway from 1999 to 2014. To identify risk factors and congenital malformations associated with SUA, generalized estimating equations and logistic regression were used to calculate odds ratios (OR) with 95% CIs. ORs were also calculated for the recurrence of SUA in subsequent pregnancy.

RESULTS

The occurrence of SUA in our population was 0.46% (4241/918 933). Parity ≥ 4, smoking, maternal pregestational diabetes, epilepsy, chronic hypertension, previous Cesarean delivery and conception by assisted reproductive technology increased the odds of having SUA. There was a particularly strong association between SUA and gastrointestinal atresia or stenosis in the neonate, with ORs of 25.8 (95% CI, 17.0-39.1) and 20.3 (95% CI, 13.4-30.9) for esophageal and anorectal atresia or stenosis, respectively, followed by an OR of 5.9 (95% CI, 1.9-18.5) for renal agenesis. SUA was associated with an up to 7-8 times increased risk of congenital heart defects. There was an association with microcephaly, congenital hydrocephalus and other congenital malformations of the brain and spinal cord. Diaphragmatic hernia, limb reductions and cleft lip or palate had a weaker association with SUA, with ORs ranging from 4.8 to 2.8. The associations with trisomy 18 and 13 were equally strong (OR 14.4 (95% CI, 9.3-22.4) and OR 13.6 (95% CI, 6.7-27.8), respectively), and the risk of trisomy 21 was doubled (OR 2.1 (95% CI, 1.2-3.6)). Pregnancies with SUA, with or without an associated malformation, had a 2-fold increased risk for SUA in a subsequent pregnancy.

CONCLUSIONS

SUA is associated strongly with gastrointestinal atresia or stenosis, suggesting common developmental mechanisms. The increased risk of recurrence of SUA suggests that genetic and/or persisting environmental factors influence the risk. We found that SUA had equally strong associations with trisomies 13 and 18. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Isolated single umbilical artery and the risk of adverse perinatal outcome and third stage of labor complications: A population-based study

INTRODUCTION

Isolated single umbilical artery (iSUA) refers to single umbilical artery cords with no other fetal malformations. The association of iSUA to adverse outcome of pregnancy has not been consistently reported, and whether iSUA carries increased risk of third stage of labor complications has not been studied. We aimed to investigate the risk of adverse perinatal outcome, third stage of labor complications, and associated placental and cord characteristics in pregnancies with iSUA. A further aim was to assess the risk of recurrence of iSUA and anomalous cord or placenta characteristics in Norway.

MATERIAL AND METHODS

This was a population-based study of all singleton pregnancies with gestational age >16 weeks at birth using data from the Medical Birth Registry of Norway from 1999 to 2014 (n = 918 933). Odds ratios (OR) with 95% confidence intervals were calculated for adverse perinatal outcome (preterm birth, perinatal and intrauterine death, low Apgar score, transferral to neonatal intensive care ward, placental and cord characteristics [placental weight, cord length and knots, anomalous cord insertion, placental abruption and previa]), and third stage of labor complications (postpartum hemorrhage and the need for manual placental removal or curettage) in pregnancies with iSUA, and recurrence of iSUA using generalized estimating equations and logistic regression.

RESULTS

Pregnancies with iSUA carried increased risk of adverse perinatal outcome (OR 5.06, 95% confidence interval [CI] 4.26-6.02) and perinatal and intrauterine death (OR 5.62, 95% CI 4.69-6.73), and a 73% and 55% increased risk of preterm birth and small-for-gestational-age neonate, respectively. The presence of iSUA also carried increased risk of a small placenta, placenta previa and abruption, anomalous cord insertion, long cord, cord knot and third stage of labor complications. Women with iSUA, long cord or anomalous cord insertion in one pregnancy carried increased risk of iSUA in the subsequent pregnancy.

CONCLUSIONS

The presence of ISUA was associated with a more than five times increased risk of intrauterine and perinatal death and with placental and cord complications. The high associated risk of adverse outcome justifies follow up with assessment of fetal wellbeing in the third trimester, intrapartum surveillance and preparedness for third stage of labor complications.

Aetiology and trends of rates of stillbirth in a tertiary care hospital in the north of India over 10 years: a retrospective study

OBJECTIVE

To analyse the aetiology of stillbirth and its changing trends in a single tertiary care referral institute of northern India over a 10-year period (2007-2016).

DESIGN

Retrospective study.

SETTING

Tertiary care hospital in the north of India.

SAMPLE

Medical records of all mothers who delivered a stillborn at the institute.

METHODS

Data was collected from monthly and annual perinatal audits and causes of stillbirths were classified using Simplified CODAC classification. Annual reduction rate was calculated by linear regression analysis and Cusick test for the changing trends over 9 years.

MAIN OUTCOME MEASURES

Of 54 160 births, 3678 babies were stillborn. Over 9 years, the annual stillbirth rate has reduced significantly from 73.6 to 62.0 per 1000 total births with an average annual reduction rate of 1%. The most common causes of stillbirths were hypertensive disorders of pregnancy (27.6%), antepartum haemorrhage (19.5%), and congenital anomalies (9.3%).

