Risk of cesarean delivery with elective induction of labor at term in nulliparous women.

OBJECTIVE: To quantify the risk of cesarean delivery associated with elective induction of labor in nulliparous women at term. METHODS: We performed a cohort study on a major urban obstetric service that serves predominantly private obstetric practices. All term, nulliparous women with vertex, singleton gestations who labored during an 8-month period (n = 1561) were divided into three groups: spontaneous labor, elective induction, and medical induction. The risk of cesarean delivery in the induction groups was determined using stepwise logistic regression to control for potential confounding factors. RESULTS: Women experiencing spontaneous labor had a 7.8% cesarean delivery rate, whereas women undergoing elective labor induction had a 17.5% cesarean delivery rate (adjusted odds ratio [OR] 1.89; 95% confidence interval [CI] 1.12, 3.18) and women undergoing medically indicated labor induction had a 17.7% cesarean delivery rate (OR 1.69; 95% CI 1.13, 2.54). Other variables that remained significant risk factors for cesarean delivery in the model included: epidural placement at less than 4 cm dilatation (OR 4.66; 95% CI 2.25, 9.66), epidural placement after 4 cm dilatation (OR 2.18; 95% CI 1.06, 4.48), chorioamnionitis (OR 4.61; 95% CI 2.89, 7.35), birth weight greater than 4000 g (OR 2.59; 95% CI 1.69, 3.97), maternal body mass index greater than 26 kg/m2 (OR 2.36; 95% CI 1.61, 3.47), Asian race (OR 2.35; 95% CI 1.04, 5.34), and magnesium sulfate use (OR 2.18; 95% CI 1.04, 4.55). CONCLUSION: Elective induction of labor is associated with a significantly increased risk of cesarean delivery in nulliparous women. Avoiding labor induction in settings of unproved benefit may aid efforts to reduce the primary cesarean delivery rate.     

Bishop score and risk of cesarean delivery after induction of labor in nulliparous women

OBJECTIVE: To quantify the risk and risk factors for cesarean delivery associated with medical and elective induction of labor in nulliparous women. METHODS: A prospective cohort study was performed in nulliparous women at term with vertex singleton gestations who had labor induced at 2 obstetrical centers. Medical and elective indications and Bishop scores were recorded before labor induction. Obstetric and neonatal data were analyzed and compared with the results in women with a spontaneous onset of labor. Data were analyzed using univariate and multivariable regression modeling. RESULTS: A total of 1,389 women were included in the study. The cesarean delivery rate was 12.0% in women with a spontaneous onset of labor (n = 765), 23.4% in women undergoing labor induction for medical reasons (n = 435) (unadjusted odds ratio [OR] 2.24; 95% confidence interval [CI] 1.64-3.06), and 23.8% in women whose labor was electively induced (n = 189) (unadjusted OR 2.29; 95% CI 1.53-3.41). However, after adjusting for the Bishop score at admission, no significant differences in cesarean delivery rates were found among the 3 groups. A Bishop score of 5 or less was a predominant risk factor for a cesarean delivery in all 3 groups (adjusted OR 2.32; 95% CI 1.66-3.25). Other variables with significantly increased risk for cesarean delivery included maternal age of 30 years or older, body mass index of 31 or higher, use of epidural analgesia during the first stage of labor, and birth weight of 3,500 g or higher. In both induction groups, more newborns required neonatal care, more mothers needed a blood transfusion, and the maternal hospital stay was longer. CONCLUSION: Compared with spontaneous onset of labor, medical and elective induction of labor in nulliparous women at term with a single fetus in cephalic presentation is associated with an increased risk of cesarean delivery, predominantly related to an unfavorable Bishop score at admission. LEVEL OF EVIDENCE: II-2.     

