Relationship of prenatal diagnosis and pregnancy termination to overall infant mortality in Canada

CONTEXT: Prenatal diagnosis and termination of affected pregnancies can prevent infant deaths due to congenital anomalies, but an effect at the population level has not been shown. OBJECTIVE: To examine the impact of recent changes in congenital anomaly-related fetal and infant deaths on overall population-based infant mortality. DESIGN, SETTING, AND SUBJECTS: Birth cohort-based study of all live births, stillbirths, and infant deaths in Canada (excluding Ontario) for 1991-1998. MAIN OUTCOME MEASURES: Cause-specific infant mortality rates and gestational age-specific fetal death rates. RESULTS: The birth cohort-based infant mortality rate fluctuated between 6.4 and 6.1 per 1000 live births between 1991 and 1995, then dropped to 5.4 per 1000 in 1996 and 5.5 per 1000 in 1997. The rate of infant death from congenital anomalies was stable between 1991 and 1995 but declined by 21% (95% confidence interval, 19%-32%) from 1.86 per 1000 in 1995 to 1.47 per 1000 in 1996 and 1997. Fetal deaths due to pregnancy termination at 20 to 23 weeks' gestation increased dramatically in 1994, while fetal deaths due to congenital anomalies at 20 to 21 weeks increased in 1995 and subsequently. Provinces/territories with high rates of fetal death due to pregnancy termination/congenital anomalies at 20 to 23 weeks had fewer infant deaths due to congenital anomalies. CONCLUSION: A large decrease in infant deaths due to congenital anomalies was associated with the most recent decline in infant mortality in Canada, suggesting that increases in prenatal diagnosis and pregnancy termination for congenital anomalies are related to decreases in overall infant mortality at the population level.     

Cost-effectiveness of induction of labour versus serial antenatal monitoring in the Canadian Multicentre Postterm Pregnancy Trial.

OBJECTIVE: To determine the cost-effectiveness of induction of labour versus serial fetal monitoring while awaiting spontaneous labour in postterm pregnancies. DESIGN: Cost-effectiveness and cost-minimization analyses conducted as part of a Canadian multicentre randomized clinical trial. SETTING: Twenty-two Canadian hospitals, of which 19 were teaching hospitals and 3 were community hospitals. PATIENTS: Women with uncomplicated pregnancies of 41 or more weeks' gestation were randomly assigned to induction of labour or serial antenatal monitoring. Of the 3418 women enrolled, no data were received on 11. Therefore, results were based on data from 1701 women in the induction arm of the study and 1706 women in the monitoring arm. MAIN OUTCOME MEASURES: Perinatal mortality and neonatal morbidity, rates of cesarean section and health care costs. Hospital costing models were developed specifically for the study. Data on use of major resources (e.g., length of hospital stay, surgical procedures, major diagnostic tests and procedures, and medications) for all trial participants were collected and combined with data on minor tests and procedures (e.g., laboratory tests) abstracted from a detailed review of medical records of a sample of patients. RESULTS: Because the results of the clinical trial showed a nonsignificant difference in perinatal mortality and neonatal morbidity between the induction and monitoring arms, the authors conducted a cost-minimization rather than a cost-effectiveness analysis. The mean cost per patient with a postterm pregnancy managed through monitoring was $3132 (95% confidence interval [CI] $3090 to $3174) and per patient who underwent induction of labour was $2939 (95% CI $2898 to $2981), for a difference of $193. The significantly higher (p < 0.0001) mean cost per patient in the monitoring arm was due mainly to the costs of additional monitoring and the significantly higher rates of cesarean section among these patients. Estimated conservatively, the savings resulting from a universal policy of managing postterm pregnancies by induction of labour in Canada may be as high as $8 million a year. CONCLUSIONS: A policy of managing postterm pregnancy through induction of labour not only results in more favourable outcomes than a monitoring strategy but does so at a lower cost.     