CONCLUSION

The annual reduction rate (1%) of stillbirth remains low. The aetiology of stillbirths remains unchanged over a 10-year period and hypertensive disorder of pregnancy remains the single most preventable cause of stillbirth.

TWEETABLE ABSTRACT

Analysis of stillbirths over a 10-year period in an Indian institute showed a high but declining trend with annual reduction rate of 1%.

The prediction of fetal death with a simple maternal blood test at 20-24 weeks: a role for angiogenic index-1 (PlGF/sVEGFR-1 ratio)

BACKGROUND

Fetal death is an obstetrical syndrome that annually affects 2.4 to 3 million pregnancies worldwide, including more than 20,000 in the United States each year. Currently, there is no test available to identify patients at risk for this pregnancy complication.

OBJECTIVE

We sought to determine if maternal plasma concentrations of angiogenic and antiangiogenic factors measured at 24-28 weeks of gestation can predict subsequent fetal death.

STUDY DESIGN

A case-cohort study was designed to include 1000 randomly selected subjects and all remaining fetal deaths (cases) from a cohort of 4006 women with a singleton pregnancy, enrolled at 6-22 weeks of gestation, in a pregnancy biomarker cohort study. The placentas of all fetal deaths were histologically examined by pathologists who used a standardized protocol and were blinded to patient outcomes. Placental growth factor, soluble endoglin, and soluble vascular endothelial growth factor receptor-1 concentrations were measured by enzyme-linked immunosorbent assays. Quantiles of the analyte concentrations (or concentration ratios) were estimated as a function of gestational age among women who delivered a live neonate but did not develop preeclampsia or deliver a small-for-gestational-age newborn. A positive test was defined as analyte concentrations (or ratios) <2.5th and 10th centiles (placental growth factor, placental growth factor/soluble vascular endothelial growth factor receptor-1 [angiogenic index-1] and placental growth factor/soluble endoglin) or >90th and 97.5th centiles (soluble vascular endothelial growth factor receptor-1 and soluble endoglin). Inverse probability weighting was used to reflect the parent cohort when estimating the relative risk.

RESULTS

There were 11 fetal deaths and 829 controls with samples available for analysis between 24-28 weeks of gestation. Three fetal deaths occurred <28 weeks and 8 occurred ≥28 weeks of gestation. The rate of placental lesions consistent with maternal vascular underperfusion was 33.3% (1/3) among those who had a fetal death <28 weeks and 87.5% (7/8) of those who had this complication ≥28 weeks of gestation. The maternal plasma angiogenic index-1 value was <10th centile in 63.6% (7/11) of the fetal death group and in 11.1% (92/829) of the controls. The angiogenic index-1 value was <2.5th centile in 54.5% (6/11) of the fetal death group and in 3.7% (31/829) of the controls. An angiogenic index-1 value <2.5th centile had the largest positive likelihood ratio for predicting fetal death >24 weeks (14.6; 95% confidence interval, 7.7-27.7) and a relative risk of 29.1 (95% confidence interval, 8.8-97.1), followed by soluble endoglin >97.5th centile and placental growth factor/soluble endoglin <2.5th, both with a positive likelihood ratio of 13.7 (95% confidence interval, 7.3-25.8) and a relative risk of 27.4 (95% confidence interval, 8.2-91.2). Among women without a fetal death whose plasma angiogenic index-1 concentration ratio was <2.5th centile, 61% (19/31) developed preeclampsia or delivered a small-for-gestational-age neonate; when the 10th centile was used as the cut-off, 37% (34/92) of women had these adverse outcomes.

CONCLUSION

(1) A maternal plasma angiogenic index-1 value <2.5th centile (0.126) at 24-28 weeks of gestation carries a 29-fold increase in the risk of subsequent fetal death and identifies 55% of subsequent fetal deaths with a false-positive rate of 3.5%; and (2) 61% of women who have a false-positive test result will subsequently experience adverse pregnancy outcomes.

Fetal death: an extreme manifestation of maternal anti-fetal rejection

OBJECTIVE

The aim of this study was to determine the association between chronic placental inflammation and amniotic fluid (AF) markers of maternal anti-fetal rejection as well as the presence of microorganisms in the AF fluid of patients with fetal death.

STUDY DESIGN

This cohort study included 40 patients with fetal death whose placentas were examined for chronic inflammatory lesions and whose AF chemokine ligand (CXCL)10 and interleukin (IL)-6 concentrations were determined by immunoassays. AF was processed for bacteria, mycoplasmas and viruses using cultivation and molecular microbiologic techniques (i.e. PCR-ESI/MS).

