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Biomedical subjects

Robert Liston

Publications and source records attributed to Robert Liston.

16 recordsLinked to original sources

An analysis of antenatal hospitalization in Canada, 1991-2003.

OBJECTIVES: To examine the incidence and temporal trends of hospitalization during pregnancy, and provide additional information on maternal morbidity among Canadian women. METHODS: A population-based cohort study was conducted using the Canadian Institute for Health Information's Discharge Abstract Database between fiscal year 1991/92 and 2002/03. This database included antenatal hospitalizations for all hospital deliveries (N=3,103,365) in Canada except for those occurring in Manitoba and Quebec. Temporal trends, and variations in the non-delivery antenatal hospitalization ratio (per 100 deliveries) by maternal age and province or territory were quantified. Primary causes for antenatal hospitalization, the lengths of in-hospital stay, and changing pattern by maternal age and time period were compared. RESULTS: The overall antenatal hospitalization ratio declined by 43%, from 24.0 per 100 deliveries in 1991/92 to 13.6 in 2002/03. Younger women tended to be hospitalized more frequently than older women: 27.1 per 100 deliveries for women aged less than 20 years and 21.5 per 100 deliveries for 20-24 years, respectively, compared to 11.5 per 100 for women aged 35-39 years. The antenatal hospitalization ratio varied greatly by province/territory--from 12.2 per 100 deliveries in Ontario to 30.7 in the Yukon. Threatened preterm labour, antenatal hemorrhage, hypertensive disorders, severe vomiting and diabetes remained the five most common causes for antenatal hospitalization, although the trends for the first four declined dramatically from 1991/92 to 2002/03. Younger women were more likely to be admitted for threatened preterm labour and severe vomiting, while older women were more likely to be admitted for antenatal hemorrhage and hypertensive disorders. CONCLUSIONS: The decline in antenatal hospitalization may reflect changes in management of pregnancy complications, e.g., transition from in-hospital care to out-of-hospital care, and introduction of antepartum home care programs. Information on interprovincial/territorial variations in antenatal hospitalization may be helpful in directing future maternal health care.

Adult↗

Fostering harmony in labor and delivery: a nursing preceptorship for clinical clerks.

OBJECTIVE: The relationship between the specialized nurses of the Labor and Delivery Suite and the medical students who are rotating through the unit as clinical clerks has traditionally been a poor one. The objective of this project was to develop a program which pairs medical students with nurse preceptors to improve their understanding of each other's roles and to provide students with an opportunity to gain basic clinical skills, and secondarily, to evaluate the students' perceptions of the program METHODS: We developed an ongoing program which pairs third-year students with Labor and Delivery nurses for one to two shifts. The evaluation of the program used the end-of-rotation questionnaire completed anonymously by students to determine their rating. RESULTS: The median rating of the program by students is 5 out of 7 (with 7 being the best rating). Seventy-seven percent rated the program 5 or higher. CONCLUSION: This program has been successful in pairing students with nurse preceptors for a total of three years so far. The process we used to develop the program may help other institutions who wish to put in place a similar program. LEVEL OF EVIDENCE: III.

Attitude of Health Personnel↗

Severe maternal morbidity in Canada, 1991-2001.

BACKGROUND: Although death rates are often used to monitor the quality of health care, in industrialized countries maternal deaths have become rare. Severe maternal morbidity has therefore been proposed as a supplementary indicator for surveillance of the quality of maternity care. Our purpose in this study was to describe severe maternal morbidity in Canada over a 10-year period, among women with or without major pre-existing conditions. METHODS: We carried out a retrospective cohort study of severe maternal morbidity involving 2,548,824 women who gave birth in Canadian hospitals between 1991 and 2000. Thirteen conditions that may threaten the life of the mother (e.g., eclampsia) and 11 major pre-existing chronic conditions (e.g., diabetes) that could be identified from diagnostic codes were noted. RESULTS: The overall rate of severe maternal morbidity was 4.38 per 1000 deliveries. The fatality rate among these women was 158 times that of the entire sample. Rates of venous thromboembolism, uterine rupture, adult respiratory distress syndrome, pulmonary edema, myocardial infarction, severe postpartum hemorrhage requiring hysterectomy, and assisted ventilation increased substantially from 1991 to 2000. The presence of major pre-existing conditions increased the risk of severe maternal morbidity to 6-fold. INTERPRETATION: Severe maternal morbidity occurs in about 1 of 250 deliveries in Canada, with marked recent increases in certain morbid conditions such as pulmonary edema, myocardial infarction, hemorrhage requiring hysterectomy, and the use of assisted ventilation.