Impact of labor induction,gestational age,and maternal age on cesarean delivery rates

OBJECTIVE: To quantify the impact of labor induction and maternal age on cesarean delivery rates in nulliparous and multiparous women between 36 and 42 weeks' gestation. METHODS: We performed a retrospective cohort study on 14,409 women delivering at two teaching hospitals in metropolitan Boston during 1998 and 1999. Women who had contraindications to labor, including a prior cesarean delivery, were excluded. The risks for cesarean delivery by induction status, gestational age by completed week between 36 and 42 weeks, maternal age <35, 35-39, and >/=40 years, and stratified by parity, were calculated by logistic regression. RESULTS: In nulliparas, labor induction was associated with an increase in cesarean delivery from 13.7% to 24.7% (adjusted odds ratio [OR] 1.70; 95% confidence interval [CI] 1.48, 1.95]). In multiparas, induction was associated with an increase from 2.4% to 4.5% (OR 1.49; 95% CI 1.10, 2.00). Other variables that placed a nulliparous woman at increased risk for cesarean delivery included maternal age of at least 35 years and gestational ages over 40 weeks. For multiparas, only maternal age 40 years or older and gestational age of 41 weeks were associated with an increase in cesarean deliveries. CONCLUSION: Induction of labor, older maternal age, and gestational age over 40 weeks each independently increase the risk for cesarean delivery in both nulliparous and multiparous women. Although the relative risk from induction is similar in nulliparas and multiparas, the absolute magnitude of the increase is much greater in nulliparas (11% versus 2.1%).     

Mode of Delivery after Epidural Analgesia in a Cohort of Low‐Risk Nulliparas

Abstract: Background: Although epidural analgesia is widespread and very effective for alleviating labor pain, its use is still controversial, as the literature is inconsistent about the risk of adverse birth outcome after administration of epidural analgesia. The aim of this study was to explore associations between epidural analgesia and mode of delivery. Methods: Data were obtained from a prospective cohort from nine Danish labor wards and comprised 2,721 term nulliparous women with spontaneous onset of labor and a singleton fetus in cephalic presentation. Information about epidural analgesia, mode of delivery, and birth complications was obtained by the staff attending labor. Additional information was provided from self‐administered questionnaires in gestational week 37. Multiple logistic regression analyses were used to estimate the association between epidural analgesia and birth outcomes. Results are presented as crude and adjusted odds ratios (OR [95% CI]). Results: Of the total cohort, 21.6 percent required epidural analgesia, 8.7 percent had emergency cesarean section, and 14.9 percent had vacuum extraction. Women with epidural analgesia had a higher risk of emergency cesarean section (adjusted OR: 5.8; 95% CI: 4.1–8.1), and vacuum extraction (adjusted OR: 1.7; 95% CI: 1.3–2.2). In a subgroup of the cohort with a very low overall risk of cesarean section, 3.4 percent had emergency cesarean section and an increased risk of emergency cesarean section was also found in this group (adjusted OR: 3.5; 95% CI: 1.5–8.2). Conclusions: In nulliparous women of a very low‐risk population, use of epidural analgesia for labor pain was associated with higher risks of emergency cesarean section and vacuum extraction. (BIRTH 38:4 December 2011)     

Complications in pregnancy, labor, and delivery with uterine leiomyomas: a population-based study

OBJECTIVE: To determine the extent to which uterine leiomyomas are associated with characteristics of pregnancy, labor, and neonatal outcome recorded on birth certificates. METHODS: In a population-based series of women who delivered singleton live infants in Washington state from 1987-1993, we linked computerized birth certificates and hospital discharge records to investigate the relationship between uterine leiomyomas and complications in pregnancy and delivery. Subjects were 2065 women with uterine leiomyomas noted on computerized hospital discharge records. From the remaining records, a comparison group of women without uterine leiomyomas diagnoses were selected at random and frequency-matched by birth year to women with leiomyomas. We used unconditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of pregnancy or delivery complications in relation to uterine leiomyomas after multivariate adjustment. RESULTS: Women with leiomyomas were more likely than controls to be over age 35 at delivery, nulliparous, or black. We observed independent associations between uterine leiomyomas and abruptio placentae (OR 3. 87, 95% CI 1.63, 9.17), first trimester bleeding (OR 1.82, 95% CI 1. 05, 3.20), dysfunctional labor (OR 1.85, 95% CI 1.26, 2.72), and breech presentation (OR 3.98, 95% CI 3.07, 5.16). The risk of cesarean was also higher among women with uterine leiomyomas (OR 6. 39, 95% CI 5.46, 7.50), but a portion of the excess risk might have been due to biased detection of leiomyomas at cesarean delivery. CONCLUSION: Leiomyomas appear to increase likelihood of complications during pregnancy, labor, and delivery.     