RESULTS

(1) The most prevalent placental findings were maternal vascular underperfusion (63.2%, 24/38), followed by chronic inflammatory lesions (57.9%, 22/38); (2) chronic chorioamnionitis (18/38) was three times more frequent than villitis of unknown etiology (6/38); (3) an elevated AF CXCL10 concentration (above the 95th centile) was present in 60% of the cases, and a receiver operating characteristics (ROC)-derived cut-off of 2.9 ng/mL had a sensitivity of 73% and a specificity of 75% in the identification of chronic placental inflammatory lesions; (4) only five cases had microbial invasion of the amniotic cavity, and the presence of microorganisms did not correlate with chronic placental inflammation.

CONCLUSION

In women with unexplained fetal death, there is an association between elevated AF CXCL10 and chronic placental inflammatory lesions. Therefore, we conclude that a subset of patients with fetal death may have endured a breakdown of maternal-fetal tolerance, which cannot be attributed to microorganisms in the amniotic cavity.

Understanding determinants of unequal distribution of stillbirth in Tehran, Iran: a concentration index decomposition approach

OBJECTIVE

The present inquiry set to determine the economic inequality in history of stillbirth and understanding determinants of unequal distribution of stillbirth in Tehran, Iran.

METHODS

A population-based cross-sectional study was conducted on 5170 pregnancies in Tehran, Iran, since 2015. Principal component analysis (PCA) was applied to measure the asset-based economic status. Concentration index was used to measure socioeconomic inequality in stillbirth and then decomposed into its determinants.

RESULTS

The concentration index and its 95% CI for stillbirth was -0.121 (-0.235 to -0.002). Decomposition of the concentration index showed that mother's education (50%), mother's occupation (30%), economic status (26%) and father's age (12%) had the highest positive contributions to measured inequality in stillbirth history in Tehran. Mother's age (17%) had the highest negative contribution to inequality.

CONCLUSIONS

Stillbirth is unequally distributed among Iranian women and is mostly concentrated among low economic status people. Mother-related factors had the highest positive and negative contributions to inequality, highlighting specific interventions for mothers to redress inequality.

Sex, drugs and rock and roll: tales from preterm fetal life

Premature fetuses and babies are at greater risk of mortality and morbidity than their term counterparts. The underlying causes are multifactorial, but include exposure to hypoxia. Immaturity of organs and their functional control may impair the physiological defence responses to hypoxia and the preterm fetal responses, or lack thereof, to moderate hypoxia appear to support this concept. However, as this review demonstrates, despite immaturity, the preterm fetus responds to asphyxia in a qualitatively similar manner to that seen at term. This highlights the importance in understanding metabolism versus homeostatic threat when assessing fetal responses to adverse challenges such as hypoxia. Data are presented to show that the preterm fetal adaptation to asphyxia is triphasic in nature. Phase one represents the rapid institution of maximal defences, designed to maintain blood pressure and central perfusion at the expense of peripheral organs. Phase two is one of adaptive compensation. Controlled reperfusion partially offsets peripheral tissue oxygen debt, while maintaining sufficient vasoconstriction to limit the fall in perfusion. Phase three is about decompensation. Strikingly, the preterm fetus generally performs better during phases two and three, and can survive for longer without injury. Paradoxically, however, the ability to survive can lead to longer exposure to hypotension and hypoperfusion and thus potentially greater injury. The effects of fetal sex, inflammation and drugs on the triphasic adaptations are reviewed. Finally, the review highlights the need for more comprehensive studies to understand the complexity of perinatal physiology if we are to develop effective strategies to improve preterm outcomes.

Association of coexisting morphological umbilical cord abnormality and clinical cord compromise with hypoxic and thrombotic placental histology

To assess the usefulness and limitations of placental histology when morphological umbilical cord (UC) abnormality coexists with clinical UC compromise, 5634 consecutive placentas were divided into four groups and statistically compared: group 1-182 placentas from pregnancies with clinical features of UC compromise (variable decelerations, UC entanglement, prolapse, or true knot at delivery); group 2-1355 placentas with abnormal UC morphology or insertion; group 3-152 placentas with at least one phenotype from group 1 and one from group 2; group 4-3945 placentas with no clinical or morphological UC-related phenotypes (control group).Differences were analyzed by ANOVA or χ (2). Of 68 phenotypes studied, 13 clinical and 18 placental phenotypes were statistically significant. In group 1, 2 phenotypes were most common (oligohydramnios and abnormal fetal heart rate tracing). In group 2, 6 phenotypes were most common, including 4 clinical (abnormal umbilical artery Dopplers, nonmacerated stillbirth, multiple pregnancy, and fetal growth restriction) and 2 placental. In group 3, 23 phenotypes were most common, including 7 clinical (gestational hypertension, polyhydramnios, induction of labor, cesarean section, macerated stillbirth, congenital malformations, and abnormal 3rd stage of labor) and 16 placental. The existence of clinical signs of UC compromise alone was associated with the absence of pathomorphological placental abnormalities. However, the coexistence of clinical and abnormal morphological UC phenotypes was statistically significantly associated with placental histological signs of decreased fetal blood flow, hypoxia (acute and chronic post uterine), shallow placental implantation, and/or amnion nodosum. Thus, confirmation of clinical UC compromise should not be expected on placental examination if no morphological UC abnormality or abnormal UC insertion has been found.