Adult↗

Customized birth weight for gestational age standards: Perinatal mortality patterns are consistent with separate standards for males and females but not for blacks and whites.

BACKGROUND: Some currently available birth weight for gestational age standards are customized but others are not. We carried out a study to provide empirical justification for customizing such standards by sex and for whites and blacks in the United States. METHODS: We studied all male and female singleton live births and stillbirths (22 or more weeks of gestation; 500 g birth weight or over) in the United States in 1997 and 1998. White and black singleton live births and stillbirths were also examined. Qualitative congruence between gestational age-specific growth restriction and perinatal mortality rates was used as the criterion for identifying the preferred standard. RESULTS: The fetuses at risk approach showed that males had higher perinatal mortality rates at all gestational ages compared with females. Gestational age-specific growth restriction rates based on a sex-specific standard were qualitatively consistent with gestational age-specific perinatal mortality rates among males and females. However, growth restriction patterns among males and females based on a unisex standard could not be reconciled with perinatal mortality patterns. Use of a single standard for whites and blacks resulted in gestational age-specific growth restriction rates that were qualitatively congruent with patterns of perinatal mortality, while use of separate race-specific standards led to growth restriction patterns that were incompatible with patterns of perinatal mortality. CONCLUSION: Qualitative congruence between growth restriction and perinatal mortality patterns provides an outcome-based justification for sex-specific birth weight for gestational age standards but not for the available race-specific standards for blacks and whites in the United States.

Journal Article↗

The perinatal effects of delayed childbearing.

OBJECTIVE: To determine if the rates of pregnancy complications, preterm birth, small for gestational age, perinatal mortality, and serious neonatal morbidity are higher among mothers aged 35-39 years or 40 years or older, compared with mothers 20-24 years. METHODS: We performed a population-based study of all women in Nova Scotia, Canada, who delivered a singleton fetus between 1988 and 2002 (N = 157,445). Family income of women who delivered between 1988 and 1995 was obtained through a confidential linkage with tax records (n = 76,300). The primary outcome was perinatal death (excluding congenital anomalies) or serious neonatal morbidity. Analysis was based on logistic models. RESULTS: Older women were more likely to be married, affluent, weigh 70 kg or more, attend prenatal classes, and have a bad obstetric history but less likely to be nulliparous and to smoke. They were more likely to have hypertension, diabetes mellitus, placental abruption, or placenta previa. Preterm birth and small-for-gestational age rates were also higher; compared with women aged 20-24 years, adjusted rate ratios for preterm birth among women aged 35-39 years and 40 years or older were 1.61 (95% confidence interval [CI] 1.42-1.82; P < .001) and 1.80 (95% CI 1.37-2.36; P < .001), respectively. Adjusted rate ratios for perinatal mortality/morbidity were 1.46 (95% CI 1.11-1.92; P = .007) among women 35-39 years and 1.95 (95% CI 1.13-3.35; P = .02) among women 40 years or older. Perinatal mortality rates were low at all ages, especially in recent years. CONCLUSION: Older maternal age is associated with relatively higher risks of perinatal mortality/morbidity, although the absolute rate of such outcomes is low.

Adult↗

Comparison of maternal mortality and morbidity between trial of labor and elective cesarean section among women with previous cesarean delivery.

