CpG-Recoding in Zika Virus Genome Causes Host-Age-Dependent Attenuation of Infection With Protection Against Lethal Heterologous Challenge in Mice.

Experimental increase of CpG dinucleotides in an RNA virus genome impairs infection providing a promising approach for vaccine development. While CpG recoding is an emerging and promising vaccine approach, little is known about infection phenotypes caused by recoded viruses in vivo. For example, infection phenotypes, immunogenicity, and protective efficacy induced by CpG-recoded viruses in different age groups were not studied yet. This is important, because attenuation of infection phenotypes caused by recoded viruses may depend on the population-based expression of cellular components targeting viral CpG dinucleotides. In the present study, we generated several Zika virus (ZIKV) variants with the increasing CpG content and compared infection in neonatal and adult mice. Increasing the CpG content caused host-age-dependent attenuation of infection with considerable attenuation in neonates and high attenuation in adults. Expression of the zinc-finger antiviral protein (ZAP)-the host protein targeting viral CpG dinucleotides-was also age-dependent. Similar to the wild-type virus, ZIKV variants with the increased CpG content evoked robust cellular and humoral immune responses and protection against lethal challenge. Collectively, the host age should be accounted for in future studies on mechanisms targeting viral CpG dinucleotides, development of safe dinucleotide recoding strategies, and applications of CpG-recoded vaccines.

No 115 - Choc hémorragique.

OBJECTIF: Passer en revue les aspects cliniques du choc hémorragique et formuler des recommandations pour son traitement. OPTIONS: La reconnaissance précoce du choc hémorragique et une intervention rapide et systématique aident à éviter des issues indésirables. RéSULTATS ATTENDUS: Formuler des directives cliniques pour aider à reconnaître rapidement le choc hémorragique et à pratiquer la réanimation d'une manière organisée et fondée sur les connaissances scientifiques. ÉVIDENCE: On a fait une recherche du terme MeSH « hemorrhagic shock ¼ sur MEDLINE et passe en revue tous les articles publiés sur le sujet en obstétrique et gynécologie, chirurgie, traumatisme, soins intensifs, anesthésie, pharmacologie et hématologie, du I er janvier 1990 au 3 I aout 2000; on a aussi examiné les principaux manuels dans ces domaines. De plus on a obtenu et revu un choix de références données par ces articles et par les chapitres de livres. Les niveaux d'évidence ont été définis à partir des critères décrits par le Groupe d'étude canadien sur les soins de santé préventifs. VALIDATION: Ces directives cliniques ont été revues par le Comité de la pratique clinique- obstétrique et approuvées par le Comité exécutif et le Conseil de la Société des obstétriciens et gynécologues du Canada. PARRAINE PAR: la Société des obstétriciens et gynécologues du Canada. RECOMMANDATIONS.

No. 115-Hemorrhagic Shock.

OBJECTIVE: To review the clinical aspects of hemorrhagic shock and provide recommendations for therapy. OPTIONS: Early recognition of hemorrhagic shock and prompt systematic intervention will help avoid poor outcomes. OUTCOMES: Establish guidelines to assist in early recognition of hemorrhagic shock and to conduct resuscitation in an organized and evidence-based manner. EVIDENCE: Medline references were sought using the MeSH term "hemorrhagic shock." All articles published in the disciplines of obstetrics and gynaecology, surgery, trauma, critical care, anesthesia, pharmacology, and hemotology between 1 January 1990 and 31 August 2000 were reviewed, as well as core textbooks from these fields. Selected references from these articles and book chapters were also obtained and reviewed. The level of evidence has been determined using the criteria described by the Canadian Task Force on Preventive Health Care. VALIDATION: These guidelines have been reviewed by the Clinical Practice Obstetrics Committee and approved by Executive and Council of the Society of Obstetricians and Gynaecologists of Canada. SPONSORS: The Society of Obstetricians and Gynaecologists of Canada.

No. 203-Rubella in Pregnancy.

OBJECTIVE: To provide an update on rubella and pregnancy so that health professionals remain aware of the potentially devastating effects on the developing fetus. OUTCOMES: Rubella vaccination has been effective in virtually eliminating congenital rubella syndrome in Canada. EVIDENCE: Medline, PubMed, and Cochrane Database were searched for articles published between 1985 and 2007. VALUES: The quality of evidence was rated using the criteria described in the report of the Canadian Task Force on Preventive Health Care. SPONSOR: The Society of Obstetricians and Gynaecologists of Canada.