Parity, mode of delivery, and pelvic floor disorders

OBJECTIVE: This study aimed to assess the associations between parity, mode of delivery, and pelvic floor disorders. METHODS: The prevalence of pelvic organ prolapse, stress urinary incontinence, overactive bladder, and anal incontinence was assessed in a random sample of women aged 25-84 years by using the validated Epidemiology of Prolapse and Incontinence Questionnaire. Women were categorized as nulliparous, vaginally parous, or only delivered by cesarean. Adjusted odds ratios and 95% confidence intervals (CIs) for each disorder were calculated with logistic regression, controlling for age, body mass index, and parity. RESULTS: In the 4,458 respondents the prevalence of each disorder was as follows: 7% prolapse, 15% stress urinary incontinence, 13% overactive bladder, 25% anal incontinence, and 37% for any one or more pelvic floor disorders. There were no significant differences in the prevalence of disorders between the cesarean delivery and nulliparous groups. The adjusted odds of each disorder increased with vaginal parity compared with cesarean delivery: prolapse = 1.82 (95% CI 1.04-3.19), stress urinary incontinence = 1.81 (95% CI 1.25-2.61), overactive bladder = 1.53 (95% CI 1.02-2.29), anal incontinence = 1.72 (95% CI 1.27-2.35), and any one or more pelvic floor disorders = 1.85 (95% CI 1.42-2.41). Number-needed-to-treat analysis revealed that 7 women would have to deliver only by cesarean delivery to prevent one woman from having a pelvic floor disorder. CONCLUSION: The risk of pelvic floor disorders is independently associated with vaginal delivery but not with parity alone. Cesarean delivery has a protective effect, similar to nulliparity, on the development of pelvic floor disorders when compared with vaginal delivery. LEVEL OF EVIDENCE: II-2.     

Maternal and neonatal outcomes after induction of labor without an identified indication

OBJECTIVE: This study was undertaken to examine associations between induction of labor and maternal and neonatal outcomes among women without an identified indication for induction. STUDY DESIGN: This was a population-based cohort study of 2886 women with induced labor and 9648 women with spontaneous labor who were delivered at 37 to 41 weeks' gestation, all without identified medical and obstetric indications for induction. RESULTS: Among nulliparous women 19% of women with induced labor versus 10% of those with spontaneous labor underwent cesarean delivery (adjusted relative risk, 1.77; 95% confidence interval, 1.50-2.08). No association was seen in multiparous women (relative risk, 1.07; 95% confidence interval, 0. 81-1.39). Among all women induction was associated with modest increases in instrumental delivery (19% vs 15%; relative risk, 1.20; 95% confidence interval, 1.09-1.32) and shoulder dystocia (3.0% vs 1. 7%; relative risk, 1.32; 95% confidence interval, 1.02-1.69). CONCLUSION: Among women who lacked an identified indication for induction of labor, induction was associated with increased likelihood of cesarean delivery for nulliparous but not multiparous women and with modest increases in the risk of instrumental delivery and shoulder dystocia for all women.     

The incidence and risk factors for retained placenta after vaginal delivery – a single center experience

Abstract

Objective: We aimed to determine the incidence and risk factors for retained placenta immediately after vaginal delivery in a single, university-affiliated tertiary center.