OBJECTIVE: This study was undertaken to assess the safety of trial of labor after previous cesarean delivery. STUDY DESIGN: Retrospective cohort study of 308,755 Canadian women with previous cesarean delivery between 1988 and 2000. Occurrences of in-hospital maternal death, uterine rupture, and other severe maternal morbidity were compared between women with a trial of labor and those with an elective cesarean section. RESULTS: Rates of uterine rupture (0.65%), transfusion (0.19%), and hysterectomy (0.10%) were significantly higher in the trial-of-labor group. Maternal in-hospital death rate, however, was lower in the trial-of-labor group (1.6 per 100,000) than in the elective cesarean section group (5.6 per 100,000). The association between trial of labor and uterine rupture was stronger in low volume (<500) than in high volume (> or =500 births per year) obstetric units. CONCLUSION: Trial of labor is associated with increased risk of uterine rupture, but elective cesarean section may increase the risk of maternal death.

Blood Transfusion↗

Recent trends in caesarean delivery rates and indications for caesarean delivery in Canada.

OBJECTIVE: To examine recent trends in Caesarean delivery rates as well as the indications for Caesarean delivery in Canada, excluding the provinces of Manitoba and Quebec. METHODS: All deliveries (N = 1 807 388) recorded in the Canadian Institute for Health Information's Discharge Abstract Database for the years 1994/95 to 2000/01 were included in the study (all hospital deliveries in Canada except for those occurring in Manitoba and Quebec). Temporal trends and inter-provincial/territorial variations in Caesarean delivery rates were quantified, and the primary indications for Caesarean delivery during the study period were compared. RESULTS: The overall Caesarean delivery rate increased from 18.0% in 1994/95 to 22.1% in 2000/01. The primary Caesarean delivery rate increased from 12.7% to 16.3%, while the rate of vaginal birth after Caesarean decreased from 33.3% to 28.5% over the same period. Most of the increase in primary Caesarean deliveries was due to increases in Caesarean deliveries for dystocia, which increased from 6.9% in 1994/95 to 9.2% in 2000/01. The largest increase in repeat Caesarean deliveries was due to elective repeat Caesarean sections, which increased from 37.7% to 40.3%. Approximately 15% of the increase in overall Caesarean delivery rates was explained by increases in maternal age. The rate of vaginal deliveries following forceps rotation declined from 1.9% in 1994/95 to 1.3% in 2000/01. CONCLUSION: Most of the recent increase in Caesarean delivery rates in Canada was attributed to increases in primary Caesarean delivery for dystocia and elective repeat Caesarean deliveries.

Adult↗

Do maternity care provider groups have different attitudes towards birth?

OBJECTIVE: To compare family physicians', obstetricians' and midwives' self-reported practices, attitudes and beliefs about central issues in childbirth. DESIGN: Mail-out questionnaire. SETTING/POPULATION; All registered midwives in the province, and a sample of family physicians and obstetricians in a maternity care teaching hospital. Response rates: 91% (n = 50), 69% (n = 97) and 89% (n = 34), respectively. METHODS: A postal survey. MAIN OUTCOME MEASURES: Twenty-three five-point Likert scale items (strongly agree to strongly disagree) addressing attitudes toward routine electronic fetal monitoring, induction of labour, epidural analgesia, episiotomy, doulas, vaginal birth after caesarean section (VBACs), birth centres, provision educational material, birth plans and caesarean section. RESULTS: Cluster analysis identified three distinct clusters based on similar response to the questions. The 'MW' cluster consisted of 100% of midwives and 26% of the family physicians. The 'OB' cluster was composed of 79% of the obstetricians and 16% of the family physicians. The 'FP' cluster was composed of 58% the family physicians and 21% the obstetricians. Members of the 'OB' cluster more strongly believed that women had the right to request a caesarean section without maternal/fetal indications (P < 0.001), that epidurals early in labour were not associated with development of fetal malpositions (P < 0.001) and that increasing caesarean rates were a sign of improvement in obstetrics (P < 0.001). The 'OB' cluster members were more likely to say they would induce women as soon as possible after 41 3/7 weeks of gestation (P < 0.001) and were least likely to encourage the use of birth plans (P < 0.001). The 'MW' cluster's views were the opposite of the 'OBs' while the 'FP' cluster's views fell between the 'MW' and 'OB' clusters. CONCLUSIONS: In our environment, obstetricians were the most attached to technology and interventions including caesarean section and inductions, midwives the least, while family physicians fell in the middle. While generalisations can be problematic, obstetricians and midwives generally follow a defined and different approach to maternity care. Family physicians are heterogeneous, sometimes practising more like midwives and sometimes more like obstetricians.

