Induction of labor or expectant management? Birth outcomes for nulliparous individuals choosing midwifery care.

BACKGROUND: Induction of labor (IOL) has been studied as a strategy to reduce rates of cesarean birth (CB). Midwifery care models are also associated with lower CB rates, even considering that midwives perform fewer IOLs. In this study, we examined childbirth outcomes among individuals undergoing IOL in certified nurse-midwifery (CNM) care as compared to two categories of expectant management (EM). METHODS: Data were from two CNM practices in the United States (2007-2018). The sample was limited to term nulliparous, nondiabetic, singleton, vertex pregnancies. Individuals having an IOL in each week of gestation (37th, 38th, etc) were compared with those having EM. Two methods for defining EM were considered as each method when used alone limits interpretation. Inclusive EM included all births starting in the same week as IOL. The exclusive EM group was comprised of all births occurring in the next gestational age week relative to the IOL cases (ie, 39th week IOL versus all births occurring at 40 weeks or later). Adjusted regression models were used to examine differences in CB by IOL versus EM (inclusive or exclusive) at each week of gestation. RESULTS: Among 4057 CNM-attended pregnancies, the overall rate of IOL was 28.9% (95% CI 27.5%-30.3%) and CB was 19.4% (95% CI 18.1%-20.6%). Most IOLs involved obstetric indications. CB rates did not differ by IOL versus inclusive EM when performed between 37 and 40 weeks, though post hoc power calculations indicate these comparisons were low-powered. In multivarable models, IOL in the 40th week was associated with lower odds for CB versus exclusive EM definition (ie, births occurring at 41 0/7 weeks or later, OR (95% CI) = 0.57 (0.36-0.90)). This finding is explained by the large increase in CB rates after IOL during the 41st week (34.3%, up from 21.9% in the 40th week). Furthermore, the adjusted odds for CB in the 41st week were 55% higher relative to inclusive EM (all labors 41st week and later), OR (95% CI) = 1.55(1.11-2.15). Neonatal outcomes (aside from macrosomia) did not differ by IOL/EM at any gestational age. DISCUSSION: Outcomes for nulliparous individuals having IOL or EM in the context of a midwifery model of care include low overall use of CB and low frequency of IOL before 41 weeks. In this model, IOL in the 40th week may lower CB odds, especially in comparison to those who do not have spontaneous labor and later undergo an IOL in the 41st week.

Using the Robson 10-Group Classification System to Compare Cesarean Birth Utilization Between US Centers With and Without Midwives.

INTRODUCTION: The Robson 10-group classification system stratifies cesarean birth rates using maternal characteristics. Our aim was to compare cesarean birth utilization in US centers with and without midwifery care using the Robson classification. METHODS: We used National Institute of Child and Human Development Consortium on Safe Labor data from 2002 to 2008. Births to women in centers with interprofessional care that included midwives (n = 48,857) were compared with births in non-interprofessional centers (n = 47,935). To compare cesarean utilization, births were classified into the Robson categories. Cesarean birth rates within each category and the contribution to the overall rate were calculated. Maternal demographics, labor and birth outcomes, and neonatal outcomes were described. Logistic regression was used to adjust for maternal comorbidities. RESULTS: Women were less likely to have a cesarean birth (26.1% vs 33.5%, P < .001) in centers with interprofessional care. Nulliparous women with singleton, cephalic, term fetuses (category 2) were less likely to have labor induced (11.1% vs 23.4%, P < .001), and women with a prior uterine scar (category 5) had lower cesarean birth rates (73.8% vs 85.1%, P < .001) in centers with midwives. In centers without midwives, nulliparous women with singleton, cephalic, term fetuses with induction of labor (category 2a) were less likely to have a cesarean birth compared with those in interprofessional care centers in unadjusted comparison (30.3% vs 35.8%, P < .001), but this was reversed after adjustment for maternal comorbidities (adjusted odds ratio, 1.21; 95% CI, 1.12-1.32; P < .001). Cesarean birth rates among women at risk for complications (eg, breech) were similar between groups. DISCUSSION: Interprofessional care teams were associated with lower rates of labor induction and overall cesarean utilization as well as higher rates of vaginal birth after cesarean. There was consistency in cesarean rates among women with higher risk for complications.

Preventing Cesarean Birth in Women with Obesity: Influence of Unit-Level Midwifery Presence on Use of Cesarean among Women in the Consortium on Safe Labor Data Set.