No. 155-Guidelines for Vaginal Birth After Previous Caesarean Birth.

OBJECTIVE: To provide evidence-based guidelines for the provision of a trial of labour (TOL) after Caesarean section. OUTCOME: Fetal and maternal morbidity and mortality associated with vaginal birth after Caesarean (VBAC) and repeat Caesarean section. EVIDENCE: MEDLINE database was searched for articles published from January 1, 1995, to February 28, 2004, using the key words "vaginal birth after Caesarean (Cesarean) section." The quality of evidence is described using the Evaluation of Evidence criteria outlined in the Report of the Canadian Task Force on the Periodic Health Exam. RECOMMENDATIONS: VALIDATION: These guidelines were approved by the Clinical Practice Obstetrics and Executive Committees of the Society of Obstetricians and Gynaecologists of Canada.

No. 245-Alcohol Use and Pregnancy Consensus Clinical Guidelines.

OBJECTIVE: To establish national standards of care for the screening and recording of alcohol use and counselling on alcohol use of women of child-bearing age and pregnant women based on the most up-to-date evidence. EVIDENCE: Published literature was retrieved through searches of PubMed, CINAHL, and the Cochrane Library in May 2009 using appropriate controlled vocabulary (e.g., pregnancy complications, alcohol drinking, prenatal care) and key words (e.g., pregnancy, alcohol consumption, risk reduction). Results were restricted to literature published in the last five years with the following research designs: systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no language restrictions. Searches were updated on a regular basis and incorporated in the guideline to May 2010. Grey (unpublished) literature was identified through searching the websites of health technology assessment (HTA) and HTA-related agencies, national and international medical specialty societies, clinical practice guideline collections, and clinical trial registries. Each article was screened for relevance and the full text acquired if determined to be relevant. The evidence obtained was reviewed and evaluated by the members of the Expert Workgroup established by the Society of Obstetricians and Gynaecologists of Canada. The quality of evidence was evaluated and recommendations were made according to guidelines developed by the Canadian Task Force on Preventive Health Care. VALUES: The quality of evidence was rated using the criteria described by the Canadian Task Force on Preventive Health Care (Table 1). SPONSOR: The Public Health Agency of Canada and the Society of Obstetricians and Gynaecologists of Canada. ENDORSEMENT: These consensus guidelines have been endorsed by the Association of Obstetricians and Gynecologists of Quebec; the Canadian Association of Midwives; the Canadian Association of Perinatal, Women's Health and Neonatal Nurses (CAPWHN); the College of Family Physicians of Canada; the Federation of Medical Women of Canada; the Society of Rural Physicians of Canada; and Motherisk. SUMMARY STATEMENTS: RECOMMENDATIONS.

Alcohol use and pregnancy consensus clinical guidelines.