Pathology of the stillborn infant for the general pathologist: part 1

As the information obtained from previable fetal and stillbirth autopsies is used not only to explain the loss to the parents, but for future pregnancy planning, general pathologists need to be comfortable in dealing with these autopsies. The importance of an adequate fetal examination has been emphasized in a recent policy on the subject by the American Board of Pathology http://www.abpath.org/FetalAutopsyPolicy.pdf. This review paper covers the approach to the fetal and stillbirth autopsy. This first article covers the approach to the nonanomalous and anomalous autopsy. Hydrops fetalis will be covered in the second part of this series to be published subsequently.

Umbilical cord accidents and legal implications

Umbilical cord accidents (UCA) are a significant cause of stillbirth. Although infrequent, litigation may occur when there is a poor outcome associated with UCA. With advances in imaging, the ability to identify UCA by ultrasound and magnetic resonance imaging raises awareness of the risk of a poor outcome. Management of a pregnancy with an identified UCA may require more fetal surveillance by both the mother and caregiver. This is especially important if there is a previous history of UCA with or without stillbirth. UCA should be an acknowledged risk which is part of prenatal screening. In the event of a poor outcome associated with UCA, it is recommended that the patient be fully informed of all prenatal information including images. Excellent communication with parents who are looking for answers after a tragic outcome may help to decrease litigation risk.

Recurrent umbilical cord accidents in a bottlenose dolphin Tursiops truncatus

Three successive umbilical cord accidents (UCAs) were diagnosed in the same female bottlenose dolphin Tursiops truncatus during consecutive gestations. In 2 of these, transabdominal ultrasonographic examination revealed coiling of the UC around the peduncle of the foetus. All 3 foetuses were male, died in utero during the last third of gestation and were spontaneously aborted. The 3 UCs were elongated, flattened and congested. For 3 subsequent pregnancies, a different sire was used for mating, handling protocols and treatments were adjusted, and 3 live female calves were successfully delivered. UC lengths were normal. UCAs are associated with excessively long UCs and are not uncommon in humans and horses but are unusual in other species. We believe this is the first detailed report of recurrent UCAs in a dolphin.

A case of meconium aspiration syndrome in a bottlenose dolphin (Tursiops truncatus) calf

Stillbirth and neonatal mortality are significant problems in captive breeding of dolphins, however, the causes of these problems are not fully understood. Here, we report a case of meconium aspiration syndrome (MAS) in a male neonate of bottlenose dolphin (Tursiops truncates) who died immediately after birth. At necropsy, a true knot was found in the umbilical cord. The lungs showed diffuse intraalveolar edema, hyperemic congestion and atelectasis due to meconium aspiration with mild inflammatory cell infiltration. Although the exact cause of MAS in this case was unknown, fetal hypoxia due possibly to the umbilical knot might have been associated with MAS, which is the first report in dolphins. MAS due to perinatal asphyxia should be taken into account as a possible cause of neonatal mortality and stillbirth of dolphin calves.

Prevalence, risk factors and outcomes of velamentous and marginal cord insertions: a population-based study of 634,741 pregnancies

Objectives

To determine the prevalence of, and risk factors for anomalous insertions of the umbilical cord, and the risk for adverse outcomes of these pregnancies.

Design

Population-based registry study.

Setting

Medical Birth Registry of Norway 1999–2009.

Population

All births (gestational age >16 weeks to <45 weeks) in Norway (623,478 singletons and 11,263 pairs of twins).

Methods

Descriptive statistics and odds ratios (ORs) for risk factors and adverse outcomes based on logistic regressions adjusted for confounders.

Main outcome measures

Velamentous or marginal cord insertion. Abruption of the placenta, placenta praevia, pre-eclampsia, preterm birth, operative delivery, low Apgar score, transferral to neonatal intensive care unit (NICU), malformations, birthweight, and perinatal death.

Results

The prevalence of abnormal cord insertion was 7.8% (1.5% velamentous, 6.3% marginal) in singleton pregnancies and 16.9% (6% velamentous, 10.9% marginal) in twins. The two conditions shared risk factors; twin gestation and pregnancies conceived with the aid of assisted reproductive technology were the most important, while bleeding in pregnancy, advanced maternal age, maternal chronic disease, female foetus and previous pregnancy with anomalous cord insertion were other risk factors. Velamentous and marginal insertion was associated with an increased risk of adverse outcomes such as placenta praevia (OR = 3.7, (95% CI = 3.1–4.6)), and placental abruption (OR = 2.6, (95% CI = 2.1–3.2)). The risk of pre-eclampsia, preterm birth and delivery by acute caesarean was doubled, as was the risk of low Apgar score, transferral to NICU, low birthweight and malformations. For velamentous insertion the risk of perinatal death at term was tripled, OR = 3.3 (95% CI = 2.5–4.3).