A perinatal perspective on South Australia in the 1980s.

OBJECTIVE: To assess changes in sociodemographic characteristics of mothers, their obstetric management and perinatal outcomes in the 1980s. DESIGN: A survey of data recorded in the South Australian perinatal data collection. For singleton births, we compared risks of stillbirth, neonatal death and perinatal death by year of birth, after adjusting for risk factors. SUBJECTS: There were 176,637 births of at least 400 g birthweight (or at least 20 weeks' gestation) notified to the perinatal data collection between 1981 and 1989. MAIN OUTCOME MEASURES: Frequency of risk factors and relative risks of stillbirth, neonatal death and perinatal death by year of birth. RESULTS: There have been changes in the sociodemographic characteristics of mothers, their obstetric management and perinatal outcomes during the 1980s. Crude perinatal mortality rates have not increased, despite increases in the frequency of low birthweight, preterm births, mothers aged 35 years and over, and some other risk factors. After adjusting for risk factors, the risks of stillbirth, neonatal death and perinatal death were lower among singletons in 1987-1989 than in the 1981-1982 reference period. CONCLUSION: Advances in clinical management may be preventing increases in stillbirths, neonatal deaths and perinatal deaths in response to increased numbers of births with low birthweight, preterm delivery and some other risk factors in South Australia.     

Diagnosis of dystocia and management with cesarean section among primiparous women in Ottawa-Carleton.

We carried out a chart review study to determine the rate of diagnosis of dystocia (abnormal progress) and the use of cesarean section to treat dystocia among 3887 primiparous women who gave birth to a single baby in the vertex presentation at four hospitals in Ottawa-Carleton in 1984. Of the 3740 women who had some labour 1127 (30.1%) were given a diagnosis of dystocia. Cesarean section for dystocia was done during all phases of labour (41% of procedures in the latent phase, 38% in the active phase and 21% in the second stage). The cesarean section rate varied among the hospitals from 11.8% to 19.6%. A total of 75% of the cesarean sections were for dystocia, disproportion or failed induction. The findings suggest that cesarean section is being done for disproportion without a trial of labour beyond the latent phase and for dystocia in the absence of fetal distress. If these practices were modified the cesarean section rate could be reduced from 16% to about 8%, the rate found in some other centres and that observed in Canada in the early 1970s.     

Rates and outcome of pregnancies achieved in the first 4 years of an in-vitro fertilization program.

Between Feb. 1, 1984, and Dec. 31, 1987, 578 couples were treated in the in-vitro fertilization (IVF) program at University Hospital, London, Ont. The 160 confirmed pregnancies resulted in 86 deliveries and the birth of 108 babies. There were 20 spontaneous abortions, 12 ectopic pregnancies, 11 presumptive pregnancies, 4 neonatal deaths and 1 stillbirth. At the time of writing, 41 pregnancies of 20 weeks' gestation or more were in progress. Except for a high cesarean section rate the obstetric outcome of pregnancies achieved with IVF does not appear to be different from that expected for a group of infertile couples treated with conventional therapies. The pregnancy rates varied according to the denominator used.     

Inducing labour with vaginally administered prostaglandin E2

In 50 consecutive pregnant women at a 125-bed community hospital with 1000 deliveries annually, labour was induced with prostaglandin E2 administered intravaginally. There were no stillbirths or neonatal deaths, and complications in the mothers were few. In nine women (18%) oxytocin was subsequently administered because of a failure of labour to progress; in spite of this, cesarean section was required in two (4%) of the patients. The overall cesarean section rate was 6%. Prostaglandins have been used routinely to induce labour in the United Kingdom for several years. This noninvasive method is safe, effective and well received by women in a community hospital setting, including those wanting "natural childbirth".     

