Colleen O'Connell

Maternal outcomes in pregnancies complicated by obesity.

OBJECTIVE: To investigate the relationship between prepregnancy obesity and maternal outcomes. METHODS: A 15-year, population-based cohort study using the Nova Scotia Atlee Perinatal Database compared maternal outcomes in obese and nonobese women. Prepregnancy weight of 55–75 kg was considered nonobese, and weight greater than 90 kg was considered obese. Obese women were categorized into moderate obesity (90–120 kg) and severe obesity (> 120 kg) groups. Univariate and multivariable logistic regression analysis was performed, and odds ratios (ORs), adjusted ORs, and 95% confidence intervals (CIs) were calculated. P < .05 was considered statistically significant. RESULTS: In 142,404 singleton pregnancies, 10,134 (7.2%) women were identified as obese (moderate obesity 92.3%, severe obesity 7.7%). The proportion of women in the obese categories increased from 3.2% in 1988 to 10.2% in 2002. Moderately obese women had an increased risk of pregnancy-induced hypertension (PIH) (adjusted OR 2.38, 95% CI 2.24–2.52), antepartum venous thromboembolism (adjusted OR 2.17, 95% CI 1.30–3.63), labor induction (adjusted OR 1.94, 95% CI 1.86–2.04), cesarean delivery (adjusted OR 1.60, 95% CI 1.53–1.67), and wound infection (adjusted OR 1.67, 95% CI 1.38–2.00). Severely obese women had an increased risk of PIH (adjusted OR 3.00, 95% CI 2.49–3.62), antepartum venous thromboembolism (adjusted OR 4.13, 95% CI 1.26–13.54), induction of labor (adjusted OR 2.77, 95% CI 2.39–3.21), cesarean delivery (adjusted OR 2.46, 95% CI 2.15–2.81), anesthesia complications (adjusted OR 2.01, 95% CI 1.33–3.06), and wound infection (adjusted OR 4.79, 95% CI 3.30–6.95). This implies that, relative to nonobese women, there was 1 excess case of PIH per 10 moderately obese women and 1 per 7 severely obese women. For antepartum venous thromboembolism, there was 1 excess case per 857 moderately obese women and 1 per 321 severely obese women. CONCLUSION: Prepregnancy maternal obesity increases the risk of PIH, antepartum venous thromboembolism, labor induction, cesarean delivery, and wound infection. LEVEL OF EVIDENCE: II-2

Fetal and neonatal outcomes of diabetic pregnancies.

OBJECTIVE: To estimate whether the incidences of adverse fetal and neonatal outcomes in infants of mothers with preexisting types 1 and 2 diabetes 1) differ from infants of nondiabetic mothers in Nova Scotia (NS); and 2) have changed between 1988 and 2002. METHODS: Population-based cohort study using the NS Atlee Perinatal Database, a well-validated source of standardized clinical information. RESULTS: A total of 516 infants of diabetic mothers and 150,589 infants of nondiabetic mothers from singleton pregnancies were studied. Infants of diabetic mothers had significantly higher rates of perinatal mortality (17.4/1,000 compared with 5.9/1,000, relative risk [RR] 3.01, 95% confidence interval [CI] 1.55–5.84), major congenital anomaly (9.1% compared with 3.1%, RR 2.97, 95% CI 2.25–3.90), and large for gestational age birth (LGA, more than 90th percentile weight for gestational age) (45.2% compared with 12.6%, RR 3.59, 95% CI 3.26–3.95) than infants of nondiabetic mothers. In infants of diabetic mothers, there was no improvement in perinatal mortality (23.4/1,000 in 1988–1995 compared with 11.5/1000 in 1996–2002, P=.340), incidence of LGA (48.0% in 1988–1995 compared with 42.3% in 1996–2002, P=.237), or rate of major congenital anomaly (8.2% in 1988–1995 compared with 10.0% in 1996–2002, P=.560). Diabetes remained an independent risk factor for LGA infants and major congenital anomaly after adjusting for possible confounders. CONCLUSION: Rates of adverse neonatal outcomes are 3–9 times greater in infants of diabetic mothers compared with those of nondiabetic mothers. There were no significant improvements in rates of perinatal mortality, congenital anomaly, or LGA birth in infants of diabetic mothers in 1996–2002 compared with 1988–95. LEVEL OF EVIDENCE: II-2

Changes in maternal characteristics and obstetric practice and recent increases in primary cesarean delivery.