Conclusion

The prevalence of velamentous and marginal insertions of the umbilical cord was 7.8% in singletons and 16.9% in twin gestations, with marginal insertion being more common than velamentous. The conditions were associated with common risk factors and an increased risk of adverse perinatal outcomes; these risks were greater for velamentous than for marginal insertion.

Umbilical Cord Pathology

Problems and abnormalities of the umbilical cord play a significant role in perinatal morbidity and mortality. Because the umbilical cord is the lifeline of the fetus, any disruption of blood flow through the umbilical vessels can lead to severe fetal consequences.

Twin pregnancies with single fetal death: analysis of 38 cases

The objective of this study is to evaluate fetal and maternal outcomes of twin pregnancies with intrauterine single fetal death. In 13 cases, intrauterine death of one fetus was found during the first trimester; in 25 cases, it was found after the first trimester. Obstetric complications and fibrinogen levels were compared. There were no significant differences in the number of preterm delivery, preeclampsia, and intrauterine growth restriction and there were significant differences in gestational age at delivery and birth weight between groups. Coagulation disorders did not occur. The risk for adverse pregnancy outcomes with a single fetal death during and after the first trimester is similar.

Caesarean delivery and subsequent stillbirth or miscarriage: systematic review and meta-analysis

OBJECTIVE

To compare the risk of stillbirth and miscarriage in a subsequent pregnancy in women with a previous caesarean or vaginal delivery.

DESIGN

Systematic review of the published literature including seven databases: CINAHL; the Cochrane library; Embase; Medline; PubMed; SCOPUS and Web of Knowledge from 1945 until November 11(th) 2011, using a detailed search-strategy and cross-checking of reference lists.

STUDY SELECTION

Cohort, case-control and cross-sectional studies examining the association between previous caesarean section and subsequent stillbirth or miscarriage risk. Two assessors screened titles to identify eligible studies, using a standardised data abstraction form and assessed study quality.

DATA SYNTHESIS

11 articles were included for stillbirth, totalling 1,961,829 pregnancies and 7,308 events. Eight eligible articles were included for miscarriage, totalling 147,017 pregnancies and 12,682 events. Pooled estimates across the stillbirth studies were obtained using random-effect models. Among women with a previous caesarean an increase in odds of 1.23 [95% CI 1.08, 1.40] for stillbirth was yielded. Subgroup analyses including unexplained stillbirths yielded an OR of 1.47 [95% CI 1.20, 1.80], an OR of 2.11 [95% CI 1.16, 3.84] for explained stillbirths and an OR of 1.27 [95% CI 0.95, 1.70] for antepartum stillbirths. Only one study reported adjusted estimates in the miscarriage review, therefore results are presented individually.

CONCLUSIONS

Given the recent revision of the National Institute for Health and Clinical Excellence guidelines (NICE), providing women the right to request a caesarean, it is essential to establish whether mode of delivery has an association with subsequent risk of stillbirth or miscarriage. Overall, compared to vaginal delivery, the pooled estimates suggest that caesarean delivery may increase the risk of stillbirth by 23%. Results for the miscarriage review were inconsistent and lack of adjustment for confounding was a major limitation. Higher methodological quality research is required to reliably assess the risk of miscarriage in subsequent pregnancies.

Gross umbilical cord complications are associated with placental lesions of circulatory stasis and fetal hypoxia

Umbilical cord complications (UCC), such as true knots (TK), velamentous (VEL) insertion, marginal umbilical cord (MUC) insertion, umbilical cord entanglement (UCE) (both nuchal and non-nuchal), excessively long umbilical cord (ELUC), and excessively twisted umbilical cord (ETUC), can lead to decreased UC blood flow and have been associated with adverse fetal outcome and intrauterine fetal demise (IUFD). Few large series exist that correlate UCC with specific pathologic findings of the placenta. We present the largest series of UCC at this time. Eight hundred forty-one 3rd-trimester placentas with UCC were identified, as well as 858 randomly selected gestational age-matched placentas with grossly unremarkable UC. Lesions associated with circulatory stasis and thrombosis, including villous capillary congestion (VC), umbilical vessel distension (UVD), chorionic plate vessel distension (CPD), umbilical vessel thrombosis (UVT), fetal vascular thrombosis (FVT), intimal fibrin cushions (IFC), and avascular villi (AV), were noted, as well as other pathologic lesions. Data were analyzed by analysis of variance and Fisher exact tests, with P < 0.05 statistically significant. Umbilical cord complications as a group was associated with a significant increase in placental circulatory stasis lesions. Lesions associated with hypoxia, namely nucleated red blood cells and chorangiosis, were also increased. Finally, the presence of any UCC was significantly associated with IUFD. We also found that multiple UCC are associated with nonreassuring fetal heart rate and chorangiosis but that the presence of a single UCC was not. This indicates that UCC may lead to intrauterine hypoxia and subsequent adverse fetal outcome and that multiple UCC may be cumulative in effect.