An audit of perinatal mortality

Perinatal mortality rates are considered in the western world to be a quantitative barometer of maternity care. This 6-year prospective perinatal audit was conducted at a tertiary hospital in order to determine foetal outcome, and the common causes of foetal and early neonatal deaths. Of a total of 30,987 births, there were 469 stillbirths and 391 early neonatal deaths, giving a perinatal mortality rate of 27.7 per 1000 total births. The leading causes of stillbirths were the hypertensive disorders of pregnancy, abruptio placentae, diabetes mellitus, intrapartum foetal distress and lethal congenital anomalies. Neonatal deaths were mainly due to the respiratory distress syndrome (57.8%), birth asphyxia (22.2%) and sepsis (13.5%). A dedicated medical team, including a neonatologist, to manage pre-eclampsia, and more senior obstetric involvement in the labour ward are recommended.     

Maternal hemoglobin concentration during pregnancy and risk of stillbirth

CONTEXT: High and low maternal hemoglobin concentrations during pregnancy have been reported to increase risk of small-for-gestational-age (SGA) birth, which is a predictor of stillbirth. The relationship between hemoglobin concentration during pregnancy and risk of stillbirth is unclear. OBJECTIVE: To study the associations among hemoglobin concentration at first measurement during antenatal care, change in hemoglobin concentration during pregnancy, and risk of stillbirth. DESIGN, SETTING, AND PARTICIPANTS: Population-based, matched case-control study of births from 1987 through 1996 in Sweden including 702 primiparous women with stillbirths occurring at 28 weeks' gestation or later and 702 primiparous women with live births. MAIN OUTCOME MEASURES: Risk of stillbirth, classified as malformed or nonmalformed, antepartum or intrapartum, preterm or term, and SGA or non-SGA, compared by maternal hemoglobin concentration at first antenatal measurement and weekly changes in hemoglobin concentration during pregnancy, adjusted for maternal age, body mass index, height, smoking, socioeconomic status, and week of first hemoglobin measurement. RESULTS: In multivariate analyses, compared with women with hemoglobin concentrations of 126 to 135 g/L at first antenatal measurement, women with concentrations of 146 g/L or higher were at increased risk of stillbirth (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.0-3.3). This risk was slightly increased when the analysis was restricted to antepartum stillbirths without malformations (OR, 2.0; 95% CI, 1.1-3.8). When we further restricted the analyses to preterm and SGA antepartum nonmalformed stillbirths, the ORs increased to 2.7 (95% CI, 1.1-6.4) and 4.2 (95% CI, 1.3-13. 9), respectively. Excluding women with preeclampsia and eclampsia further increased these risks. Average weekly change in hemoglobin concentration during early or late pregnancy was not significantly associated with risk of stillbirth, although a larger decrease in concentration tended to be protective. Anemia (hemoglobin concentration <110 g/L) was not significantly associated with risk of stillbirth in multivariate analyses (OR, 1.2; 95% CI, 0.5-2.7). CONCLUSIONS: High hemoglobin concentration at first measurement during antenatal care appears to be associated with increased risk of stillbirth, especially preterm and SGA antepartum stillbirths. JAMA. 2000;284:2611-2617.     

International differences in the use of obstetric interventions

This study investigated current levels and trends between 1975 and 1986 in the rates of cesarean section in 21 countries and of operative vaginal delivery in 14 countries. Sharp differences in national obstetric practice were found, with cesarean rates ranging from a high of 32 (Brazil) to 7 (Czechoslovakia) per 100 hospital deliveries, and operative vaginal rates from 16 (Canada) to 2 (Czechoslovakia) per 100 hospital deliveries. For most countries, rates of cesarean section have risen as operative vaginal rates have fallen, but some important exceptions exist. A comparison of cesarean section rates for two complications of labor and delivery that can be objectively diagnosed, multiple births and breech delivery, demonstrates that cesarean section rates for these complications rose sharply in almost every country from 1980 to 1985. A comparison of 1985 national rates of intervention and measures of birth outcome found no significant relationship between the two. While such ecological comparisons are imperfect at best, this does indicate that low levels of early infant mortality can be achieved in some populations despite a low rate of cesarean deliveries.     