OBJECTIVE: to establish national standards of care for the screening and recording of alcohol use and counselling on alcohol use of women of child-bearing age and pregnant women based on the most up-to-date evidence. EVIDENCE: published literature was retrieved through searches of PubMed, CINAHL, and the Cochrane Library in May 2009 using appropriate controlled vocabulary (e.g., pregnancy complications, alcohol drinking, prenatal care) and key words (e.g., pregnancy, alcohol consumption, risk reduction). Results were restricted to literature published in the last five years with the following research designs: systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no language restrictions. Searches were updated on a regular basis and incorporated in the guideline to May 2010. Grey (unpublished) literature was identified through searching the websites of health technology assessment (HTA) and HTA-related agencies, national and international medical specialty societies, clinical practice guideline collections, and clinical trial registries. Each article was screened for relevance and the full text acquired if determined to be relevant. The evidence obtained was reviewed and evaluated by the members of the Expert Workgroup established by the Society of Obstetricians and Gynaecologists of Canada. The quality of evidence was evaluated and recommendations were made according to guidelines developed by the Canadian Task Force on Preventive Health Care. VALUES: the quality of evidence was rated using the criteria described by the Canadian Task Force on Preventive Health Care (Table 1). SPONSOR: the Public Health Agency of Canada and the Society of Obstetricians and Gynaecologists of Canada. ENDORSEMENT: these consensus guidelines have been endorsed by the Association of Obstetricians and Gynecologists of Quebec; the Canadian Association of Midwives; the Canadian Association of Perinatal, Women's Health and Neonatal Nurses (CAPWHN); the College of Family Physicians of Canada; the Federation of Medical Women of Canada; the Society of Rural Physicians of Canada; and Motherisk. SUMMARY STATEMENTS: 1. There is evidence that alcohol consumption in pregnancy can cause fetal harm. (II-2) There is insufficient evidence regarding fetal safety or harm at low levels of alcohol consumption in pregnancy. (III) 2. There is insufficient evidence to define any threshold for low-level drinking in pregnancy. (III) 3. Abstinence is the prudent choice for a woman who is or might become pregnant. (III) 4. Intensive culture-, gender-, and family-appropriate interventions need to be available and accessible for women with problematic drinking and/or alcohol dependence. (II-2). RECOMMENDATIONS: 1. Universal screening for alcohol consumption should be done periodically for all pregnant women and women of child-bearing age. Ideally, at-risk drinking could be identified before pregnancy, allowing for change. (II-2B) 2. Health care providers should create a safe environment for women to report alcohol consumption. (III-A) 3. The public should be informed that alcohol screening and support for women at risk is part of routine women's health care. (III-A) 4. Health care providers should be aware of the risk factors associated with alcohol use in women of reproductive age. (III-B) 5. Brief interventions are effective and should be provided by health care providers for women with at-risk drinking. (II-2B) 6. If a woman continues to use alcohol during pregnancy, harm reduction/treatment strategies should be encouraged. (II-2B) 7. Pregnant women should be given priority access to withdrawal management and treatment. (III-A) 8. Health care providers should advise women that low-level consumption of alcohol in early pregnancy is not an indication for termination of pregnancy. (II-2A).

Rubella in pregnancy.

OBJECTIVE: To provide an update on rubella and pregnancy so that health professionals remain aware of the potentially devastating effects on the developing fetus. OUTCOMES: Rubella vaccination has been effective in virtually eliminating congenital rubella syndrome in Canada. EVIDENCE: Medline, PubMed, and Cochrane Database were searched for articles published between 1985 and 2007. VALUES: The quality of evidence was rated using the criteria described in the report of the Canadian Task Force on Preventive Health Care. SPONSOR: The Society of Obstetricians and Gynaecologists of Canada.

RETIRED: Postpartum maternal and newborn discharge.

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.

Guidelines for vaginal birth after previous Caesarean birth.

