The role of uterine closure in the risk of uterine rupture.

OBJECTIVE: To evaluate the effects of prior single-layer compared with double-layer closure on the risk of uterine rupture. METHODS: A multicenter, case-control study was performed on women with a single, prior, low-transverse cesarean who experienced complete uterine rupture during a trial of labor. For each case, three women who underwent a trial of labor without uterine rupture after a prior low-transverse cesarean delivery were selected as control participants. Risk factors such as prior uterine closure, suture material, diabetes, prior vaginal delivery, labor induction, cervical ripening, birth weight, prostaglandin use, maternal age, gestational age, and interdelivery interval were compared between groups. Conditional logistic regression analyses were conducted. RESULTS: Ninety-six cases of uterine rupture, including 28 with adverse neonatal outcome, and 288 control participants were assessed. The rate of single-layer closure was 36% (35 of 96) in the case group and 20% (58 of 288) in the control group (P<.01). In multivariable analysis, single-layer closure (odds ratio [OR] 2.69; 95% confidence interval [CI] 1.37-5.28) and birth weight greater than 3,500 g (OR 2.03; 95% CI 1.21-3.38) were linked with increased rates of uterine rupture, whereas prior vaginal birth was a protective factor (OR 0.47; 95% CI 0.24-0.93). Single-layer closure was also related to uterine rupture associated with adverse neonatal outcome (OR 2.89; 95% CI 1.01-8.27). CONCLUSION: Prior single-layer closure carries more than twice the risk of uterine rupture compared with double-layer closure. Single-layer closure should be avoided in women who could contemplate future vaginal birth after cesarean delivery. LEVEL OF EVIDENCE: II.

Evaluating the role of bedrest on the prevention of hypertensive diseases of pregnancy and growth restriction.

BACKGROUND: Evaluating the effect of restricted activity on the development of preeclampsia under experimental clinical settings has been compromised by inherent selection bias and differential misclassification. The aim of our study was to overcome such limitations by using hospitalized bedrest for preterm labor/birth-related indications as an unbiased measure of restricted activity and evaluate its effect on the development of hypertensive diseases of pregnancy. METHODS: We conducted a retrospective cohort study using data from the McGill Obstetrical and Neonatal Database on all pregnancies that took place between 1991 and 2001. We defined "exposure" as hospitalized bed rest for preterm labor/birth related indications and used unconditional logistic regression models to estimate its adjusted effect on the development of hypertensive diseases of pregnancy. RESULTS: Data were available on 36,140 pregnancies. 677 women were hospitalized and prescribed bedrest for either preterm contractions (71%), preterm premature rupture of membranes (18%), an incompetent cervix (8%), or other indications. Among all women, bedrest was associated with a significant reduced risk for developing preeclampsia, 0.27 (0.16-0.48). In a stratified analysis, women delivering prior to 34 weeks of gestation had an even more pronounced reduced risk for developing preeclampsia 0.12 (0.03-0.50) as well as a reduced risk for developing intrauterine growth restriction 0.38 (0.18-0.84). CONCLUSION: When strictly adhered to, bedrest may be an effective measure in the prevention of preeclampsia and early intrauterine growth restriction.

Comparison of obstetric outcomes between on-call and patients' own obstetricians.

BACKGROUND: The question "will you be delivering my baby?" is one that pregnant women frequently ask their physicians. We sought to determine whether obstetric outcomes differed between women whose babies were delivered by their own obstetrician (regular-care obstetrician) and those attended by an on-call obstetrician who did not provide antenatal care. METHODS: We performed a cohort study of all live singleton term births between 1991 and 2001 at the Royal Victoria Hospital in Montréal. We excluded breech deliveries, elective cesarean sections and deliveries with placenta previa or prolapse of the umbilical cord. Logistic regression analysis was used to compare obstetric outcomes (e.g., cesarean delivery, instrumental vaginal delivery and episiotomy) between the regular-care and on-call obstetricians after adjustment for potential confounders. RESULTS: A total of 28,332 eligible deliveries were attended by 26 obstetricians: 21,779 (76.9%) by the patient's own obstetrician and 6553 (23.1%) by the on-call obstetrician. Compared with women attended by their regular-care obstetrician, those attended by an on-call obstetrician had higher rates of cesarean delivery (11.9% v. 11.4%, adjusted odds ratio [OR] 1.13, 95% confidence interval [CI] 1.03-1.24, p < 0.01) and of third-or fourth-degree tears (7.9% v. 6.4%, adjusted OR 1.21, 95% CI 1.07-1.36, p < 0.01) but lower rates of episiotomy (38.5% v. 42.9%, OR 0.77, 95% CI 0.72-0.82, p < 0.001). No differences were observed between the groups in the rate of instrumental vaginal delivery. The increase in the overall rate of cesarean delivery among women attended by an on-call obstetrician was due mainly to an increase in cesarean deliveries during the first stage of labour because of nonreassuring fetal heart tracing (2.9% v. 1.7%, adjusted OR 1.79, 95% CI 1.49-2.15, p < 0.001). The time of day of delivery did not modify the observed effects. INTERPRETATION: The type of attending obstetrician (regular care v. on call) had a minor effect on obstetric outcomes.