INTRODUCTION: Maternal obesity is associated with slow labor progression and unplanned cesarean birth. Midwives use fewer medical interventions during labor, and the women they care for have lower cesarean birth rates, compared with low-risk, matched groups of women cared for by physicians. The primary aim of this study was to examine associations between midwifery unit-level presence and unplanned cesarean birth in women with different body mass index (BMI) ranges. Unit-level presence of midwives was analyzed as a representation of a unique set of care practices that exist in settings where midwives work. METHODS: A retrospective cohort study was conducted using Consortium on Safe Labor data from low-risk, healthy women who labored and gave birth in medical centers with (n = 9795) or without (n = 13,398) the unit-level presence of midwives. Regression models were used to evaluate for associations between unit-level midwifery presence and 1) the incidence of unplanned cesarean birth and 2) in-hospital labor durations with stratification by maternal BMI and adjustment for maternal demographic and pregnancy factors. RESULTS: The odds of unplanned cesarean birth among women who gave birth in centers with midwives were 16% lower than the odds of cesarean birth among similar women at who gave birth at centers without midwives (adjusted odds ratio, 0.84; 95% CI, 0.77-0.93). However, women whose BMI was above 35.00 kg/m2 at labor admission had similar odds of cesarean birth, regardless of unit-level midwifery presence. In-hospital labor duration prior to unplanned cesarean was no different by unit-level midwifery presence in nulliparous women whose BMI was above 35.00 kg/m2 . DISCUSSION: Although integration of midwives into the caregiving environment of medical centers in the United States was associated with overall decrease in the incidence of cesarean birth, increased maternal BMI nevertheless remained positively associated with these outcomes.

Influence of midwifery presence in United States centers on labor care and outcomes of low-risk parous women: A Consortium on Safe Labor study.

BACKGROUND: Sixty percent of United States births are to multiparous women. Hospital-level policies and culture may influence intrapartum care and birth outcomes for this large population, yet have been poorly explored using a large, diverse sample. We sought to use national United States data to analyze the association between midwifery presence in maternity care teams and the birth processes and outcomes of low-risk parous women. METHODS: We conducted a retrospective cohort study using Consortium on Safe Labor data from low-risk parous women in either interprofessional care (n = 12 125) or noninterprofessional care centers (n = 8996). Unadjusted, adjusted (age, race, health insurance type), propensity-adjusted, and propensity-matched logistic regression models were used to assess processes and outcomes. RESULTS: There was concordance in outcome differences across regression models. With propensity score matching, women at interprofessional centers, compared with women at noninterprofessional centers, were 85% less likely to have labor induced (risk ratio [RR] 0.15; 95% CI 0.14-0.17). The risk for primary cesarean birth among low-risk parous women was 36% lower at interprofessional centers (RR 0.64; 95% CI 00.52-0.79), whereas the likelihood of vaginal birth after cesarean for this population was 31% higher (RR 1.31; 95% CI 1.10-1.56). There were no significant differences in neonatal outcomes. CONCLUSIONS: Parous women have significantly higher rates of vaginal birth, including vaginal birth after cesarean, and lower likelihood of labor induction when cared for in centers with midwives. Our findings are consistent with smaller analyses of midwifery practice and support integrated, team-based models of perinatal care to improve maternal outcomes.

Midwifery presence in United States medical centers and labor care and birth outcomes among low-risk nulliparous women: A Consortium on Safe Labor study.

BACKGROUND: The presence of midwives in a health system may affect perinatal outcomes but has been inadequately described in United States settings. Our objective was to compare labor processes and outcomes for low-risk nulliparous women birthing in United States medical centers with interprofessional care (midwives and physicians) versus noninterprofessional care (physicians only). METHODS: We conducted a retrospective cohort study using Consortium on Safe Labor data from low-risk nulliparous women who birthed in interprofessional (n = 7393) or noninterprofessional centers (n = 6982). Unadjusted, adjusted (age, race, health insurance type), propensity-adjusted, and propensity-matched logistic regression models were used to compare outcomes. RESULTS: There was concordance across logistic regression models, the most restrictive and conservative of which were propensity-matched models. With this approach, women at interprofessional medical centers, compared with women at noninterprofessional centers, were 74% less likely to undergo labor induction (risk ratio [RR] 0.26; 95% CI 0.24-0.29) and 75% less likely to have oxytocin augmentation (RR 0.25; 95% CI 0.22-0.29). The cesarean birth rate was 12% lower at interprofessional centers (RR 0.88; 95% CI 0.79-0.98). Adverse neonatal outcomes occurred in only 0.3% of births and were thus too rare to be modeled. CONCLUSIONS: The care processes and birth outcomes at interprofessional and noninterprofessional medical centers differed significantly. Nulliparous women receiving care at interprofessional centers were less likely to experience induction, oxytocin augmentation, and cesarean than women at noninterprofessional centers. Labor care and birth outcome differences between interprofessional and noninterprofessional centers may be the result of the presence of midwives and interprofessional collaboration, organizational culture, or both.