Methods: A case-control study. Women who delivered vaginally and diagnosed with suspected retained placenta were compared to control group of women with spontaneous vaginal delivery with spontaneous non-complicated placental separation between the years 2007 and 2012. Eligibility was limited to singleton fetuses in vertex presentation with no history of more than one cesarean section, stillbirth or major fetal anomaly.

Results: Overall, 33?925 women delivered vaginally, of them, 491 (1.4%) underwent revision of uterine cavity due to suspected retained placenta. Women with retained placenta were characterized by a higher rate of previous cesarean section (OR 1.71, 95% CI 1.23–2.36), previous abortions, lower parity (OR 0.79, 95% CI 0.68–0.91), lower gestational age at delivery. Hypertensive disorders, oligohydramnios and labor and delivery interventions as induction of labor (OR 1.84, 95% CI 1.30–2.59), neuro-axial analgesia (OR 1.60, 95% CI 1.27–2.00) and vacuum delivery (OR 1.89, 95% CI 1.48–2.41) were independently associated with uterine revision for retained placenta.

Conclusion: Risk factors for manual revision due to retained placenta can be recognized. This data should be taken into consideration in the assessment of women immediately after delivery.     

Maternal body mass index, delivery route, and induction of labor in a midwifery caseload

The purpose of this study was to identify the association between prepregnancy body mass index (BMI), weight gain in pregnancy, and newborn birth weight on route of delivery and induction of labor in patients receiving nurse-midwifery care. This retrospective cohort study examined the outcomes of 1500 consecutively delivered women who were cared for by two midwifery practices and delivered between January 1, 1998, and December 31, 2000. Cesarean delivery was significantly associated with the obese BMI (P < .001), nulliparity (P < .02), and newborn birth weight (P =.006). Prenatal weight gain did not have a significant correlation with cesarean birth (P = .24). In multivariable modeling, obese BMI, high newborn birth weight, nulliparity, and induction of labor increased the risk of cesarean birth. There was also a significant association between higher BMI and risk of induction of labor (P < .001). In a secondary analysis, obese BMI was associated with increased risk of induction in cases with ruptured membranes (OR 2.2; 95% CI 1.4-3.4) and postdates pregnancy (OR 2.0; 95% CI 1.1-3.4).     

Elective induction of labor: failure to follow guidelines and risk of cesarean delivery

BACKGROUND: Estimate the frequency of failure to follow the French consensus guidelines for elective induction, and assess how failure affects the rate of cesarean delivery. METHODS: We compared cesarean rates according to mode of onset of labor among 5,046 low-risk patients. Violation of the guidelines was defined as induction before 38 weeks or with a Bishop score <5 or with prostaglandins. The cesarean risk was analysed with a bivariable and then a multivariable analysis, which used a multilevel logistic model. RESULTS: Women with electively induced and spontaneous labor had identical cesarean rates (4.1%). The guidelines were not followed in 23.2% of elective inductions. The risk of cesarean was higher after induction with a Bishop score <5, than after spontaneous labor (adjusted OR=4.1, 95% CI [1.3-12.9]), while elective induction with a favourable cervix did not increase the cesarean risk. In nulliparas, failure to follow the guidelines tripled the risk of cesarean (adjusted OR=3.2 [1.0-10.2]). On the other hand, elective induction of labor for women with a favourable cervix did not increase the risk of cesarean over the risk with spontaneous labor. CONCLUSION: Elective induction does not appear to increase the cesarean rate when the guidelines are met. Electively inducing labor with a low Bishop score increased the risk of cesarean, especially in nulliparas.     

Maternal pre-pregnancy overweight status and obesity as risk factors for cesarean delivery.

