The physiology and pharmacology of oxytocin in labor and in the peripartum period

Association of oxytocin augmentation with postpartum hemorrhage: a systematic review and meta-analysis

OBJECTIVE

The current study aims to evaluate the correlation between oxytocin augmentation and postpartum hemorrhage.

METHOD

PubMed, Web of Science, and Scopus has been searched for studies assessing the correlation between oxytocin augmentation and postpartum hemorrhage up to January 24, 2024. The search strategy included relevant keywords related to PPH and oxytocin augmentation. The risk of bias assessment was conducted by two reviewers using the Newcastle-Ottawa Scale (NOS). To pool the effects sized of included studies odds ratios (OR) of interest outcome with their 95% confidence interval (CI) were used.

RESULTS

Eight studies were included in this meta-analysis. The pooled analysis of the included studies showed a statistically significant association between oxytocin augmentation and increased odds of PPH (pooled odds ratio [OR] = 1.27, 95% confidence interval [CI]: 1.05-1.53; I2 = 84.94%; p = 0.01). Publication bias was assessed using funnel plots, which appeared relatively asymmetrical, indicating significant publication bias. Galbraith plot and trim and fill plot were used for publication bias. Sensitivity analyses were performed by leave one out method.

CONCLUSION

This meta-analysis suggests that using oxytocin for labor augmentation is linked to a significant increase in the risk of PPH. It highlights the need for careful monitoring and consideration when using oxytocin, especially in low and middle-income countries where guidelines and supervision are crucial.

Oscillations in delayed positive feedback systems

Positive feedback loops exist in many biological circuits important for organismal function. In this work, we investigate how temporal delay affects the dynamics of two canonical positive feedback models. We consider models of a genetic toggle switch and a one-way switch with delay added to the feedback terms. We show that long-lasting transient oscillations exist in both models under general conditions and that the duration depends strongly on the magnitude of the delay and initial conditions. We then show the existence of long-lasting oscillations in specific biological examples: the Cdc2-Cyclin B/Wee1 system and a genetic regulatory network. Our results challenge fundamental assumptions underlying oscillatory behavior in biological systems. While generally delayed negative feedback systems are canonical in generating oscillations, we show that delayed positive feedback systems are a mechanism for generating oscillations as well.

Variations in the use of oxytocin for augmentation of labour in Sweden: a population-based cohort study

National Swedish data shows substantial variation in the use of oxytocin for augmentation of spontaneous labour between obstetric units. This study aimed to investigate if variations in the use of oxytocin augmentation are associated with maternal and infant characteristics or clinical factors. We used a cohort design including women allocated to Robson group 1 (nulliparous women, gestational week ≥ 37 + 0, with singleton births in cephalic presentation and spontaneous onset of labour) and 3 (parous women, gestational week ≥ 37 + 0, with singleton births in cephalic presentation, spontaneous onset of labour, and no previous caesarean birth). Crude and adjusted logistic regression models with marginal standardisation were used to estimate risk ratios (RR) and risk differences (RD) with 95% confidence intervals (CI) for oxytocin use by obstetric unit. An interaction analysis was performed to investigate the potential modifying effect of epidural. The use of oxytocin varied between 47 and 73% in Robson group 1, and 10% and 33% in Robson group 3. Compared to the remainder of Sweden, the risk of oxytocin augmentation ranged from 13% lower (RD - 13.0, 95% CI - 15.5 to - 10.6) to 14% higher (RD 14.0, 95% CI 12.3-15.8) in Robson group 1, and from 6% lower (RD - 5.6, 95% CI - 6.8 to - 4.5) to 18% higher (RD 17.9, 95% CI 16.5-19.4) in Robson group 3. The most notable differences in risk estimates were observed among women in Robson group 3 with epidural. In conclusion, variations in oxytocin use remained despite adjusting for risk factors. This indicates unjustified differences in use of oxytocin in clinical practice.

A qualitative exploration of the challenges providers experience during peripartum management of patients with a body mass index ≥ 50 kg/m2 and recommendations for improvement

BACKGROUND

The objective of this research was to conduct a qualitative study among a diverse group of providers to identify their clinical needs, barriers, and adverse safety events in the peripartum care of people with a body mass index (BMI) ≥ 50 kg/m2.

METHODS

Obstetricians, anesthesiologists, certified nurse midwives, nurse practitioners, and nurses were invited to participate in focus group discussions if they were employed at the hospital for >6 months. Key concepts in the focus group guide included: (1) Discussion of challenging situations, (2) Current peripartum management approaches, (3) Patient and family knowledge and counseling, (4) Design and implementation of a guideline (e.g., checklist or toolkit) for peripartum care. The audiotaped focus groups were transcribed verbatim, uploaded to a qualitative analysis software program, and analyzed using inductive and constant comparative approaches. Emerging themes were summarized along with representative quotes.

RESULTS

Five focus groups of 27 providers were completed in 2023. The themes included staffing (level of experience, nursing-patient ratios, safety concerns), equipment (limitations of transfer mats, need for larger sizes, location for blood pressure cuff, patient embarrassment), titrating oxytocin (lack of guidelines, range of uses), monitoring fetal heart rate and contractions, patient positioning, and communication (lack of patient feedback, need for bias training, need for interdisciplinary relationships). Providers gave examples of items to include in a "BMI cart" and suggestions for a guideline including designated rooms for patients with a BMI ≥ 50 kg/m2, defining nursing ratios and oxytocin titration plans, postpartum incentive spirometer, and touch points with providers (nursing, physicians) at every shift change.

CONCLUSIONS

Providers discussed a range of challenges and described how current approaches to care may negatively affect the peripartum experience and pose threats to safety for patients with a BMI ≥ 50 kg/m2 and their providers. We gathered information on improving equipment and communication among providers.