OBJECTIVE To estimate the contribution of changes in maternal characteristics (namely, age, parity, prepregnancy weight, weight gain in pregnancy, smoking status) and obstetric practice (namely, labor induction, epidural anesthesia, delivery by an obstetrician, midpelvic forceps delivery) to recent increases in primary cesarean delivery rates. METHODS We studied all deliveries in Nova Scotia, Canada, between 1988 and 2000 after excluding women who had a previous cesarean delivery (n = 127,564). Logistic regression was used to study the effect of changes in maternal characteristics and obstetric practice on primary cesarean delivery rates. The effect of changes in midpelvic forceps delivery was examined through ecologic Poisson regression. RESULTS Primary cesarean delivery rates increased from 13.4% of deliveries in 1988 to 17.5% in 2000. This was due to increases in cesarean deliveries for dystocia (14% increase), breech (24% increase), suspected fetal distress (21% increase), hypertension (47% increase), and miscellaneous indications (73% increase). Adjustment for maternal characteristics reduced the temporal increase in primary cesarean delivery rates between 1988-1991 and 1998-2000 from 21% (95% confidence interval [CI] 16%, 25%) to 2% (95% CI -2%, 7%). Additional adjustment for obstetric practice factors further reduced period effects. Midpelvic forceps delivery was significantly and negatively associated with primary cesarean delivery (P =.001). CONCLUSION Recent increases in primary cesarean delivery rates are a consequence of changes in maternal characteristics. Obstetric practice, which has altered due to changes in maternal characteristics and concerns related to fetal and maternal safety, has also contributed to increases in primary cesarean delivery.

Determinants of perinatal mortality and serious neonatal morbidity in the second twin

OBJECTIVE: To identify potential determinants of perinatal mortality and neonatal morbidity among second twins relative to first twins. METHODS: A retrospective cohort design was used to study twin deliveries in Nova Scotia from 1988 to 2002. Monoamniotic or conjoined twins and twin pairs with major congenital anomaly or antepartum fetal death of either twin were excluded. The primary outcome was a composite measure of perinatal mortality and neonatal morbidity, including birth asphyxia, respiratory distress, neonatal trauma, and infection. Risk of adverse outcome of second twins relative to first-born co-twins was determined by matched-pair analysis. RESULTS: Of 1,542 twin pairs, the second twin was at greater risk of composite adverse outcome (relative risk [RR] 1.62, 95% confidence interval [CI] 1.38–1.9) than the first twin. This excess risk was evident independent of presentation, chorionicity, or infant sex but was associated with planned vaginal delivery, birth weight discordance, and prolonged interdelivery interval. Term second twins were less likely to suffer excess morbidity with elective cesarean (RR 1.0, 95% CI 0.14–7.10) than with planned vaginal delivery (RR 3.0, 95% CI 1.47–6.11). The major contributors to neonatal morbidity in the second twin were birth asphyxia at 37 weeks or later and respiratory distress syndrome at less than 37 weeks. CONCLUSION: The second twin is at greater risk of adverse perinatal outcome than the first twin, independent of presentation, chorionicity, or infant sex. Planned vaginal delivery, birth weight discordance, and prolonged interdelivery interval increase this infant risk. Elective cesarean delivery at term may improve perinatal outcome for the second twin. However, the number of cesarean births required to prevent one case of composite adverse outcome, assuming causality, was 33. LEVEL OF EVIDENCE: II-2

Maternal and perinatal outcomes with increasing duration of the second stage of labor.