OBJECTIVE: To determine the extent to which, if at all, maternal pre-pregnancy adiposity and other anthropometric factors are related to risk of cesarean delivery. METHODS: This hospital-based prospective cohort study included 738 nulliparous women who initiated prenatal care prior to 16 weeks gestation. Participants provided information about their pre-pregnancy weight and height and other sociodemographic and reproductive covariates. Labor and delivery characteristics were obtained from maternal and infant medical records. Risk ratios (RR) and 95% CI were estimated by fitting generalized linear models. RESULTS: The proportion of cesarean deliveries in this population was 26%. Women who were overweight (BMI 25.00-29.99 kg/m2) were twice as likely to deliver their infants by cesarean section as lean women (BMI<20.00 kg/m2) (RR=2.09; 95% CI 1.27-3.42). Obese women (BMI>or=30.00 kg/m2) experienced a three-fold increase in risk of cesarean delivery when compared with this referent group (RR=3.05; 95% CI 1.80-5.18). The joint association between maternal pre-pregnancy overweight status and short stature was additive. When compared with tall (height>or=1.63 m), lean women, short (<1.63 m), overweight (BMI>or=25.00 kg/m2) women were nearly three times as likely to have a cesarean delivery (RR=2.79; 95% CI 1.72-4.52). CONCLUSION: Our findings suggest that nulliparous women who are overweight or obese prior to pregnancy, and particularly those who are also short, have an increased risk of delivering their infants by cesarean section.     

Risk of preterm delivery in relation to maternal low birth weight

OBJECTIVE: We examined the relationship between maternal low birth weight and preterm delivery risk. METHODS: Information concerning maternal birth weight was collected during in-person interviews. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI). Preterm delivery cases were studied in aggregate, in subgroups (spontaneous preterm labor, preterm premature rupture of membranes, medically induced preterm delivery, moderate preterm delivery [gestational age at delivery 34-36 weeks], and early preterm delivery [gestational age at delivery<34 weeks]). RESULTS: After adjusting for confounders, women weighing<2,500 g at birth had a 1.54-fold increased risk of preterm delivery versus women weighing=2,500 g (95% CI 0.97-2.44). Maternal low birth weight was associated with a 2-fold increased risk of spontaneous preterm delivery (95% CI 1.03-3.89), but weakly associated with preterm premature rupture of membranes (OR=1.44; 95% CI 0.67-3.09) and medically induced preterm delivery (OR=1.10; 95% CI 0.43-2.82). Maternal low birth weight was more strongly associated with early preterm delivery (OR=1.94) than with moderate preterm delivery (OR=1.46). Women weighing<2,500 g at birth and who became obese (pre-pregnancy body mass index, =30 kg/m2) before pregnancy had a 3.65-fold increased risk of preterm delivery (95% CI 1.33-10.02) versus women weighing=2,500 g at birth and who were not obese prior to pregnancy (<30 kg/m2). CONCLUSIONS: Results confirm earlier findings linking maternal low birth weight with future risk of preterm delivery.     

Uterine rupture: risk factors and pregnancy outcome

OBJECTIVES: This study aimed at determining risk factors and pregnancy outcome in women with uterine rupture. STUDY DESIGN: We conducted a population-based study, comparing all singleton deliveries with and without uterine rupture between 1988 and 1999. RESULTS: Uterus rupture occurred in 0.035% (n=42) of all deliveries included in the study (n=117,685). Independent risk factors for uterine rupture in a multivariable analysis were as follows: previous cesarean section (odds ratio [OR]=6.0, 95% CI 3.2-11.4), malpresentation (OR=5.4, 95% CI 2.7-10.5), and dystocia during the second stage of labor (OR=13.7, 95% CI 6.4-29.3). Women with uterine rupture had more episodes of postpartum hemorrhage (50.0% vs 0.4%, P<.01), received more packed cell transfusions (54.8% vs 1.5%, P<.01), and required more hysterectomies (26.2% vs 0.04%, P<.01). Newborn infants delivered after uterine rupture were more frequently graded Apgar scores lower than 5 at 5 minutes and had higher rates of perinatal mortality when compared with those without rupture (10.3% vs 0.3%, P<.01; 19.0% vs 1.4%, P<.01, respectively). CONCLUSION: Uterine rupture, associated with previous cesarean section, malpresentation, and second-stage dystocia, is a major risk factor for maternal morbidity and neonatal mortality. Thus, a repeated cesarean delivery should be considered among parturients with a previous uterine scar, whose labor failed to progress.     

