Gregory Davies

Canadian guidelines for exercise in pregnancy.

The need for guidelines for exercise during pregnancy and the postpartum period was stimulated during the early 1980s when active women of the “baby boom” generation became interested in whether it was safe to continue their active lifestyles during pregnancy. As a result of the strong demand for information, important questions were raised concerning the risk/benefit ratio of such exercise. Postulated risks included the possibility that the fetus may be forced to compete with contracting maternal skeletal muscle for oxygenated blood flow (leading to fetal hypoxia and distress), essential substrates (leading to fetal growth restriction), and heat dissipation (leading to fetal hyperthermia and potential teratogenic effects). Concern was also expressed that exercise may increase the chance of early miscarriage, spontaneous abortion, and premature labor, as well as chronic fatigue and musculoskeletal injury. Putative benefits included maintenance of prenatal aerobic and musculoskeletal fitness levels, prevention of excessive maternal weight gain, facilitation of labor and recovery from labor, promotion of good posture, prevention of gestational glucose intolerance and low back pain, and improved psychological adjustment to the changes of pregnancy. As a result of the conflict between these postulated benefits and risks, the idea that a dose-response relationship existed between the quantity and quality of exercise and maternal/fetal well-being quickly emerged (Fig. 1). The concept that exercise is safe for some pregnant women but not others also led to the need for absolute and relative medical contraindications to exercise and the need for medical screening by a qualified health care provider before engaging in fitness training after becoming pregnant. As a result of a lack of scientific information, early guidelines for exercise during pregnancy were necessarily conservative and based primarily on common sense and Note: A copy of the Physical Activity Readiness Medical Examination for Pregnancy can be obtained from the Internet at: www.csep.ca/forms.asp Correspondence: Larry A. Wolfe, PhD, School of Physical and Health Education, Queen’s University, Kingston, Ontario K7L 3N6, Canada. E-mail: wolfel@post. queensu.ca CLINICAL OBSTETRICS AND GYNECOLOGY Volume 46, Number 2, 488–495

Obesity in Pregnancy

OBJECTIVE To review the evidence and provide recommendations for the counselling and management of obese parturients. OUTCOMES Outcomes evaluated include the impact of maternal obesity on the provision of antenatal and intrapartum care, maternal morbidity and mortality, and perinatal morbidity and mortality. EVIDENCE Literature was retrieved through searches of Statistics Canada, Medline, and The Cochrane Library on the impact of obesity in pregnancy on antepartum and intrapartum care, maternal morbidity and mortality, obstetrical anaesthesia, and perinatal morbidity and mortality. Results were restricted to systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to April 2009. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies. VALUES The evidence obtained was reviewed and evaluated by the Maternal Fetal Medicine and Clinical Practice Obstetric Committees of the SOGC under the leadership of the principal authors, and recommendations were made according to guidelines developed by the Canadian Task Force on Preventive Health Care. BENEFITS, HARMS, AND COSTS Implementation of the recommendations in this guideline should increase recognition of the issues clinicians need to be aware of when managing obese women in pregnancy, improve communication and consultation amongst the obstetrical care team, and encourage federal and provincial agencies to educate Canadians about the values of entering pregnancy with as healthy a weight as possible. RECOMMENDATIONS 1. Periodic health examinations and other appointments for gynaecologic care prior to pregnancy offer ideal opportunities to raise the issue of weight loss before conception. Women should be encouraged to enter pregnancy with a BMI < 30 kg/m(2), and ideally < 25 kg/m(2). (III-B). 2. BMI should be calculated from pre-pregnancy height and weight. Those with a pre-pregnancy BMI > 30 kg/m(2) are considered obese. This information can be helpful in counselling women about pregnancy risks associated with obesity. (II-2B). 3. Obese pregnant women should receive counselling about weight gain, nutrition, and food choices. (II-2B). 4. Obese women should be advised that they are at risk for medical complications such as cardiac disease, pulmonary disease, gestational hypertension, gestational diabetes, and obstructive sleep apnea. Regular exercise during pregnancy may help to reduce some of these risks. (II-2B). 5. Obese women should be advised that their fetus is at an increased risk of congenital abnormalities, and appropriate screening should be done. (II-2B). 6. Obstetric care providers should take BMI into consideration when arranging for fetal anatomic assessment in the second trimester. Anatomic assessment at 20 to 22 weeks may be a better choice for the obese pregnant patient. (II-2B). 7. Obese pregnant women have an increased risk of Caesarean section, and the success of vaginal birth after Caesarean section is decreased. (II-2B). 8. Antenatal consultation with an anaesthesiologist should be considered to review analgesic options and to ensure a plan is in place should a regional anaesthetic be chosen. (III-B). 9. The risk of venous thromboembolism for each obese woman should be evaluated. In some clinical situations, consideration for thromboprophylaxis should be individualized. (III-B).

