Over a third of women of childbearing age in the United States are obese, and during pregnancy they are at increased risk for delayed labor onset and slow labor progress that often results in unplanned cesarean delivery. The biology behind this dysfunctional parturition is not well understood. Studies of obesity-induced changes in parturition physiology may facilitate approaches to optimize labor in obese women. In this review, we summarize known and proposed biologic effects of obesity on labor preparation, contraction/synchronization, and endurance, drawing on both clinical observation and experimental data. We present evidence from human and animal studies of interactions between obesity and parturition signaling in all elements of the birth process, including: delayed cervical ripening, prostaglandin insensitivity, amniotic membrane strengthening, decreased myometrial oxytocin receptor expression, decreased myocyte action potential initiation and contractility, decreased myocyte gap junction formation, and impaired myocyte neutralization of reactive oxygen species. We found convincing clinical data on the effect of obesity on labor initiation and successful delivery, but few studies on the underlying pathobiology. We suggest research opportunities and therapeutic interventions based on plausible biologic mechanisms.
Introduction:
Postpartum hemorrhage (PPH) is an important contributor to maternal morbidity and mortality. Predicting which laboring women are likely to have a PPH is an active area of research and a component of quality improvement bundles. The purpose of this study was to identify phenotypes of labor processes (ie, labors that have similar features, such as duration and type of interventions) in a cohort of women who had vaginal births, estimate the likelihood of PPH by phenotype, and analyze how maternal and fetal characteristics relate to PPH risk by phenotype.
Methods:
This study utilized the Consortium for Safe Labor dataset (2002-2008) and examined term, singleton, vaginal births. Using 16 variables describing the labor and birth processes, a latent class analysis was performed to describe distinct labor process phenotypes.
Results:
Of 24,729 births, 1167 (4.72%) women experienced PPH. Five phenotypes best fit the data, reflecting labor interventions, duration, and complications. Women who had shorter duration of admission after spontaneous labor onset (admitted in latent or active labor) had the lowest rate of PPH (3.8%-3.9%). The 2 phenotypes of labor progress characterized by women who had complicated prolonged labors (spontaneous or induced) had the highest rate of PPH (8.0% and 12.0%, respectively). However, the majority of PPH (n = 881, 75%) occurred in the phenotypes with fewer complications. Prepregnancy body mass index did not predict PPH. Overall, the odds of PPH were highest among nulliparous women (odds ratio [OR], 1.52; 95% CI, 1.30-1.77), as well as Black women (OR, 1.39; 95% CI, 1.13-1.73) and Hispanic women (OR, 1.85; 95% CI, 1.56-2.20). Within phenotypes, maternal race and ethnicity, nulliparity, macrosomia, hypertension, and depression were associated with increased odds of PPH.
Discussion:
Women who were classified into a lower-risk labor phenotype and still experienced PPH were more likely to be nulliparous, a person of color, or diagnosed with hypertension.
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.
Objectives The purpose of this study was to evaluate the metabolic pathways activated in the serum of African-American women during late pregnancy that predicted term labor dystocia. Study Design Matched case-control study (n = 97; 48 cases of term labor dystocia and 49 normal labor progression controls) with selection based on body mass index (BMI) at hospital admission and maternal age. Late pregnancy serum samples were analyzed using ultra-high-resolution metabolomics. Differentially expressed metabolic features and pathways between cases experiencing term labor dystocia and normal labor controls were evaluated in the total sample, among women who were obese at the time of labor (BMI ≥ 30 kg/m2), and among women who were not obese. Results Labor dystocia was predicted by different metabolic pathways in late pregnancy serum among obese (androgen/estrogen biosynthesis) versus nonobese African-American women (fatty acid activation, steroid hormone biosynthesis, bile acid biosynthesis, glycosphingolipid metabolism). After adjusting for maternal BMI and age in the total sample, labor dystocia was predicted by tryptophan metabolic pathways in addition to C21 steroid hormone, glycosphingolipid, and androgen/estrogen metabolism. Conclusion Metabolic pathways consistent with lipotoxicity, steroid hormone production, and tryptophan metabolism in late pregnancy serum were significantly associated with term labor dystocia in African-American women.