Cesarean delivery and peripartum hysterectomy

OBJECTIVE: To estimate the national incidence of peripartum hysterectomy and quantify the risk associated with cesarean deliveries and other factors. METHODS: A population-based, matched case-control study using the United Kingdom Obstetric Surveillance System, including 318 women in the United Kingdom who underwent peripartum hysterectomy between February 2005 and February 2006 and 614 matched control women. RESULTS: The incidence of peripartum hysterectomy was 4.1 cases per 10,000 births (95% confidence interval [CI] 3.6-4.5). Maternal mortality was 0.6% (95% CI 0-1.5%). Previous cesarean delivery (odds ratio [OR] 3.52, 95% CI 2.35-5.26), maternal age over 35 years (OR 2.42, 95% CI 1.66-3.58), parity of three or greater (OR 2.30, 95% CI 1.26-4.18), previous manual placental removal (OR 12.5, 95% CI 1.17-133.0), previous myomectomy (OR 14.0, 95% CI 1.31-149.3), and twin pregnancy (OR 6.30, 95% CI 1.73-23.0) were all risk factors for peripartum hysterectomy. The risk associated with previous cesarean delivery was higher with increasing numbers of previous cesarean deliveries (OR 2.14 with one previous delivery [95% CI 1.37-3.33], 18.6 with two or more [95% CI 7.67-45.4]). Women undergoing a first cesarean delivery in the current pregnancy were also at increased risk (OR 7.13, 95% CI 3.71-13.7). CONCLUSION: Peripartum hysterectomy is strongly associated with previous cesarean delivery, and the risk rises with increasing number of previous cesarean deliveries, maternal age over 35 years, and parity greater than 3. LEVEL OF EVIDENCE: II.     

Early labor assessment and support at home versus telephone triage: a randomized controlled trial

OBJECTIVE: To compare rates of cesarean delivery among women who were triaged by obstetric nurses, either by telephone or by means of home visits. METHODS: Healthy, nulliparous women in labor at term with uncomplicated pregnancies residing in the City of Vancouver, British Columbia, and suburbs between November 2001 and October 2004 were randomized when they sought advice about when to come to hospital. Women randomized to telephone triage (n=731) were provided with advice by telephone. Women randomized to a home visit (n=728) were triaged after a "hands-on" assessment in their homes. RESULTS: The relative risk (RR) for cesarean delivery among home-triaged women compared with those receiving only telephone support was 1.12 (95% confidence interval [CI] 0.94-1.32). The study was designed to have 80% power to detect a RR less than 0.78 or greater than 1.27 for cesarean delivery. Significantly fewer women in the home visit group were admitted to hospital with cervical dilatation at 3 cm or less (RR 0.85, 95% CI 0.76-0.94). Significantly more women in the home visit group managed their labor without a visit to hospital for assessment (RR 1.54, 95% CI 1.23-1.92). There were no statistically significant differences in use of narcotic analgesia, epidural analgesia, and augmentation of labor. Adverse neonatal outcomes were rare and did not differ between study groups. CONCLUSION: Early labor assessment and support at home versus support by telephone reduces the number of visits to hospital in latent phase labor but does not impact cesarean delivery rates among healthy nulliparous women. CLINICAL TRIAL REGISTRATION: ISRCTN, www.controlled-trials.com/isrctn, MCT-44153 LEVEL OF EVIDENCE: I.     