Birth weight differences between preterm stillbirths and live births: analysis of population-based studies from the U.S. and Sweden

BACKGROUND

Many stillbirths show evidence of fetal growth restriction, and most occur at preterm gestational age. The objective of this study is to compare birth weights at preterm gestational ages between live births and stillbirths, and between those occurring before or during labour.

METHODS

Based on singleton births from the United States (U.S.) 2003-2005 (n=902,491) and Sweden 1992-2001 (n=946,343), we compared birth weights between singleton live births and stillbirths at 24-36 completed weeks of gestation from the U.S. and at 28-42 completed weeks from Sweden.

RESULTS

In both the U.S. and Sweden, stillbirth weight-for-gestational-age z-scores were at least one standard deviation lower than live birth z-scores at all preterm gestational ages (GA). In Sweden, no birth weight difference was observed between antepartum and intrapartum stillbirths at preterm GAs, whereas birth weights among intrapartum stillbirths were similar to those among live births at 37-42 weeks.

CONCLUSIONS

Birth weights observed at preterm gestation are abnormal, but preterm stillbirths appear to be more growth-restricted than preterm live birth. Similar birth weights among ante- and intrapartum preterm stillbirths suggest serious fetal compromise before the onset of labor.

Clustering of maternal-fetal clinical conditions and outcomes and placental lesions

OBJECTIVE

To identify by an inductive statistical analysis mutually similar and clinically relevant clinicoplacental clusters.

STUDY DESIGN

Twenty-nine maternofetal and 49 placental variables have been retrospectively analyzed in a 3382 case clinicoplacental database using a hierarchical agglomerative Ward dendrogram and multidimensional scaling.

RESULTS

The exploratory cluster analysis identified 9 clinicoplacental (macerated stillbirth, fetal growth restriction, placenta creta, acute fetal distress, uterine hypoxia, severe ascending infection, placental abruption, and mixed etiology [2 clusters]), 5 purely placental (regressive placental changes, excessive extravillous trophoblasts, placental hydrops, fetal thrombotic vasculopathy, stem obliterative endarteritis), and 1 purely clinical (fetal congenital malformations) statistically significant clusters/subclusters. The clusters of such variables like clinical umbilical cord compromise, preuterine and postuterine hypoxia, gross umbilical cord or gross chorionic disk abnormalities did not reveal statistically significant stability.

CONCLUSION

Although clinical usefulness of several well-established placental lesions has been confirmed, claims about high predictability of others have not.

Diverse placental pathologies as the main causes of fetal death

OBJECTIVE

To estimate the occurrence of placental causes of fetal death in relation to different gestational ages and their clinical manifestations during pregnancy.

METHODS

In a prospective cohort study conducted from 2002 to 2006, we studied 750 couples with singleton intrauterine fetal death after 20 weeks of gestation. Cause of death was classified according to the Dutch Tulip cause of death classification for perinatal mortality. Differences between groups for categorical data were evaluated by the Fisher exact test or chi test.

RESULTS

The main causes were placental pathology (64.9%), congenital anomaly (5.3%), infection (1.9%), other (4.8%), and unknown (23.1%). The contribution of causes differed over gestational age periods. At lower gestational age, placental and unknown were the most dominant causes of death (34.8% and 41.7%, respectively); at higher gestational age, the relative importance of an unknown cause decreased and a placental cause increased (16.5% and 77.6%) (P<.001). Placental bed pathology was observed in 33.6% of all fetal deaths, with the highest occurrence between 24 0/7 and 31 6/7 weeks and a strong decline after 32 weeks. In contrast, contribution of developmental placental pathology (17.6%) increased after 32 weeks of gestation (P<.001), as did umbilical cord complications (5.2%) and combined placental pathology (5.4%). Solitary placental parenchyma pathology was less frequent (3.1%). Hypertension-related disease was observed in 16.1% (95% confidence interval [CI] 13.6-19.0) of the cohort, small for gestational age fetuses in 37.9% (95% CI 34.1-41.7), and diabetes-related disease in 4.1% (95% CI 2.8-5.8).

CONCLUSION

Most fetal deaths were caused by a variety of placental pathologies. These were related to gestational age, and their clinical manifestations varied during pregnancy.

LEVEL OF EVIDENCE

II.