Objectives: Hospital admission during early labor may increase women's risk for medical and surgical interventions. However, it is unclear which diagnostic guideline is best suited for identifying the active phase of labor among parous women. Dr. Emanuel Friedman, the United Kingdom's National Institute for Health and Care Excellence (NICE), and the American College of Obstetricians and Gynecologists/Society for Maternal-Fetal Medicine (ACOG/SMFM) support different active labor diagnostic guidelines. Our aims were (1) to determine the proportions of parous women admitted to the hospital before or in active labor per these leading guidelines and (2) to compare associations of labor status at admission (i.e., early labor or active labor) with oxytocin augmentation, cesarean birth, and adverse birth outcomes when using the different active labor diagnostic guidelines.
Design: Active labor diagnostic guidelines were applied retrospectively to cervical examination data. Binomial logistic regression was used to assess associations of labor status at admission (i.e., early labor relative to active labor) and outcomes.
Setting: A large, academic, tertiary medical center in the Midwestern United States.
Participants: Parous women with spontaneous labor onset who gave birth to a single, cephalic-presenting fetus at term gestation between 2006 and 2010 (n = 3,219).
Findings: At admission, 28.8%, 71.9%, and 24.4% of parous women were in active labor per Friedman, NICE, and ACOG/SMFM diagnostic guidelines, respectively. Oxytocin augmentation was more likely among women admitted in early labor, regardless of the diagnostic strategy used (p < 0.001 for each guideline). Cesarean birth was also more likely among women admitted before versus in active labor according to all guidelines (Friedman: adjusted odds ratio [AOR] 3.63 [95% CI 1.46–9.03]), NICE: AOR 2.71 [95% CI 1.47–4.99]), and ACOG/SMFM: AOR 2.11 [95% CI 1.02–4.34]). There were no differences in a composite measure of adverse outcomes within active labor diagnostic guidelines after adjusting for covariates. Key
conclusions: Many parous women with spontaneous labor onset are admitted to the hospital before active labor. These women are more likely to receive oxytocin augmentation during labor and are more likely to have a cesarean birth.
Implications for practice: Diagnosing active labor prior to admission or prior to intervention aimed at speeding labor after admission may decrease likelihoods for primary cesarean births. The NICE dilation-rate based active labor diagnostic guideline is more inclusive than Friedman or ACOG/SMFM guidelines and its use may be the most clinically-useful for improving the likelihood of vaginal birth among parous women.
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.
Background: The timing of hospital admission for women with spontaneous labor onset and the criteria used to assess active labor progress and diagnose labor dystocia may significantly influence women's risk for primary cesarean birth. Our aims were to assess associations of labor status at admission (i.e., preactive or active) and active labor progress (i.e., dystocic or physiologic) with oxytocin augmentation, cesarean birth, and adverse neonatal outcome rates. Methods: A sample of low-risk, nulliparous women admitted to hospitals for spontaneous labor onset was extracted from the Consortium on Safe Labor (n = 27 077). Binomial logistic regression was used to assess associations between labor classifications and outcomes. Results: At admission, 68.0% of women were in preactive labor and 32.0% were in active labor. Cesarean rates for these groups were 18.0% and 7.2%, respectively (adjusted odds ratio [AOR] 2.69; 95% CI 2.45-2.96). Oxytocin augmentation and adverse neonatal outcomes were more likely for women admitted in preactive labor. Among women admitted in active labor, 9.3% experienced labor dystocia and 90.7% progressed physiologically. Cesarean rates for these groups were 20.4% and 5.9%, respectively (AOR 3.02; 95% CI 2.45-3.73). Nearly half of the cesareans performed for dystocia among women admitted in active labor occurred when cervical dilation was physiologic. Oxytocin augmentation and adverse neonatal outcomes were more likely when active labor was dystocic. Conclusions: Adoption of evidence-based, standardized approaches for diagnosing active labor onset, assessing labor progress, and diagnosing dystocia may safely decrease oxytocin augmentation and cesarean birth rates in the United States.