Cesarean Delivery in Adolescents

Study ObjectiveTo examine the effect of maternal age on indication for primary cesarean delivery in low-risk nulliparous women.DesignRetrospective cohort study.SettingUrban academic tertiary care center.ParticipantsNulliparous women younger than 35 years of age delivering vertex-presenting singletons at term.InterventionsParticipants underwent spontaneous, operative or cesarean delivery.Main Outcome MeasuresMode of delivery, indication, and timing of cesarean delivery.ResultsAdolescents were half as likely to undergo cesarean delivery overall (odds ratio [OR], 0.48; 95% confidence interval [CI], 0.43-0.54), and more than one-third less likely to undergo cesarean delivery in labor (OR, 0.59; 95% CI, 0.53-0.66). Adjustment for potential confounders did not alter the strength of these associations. Adolescents were half as likely to undergo cesarean delivery for failure to progress (OR, 0.49; 95% CI, 0.43-0.54). There was no difference in the odds of cesarean delivery for nonreassuring fetal status (OR, 0.91; 95% CI, 0.77-1.06), or genital herpes (OR, 1.44; 95% CI, 0.57-3.68). Induction, macrosomia, oxytocin augmentation, and any labor complication were all associated with increased risk of cesarean delivery. There was no difference in the duration of second stage for adolescents who delivered by cesarean delivery compared with adults (240.0 vs 237.7 minutes; P = .84), but adolescents who delivered vaginally had a second stage that was one-third shorter than adults (62.5 vs 100.3 minutes; P < .001).ConclusionAdolescents are half as likely to undergo primary cesarean delivery overall, and 40% less likely to undergo a primary cesarean delivery in labor, even after adjustment for multiple maternal, neonatal, and labor characteristics. This difference is not explained by differences in the duration of the second stage of labor.     

Trial of labor after 40 weeks' gestation in women with prior cesarean

OBJECTIVE: To compare outcomes in women with prior cesareans delivering at or before 40 weeks' gestation with those delivering after 40 weeks. METHODS: We reviewed labor outcomes over 12 years at one institution for women with one prior cesarean and no other deliveries who had a trial of labor at term. We analyzed the rates of symptomatic uterine rupture and cesarean for term deliveries before or after 40 weeks and stratified for spontaneous and induced labor. Potential confounding by birth weight was controlled using logistic regression. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated. RESULTS: Of 2775 women with one prior scar and no other deliveries, 1504 delivered at or before 40 weeks and 1271 delivered after 40 weeks. For spontaneous labor, rupture rate at or before 40 weeks was 0.5% compared with 1.0% after 40 weeks (P =.2, adjusted OR 2.1, CI 0.7, 5.7). For induced labor, uterine rupture rates were 2.1% at or before 40 weeks and 2.6% after 40 weeks (P =.7, adjusted OR 1.1, CI 0.4, 3.4). For spontaneous labor, rate of cesareans during subsequent trials of labor at or before 40 weeks was 25% compared with 33.5% after 40 weeks (P =.001, adjusted OR 1.5, CI 1.2, 1.8). For induced labor, rate of cesareans during subsequent trials of labor at or before 40 weeks was 33.8% compared with 43% after 40 weeks (P =.03, adjusted OR 1.5, CI 1.1, 2.2). CONCLUSION: The risk of uterine rupture does not increase substantially after 40 weeks but is increased with induction of labor regardless of gestational age. Because spontaneous labor after 40 weeks is associated with a cesarean rate similar to that following induced labor before 40 weeks, awaiting spontaneous labor after 40 weeks does not decrease the likelihood of successful vaginal delivery.     

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

OBJECTIVE: To estimate the maternal morbidity associated with cesarean deliveries performed at term without labor compared with morbidity associated with spontaneous labor. METHODS: A 14-year, population-based, cohort study (1988-2001) using the Nova Scotia Atlee Perinatal Database compared maternal outcomes in nulliparous women at term undergoing spontaneous labor for planned vaginal delivery with singleton, cephalic presentation and nulliparous women delivering by cesarean without labor. RESULTS: From a total of 18,435 pregnancies, which satisfied inclusion and exclusion criteria, 721 were cesarean deliveries without labor. There were no maternal deaths or transfers for intensive care. There was no difference in wound infection, blood transfusion, or intraoperative trauma. Women undergoing cesarean deliveries without labor were more likely to have puerperal febrile morbidity (relative risk [RR] 2.2; 95% confidence interval [CI] 1.1, 4.5; P=.03), but were less likely to have early postpartum hemorrhage (RR 0.6; 95% CI 0.4, 0.9; P=.01) compared with women entering spontaneous labor. Subgroup analyses of maternal outcomes in women delivering by spontaneous and assisted vaginal delivery and cesarean delivery in labor were also performed. The highest morbidity was found in the assisted vaginal delivery and cesarean delivery in labor groups. CONCLUSION: The increased maternal morbidity in elective cesarean delivery compared with spontaneous onset of labor is limited to puerperal febrile morbidity. Maternal morbidity is increased after assisted vaginal delivery and cesarean delivery in labor compared with cesarean delivery without labor.     