OBJECTIVE: To provide evidence-based guidelines for the provision of a trial of labour (TOL) after Caesarean section. OUTCOME: Fetal and maternal morbidity and mortality associated with vaginal birth after Caesarean (VBAC) and repeat Caesarean section. EVIDENCE: MEDLINE database was searched for articles published from January 1, 1995, to February 28, 2004, using the key words "vaginal birth after Caesarean (Cesarean) section". The quality of evidence is described using the Evaluation of Evidence criteria outlined in the Report of the Canadian Task Force on the Periodic Health Exam. RECOMMENDATIONS: 1. Provided there are no contraindications, a woman with 1 previous transverse low-segment Caesarean section should be offered a trial of labour (TOL) with appropriate discussion of perinatal risks and benefits. The process of informed consent with appropriate documentation should be an important part of the birth plan in a woman with a previous Caesarean section (II-2B). 2. The intention of a woman undergoing a TOL after Caesarean section should be clearly stated, and documentation of the previous uterine scar should be clearly marked on the prenatal record (II-2B). 3. For a safe labour after Caesarean section, a woman should deliver in a hospital where a timely Caesarean section is possible. The woman and her health care provider must be aware of the hospital resources and the availability of obstetric, anesthetic, pediatric, and operating-room staff (II-2A). 4. Each hospital should have a written policy in place regarding the notification and (or) consultation for the physicians responsible for a possible timely Caesarean section (III-B). 5. In the case of a TOL after Caesarean, an approximate time frame of 30 minutes should be considered adequate in the set-up of an urgent laparotomy (III-C). 6. Continuous electronic monitoring of women attempting a TOL after Caesarean section is recommended (II-2A). 7. Suspected uterine rupture requires urgent attention and expedited laparotomy to attempt to decrease maternal and perinatal morbidity and mortality (II-2A). 8. Oxytocin augmentation is not contraindicated in women undergoing a TOL after Caesarean section (11-2A). 9. Medical induction of labour with oxytocin may be associated with an increased risk of uterine rupture and should be used carefully after appropriate counselling (II-2B). 10. Medical induction of labour with prostaglandin E2 (dinoprostone) is associated with an increased risk of uterine rupture and should not be used except in rare circumstances and after appropriate counselling (II-2B). 11. Prostaglandin E1 (misoprostol) is associated with a high risk of uterine rupture and should not be used as part of a TOL after Caesarean section (II-2A). 12. A foley catheter may be safely used to ripen the cervix in a woman planning a TOL after Caesarean section (II-2A). 13. The available data suggest that a trial of labour in women with more than 1 previous Caesarean section is likely to be successful but is associated with a higher risk of uterine rupture (II-2B). 14. Multiple gestation is not a contraindication to TOL after Caesarean section (II-2B). 15. Diabetes mellitus is not a contraindication to TOL after Caesarean section (II-2B). 16. Suspected fetal macrosomia is not a contraindication to TOL after Caesarean section (II-2B). 17. Women delivering within 18 to 24 months of a Caesarean section should be counselled about an increased risk of uterine rupture in labour (II-2B). 18. Postdatism is not a contraindication to TOL after Caesarean section (II-2B). 19. Every effort should be made to obtain the previous Caesarean section operative report to determine the type of uterine incision used. In situations where the scar is unknown, information concerning the circumstances of the delivery is helpful in determining the likelihood of a low transverse incision. If the likelihood of a low transverse incision is high, a TOL after Caesarean section can be offered (II-2B). VALIDATION: These guidelines were approved by the Clinical Practice Obstetrics and Executive Committees of the Society of Obstetricians and Gynaecologists of Canada.

Guidelines for operative vaginal birth.

OBJECTIVE: To provide guidelines for operative vaginal birth in the management of the second stage of labour. OPTIONS: Non-operative techniques, episiotomy, and Caesarean section are compared to operative vaginal birth. outcome: Reduced fetal and maternal morbidity and mortality. EVIDENCE: MEDLINE and Cochrane databases were searched using the key words 'vacuum' and 'birth' as well as 'forceps' and 'birth' for literature published in English from January 1970 to June 2004. The level of evidence and quality of recommendations made are described using the Evaluation of Evidence from the Canadian Task Force on the Periodic Health Examination. RECOMMENDATIONS: 1. Non-operative interventions such as one-to-one support, partogram use, oxytocin use, and delayed pushing in women using epidurals will decrease need for operative birth. (I-A) 2. Manual rotation may be used alone or in conjunction with instrumental birth with little or no increased risk to the pregnant woman or to the fetus. (III-B) 3. Routine episiotomy is not necessary for an assisted vaginal birth. (II-1E) 4. When operative intervention in the second stage of labour is required, the options, risks, and benefits of vacuum, forceps, and Caesarean section must be considered. The choice of intervention needs to be individualized, as one is not clearly safer or more effective than the other. (II-B) 5. Failure of the chosen method, vacuum and/or forceps, to achieve delivery of the fetus in a reasonable time should be considered an indication for abandonment of the method. (III-C) 6. Adequate clinical experience and appropriate training of the operator are essential to the safe performance of operative deliveries. Hospital credentialing boards should grant privileges for performing these techniques only to an appropriately trained individual who demonstrates adequate skills. (III-C). VALIDATION: The Clinical Practice Obstetrics Committee and Executive and Council of the Society of Obstetricians and Gynaecologists of Canada approved these guidelines.

Guidelines for vaginal birth after previous Caesarean birth.