Substance Use in Pregnancy

OBJECTIVE To improve awareness and knowledge of problematic substance use in pregnancy and to provide evidence-based recommendations for the management of this challenging clinical issue for all health care providers. OPTIONS This guideline reviews the use of screening tools, general approach to care, and recommendations for clinical management of problematic substance use in pregnancy. OUTCOMES Evidence-based recommendations for screening and management of problematic substance use during pregnancy and lactation. EVIDENCE Medline, PubMed, CINAHL, and The Cochrane Library were searched for articles published from 1950 using the following key words: substance-related disorders, mass screening, pregnancy complications, pregnancy, prenatal care, cocaine, cannabis, methadone, opioid, tobacco, nicotine, solvents, hallucinogens, and amphetamines. Results were initially restricted to systematic reviews and randomized control trials/controlled clinical trials. A subsequent search for observational studies was also conducted because there are few RCTs in this field of study. Articles were restricted to human studies published in English. Additional articles were located by hand searching through article reference lists. Searches were updated on a regular basis and incorporated in the guideline up to December 2009. Grey (unpublished) literature was also identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies. VALUES The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on the Preventive Health Care. Recommendations for practice were ranked according to the method described in that report (Table 1). BENEFITS, HARMS, AND COSTS This guideline is intended to increase the knowledge and comfort level of health care providers caring for pregnant women who have substance use disorders. Improved access to health care and assistance with appropriate addiction care leads to reduced health care costs and decreased maternal and neonatal morbidity and mortality. RECOMMENDATIONS 1. All pregnant women and women of childbearing age should be screened periodically for alcohol, tobacco, and prescription and illicit drug use. (III-A) 2. When testing for substance use is clinically indicated, urine drug screening is the preferred method. (II-2A) Informed consent should be obtained from the woman before maternal drug toxicology testing is ordered. (III-B) 3. Policies and legal requirements with respect to drug testing of newborns may vary by jurisdiction, and caregivers should be familiar with the regulations in their region. (III-A) 4. Health care providers should employ a flexible approach to the care of women who have substance use problems, and they should encourage the use of all available community resources. (II-2B) 5. Women should be counselled about the risks of periconception, antepartum, and postpartum drug use. (III-B) 6. Smoking cessation counselling should be considered as a first-line intervention for pregnant smokers. (I-A) Nicotine replacement therapy and/or pharmacotherapy can be considered if counselling is not successful. (I-A) 7. Methadone maintenance treatment should be standard of care for opioid-dependent women during pregnancy. (II-IA) Other slow-release opioid preparations may be considered if methadone is not available. (II-2B) 8. Opioid detoxification should be reserved for selected women because of the high risk of relapse to opioids. (II-2B) 9. Opiate-dependent women should be informed that neonates exposed to heroin, prescription opioids, methadone, or buprenorphine during pregnancy are monitored closely for symptoms and signs of neonatal withdrawal (neonatal abstinence syndrome). (II-2B) Hospitals providing obstetric care should develop a protocol for assessment and management of neonates exposed to opiates during pregnancy. (III-B) 10. Antenatal planning for intrapartum and postpartum analgesia may be offered for all women in consultation with appropriate health care providers. (III-B) 11. The risks and benefits of breastfeeding should be weighed on an individual basis because methadone maintenance therapy is not a contraindication to breastfeeding. (II-3B).