Trends in ectopic pregnancy in Canada.

The incidence in Canada of one complication of sexually transmitted disease, ectopic pregnancy, was examined by age group for the years 1971 through 1980 by means of hospital statistics provided by Statistics Canada. The denominator was "reported pregnancies"--the total of live births, stillbirths, legal abortions and ectopic pregnancies in a given year. In 1980, 4123 ectopic pregnancies (9.3/1000 reported pregnancies) were reported, a 63% increase from 1970. The incidence had increased in each age stratum. This trend may be related to increasing rates of gonococcal infection and of hospitalization for pelvic inflammatory disease and lends confirmation to data from other countries that relate the increase in the rate of ectopic pregnancy to rising rates of sexually transmitted disease.     

The experience and effectiveness of the Nova Scotia Rh program, 1964-84.

A program to reduce the incidence of erythroblastosis fetalis was started in Nova Scotia in 1964. Up to the end of 1984, 120 fetuses received 247 intrauterine transfusions. The survival rate was 45.6% in the first 10 years of the program and 66.7% in the next 11 years. For fetuses at or over 26 weeks' gestation the figures were 51.5% and 73.7% respectively. Postpartum prevention was started in 1968, with administration of Rh immune globulin (RhIG) to Rh-negative unimmunized women within 72 hours after the birth of an Rh-positive infant. Antepartum prevention, started in 1979, consisted of administration of RhIG at 28 weeks' gestation to Rh-negative unimmunized women. The effectiveness of the prevention program was evaluated by enumerating the known cases of Rh(D) alloimmunization in the province from 1982 to 1984: 55 cases were identified, a rate of 1.5 per 1000 births instead of the expected rate of about 10 per 1000.     

Prolonged pregnancy: the management debate

A prospective trial was conducted to compare the effects of conservative management of prolonged pregnancy (conservative group) with routine induction of labour at 42 weeks' gestation (active group) in otherwise uncomplicated pregnancies. Of the 402 pregnancies studied, 207 (51%) were allocated to conservative management and 195 (49%) were allocated to have labour induced. The groups were well matched for age, parity, and smoking habits. One hundred and sixty six (80%) of the patients in the conservative group went into spontaneous labour. Of the remainder, two underwent elective caesarean section, 19 had labour induced because of clinical concern, and the remaining 20 had labour induced at the patient's own request. One hundred and twenty five (64%) of the patients in the planned active group underwent induction of labour. Of the remaining 70, 49 went into spontaneous labour and 21 (11%) asked that they should not have labour induced. Comparison of the two groups showed no difference in the length of the first stage of labour but a trend towards an increased need for intervention for fetal distress (p less than 0.06) in the active group. There were no differences in the length of the second stage, the need for intervention, or the mode of delivery. In terms of Apgar scores the neonatal outcome was not significantly different between the two groups, but a greater proportion of the babies (15% v 8%) in the active group required intubation. Umbilical cord venous pH estimated in the last 183 consecutive deliveries in the study showed a significantly lower mean value in the active group (p less than 0.05). There was no difference in birth weight between the two groups. Two deaths occurred in the study. There was a stillbirth in the conservative group at 292 days after massive abruption, and one neonatal death in the active group owing to multiple congenital abnormalities. The outcome for mother and baby in patients from both groups who went into spontaneous labour was generally good. The outcome for patients for whom conservative management was planned but induction became necessary was no different from that of patients who underwent planned induction at term. Thus from our results we can find no evidence to support the view that women with normal prolonged pregnancy should undergo routine induction of labour at 42 weeks' gestation.     