Stillbirth classification--developing an international consensus for research: executive summary of a National Institute of Child Health and Human Development workshop

Stillbirth is a major obstetric complication, with 3.2 million stillbirths worldwide and 26,000 stillbirths in the United States every year. The Eunice Kennedy Shriver National Institute of Child Health and Human Development held a workshop from October 22-24, 2007, to review the pathophysiology of conditions underlying stillbirth to define causes of death. The optimal classification system would identify the pathophysiologic entity initiating the chain of events that irreversibly led to death. Because the integrity of the classification is based on available pathologic, clinical, and diagnostic data, experts emphasized that a complete stillbirth workup should be performed. Experts developed evidence-based characteristics of maternal, fetal, and placental conditions to attribute a condition as a cause of stillbirth. These conditions include infection, maternal medical conditions, antiphospholipid syndrome, heritable thrombophilias, red cell alloimmunization, platelet alloimmunization, congenital malformations, chromosomal abnormalities including confined placental mosaicism, fetomaternal hemorrhage, placental and umbilical cord abnormalities including vasa previa and placental abruption, complications of multifetal gestation, and uterine complications. In all cases, owing to lack of sufficient knowledge about disease states and normal development, there will be a degree of uncertainty regarding whether a specific condition was indeed the cause of death.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Epidemiology of stillbirth and fetal central nervous system injury

The epidemiology of stillbirth and fetal central nervous system (CNS) injury is described with some emphasis on maternal and feto-placental risk factors. To maximize utility of the discussion and because it also represents the classical manifestation of fetal CNS injury, we have selected cerebral palsy (CP) to illustrate the epidemiologic aspects of injury to the fetal CNS in general. While trends in stillbirth rates have modestly decreased over time, those of CP seem to be increasing. Interestingly, both stillbirth and CP share traditional as well as emerging risk factors lending credence to the hypothesis that fetuses that would previously have been stillborn are increasingly surviving albeit with some form of morbidity. The existence of shared risk factors also suggests that in some cases of stillbirth fetal CNS injury precedes the in utero fetal demise. Pregnant women bearing these risk indicators represent potential candidates for appropriate and tailored protocols for antenatal fetal testing.

Trends in intrapartum fetal death, 1979-2003

OBJECTIVES

This study was undertaken to analyze trends in intrapartum fetal death and rates of perinatal autopsy over a 25-year period in Dublin, Ireland.

STUDY DESIGN

A retrospective multicenter analysis of 508,342 nonanomalous infants 500 g or more, delivering in 3 tertiary-referral university institutions between 1979-2003.

RESULTS

There has been a significant downward trend in the rate of intrapartum fetal death over the past 25 years (P < .0001). Nulliparous labors were statistically more likely to be complicated by an intrapartum fetal demise than parous labors (odds ratio, 1.49; 95% confidence interval [CI], 1.16-1.92; P = .0018). Intrapartum deaths secondary to hypoxia fell significantly over the study period (P < .0001). Infants of multiple gestations were twice as likely to die in labor as singletons (odds ratio, 2.2; 95% CI, 1.22-3.74; P = .0058). Rates of perinatal autopsy fell significantly over the 25 years studied (P < .0001).

CONCLUSION

There has been a significant fall in rates of intrapartum fetal death. This has primarily resulted from a reduction in deaths attributable to intrapartum hypoxia. Infants of multiple gestations still retain a significantly higher chance of intrapartum death. The fall in uptake rates of perinatal autopsy in recent years is concerning.

Cord abnormalities, structural lesions, and cord “accidents”

As the umbilical cord is the lifeline of the fetus, obstruction or disruption of blood flow through the umbilical vessels can lead to severe fetal compromise. Obstruction is usually mechanical in nature and is associated with compression of the umbilical cord and umbilical vessels. Disruption of umbilical or fetal vessels is usually traumatic in origin. These conditions have in common a loss of blood flow to the fetus and an association with adverse perinatal outcome.

Intrapartum stillbirths in hospital unrelated to uteroplacental vascular insufficiency

The aim of this study was to investigate the causes of intrapartum asphyxia and its relationship to placental abnormalities. Twenty intrapartum fetal death autopsies carried out over a 10-year period in one hospital pathology department associated with a large obstetric unit were reviewed. All the intrapartum fetal deaths occurred in the hospital, while the mothers were being monitored during and after labor. On morphologic grounds, all the fetal deaths were thought to be caused by intrapartum asphyxia. Seven of the intrapartum fetal deaths were associated with intrauterine infection causing funisitis, and in 6 of these cases, chorioamnionitis was present as well. Two cases were caused by placental abruption, and 1 case was caused by cord compression. In 8 of the 10 remaining cases in which the placenta was examined, a minor placental abnormality was detected in only 1 case. Five of the 10 cases had a mild astrocytosis in the intracerebral periventricular white matter, suggestive of intrauterine ischemia at least 12 hours before death. Five of the 10 cases were thought by the delivering obstetrician to have umbilical cord abnormalities. The main conclusions from this study are that, except in cases of intrauterine infection, placental vascular abnormalities are unlikely to be associated with intrapartum asphyxia leading to fetal death during labor. The number of cases with umbilical cord abnormalities raises the possibility that cord accidents may be a significant cause of intrapartum stillbirth.