OBJECTIVE: To provide evidence-based guidelines for the provision of a trial of labour (TOL) after Caesarean section. OUTCOME: Fetal and maternal morbidity and mortality associated with vaginal birth after Caesarean (VBAC) and repeat Caesarean section. EVIDENCE: MEDLINE database was searched for articles published from January 1995 to February 2004, using the key words "vaginal birth after Caesarean (Cesarean) section." The quality of evidence is described using the Evaluation of Evidence criteria outlined in the Report of the Canadian Task Force on the Periodic Health Exam. RECOMMENDATIONS: 1. Provided there are no contraindications, a woman with 1 previous transverse low-segment Caesarean section should be offered a trial of labour after Caesarean with appropriate discussion of maternal and perinatal risks and benefits. The process of informed consent with appropriate documentation should be an important part of the birth plan in a woman with a previous Caesarean section. (II-2B) 2. The intention of a woman undergoing a TOL after Caesarean should be clearly stated and documentation of the previous uterine scar should be clearly marked on the prenatal record. (II-2B) 3. For a safe labour after Caesarean section, the woman should deliver in a hospital where an immediate Caesarean section is available. The woman and her health-care provider must be aware of the hospital resources and the availability of obstetric, anaesthesia, pediatric, and operating-room staff. (II-2A) 4. Each hospital should have a written policy in place regarding the notification and/or consultation for the physicians responsible for a possible immediate Caesarean. (III B) 5. Continuous electronic fetal monitoring of women attempting a TOL after Caesarean is recommended. (II-2A) 6. Suspected uterine rupture requires urgent attention and expedited laparotomy in order to attempt to decrease maternal and perinatal morbidity and mortality. (II-2A) 7. Oxytocin augmentation is not contraindicated in women undergoing a TOL after Caesarean. (II-2A) 8. Medical induction of labour with oxytocin may be associated with an increased risk of uterine rupture and should be used carefully after appropriate counselling. (II-2B)9. Medical induction of labour with prostaglandin E2 (dinoprostone) is associated with an increased risk of uterine rupture and should not be used except in rare circumstances after appropriate counselling. (II-2B) 10. Prostaglandin E1 (misoprostol) is associated with a high risk of uterine rupture and should not be used as part of a TOL after Caesarean. (II-2A) 11. A foley catheter may be used safely to ripen the cervix in a woman planning a TOL after Caesarean. (II-2A) 12. The available data suggest that a trial of labour in women with more than one previous Caesarean section is likely to be successful but is associated with a higher risk of uterine rupture. (II-2B) 13. Multiple gestation is not a contraindication to a TOL after Caesarean. (II-2B) 14. Diabetes mellitus is not a contraindication to TOL after Caesarean. (II-2B) 15. Suspected fetal macrosomia is not a contraindication to a TOL after Caesarean. (II-2B) 16. Women delivering within 18 to 24 months of a Caesarean section should be counselled about an increased risk of uterine rupture in labour. (II-2B) 17. Postdatism is not a contraindication to a TOL after Caesarean. (II-2B) 18. Every effort should be made to obtain the previous Caesarean section operative report to determine the type of uterine incision used. In situations where the scar is unknown, information concerning the circumstances of the previous delivery is helpful in determining the likelihood of a low transverse incision. If the likelihood of a lower transverse incision is high, TOL after Caesarean can be offered. (II-2B) VALIDATION: These guidelines were approved by the Clinical Practice Obstetrics and Executive Committees of the Society of Obstetricians and Gynaecologists of Canada.

Exercise in pregnancy and the postpartum period.

OBJECTIVE: To design Canadian guidelines advising obstetric care providers of the maternal, fetal, and neonatal implications of aerobic and strength-conditioning exercises in pregnancy. OUTCOMES: Knowledge of the impact of exercise on maternal, fetal, and neonatal morbidity, and of the maternal measures of fitness. EVIDENCE: MEDLINE search from 1966 to 2002 for English-language articles related to studies of maternal aerobic and strength conditioning in a previously sedentary population, maternal aerobic and strength conditioning in a previously active population, impact of aerobic and strength conditioning on early and late pregnancy outcomes, and impact of aerobic and strength conditioning on neonatal outcomes, as well as for review articles and meta-analyses related to exercise in pregnancy. VALUES: The evidence collected was reviewed by the Society of Obstetricians and Gynaecologists of Canada (SOGC Clinical Practice Obstetrics Committee) with representation from the Canadian Society for Exercise Physiology, and quantified using the evaluation of evidence guidelines developed by the Canadian Task Force on the Periodic Health Exam. RECOMMENDATIONS: 1. All women without contraindications should be encouraged to participate in aerobic and strength-conditioning exercises as part of a healthy lifestyle during their pregnancy. (II-1,2B) 2. Reasonable goals of aerobic conditioning in pregnancy should be to maintain a good fitness level throughout pregnancy without trying to reach peak fitness or train for an athletic competition. (II-1,2C) 3. Women should choose activities that will minimize the risk of loss of balance and fetal trauma. (III-C) 4. Women should be advised that adverse pregnancy or neonatal outcomes are not increased for exercising women. (II-1,2B) 5. Initiation of pelvic floor exercises in the immediate postpartum period may reduce the risk of future urinary incontinence. (II-1C) 6. Women should be advised that moderate exercise during lactation does not affect the quantity or composition of breast milk or impact infant growth. (I-A) VALIDATION: This guideline has been approved by the SOGC Clinical Practice Obstetrics Committee, the Executive and Council of SOGC, and the Board of Directors of the Canadian Society for Exercise Physiology. SPONSORS: This guideline has been jointly sponsored by the Society of Obstetricians and Gynaecologists of Canada and the Canadian Society for Exercise Physiology.