The Use of Magnetic Resonance Imaging in the Obstetric Patient

OBJECTIVE To review the biological effects and safety of magnetic resonance imaging (MRI) in the obstetric patient and to review procedural issues, indications, and contraindications for obstetrical MRI. OUTCOMES This guideline is intended to reassure patients and clinicians of the safety of MRI in pregnancy and to provide a framework for its use. EVIDENCE Published literature was retrieved through searches of PubMed or Medline in 2013 using controlled vocabulary and key words (e.g., MRI, safety, pregnancy). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies published in English and in French. There were no date restrictions. Searches were updated on a regular basis and incorporated in the guideline to July 2013. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies. VALUES The quality of evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table). BENEFITS, HARMS, AND COSTS This article is intended to reassure obstetric care providers that if used in an appropriate manner without the use of contrast agents, MRI in the obstetrical patient is safe for mother and fetus in the second and third trimesters. Because obstetrical MRI is expensive and has limited availability in Canada, this clinical guideline is intended to encourage the judicious use of this resource. SUMMARY STATEMENTS: 1. Fetal magnetic resonance imaging is safe at 3.0 tesla or less during the second and third trimesters. (II-2) 2. It is safe to continue breastfeeding after receiving a gadolinium contrast agent. (III) RECOMMENDATIONS: 1. Use of magnetic resonance imaging during the first trimester of pregnancy should be restricted to maternal indications for which the information is considered clinically imperative. Inadvertent exposure to magnetic resonance imaging during the first trimester has not been associated with any long-term sequelae and should not raise clinical concern. (III-C) 2. Gadolinium contrast may be used in pregnant women when the benefits outweigh the potential risks. (III-C).

Intrauterine Growth Restriction: Screening, Diagnosis, and Management

BACKGROUND Intrauterine growth restriction (IUGR) is an obstetrical complication, which by definition would screen in 10% of fetuses in the general population. The challenge is to identify the subset of pregnancies affected with pathological growth restriction in order to allow intervention that would decrease morbidity and mortality. OBJECTIVE The purpose of this guideline is to provide summary statements and recommendations and to establish a framework for screening, diagnosis, and management of pregnancies affected with IUGR. METHODS Affected pregnancies are compared with pregnancies in which the fetus is at an appropriate weight for its gestational age. History, physical examination, and laboratory investigations including biochemical markers and ultrasound characteristics of IUGR are reviewed, and a management strategy is suggested. EVIDENCE Published literature in English was retrieved through searches of PubMed or MEDLINE, CINAHL, and The Cochrane Library in January 2013 using appropriate controlled vocabulary via MeSH terms (fetal growth restriction and small for gestational age) and key words (fetal growth, restriction, growth retardation, IUGR, low birth weight, small for gestational age). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies. VALUES The quality of evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table). BENEFITS, HARMS, AND COSTS Implementation of the recommendations in this guideline should increase clinician recognition of IUGR and guide intervention where appropriate. Optimal long-term follow-up of neonates diagnosed as IUGR may improve their long-term health.

Phasic menstrual cycle effects on the control of breathing in healthy women

This study examined the effects of menstrual cycle phase on ventilatory control. Fourteen eumenorrheic women were studied in the early follicular (FP; 1-6 days) and mid-luteal (LP; 20-24 days) phase of the menstrual cycle. Blood for the determination of arterial PCO(2) (PaCO(2)) , plasma strong ion difference ([SID]), progesterone ([P(4)]), and 17beta-estradiol ([E(2)]) concentrations were obtained at rest. Subjects performed a CO(2) rebreathing procedure that included prior hyperventilation and maintenance of iso-oxia to evaluate central and peripheral chemoreflex, and nonchemoreflex drives to breathe. Resting PaCO(2) and [SID] were lower; minute ventilation (V (E)), [P(4)] and [E(2)] were higher in the LP versus FP. Within the LP, significant correlations were observed for PaCO(2) with [P(4)], [E(2)] and [SID]. Menstrual cycle phase had no effect on the threshold or sensitivity of the central and/or peripheral ventilatory chemoreflex response to CO(2). Both (V (E)) and the ventilatory response to hypocapnia (representing nonchemoreflex drives to breathe) were approximately 1L/min greater in the LP versus FP accounting for the reduction in PaCO(2) . These data support the hypothesis that phasic menstrual cycle changes in PaCO(2) may be due, at least in part, to the stimulatory effects of [P(4)], [E(2)] and [SID] on ventilatory drive.