Umbilical vein constriction at the umbilical ring: a longitudinal study

OBJECTIVE

It has been suggested that constriction of the umbilical vein (UV) at the umbilical ring has hemodynamic effects. We aimed to determine the occurrence and extent of such constriction in serial observations.

METHODS

This was a prospective longitudinal study of UV velocities at the umbilicus measured at approximately 4-week intervals between 19 and 42 weeks' gestation in 129 low-risk singleton pregnancies. Each participant was examined three to five times. Multilevel modeling was used to construct the reference ranges and to test associations between variables.

RESULTS

Gestational age-specific reference percentiles of UV velocities at the umbilicus were established based on 469 observations. Fetuses were able to alter the UV velocities considerably during the second half of pregnancy, signifying a varying degree of UV constriction. Of a total of 129 fetuses, 56 (43.4%) never had high UV blood velocity (i.e. > 46 cm/s, the highest quartile), 42 (32.6%) fetuses had high UV blood velocity on one occasion and 31 (24.0%) fetuses on two or more occasions. In 36 (27.9%) fetuses the UV velocity at the umbilical ring was > 300% of the mean gestational age-specific reference value at the intra-abdominal section on at least one occasion. Constriction of the UV at the umbilical ring did not affect the pulsatility of the umbilical artery, and was not associated with adverse perinatal outcome in this study.

CONCLUSIONS

Low-risk fetuses may well constrict the UV at the abdominal wall with velocities extending over wide ranges on one or more occasions during the second half of pregnancy. Rather than being a risk for complications, the constriction seems to be part of physiological development and possibly a regulatory mechanism.

Nuchal cord is not associated with adverse perinatal outcome

OBJECTIVE

The present study was aimed at evaluating the outcome of pregnancies with nuchal cord.

METHODS

A retrospective population-based study of all deliveries during the years 1988-2003 in a tertiary medical center was conducted. Immediate perinatal outcome of patients with and without nuchal cord was compared.

RESULTS

Of 166,318 deliveries during the study period, 14.7% had a nuchal cord, documented at birth (n=24,392). Higher rates of labor induction and non-reassuring fetal heart rate patterns were noted among pregnancies with nuchal cord as compared with the control group (30.1% vs. 24.2%; OR=1.3, 95% CI 1.3-1.4, P<0.001 and 4.5% vs. 2.6%; OR=1.8, 95% CI 1.6-1.9, P<0.001; respectively). The cesarean delivery rate was significantly lower among pregnancies with nuchal cord (11.5% vs. 12.7%; OR=0.9, 95% CI 0.8-0.9, P=0.001). Although 1 min Apgar scores lower than 7 were more common in pregnancies with nuchal cord (4.8% vs. 4.4%; OR=1.1, 95% CI 1.01-1.2, P=0.008), these pregnancies actually had lower rates of 5 min Apgar scores less than 7 (0.5% vs. 0.7%; OR=0.8, 95% CI 0.6-0.9, P=0.004). Likewise, the perinatal mortality rate was significantly lower in pregnancies with nuchal cord as compared with the comparison group (11/1,000 vs. 16/1,000; OR=0.7, 95% CI 0.6-0.8, P=0.001).

CONCLUSIONS

Nuchal cord is not associated with adverse perinatal outcome. Thus, labor induction in such cases is probably unnecessary.

Management of single fetal demise in a multiple gestation

Intrauterine fetal demise of 1 twin in a multiple gestation is a complex clinical situation. Chorionicity, gestational age at diagnosis, problems specific to the pregnancy, and the emotional needs of the patient can impact management. Strategies to optimize outcomes may include a multidisciplinary team approach and fetal surveillance. The following article reviews (1) adverse fetal and neonatal outcomes associated with intrauterine fetal demise of 1 twin, (2) the potential maternal impact, and (3) the strategies to possibly prevent poor outcomes. It is important to remember that even the most vigilant care may not avoid adverse sequelae in a portion of at-risk pregnancies.

The natural history of antenatal nuchal cords

OBJECTIVE

The purpose of this study was to test the null hypotheses that nuchal cords occur with equal frequency throughout gestation, the presence of an antenatal nuchal cord is usually a random or chance event, nuchal cords do not usually persist, and nuchal cords do not usually produce evidence of acute fetal compromise before labor.

STUDY DESIGN

A prospective subject-, examiner-, and physician-blinded study design was used. The fetuses were examined serially at 24 to 26, 30 to 32, and 36 to 38 weeks' gestation and during labor and delivery. Measurements included: ultrasonic or visual detection of nuchal cords and assessment of fetal and neonatal well-being by using standard clinical techniques.

RESULTS

The incidence of nuchal cord rose with advancing gestation from 12% at 24 to 26 weeks to 37% at term. However, at each gestational age, its occurrence was a random or chance event and was not associated with clinical evidence of fetal compromise before labor.

CONCLUSION

Antenatal nuchal cords usually occur randomly with increased frequency in late gestation and appear to be a normal part of intrauterine life that is rarely associated with perinatal morbidity and mortality.