Analgesia, Epidural↗

A multicenter randomized controlled trial comparing patient-controlled epidural with intravenous analgesia for pain relief in labor.

In this multicenter, randomized, controlled trial, we sought to determine whether patient-controlled epidural analgesia (PCEA) for labor affected the incidence of cesarean delivery when compared with patient-controlled IV opioid analgesia (PCIA). Healthy, term nulliparous patients in 4 Canadian institutions were randomly assigned to receive PCIA with fentanyl (n = 118) or PCEA with 0.08% bupivacaine and fentanyl 1.6 microg/mL (n = 124). There was no difference in the incidence of cesarean delivery-10.2% (12 of 118) versus 9.7% (12 of 124)-or instrumental vaginal delivery-21.2% (25 of 118) versus 29% (36 of 124)-between groups. The duration of the second stage of labor was increased in the PCEA group by a median of 23 min (P = 0.02). Fifty-one patients (43%) in the PCIA group received epidural analgesia: 39 (33%) because of inadequate pain relief and 12 (10%) to facilitate operative delivery. Patients in the PCIA group required more antiemetic therapy (17% versus 6.4%; P = 0.01) and had more sedation (39% versus 5%; P < 0.001). Maternal mean pain and satisfaction with analgesia scores were better in the PCEA group (P < 0.001 and P = 0.02, respectively). More neonates in the PCIA group required active resuscitation (52% versus 31%; P = 0.001) and naloxone (17% versus 3%; P < 0.001). These observations support the hypothesis that PCEA does not result in an increased incidence of obstetrical intervention compared with PCIA. PCEA provides superior analgesia and less maternal and neonatal sedation compared with PCIA.

Adult↗

The benefit of preterm birth at tertiary care centers is related to gestational age.

OBJECTIVE: The purpose of this study was to examine the relationship between gestational age and outcomes of outborn versus inborn preterm infants. STUDY DESIGN: Multivariable logistic regression analysis was used to examine gestational age-specific, risk-adjusted outcomes of 2962 singleton infants who were born at <32 weeks of gestation who were admitted to 17 Canadian neonatal intensive care units from 1996 through 1997. RESULTS: The risk-adjusted incidence was significantly (P <.05) higher among outborn versus inborn infants for mortality rates (odds ratio, 2.2) and > or =grade 3 intraventricular hemorrhage (odds ratio, 2.1) at < or =26 weeks of gestation and for chronic lung disease (odds ratio, 1.7) at 27 to 29 weeks of gestation. Outcomes of outborn and inborn infants at 30 to 31 weeks of gestation were not significantly different. CONCLUSION: The short-term benefit of preterm birth at tertiary centers is related inversely to gestational age and may not extend beyond 29 weeks of gestation.

Cerebral Hemorrhage↗

The effect of factor V Leiden carriage on maternal and fetal health.

Factor V Leiden is a common genetic mutation that predisposes its carriers to venous thromboembolism. When combined with the hypercoagulable state that is characteristic of pregnancy, there is an increased risk of severe and recurrent pregnancy complications. Factor V Leiden is the most common cause of primary and recurrent venous thromboembolism in pregnancy. Factor V Leiden carriage has consistently been shown to increase the risk of early onset gestational hypertension and HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets) in pregnancy. Maternal carriage of factor V Leiden is also associated with severe placental abruption and fetal growth disturbances. Although it is unclear whether factor V Leiden causes an increased risk of first trimester miscarriage, it is associated with stillbirth and placental infarction. Patients with venous thromboembolism or severe pregnancy complications should be tested for factor V Leiden and other inherited and acquired thrombophilia. Therapeutic heparin is required for acute thromboembolic events in pregnancy. Patients with factor V Leiden and a previous venous thromboembolism may, according to their level of risk, be offered either prophylactic or therapeutic heparin. The role of antithrombotic therapy in the prevention of severe pregnancy complications remains unclear.