Infertility treatment is an independent risk factor for cesarean section among nulliparous women aged 40 and above

OBJECTIVE: To determine whether nulliparous women > 40 years old with singleton pregnancies who conceived after infertility treatment are at an increased risk for cesarean section compared with older nulliparous patients who conceived spontaneously. STUDY DESIGN: All subjects in this study were nulliparous women > 40 years old with singleton gestations who were delivered of their infants between 1990 and 1998. The Mantel-Haenszel procedure was used to obtain the weighted odds ratios and to control for confounding variables. RESULTS: During the study period, 115 nulliparous women > 40 years old with singleton pregnancies were delivered of their infants in our institute. Of those, 80 pregnancies were spontaneous and 35 pregnancies occurred after infertility treatment. Women treated for infertility had a higher rate of low-birth-weight (< 2500 g) newborns (34.3% versus 10.1%; odds ratio, 4.7; 95% CI, 1.5 to 14.6; P = .002). No other statistically significant demographic and obstetric differences were found between the groups. There were no cases of perinatal death in the study population. Women treated for infertility had statistically significant higher rates of cesarean section compared with those who conceived spontaneously (71.4% versus 41.3%; odds ratio, 3.6; 95% CI, 1.4 to 9.2; P =.002). Stratified analysis (the Mantel-Haenszel technique) was used to control for possible confounders such as low birth weight, pathologic presentations, failed induction, nonprogressive labor, and nonreassuring fetal heart rate tracings. None of those variables explained the higher incidence of cesarean section in the group treated for infertility. CONCLUSION: A history of infertility treatment among nulliparous women > 40 years old with singleton pregnancies increases the risk for cesarean delivery independently of other known risk factors.     

Term induction of labor and risk of cesarean delivery by parity

Abstract

Objective: To evaluate the risk of cesarean delivery among both nulliparous and multiparous women undergoing a term induction of labor compared to women that present in spontaneous labor at term.

Methods: We performed a retrospective cohort study of term (≥37 weeks) singleton pregnancies between 2005 and 2010 comparing women that had an induction to those that presented in spontaneous labor. Multiparity was defined as a prior delivery after 20 weeks’ gestation. Chi-square was used to compare categorical variables. Multivariable logistic regression was used to control for confounders. Analyses were stratified by parity.

Results: 863 women were included in the analysis. There were 605 inductions (cesarean rate 23%) and 257 spontaneous labor (cesarean rate 7%), OR 3.4, 95% CI [2.1–5.4]. Stratified by parity, nulliparas undergoing induction had an increased cesarean rate compared to spontaneous labor (27% versus 11%, OR 3.13, 95% CI [1.76–5.57]) as did multiparas (13% versus 3%, OR 4.04, 95% CI [1.36–11.94]). This increased risk for cesarean after induction remained in both nulliparous and multiparous women even after controlling for confounders (aOR 2.90, 95% CI [1.60–5.25] and aOR 3.47, 95% CI [1.12–10.67], respectively). Neither starting cervical exam nor indication for induction altered this increased risk.

Conclusions: The increased risk of cesarean in women undergoing an induction is present regardless of parity and indication for induction. This should be taken into account when counseling women regarding risks of induction, regardless of parity. Future studies should focus on other clinical characteristics of induction that may mitigate this risk.