Cervical Insufficiency and Cervical Cerclage

OBJECTIVE The purpose of this guideline is to provide a framework that clinicians can use to determine which women are at greatest risk of having cervical insufficiency and in which set of circumstances a cerclage is of potential value. EVIDENCE Published literature was retrieved through searches of PubMed or MEDLINE, CINAHL, and The Cochrane Library in 2012 using appropriate controlled vocabulary (e.g., uterine cervical incompetence) and key words (e.g., cervical insufficiency, cerclage, Shirodkar, cerclage, MacDonald, cerclage, abdominal, cervical length, mid-trimester pregnancy loss). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to January 2011. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies. VALUES The quality of evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table). Recommendations 1. Women who are pregnant or planning pregnancy should be evaluated for risk factors for cervical insufficiency. A thorough medical history at initial evaluation may alert clinicians to risk factors in a first or index pregnancy. (III-B) 2. Detailed evaluation of risk factors should be undertaken in women following a mid-trimester pregnancy loss or early premature delivery, or in cases where such complications have occurred in a preceding pregnancy. (III-B) 3. In women with a history of cervical insufficiency, urinalysis for culture and sensitivity and vaginal cultures for bacterial vaginosis should be taken at the first obstetric visit and any infections so found should be treated. (I-A) 4. Women with a history of three or more second-trimester pregnancy losses or extreme premature deliveries, in whom no specific cause other than potential cervical insufficiency is identified, should be offered elective cerclage at 12 to 14 weeks of gestation. (I-A) 5. In women with a classic history of cervical insufficiency in whom prior vaginal cervical cerclage has been unsuccessful, abdominal cerclage can be considered in the absence of additional mitigating factors. (II-3C) 6. Women who have undergone trachelectomy should have abdominal cerclage placement. (II-3C) 7. Emergency cerclage may be considered in women in whom the cervix has dilated to < 4 cm without contractions before 24 weeks of gestation. (II-3C) 8. Women in whom cerclage is not considered or justified, but whose history suggests a risk for cervical insufficiency (1 or 2 prior mid-trimester losses or extreme premature deliveries), should be offered serial cervical length assessment by ultrasound. (II-2B) 9. Cerclage should be considered in singleton pregnancies in women with a history of spontaneous preterm birth or possible cervical insufficiency if the cervical length is ≤ 25 mm before 24 weeks of gestation. (I-A) 10. There is no benefit to cerclage in a woman with an incidental finding of a short cervix by ultrasound examination but no prior risk factors for preterm birth. (II-1D) 11. Present data do not support the use of elective cerclage in multiple gestations even when there is a history of preterm birth; therefore, this should be avoided. (I-D) 12. The literature does not support the insertion of cerclage in multiple gestations on the basis of cervical length. (II-1D).

Physiological mechanisms of hyperventilation during human pregnancy

This study examined the role of pregnancy-induced changes in wakefulness (or non-chemoreflex) and central chemoreflex drives to breathe, acid-base balance and female sex hormones in the hyperventilation of human pregnancy. Thirty-five healthy women were studied in the third trimester (TM(3); 36.3+/-1.0 weeks gestation; mean+/-S.D.) and again 20.2+/-7.8 weeks post-partum (PP). An iso-oxic hyperoxic rebreathing procedure was used to evaluate wakefulness and central chemoreflex drives to breathe. At rest, arterialized venous blood was obtained for the estimation of arterial PCO(2) (PaCO(2)) and [H(+)]. Blood for the determination of plasma strong ion difference ([SID]), albumin ([Alb]), as well as serum progesterone ([P(4)]) and 17beta-estradiol ([E(2)]) concentrations was also obtained at rest. Wakefulness and central chemoreflex drives to breathe, [P(4)] and [E(2)], ventilation and V CO(2) increased, whereas PaCO(2) and the central chemoreflex ventilatory recruitment threshold for PCO(2) (VRTCO(2)) decreased from PP to TM(3) (all p<0.01). The reductions in PaCO(2) were not related to the increases in [P(4)] and [E(2)]. The alkalinizing effects of reductions in PaCO(2) and [Alb] were partly offset by the acidifying effects of a reduced [SID], such that arterial [H(+)] was still reduced in TM(3) vs. PP (all p<0.001). A mathematical model of ventilatory control demonstrated that pregnancy-induced changes in wakefulness and central chemoreflex drives to breathe, acid-base balance, V CO(2) and cerebral blood flow account for the reductions in PaCO(2), [H(+)] and VRTCO(2). This is the first study to demonstrate that the hyperventilation and attendant hypocapnia/alkalosis of human pregnancy results from a complex interaction of pregnancy-induced changes in wakefulness and central chemoreflex drives to breathe, acid-base balance, metabolic rate and cerebral blood flow.