Activated Protein C Resistance↗

RETIRED: Fetal health surveillance in labour.

This document has been archived because it contains outdated information. It should not be consulted for clinical use, but for historical research only. Please visit the journal website for the most recent guidelines.

Blood Gas Analysis↗

Preterm birth, stillbirth and infant mortality among triplet births in Canada, 1985-96.

Recent increases in the frequency of multiple births and simultaneous increases in preterm birth among multiple births have focused attention on such births. However, most previous studies have examined twins rather than higher-order multiples. We carried out a study to examine rates and trends in preterm birth and in gestational age-specific fetal and infant mortality among triplet births in Canada. We used data from the stillbirth, live birth and mortality files of Statistics Canada for the years 1985-97. All births in Canada (excluding those occurring in Ontario and Newfoundland) were included in the study, with two periods (1985-90 vs. 1991-96) being contrasted for assessing temporal change. Changes were estimated using relative risks, 95 confidence intervals [CI] and two-tailed P-values. The rate of preterm birth among triplet live births increased by 6 (95 CI 3, 9) from 90.4 in 1985-90 to 96.0 in 1991-96. Stillbirth rates among triplets did not change significantly and were 30.3 per 1000 total births in 1985-90 and 33.8 per 1000 total births in 1991-96. Infant mortality among triplets declined from 112.7 per 1000 live births in 1985-90 to 73.8 per 1000 live births in 1991-96. In spite of temporal reductions in infant mortality, triplet births continue to be associated with very high rates of preterm birth and fetal and infant mortality. Fetal mortality among triplets has not changed over the last ten years.

Birth Weight↗

Under-reporting of maternal mortality in Canada: a question of definition.

In Canada, maternal mortality reporting is based on information contained on death certificates. To examine the extent to which maternal deaths are under-reported in Canada and whether this is likely to change under the 10th revision of the International Classification of Diseases (ICD), we linked live birth and stillbirth registrations to In Canada death registrations of women aged 10 to 50 for 1988 through 1992. We reviewed the death certificates of women found to have died while pregnant or within a year of the termination of pregnancy. The officially reported maternal mortality ratio for the study years was 3.7 deaths per 100,000 live births. Depending on whether we included deaths not certified as maternal deaths at the time the deaths occurred, revised ratios under ICD-9 ranged from 4.9 to 5.1 per 100,000 live births for deaths from direct obstetric causes and from 0.5 to 1.2 per 100,000 live births for deaths from indirect obstetric causes. Reflecting changes in classification criteria, revised ratios under ICD-10 were lower than those under ICD-9 for deaths from direct obstetric causes - ranging from 3.9 to 4.1 per 100,000 live births - and higher for deaths from indirect obstetric causes ranging from 2.0 to 3.0 per 100,000 live births. Of deaths from direct obstetric causes, those from cerebrovascular disease were the most numerous and also the most likely to be underreported. Deaths from pulmonary embolism and indirect obstetric causes were the next most likely to be underreported. In a companion article we report an investigation of whether deaths from causes not directly related to pregnancy -such as injury, infectious disease and epilepsy - are more or less likely to occur among pregnant and recently pregnant women.

Canada↗

Fetal health surveillance in labour.