Stillbirths--ten years experience at Toa Payoh Hospital

An analysis of 287 consecutive stillbirths associated with 47,171 deliveries in Toa Payoh Hospital between 1978 and 1987 was undertaken. The incidence of stillbirths was 6.1 +/- 1.26 per 1,000 total births. 149 out of 287 cases (51.9%) had known causes of death. Intrauterine anoxia and congenital malformations are the commonest diagnosis. In contrast, in 48.1% (138/287) of the stillbirths, we were unable to determine the underlying causes because of maceration and a low autopsy rate. Among the 287 stillborn infants, 54% were born prematurely, and 64.2% were born with birth weights of less than 2,500 g. 8.4% of the mothers had a past history of one to three abortions, and 5.6% of the mothers had a past history of one or more stilbirths. This study showed that the stillbirth rate in this hospital has not changed significantly in the last ten years.     

The safety of obstetric services in small communities in northern Ontario.

The safety of the obstetric care system in the small hospitals of northern Ontario was assessed by analysing the outcomes of all obstetric cases over a 2-year period. Information was retrieved by place of residence rather than hospital of delivery so that the overall perinatal system, including the referral patterns, would be assessed. There was little difference in perinatal loss rate (stillbirths and neonatal deaths up to 28 days per 1000 births) for residents of areas served by different levels of obstetric care. Areas served by units where cesarean sections are done regularly but which do not have specialists in obstetrics or pediatrics had a perinatal loss rate of 10.43, whereas areas served by units staffed with two or more specialists in both obstetrics and pediatrics and handling more than 1000 deliveries per year had a perinatal loss rate of 12.13. Although many of the smaller hospitals did not have the minimum capabilities suggested for obstetric units relatively safe care was being provided. These results do not support the need for further centralization of obstetric services in northern Ontario.     

A study of prolonged labour.

Two hundred and three consecutive cases of prolonged labour have been retrospectively reviewed from January 1984 to December 1986. The incidence of prolonged labour was 4.39%. It was noted that 66.5% of the patients with prolonged labour were unbooked emergency admissions, and 73.3% were primipara. The causes of prolonged labour were the occipitoposterior position (10.8%), relative cephalopelvie disproportion (18.2%), uterine dysfunction (44.5%), and in 26.1% an obstructive cause was present. A spontaneous vaginal delivery occurred in 34.4%, a forceps delivery in 22.6% and the caesarean section rate was 29%. The maternal mortality, febrile and non-febrile morbidity were 9.7 per 1000 total births, 42.8% and 17.2% respectively, which showed a direct relation to the duration of labour, and a significant increase in the patients with obstructed labour, and after an abdominal delivery. The corrected perinatal mortality was 165 per 1000 total births, which was also directly related to the duration of labour, and 74.3% of the perinatal deaths occurred in the patients with obstructed labour. The perinatal mortality in the study group was nearly three times higher than the overall hospital group. Neonatal morbidity occurred in 48.8% of the newborns.     

Rh immunization in Manitoba: progress in prevention and management.

For two decades the perinatal mortality caused by erythroblastosis has been decreasing in Manitoba. The improved management of Rh-immunized pregnancies has lowered the death rate among affected infants from 10.8% to 3.4%, while the prevention of Rh immunization has reduced its incidence from 9.1 to 2.2 per 1000 total births. In its first 6 years and 8 months Manitoba's antenatal prophylaxis program, in which immunoglobulin is administered to Rh-negative women at 28 weeks' gestation, reduced the incidence of Rh immunization during pregnancy by 93%. In combination with post-abortion and postpartum prophylaxis the antenatal treatment has provided a protection rate of 98.6% among primigravidas at risk. Further improvements are expected.     

Prevalence and prenatal diagnosis of neural tube defects in Nova Scotia in 1980-84.

A survey of the records of all hospitals with obstetric services in Nova Scotia revealed that during 1980-84 there were 122 pregnancies involving a neural tube defect. The mean rate was 2/1000 births. Of the affected fetuses or infants 54% had spina bifida, 35% had anencephaly and 11% had encephalocele. The records showed that in the early part of the period studied at least one prenatal ultrasonographic examination had been performed in 60% of the pregnancies; in 1984 the rate was 74%. When examinations done before 16 weeks' gestation were excluded, the overall detection rates at the first ultrasonographic examination were 100% for anencephaly and 73% for spina bifida and encephalocele; the rates improved toward the end of the study period.     