Maternal Hemodynamics After Oxytocin Bolus Compared With Infusion in the Third Stage of Labor: A Randomized Controlled Trial

OBJECTIVE: To assess the effects of oxytocin bolus or infusion on maternal hemodynamics in the third stage of labor. METHODS: In a randomized, double-blind, double-dummy fashion, 99 women received an intravenous oxytocin bolus (10 IU push) and 102 women received an infusion (10 IU in 500 mL saline at 125 mL/h) at delivery of the anterior shoulder. Mean arterial pressure and heart rate were measured every minute for 10 minutes, then every 5 minutes for the next 20 minutes. These serial measurements were analyzed using a 2-factor analysis of variance for repeated measures. RESULTS: Serial mean arterial pressure measures varied significantly between groups (interaction effect, P = .002). Mean arterial pressure (± standard deviation) nadirs were reached after 10 minutes, 80.9 (± 11.0) mm Hg in the bolus group compared with 77.0 (± 12.1) mm Hg in the dilute infusion group. The mean difference (95% confidence interval) between groups was 4.0 (0.7–7.2) mm Hg. Serial heart rate measures also varied between groups (interaction effect, P < .001). Mean heart rate (± standard deviation) peaked 1 minute after the oxytocin infusion, 115 (± 27) beats per minute (bpm) in the bolus group compared with 109 (± 21) bpm in the dilute infusion group. The mean difference (95% confidence interval) between groups was 6.6 bpm (−0.1 to 13.3). The dilute oxytocin infusion group experienced a greater mean estimated blood loss (423.7 mL compared with 358.1 mL, P = .029, t test), increased use of additional oxytocics (35.3% compared with 22.2%, P = .044, Fisher exact test) and a greater drop in hemoglobin (admission minus postpartum) (17.4g/L compared with 11.4g/L, P = .002, t test) compared with the oxytocin bolus group. CONCLUSION: Bolus oxytocin of 10 IU is not associated with adverse hemodynamic responses and can safely be administered to women with intravenous access in the third stage of labor for postpartum hemorrhage prophylaxis. LEVEL OF EVIDENCE: I

Ultrasonographic Cervical Length Assessment in Predicting Preterm Birth in Singleton Pregnancies

OBJECTIVES To review (1) the use of ultrasonographic-derived cervical length measurement in predicting preterm birth and (2) interventions associated with a short cervical length. OUTCOMES Reduction in rates of prematurity and/or better identification of those at risk, as well as possible prevention of unnecessary interventions. EVIDENCE Published literature was retrieved through searches of PubMed and The Cochrane Library up to December 2009, using appropriate controlled vocabulary and key words (preterm labour, ultrasound, cervix, incompetent cervix, transvaginal, transperineal, cervical length, fibronectin). Results were restricted to general and systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies. VALUES The evidence and this guideline were reviewed by the Diagnostic Imaging Committee and the Maternal Fetal Medicine Committee of the Society of Obstetricians and Gynaecologists of Canada, and the recommendations were made according to the guidelines developed by The Canadian Task Force on Preventive Health Care (Table 1). BENEFITS, HARMS, AND COSTS Preterm birth is a leading cause of perinatal morbidity and mortality. Use of the ultrasonographic technique reviewed in this guideline may help identify women at risk of preterm birth and, in some circumstances, lead to interventions that may reduce the rate of preterm birth. SPONSORS The Society of Obstetricians and Gynaecologists of Canada.