Sacred space: a qualitative interpretive meta-synthesis of women's experiences of supportive birthing environments

BACKGROUND

In the United States there are roughly three million births a year, ranging from cesarean to natural births. A major aspect of the birthing process is related to the healing environment, and how that helps or harms healing for the mother and child. Using the theoretical framework, Theory of Supportive Care Settings (TSCS), this study aimed to explore what is necessary to have a safe and sacred healing environment for mothers.

METHOD

This study utilized an updated Qualitative Interpretive Meta-synthesis (QIMS) design called QIMS-DTT [deductive theory testing] to answer the research question, What are mother's experiences of environmental factors contributing to a supportive birthing environment within healthcare settings?

RESULTS

Key terms were run through multiple databases, which resulted in 5,688 articles. After title and abstract screening, 43 were left for full-text, 12 were excluded, leaving 31 to be included in the final QIMS. Five main themes emerged from analysis: 1) Service in the environment, 2) Recognizing oneself within the birthing space, 3) Creating connections with support systems, 4) Being welcomed into the birthing space, and 5) Feeling safe within the birthing environment.

CONCLUSIONS

Providing a warm and welcoming birth space is crucial for people who give birth to have positive experiences. Providing spaces where the person can feel safe and supported allows them to find empowerment in the situation where they have limited control.

Effects of systemic oxytocin receptor activation and blockade on risky decision making in female and male rats

The neuropeptide oxytocin is traditionally known for its roles in parturition, lactation, and social behavior. Other data, however, show that oxytocin can modulate behaviors outside of these contexts, including drug self-administration and some aspects of cost-benefit decision making. Here we used a pharmacological approach to investigate the contributions of oxytocin signaling to decision making under risk of explicit punishment. Female and male Long-Evans rats were trained on a risky decision-making task in which they chose between a small, "safe" food reward and a large, "risky" food reward that was accompanied by varying probabilities of mild footshock. Once stable choice behavior emerged, rats were tested in the task following acute intraperitoneal injections of oxytocin or the oxytocin receptor antagonist L-368,899. Neither drug affected task performance in males. In females, however, both oxytocin and L-368,899 caused a dose-dependent reduction in preference for large risky reward. Control experiments showed that these effects could not be accounted for by alterations in food motivation or shock sensitivity. Together, these results reveal a sex-dependent effect of oxytocin signaling on risky decision making in rats.

Signaling mechanisms underlying activity-dependent integration of adult-born neurons in the mouse olfactory bulb

Adult neurogenesis has fascinated the field of neuroscience for decades given the prospects of harnessing mechanisms that facilitate the rewiring and/or replacement of adult brain tissue. The subgranular zone of the hippocampus and the subventricular zone of the lateral ventricle are the two main areas in the brain that exhibit ongoing neurogenesis. Of these, adult-born neurons within the olfactory bulb have proven to be a powerful model for studying circuit plasticity, providing a broad and accessible avenue into neuron development, migration, and continued circuit integration within adult brain tissue. This review focuses on some of the recognized molecular and signaling mechanisms underlying activity-dependent adult-born neuron development. Notably, olfactory activity and behavioral states contribute to adult-born neuron plasticity through sensory and centrifugal inputs, in which calcium-dependent transcriptional programs, local translation, and neuropeptide signaling play important roles. This review also highlights areas of needed continued investigation to better understand the remarkable phenomenon of adult-born neuron integration.

Parturition at term: induction, second and third stages of labor, and optimal management of life-threatening complications-hemorrhage, infection, and uterine rupture

Childbirth is a defining moment in anyone's life, and it occurs 140 million times per year. Largely a physiologic process, parturition does come with risks; one mother dies every two minutes. These deaths occur mostly among healthy women, and many are considered preventable. For each death, 20 to 30 mothers experience complications that compromise their short- and long-term health. The risk of birth extends to the newborn, and, in 2020, 2.4 million neonates died, 25% in the first day of life. Hence, intrapartum care is an important priority for society. The American Journal of Obstetrics & Gynecology has devoted two special Supplements in 2023 and 2024 to the clinical aspects of labor at term. This article describes the content of the Supplements and highlights new developments in the induction of labor (a comparison of methods, definition of failed induction, new pharmacologic agents), management of the second stage, the value of intrapartum sonography, new concepts on soft tissue dystocia, optimal care during the third stage, and common complications that account for maternal death, such as infection, hemorrhage, and uterine rupture. All articles are available to subscribers and non-subscribers and have supporting video content to enhance dissemination and improve intrapartum care. Our hope is that no mother suffers because of lack of information.

Calm Contact Technique Based on the Endocrinological Mechanism of Hypnosis-A Theoretical Proposal

This paper proposes the "calm contact" technique: an imaginative scenario where someone is in gentle contact with a loved one where the essence of the experience is to enjoy safety and calmness in peaceful social contact. The theoretical background is outlined by combining the brain mechanisms of stress reactions and hypnosis. In addition to the ancient stress responses (flight or fight or freeze), there are oxytocin-based options at the human level: tend and befriend behavior and the state of calm and connection, which is not a stress reaction but a resting reaction. These social-based reactions could prevent the organism from the primitive freezing response. Some studies proved that "hypnosis" as a setting reduces cortisol levels and could raise oxytocin levels. The beneficial mechanisms of the "calm contact" technique are analyzed in relation to "social support" and the psychoaffective effects of central oxytocin. The subjective effects of the proposed technique are outlined based on reports of healthy volunteers. The "calm contact" technique could be an alternative or adjunct to the "safe place" technique, applying the recent findings of endocrinological brain mechanisms of hypnosis. Clinical implications and limitations are briefly summarized.