OBJECTIVE: This guideline defines the standards pertaining to the application and documentation of fetal surveillance in labour that will decrease the incidence of birth asphyxia while maintaining the lowest possible rate of obstetrical intervention. Both high- and low-risk obstetrical populations are considered. It is intended that this guideline could be used by all persons providing intrapartum care in Canada, including nurses, physicians, and midwives. OPTIONS: Consideration has been given to methods of fetal surveillance currently available in Canada, including intermittent auscultation, electronic fetal monitoring (alone and when paired with vibro-acoustic or scalp stimulation and fetal scalp blood sampling), the "admission strip," computerized heart rate analysis, fetal oxygen saturation monitoring, fetal electrocardiogram analysis, and near-infrared spectroscopy. OUTCOMES: Short- and long-term outcomes were considered that may indicate the presence of birth asphyxia. The associated rates of operative or other labour interventions were also considered. EVIDENCE: A comprehensive review of randomized controlled trials performed from 1995 to date and a search of the literature using Medline and the Cochrane Database of all new studies on fetal surveillance. The level of evidence has been determined using the criteria described by the Canadian Task Force on the Periodic Health Examination. RECOMMENDATIONS: Part I: Standard Fetal Surveillance in Labour 1. Women in active labour should receive continuous close support from an appropriately trained professional. One-to-one nursing is recommended. (I-A) 2. Intermittent auscultation following an established protocol of surveillance and response (Figure 1) is the preferred method of fetal surveillance in healthy pregnancies in the active phase of labour. (I-A) 3. Labour induction requires close monitoring of uterine activity and fetal heart rate. (III-B) 4. In the presence of abnormal fetal heart rate characteristics detected by intermittent auscultation and unresponsive to resuscitative measures, increased surveillance by continuous electronic fetal monitoring or fetal scalp sampling or delivery should be instituted. (I-A) 5. Continuous intrapartum electronic fetal monitoring is recommended: a) for pregnancies where there is an increased risk of perinatal death, cerebral palsy, or neonatal encephalopathy (III-C) b) when oxytocin is being used for augmentation of labour (1-A) c) when oxytocin is being used for induction of labour (III-C). 6. With respect to continuous electronic fetal monitoring, all professionals must be familiar with the paper speed used in each case to avoid misinterpretation. The correct time should be recorded on the electronic fetal monitoring record. (III-C) 7. Electronic fetal monitoring records should be inspected and documented every 15 minutes in the active phase of labour and at least every 5 minutes in the second stage of labour. (III-C) 8. The timing of electronic fetal monitoring patterns should be determined in association with uterine contractions. The contraction frequency, duration, intensity, and resting tone should be assessed and documented. Abdominal palpation, a tocodynamometer, or an intrauterine pressure catheter may be used to facilitate the assessment. (III-C) 9. Practitioners should use standard terminology when describing fetal heart rate characteristics of an electronic fetal monitoring record. (III-C) 10. Fetal scalp blood sampling is recommended in association with electronic fetal monitoring patterns that are uninterpretable or non-reassuring, such as sustained minimal or absent variability, uncorrectable late decelerations, increasing fetal tachycardia, and abnormal FHR characteristics on auscultation. (II-3B) 11. The limited knowledge available on the use of labour admission tests warrants further research to establish the usefulness of this screening approach. (III-C) Part II: New Technologies for Fetal Surveillance in Labour 12. The use of computer-based algorithms alone to interpret fetal heart rate patterns is not recommended as a standard of care at the present time. (III-D) 13. Fetal pulse oximetry as an adjunct to electronic fetal heart monitoring in patients with non-reassuring HR status is not recommended as a standard of care at the present time. (III-D) 14. ST waveform analysis technology is under development but is not recommended as a standard of care at this time. (III-C) 15. Near-infrared spectroscopy as an adjunct to electronic fetal monitoring is currently not recommended as there is insufficient evidence to assess its efficacy in fetal surveillance. (III-D) 16. Further study of fetal pulse oximetry, ST waveform analysis, and near-infrared technology in clinical research settings is encouraged. (III-B) VALIDATION: This guideline was reviewed by the SOGC Clinical Practice Obstetrics Committee, Maternal Fetal Medicine Committee, and ALARM Committee, as well as by the Canadian Medical Protective Association. SPONSOR: The Society of Obstetricians and Gynaecologists of Canada.

Algorithms↗