OBJECTIVE: To estimate maternal and perinatal outcomes among women with increasing duration of the second stage of labor. METHODS: A population-based cohort study was conducted among women with low-risk, singleton, vertex, nonanomalous deliveries at or after 37 weeks of gestation between 1988 and 2006. Individual maternal (hemorrhagic, infectious, and traumatic), perinatal (birth depression, infectious, and traumatic), and composite outcomes were evaluated with increasing duration of the second stage. Logistic regression was used to estimate adjusted odds ratios and 95% confidence intervals for all outcomes and to account for confounding variables, including maternal age, prelabor rupture of membranes, augmentation of labor, antibiotics in labor, regional analgesia, gestational age, birth weight, and year of birth. Effect modification caused by method of delivery was considered. RESULTS: From a population of 193,823 women, 121,517 women met inclusion and exclusion criteria, of whom 63,404 (52%) were nulliparous. There was an increase in risk of maternal obstetric trauma, postpartum hemorrhage, puerperal febrile morbidity and composite maternal morbidity, and low 5-minute Apgar score, birth depression, admission to the neonatal intensive care unit, and composite perinatal morbidity among both nulliparous women and multiparous women, with increasing duration of the second stage of labor. Method of delivery only modified the effect of duration of second stage among nulliparous women. CONCLUSION: Risks of both maternal and perinatal adverse outcomes rise with increased duration of the second stage, particularly for duration longer than 3 hours in nulliparous women and longer than 2 hours in multiparous women. LEVEL OF EVIDENCE: II

Maternal and perinatal morbidity of caesarean delivery at full cervical dilatation compared with caesarean delivery in the first stage of labour

To estimate maternal and perinatal morbidity associated with caesarean delivery at full cervical dilatation, a population‐based cohort study from 1997 to 2002 was used, which included 1623 nullipara with singleton pregnancies at 37–42 weeks of gestation requiring caesarean delivery in labour. Compared to caesarean delivery at less than full dilatation, women undergoing caesarean delivery at full dilatation were more likely to have complications of intraoperative trauma (RR 2.6, P < 0.001) and infants with perinatal asphyxia (RR 1.5, P < 0.05). There was no difference in maternal or perinatal morbidity when duration of the second stage of labour or when failed assisted vaginal delivery was considered.

Dilatation of the ascending aorta in paediatric patients with bicuspid aortic valve: frequency, rate of progression and risk factors

Objectives: To describe the incidence and rate of dilatation of the ascending aorta in children with bicuspid aortic valve (BAV) and to determine factors that predict rapid aortic dilatation. Design: Retrospective cohort study. Setting: Regional tertiary care children’s hospital. Patients: All children aged 0–18 years seen at the authors’ institution between 1990 and 2003 with an “isolated” BAV. All patients had had more than one technically adequate echocardiogram, at least six months apart, with concomitant height and weight data. Interventions: Offline echocardiographic measurements of multiple levels of the aortic root were completed for each participant at each serial echocardiogram. These measurements were then compared with expected measurements derived from a normal local control population. Main outcome measures: Rate of change of the ascending aorta size over time, where aortic size is expressed as the number of standard deviations above or below the mean size expected for a given body surface area (z score). Results: 279 echocardiograms spanning a period of from 9 months to 13.3 years were analysed for 88 patients with BAV. The ascending aorta in the BAV group was larger than expected for body surface area at diagnosis and continued to increase in relative size at each of the four subsequent follow-up echocardiograms. Ascending aortic z score increased at an average rate of 0.4/year. A faster rate of increase in z score was predicted by both larger initial aortic valve gradient and non-use of β blockers. Conclusions: Children with BAV are at risk of having a dilated ascending aorta. This risk increases with longer follow up.

Maternal morbidity associated with cesarean delivery without labor compared with induction of labor at term