延期妊娠临床处理选择的探讨

目的探讨延期妊娠引产时机及方式的选择对产妇剖宫产率、并发症率及新产儿窒息率等的影响,为临床处理选择提供参考,以期有效减少剖宫产率及分娩并发症。方法对本院2006年1月～2008年1月收治382例孕41～41+6周、无妊娠合并症及并发症的产妇分成两组,一组予引产(205例):如宫颈评分≥7分,予人工破膜引产;如宫颈评分≤6分,予催产素引产;另一组为自然临产组(177例):即在严格监护下等待自然临产,将两组的母儿结局进行统计学分析比较。结果引产组较自然临产组剖宫产率有明显增加,差异有显著性(P0.05),其他母儿并发症差异无统计学意义(P0.05)。结论对于无妊娠合并症及并发症的延期妊娠,在现有多种手段对胎儿进行密切监护的条件下可以等待自然临产。     

Induction of Labour for Prevention of Stillbirth from Rh Hemolytic Disease

The fate of 80 infants delivered after induction of labour in 72 Rh-sensitized mothers was studied to determine whether the stillbirth rate could be reduced. Labour was induced at 32 to 39 weeks of gestation; the criteria for induction were based on the history of previously affected infants, and a maternal Rh-antibody titre of 1/40 or greater, using an indirect antiglobulin technique. Nine mothers were delivered by Cesarean section. It was estimated that 26 infants were so severely affected as to be unlikely to have survived to term. However, only seven died, and one was stillborn. Two of these would normally have survived, one being Rh-negative. These two cases demonstrated the main danger in this method of management. There was a probable saving of 18 infants. In 22 mothers there was no history of previous delivery of an affected infant; in all 22 the infants survived, though six probably would not have survived to term. In 15 pregnancies in which the mothers had had a previous stillbirth, 12 infants survived. Sixty-seven infants required a total of 116 exchange transfusions. Despite the hazards it is concluded that early induction has an important place in management of Rh hemolytic disease.     

Classification and description of stillbirths in New South Wales, 2002-2004

OBJECTIVE: To describe the pattern of stillbirths by cause and gestation period in New South Wales since the introduction of the Perinatal Society of Australia and New Zealand perinatal death classification (PSANZ-PDC); and to assess the agreement between classifications on cause of death between local hospital committees and the Perinatal Outcomes Working Party (POWP - a subgroup of the NSW Department of Health Ministerial Maternal and Perinatal Committee). DESIGN, PARTICIPANTS AND SETTING: Population-based retrospective cohort study of all 258 045 births in NSW and all 1264 stillbirths classified by the POWP in 2002-2004, based on linked data on perinatal deaths from the NSW Midwives Data Collection and the NSW Ministerial Maternal and Perinatal Committee. MAIN OUTCOME MEASURES: Pattern of stillbirths by cause and gestation period; and interobserver agreement on classification of cause of death (according to the PSANZ-PDC) between local hospital review committees and the POWP. RESULTS: The most common classification was unexplained antepartum death, comprising 41.5% of the cohort and 60% of stillbirths of > or = 37 weeks' gestation. These unexplained stillbirths were more likely to have had an autopsy performed than the explained stillbirths (45% v 36%; x2 = 10.1; df = 1; P = 0.001). Agreement on cause of death differed by cause of death classification, with an overall kappa statistic of 0.638. CONCLUSION: Unexplained antepartum death is the most common classification of stillbirths near term, and these stillbirths are more likely to have had an autopsy. Although reported interobserver agreement is high for PSANZ-PDC, in practice it is relatively low between hospital mortality review committees and the POWP.