Background: Racial disparities exist in maternal morbidity and mortality, with most of these events occurring in healthy pregnant people. A known driver of these outcomes is unplanned cesarean birth. Less understood is to what extent maternal presenting race/ethnicity is associated with unplanned cesarean birth in healthy laboring people, and if there are differences by race/ethnicity in intrapartum decision-making prior to cesarean birth. Methods: This secondary analysis of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be (nuMoM2b) dataset involved nulliparas with no significant health complications at pregnancy onset who had a trial of labor at ≥ 37 weeks with a singleton, non-anomalous fetus in cephalic presentation (N = 5,095). Logistic regression models were used to examine associations between participant-identified presenting race/ethnicity and unplanned cesarean birth. Participant-identified presenting race/ethnicity was used to capture the influence of racism on participant’s healthcare experiences. Results: Unplanned cesarean birth occurred in 19.6% of labors. Rates were significantly higher among Black- (24.1%) and Hispanic- (24.7%) compared to white-presenting participants (17.4%). In adjusted models, white participants had 0.57 (97.5% CI [0.45–0.73], p < 0.001) lower odds of unplanned cesarean birth compared to Black-presenting participants, while Hispanic-presenting had similar odds as Black-presenting people. The primary indication for cesarean birth among Black- and Hispanic- compared to white-presenting people was non-reassuring fetal heart rate in the setting of spontaneous labor onset. Conclusions: Among healthy nulliparas with a trial of labor, white-presenting compared to Black or Hispanic-presenting race/ethnicity was associated with decreased odds of unplanned cesarean birth, even after adjustment for pertinent clinical factors. Future research and interventions should consider how healthcare providers’ perception of maternal race/ethnicity may bias care decisions, leading to increased use of surgical birth in low-risk laboring people and racial disparities in birth outcomes.
Postpartum depression (PPD) is a significant mental health concern, especially for women in vulnerable populations. Oxytocin (OT), a hormone essential for a variety of maternal tasks, including labor, lactation, and infant bonding, has also been hypothesized to have a role in postpartum depression. Women are routinely given synthetic oxytocin to induce or augment labor and to prevent postpartum hemorrhage. The aim of this study was to review the quality and reliability of literature that examines potential relationships between OT and PPD to determine if there is sufficient data to reliably assess the strength of these relationships. We conducted a literature search in December of 2018 using five databases (PubMed, Web of Science, Embase, PsycInfo, and CINAHL). Eligible studies were identified, selected, and appraised using the Newcastle-Ottawa quality assessment scale and Cochrane Collaboration's tool for assessing risk of bias, as appropriate. Sixteen studies were included in the analysis and broken into two categories: correlations of endogenous OT with PPD and administration of synthetic OT with PPD. Depressive symptoms were largely measured using the Edinburgh Postnatal Depression Scale. OT levels were predominately measured in plasma, though there were differences in laboratory methodology and control of confounders (primarily breast feeding). Of the twelve studies focused on endogenous oxytocin, eight studies suggested an inverse relationship between plasma OT levels and depressive symptoms. We are not able to draw any conclusions regarding the relationship between intravenous synthetic oxytocin and postpartum depression based on current evidence due to the heterogeneity and small number of studies (n = 4). Considering limitations of the current literature and the current clinical prevalence of synthetic OT administration, we strongly recommend that rigorous studies examining the effects of synthetic OT exposure on PPD should be performed as well as continued work in defining the relationship between endogenous OT and PPD.
Metabolomics, one of the newest omics, allows for investigation of holistic responses of living systems to myriad biological, behavioral, and environmental factors. Researcher use metabolomics to examine the underlying mechanisms of clinically observed phenotypes. However, these methods are complex, potentially impeding their uptake by scientists. In this scoping review, we summarize literature illustrating nurse scientists’ use of metabolomics. Using electronic search methods, we identified metabolomics investigations conducted by nurse scientists and published in English-language journals between 1990 and November 2019. Of the studies included in the review (N = 30), 9 (30%) listed first and/or senior authors that were nurses. Studies were conducted predominantly in the United States and focused on a wide array of clinical conditions across the life span. The upward trend we note in the use of these methods by nurse scientists over the past 2 decades mirrors a similar trend across scientists of all backgrounds. A broad range of study designs were represented in the literature we reviewed, with the majority involving untargeted metabolomics (n = 16, 53.3%) used to generate hypotheses (n = 13, 76.7%) of potential metabolites and/or metabolic pathways as mechanisms of clinical conditions. Metabolomics methods match well with the unique perspective of nurse researchers, who seek to integrate the experiences of individuals to develop a scientific basis for clinical practice that emphasizes personalized approaches. Although small in number, metabolomics investigations by nurse scientists can serve as the foundation for robust programs of research to answer essential questions for nursing.