OBJECTIVE: To estimate the maternal morbidity associated with cesarean deliveries performed at term without labor compared with morbidity associated with induction of labor at term. METHODS: A 15-year population-based cohort study (1988–2002) using the Nova Scotia Atlee Perinatal Database compared maternal outcomes in nulliparous women delivering by cesarean delivery without labor and nulliparous women at term undergoing induction of labor for planned vaginal delivery with singleton, cephalic presentation. RESULTS: A total of 5,779 pregnancies satisfied inclusion and exclusion criteria, 879 of which were cesarean deliveries without labor. There were no maternal deaths. There was no difference in wound infection, puerperal febrile morbidity, blood transfusion or intraoperative trauma. After controlling for potential confounders, women undergoing cesarean delivery without labor were less likely to have complications of early postpartum hemorrhage (relative risk 0.61, 95% confidence interval 0.42–0.88, number needed to treat 32) and composite maternal morbidity (relative risk 0.71, 95% confidence interval 0.52–0.95, number needed to treat 34) compared with women undergoing induction of labor. Subgroup analyses of maternal outcomes after induction of labor in women by method of delivery were also performed and demonstrated additional risks of traumatic morbidity after induction of labor. The highest morbidity was found in the assisted vaginal delivery and cesarean delivery in labor groups. CONCLUSION: Early postpartum hemorrhage and composite maternal morbidity were decreased in cesarean delivery without labor compared with induction of labor. Hemorrhagic and traumatic morbidities with labor induction are increased after assisted vaginal delivery and cesarean delivery in labor compared with cesarean delivery without labor. LEVEL OF EVIDENCE: II-2

Combined vaginal-cesarean delivery of twin pregnancies.

OBJECTIVE To estimate the incidence and factors associated with combined vaginal‐cesarean delivery in twin pregnancies. METHODS We studied all twin births weighing 500 g or more during a 20‐year period (1980–1999) at a tertiary care center. Major anomalies, monoamniotic and conjoined twins, and antepartum fetal deaths were excluded. RESULTS During this 20‐year period, 105,987 women delivered, of whom 1565 (1.5%) had twins. Of these, 1151 twin sets fulfilled the study criteria. The mode of delivery was vaginal in 653 (56.8%), cesarean in 448 (38.9%), and vaginal‐cesarean in 50 (4.3%). During the 20 years there was a statistically significant increase in combined vaginal‐cesarean and elective cesarean deliveries, with a decrease in vaginal deliveries. Parity, gestational age, and birth weight discordance (>25%) were not associated with combined delivery. Compared with vaginal delivery, the nonvertex second twin was associated with a twofold higher risk of cesarean delivery (relative risk [RR] 2.3; 95% confidence interval [CI] 1.3, 3.8; P = .002); and an interdelivery interval of over 60 minutes with an eightfold higher risk (RR 8.2; CI 4.6,14.6; P < .001). Vaginal‐cesarean delivery had a 22‐fold higher use of general anesthesia compared with vaginal delivery (RR 21.8; CI 5.4, 88.5; P < .001). CONCLUSION There has been a significant increase in combined vaginal‐cesarean and elective cesarean deliveries among twin gestations, with a decrease in vaginal births. Vaginal‐cesarean delivery is associated with nonvertex second twin and a prolonged interdelivery interval.

Neonatal outcomes with caesarean delivery at term

Objective: To estimate the impact of caesarean delivery on the incidence of selected neonatal outcomes. Patients and methods: A 15-year, population-based, cohort study (1988–2002) using the Nova Scotia Atlee Perinatal Database compared neonatal outcomes in term newborns born by spontaneous and assisted vaginal delivery, with newborns born by caesarean delivery, with and without labour, using multiple logistic regression. Results: From a total of 142 929 deliveries, there were 27 263 caesarean deliveries, 61% of which were performed in labour. Relative risks were adjusted for year of birth, maternal age, parity, smoking, maternal weight at delivery, hypertensive diseases, diabetes, previous caesarean delivery, use of regional anaesthesia, induction of labour, gestational age at delivery and large and small for gestational age, where significant. Caesarean delivery in labour, but not caesarean delivery without labour, had increased risks for depression at birth and neonatal respiratory conditions compared with spontaneous or assisted vaginal delivery. Compared with spontaneous vaginal delivery and assisted vaginal delivery, the risk of major neonatal birth trauma was decreased for infants after caesarean delivery with labour (odds ratio (OR) = 0.34, 95% CI 0.21 to 0.56 and OR = 0.07, 95% CI 0.04 to 0.11, respectively) and caesarean delivery without labour (OR = 0.20, 95% CI 0.08 to 0.52 and OR = 0.04, 95% CI 0.02 to 0.10, respectively). Conclusion: Caesarean delivery in labour, compared with vaginal delivery, is more likely to be associated with an increased risk for respiratory conditions and depression at birth than caesarean delivery without labour. Caesarean delivery appears protective against neonatal birth trauma, especially when performed without labour.