The management of nausea and vomiting of pregnancy.

OBJECTIVES: To review the evidence-based management of nausea and vomiting of pregnancy (NVP) and hyperemesis gravidarum. EVIDENCE: MEDLINE and Cochrane database searches were performed using the medical subject headings (MeSH) of treatment, nausea, vomiting, pregnancy, and hyperemesis gravidarum. The quality of evidence reported in these guidelines has been described using the Evaluation of Evidence criteria outlined in the Report of the Canadian Task Force on the Periodic Health Exam. BENEFITS: NVP has a profound effect on women's health and quality of life during pregnancy, as well as a financial impact on the health care system, and its early recognition and management are recommended. (III-B) COST: Costs, including hospitalizations, additional office visits, and time lost from work, may be reduced if NVP is treated early.

Hemorrhagic shock.

OBJECTIVE: To review the clinical aspects of hemorrhagic shock and provide recommendations for therapy. OPTIONS: Early recognition of hemorrhagic shock and prompt systematic intervention will help avoid poor outcomes. OUTCOMES: Establish guidelines to assist in early recognition of hemorrhagic shock and to conduct resuscitation in an organized and evidence-based manner. EVIDENCE: Medline references were sought using the MeSH term "hemorrhagic shock." All articles published in the disciplines of obstetrics and gynaecology, surgery, trauma, critical care, anesthesia, pharmacology, and hematology between 1 January 1990 and 31 August 2000 were reviewed, as well as core textbooks from these fields. Selected references from these articles and book chapters were also obtained and reviewed. The level of evidence has been determined using the criteria described by the Canadian Task Force on the Periodic Health Examination. RECOMMENDATIONS: 1. Clinicians should be familiar with the clinical signs of hemorrhagic shock. (III-B) 2. Clinicians should be familiar with the stages of hemorrhagic shock. (III-B) 3. Clinicians should assess each woman's risk for hemorrhagic shock and prepare for the procedure accordingly. (III-B) 4. Resuscitation from hemorrhagic shock should include adequate oxygenation. (II-3A) 5. Resuscitation from hemorrhagic shock should include restoration of circulating volume by placement of two large-bore IVs, and rapid infusion of a balanced crystalloid solution. (I-A) 6. Isotonic crystalloid or colloid solutions can be used for volume replacement in hemorrhagic shock (I-B). There is no place for hypotonic dextrose solutions in the management of hemorrhagic shock (I-E). 7. Blood component transfusion is indicated when deficiencies have been documented by clinical assessment or hematological investigations (II-2B). They should be warmed and infused through filtered lines with normal saline, free of additives and drugs (II-3B). 8. Vasoactive agents are rarely indicated in the management of hemorrhagic shock and should be considered only when volume replacement is complete, hemorrhage is arrested, and hypotension continues. They should be administered in a critical care setting with the assistance of a multidisciplinary team. (III-B) 9. Appropriate resuscitation requires ongoing evaluation of response to therapy, including clinical evaluation, and hematological, biochemical, and metabolic assessments. (III-B) 10. In hemorrhagic shock, prompt recognition and arrest of the source of hemorrhage, while implementing resuscitative measures, is recommended. (III-B)VALIDATION: These guidelines have been reviewed by the Clinical Practice Obstetrics Committee and approved by Executive and Council of the Society of Obstetricians and Gynaecologists of Canada. SPONSORS: The Society of Obstetricians and Gynaecologists of Canada.