Effect of prepregnancy body mass index categories on obstetrical and neonatal outcomes.

OBJECTIVES: To examine the association between body mass index (BMI) and obstetrical and neonatal outcomes. METHODS: We conducted a cohort study comparing prepregnant BMI categories with obstetrical and neonatal outcomes using the McGill Obstetrical and Neonatal Database on all deliveries in 10 year period (1987-1997). Prepregnant BMI was categorized into underweight (<20), normal (20-24.9), overweight (25-29.9), obese (30-39.9), and morbidly obese (40+). Logistic regression analysis was used to adjust for age, smoking, parity, and preexisting diabetes using normal BMI as the reference. RESULTS: The population consisted of underweight 4,312 (23.1%), normal weight 10,021 (53.8%), overweight 3,069 (16.5%), obese 1,137 (6.1%), and morbidly obese 104 (0.6%). As compared to women with normal BMIs, overweight, obese, and morbidly obese women had an increased risk of preeclampsia 2.28 (1.88-2.77), 4.65 (3.71-5.83), 6.26 (3.48-11.26); gestational hypertension 1.56 (1.35-1.81), 2.01 (1.64-2.45), 2.77 (1.60-4.78); gestational diabetes 1.89 (1.63-2.19), 3.22 (2.68-3.87), 4.71 (2.89-7.67); preterm birth 1.20 (1.04-1.38), 1.60 (1.32-1.94), 2.43 (1.46-4.05); cesarean section 1.48 (1.35-1.62), 1.85 (1.62-2.11), 2.92 (1.97-4.34); and macrosomia 1.66 (1.23-2.24), 2.32 (1.58-3.41), 2.10 (0.64-6.86). Underweight women were less likely to have: preeclampsia 0.67 (0.52-0.86), gestational hypertension 0.71 (0.60-0.83), gestational diabetes 0.82 (0.69-0.97), cesarean section 0.89 (0.81-0.97), shoulder dystocia 0.88 (0.80-0.96), birth injuries 0.40 (0.21-0.77), and macrosomia 0.43 (0.28-0.68) but more likely to have small for gestational age infants 1.54 (1.37-1.72) and intrauterine growth restricted infants 1.33 (1.07-1.67). CONCLUSION: In a large Canadian teaching hospital, increasing prepregnancy BMI category was associated with an increasing risk of adverse pregnancy outcomes. Underweight prepregnancy BMI was associated with a reduced risk of adverse pregnancy outcomes.

Effect of instrument preference for operative deliveries on obstetrical and neonatal outcomes.

OBJECTIVES: To examine the relationship between physicians' instrument preference and obstetrical and neonatal outcomes. STUDY DESIGN: A retrospective cohort study comparing obstetrical and neonatal outcomes of second stage deliveries between obstetricians who prefer forceps (forceps >/=90%) with obstetricians with no preference to forceps (either instrument <90%) was completed using the McGill Obstetrical and Neonatal Database. Logistic regression analysis was used to obtain an adjusted odds ratio controlling for maternal, intrapartum and neonatal confounders. RESULTS: Two thousand and three hundred thirteen infants were delivered by 5 obstetricians who preferred forceps, and 9261 infants were delivered by 15 obstetricians with no instrument preference. Baseline characteristics were similar between the two groups. As compared to obstetricians who preferred forceps, obstetricians with no instrument preference had a higher rate of operative vaginal deliveries 1.5 (1.1-2.0), a higher cesarean section rate 2.5 (1.3-4.9) and a higher episiotomy rate in non-operative vaginal deliveries 3.4 (2.7-4.3). Infants delivered by obstetricians with no instrument preference were less likely to have significant bruising 0.3 (0.2-0.6) but more likely to have a cephalohematoma 3.0 (1.1-8.3). CONCLUSION: Physician instrument preference is an important determinant of outcomes that should be considered in studies evaluating instrumental deliveries.

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.

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.