Uterine activity during the two hours after placental delivery among low-risk pregnancies: an observational study

The intertwining of oxytocin's effects on social affiliation and inflammation

•Oxytocin is an ancient adaptive hormone that promotes social affiliation to maximize fitness and longevity.•Oxytocin is a multifaceted hormone that regulates stress responses at all levels of cellular organization within individuals.•Oxytocin's dual actions on sociability and inflammation highlight its powerful capacity as a modulator of human health.

Assessment of Uterine Contraction and Atonic Bleeding during the Third Stage of Labor Using Shear Wave Elastography

OBJECTIVE

This study aimed to clarify the relationship between fluctuations in uterine stiffness during the third stage of labor and blood loss upon placenta delivery using shear wave elastography.

METHODS

This prospective cohort study enrolled consecutive singleton pregnant women above 37 weeks of gestation who delivered infants transvaginally at a single perinatal center. Shear wave velocities (SWV) were continuously measured during the third stage of transvaginal labor using transabdominal ultrasound and these values were compared between groups with large (≥500 g) and small amounts of bleeding during this stage.

RESULTS

In total, 8 cases of large bleeding and 47 cases of small bleeding were compared. The large amount of bleeding group had a significantly lower median of minimum SWV values (0.97 [0.52-1.01] m/s than the small amount of bleeding group (1.25 [1.04-1.48] m/s p = 0.02). However, no significant differences were observed between the two groups in terms of median, mean, and maximum SWV values. The time from delivery of the infant to placental delivery was significantly longer in the large amount of bleeding group (median time: 370.5 s vs. 274 s, p < 0.05).

CONCLUSION

Ultrasound quantification of uterine stiffness using shear wave elastography demonstrated that uterine contractions may influence the biological hemostasis of the uterus during the third stage of labor. Baseline uterine stiffness was weak and a longer duration of placental separation might be associated with cases of large amounts of bleeding during this stage.

Detection of postpartum uterine activity with electrohysterography

OBJECTIVE

Uterine contractions are essential for childbirth, but also for expulsion of the placenta and for limiting postpartum blood loss. Postpartum hemorrhage is associated with almost 25% of the maternal deaths worldwide and the leading cause of maternal death in most low-income countries. Little is known about the physiology of the uterus postpartum, particularly due to the lack of an accurate measurement tool. The primary objective of this pilot study is to explore the potential of using electrohysterography to detect postpartum uterine contractions. If postpartum uterine activity can be objectified, this could contribute to understanding the physiology of the uterus and improve diagnosis and treatment of postpartum hemorrhage.

STUDY DESIGN

In this observational study we included women aiming for a vaginal birth in two large maternity clinics in the Netherlands, Amphia Hospital Breda (group A, N2018-0161) and Máxima Medical Center Veldhoven (group B, N17.149). An electrode patch was placed on the maternal abdomen to record real-time electrical uterine activity until one hour postpartum continuously. In group A, the placement of the patch was lower than in group B. For analysis, tracings were divided into five different phases (1: dilatation until start pushing, 2: from start pushing until childbirth, 3: from childbirth until placental expulsion, 4: first hour after placental expulsion and 5: after one hour postpartum). Readability, signal quality and contraction frequency per hour were assessed. Additionally, patient satisfaction was evaluated through a survey.

RESULTS

In total 91 pregnant women were included of whom 45 in group A and 46 women in group B. Complete registrations were obtained throughout the five labor phases with very little artefacts or signal loss. The readability of the tracings decreased after childbirth. A significantly better readability was found in tracings where the patch placement was lower on the abdomen for phases 4 and 5. Contraction frequency was highest during phase 2 and decreased towards phase 5. Women rated the satisfaction with electrohysterography as high and mostly did not notice the patch.

CONCLUSION

It is possible to detect uterine activity postpartum with electrohysterography. Further investigation is recommended to improve diagnosis and treatment of postpartum hemorrhage.

Factors of early breastfeeding initiation among Filipino women: A population-based cross-sectional study

BACKGROUND

Early breastfeeding initiation (EBI) within the first hour after birth has the potential to reduce neonatal mortality. However, the prevalence of EBI still falls short of the 70 % target set by the WHO for 2030. Limited research has been conducted on this issue. Therefore, the study aimed to assess the prevalence and factors of EBI in the Philippines.

METHODS

This study is a secondary analysis of the data from the Philippine National Demographic and Health Survey (PNDHS) in 2017. Women survey participants aged 15 to 49 (n = 3750) who had given birth within the two years prior to the survey were included in this study. A p-value < 0.05 was used to define statistical significance when identifying the factors associated with EBI using hierarchical logistic regression analysis.

RESULTS

Women who were more likely to practice EBI were those from the Cordillera Administrative Region, who read newspaper/magazines, and delivered infants at 2 or later birth order. On the contrary, women from Central Luzon, CALABARZON (Cavite, Laguna, Batangas, Rizal, and Quezon provinces), Central Visayas, Eastern Visayas, and the Autonomous Region of Muslim Mindanao; who listen to the radio at least once a week; and give birth through cesarean section were less likely to practice EBI.

CONCLUSION

Channeling breastfeeding messages through printed mass media and provision of specialized breastfeeding support to mothers with cesarean section delivery may help in reducing the barriers to early breastfeeding initiation. Targeted interventions and strategies that promote breastfeeding practices, particularly among primigravida women and in regions with lower rates of EBI contribute to increased rate of optimal breastfeeding.

Progesterone control of myometrial contractility

During pregnancy, the primary function of the uterus is to be quiescent and not contract, which allows the growing fetus to develop and mature. A uterine muscle layer, myometrium, is composed of smooth muscle cells (SMCs). Before the onset of labor contractions, the uterine SMCs experience a complex biochemical and molecular transformation involving the expression of contraction-associated proteins. Labor is initiated when genes in SMCs are activated in response to a combination of hormonal, inflammatory and mechanical signals. In this review, we provide an overview of molecular mechanisms regulating the process of parturition in humans, focusing on the hormonal control of the myometrium, particularly the steroid hormone progesterone. The primary reason for discussing the regulation of myometrial contractility by progesterone is the importance of the clinical problem of preterm birth. It is thought that the hormonal mechanisms regulating premature uterine contractions represent an untimely triggering of the normal events occurring during term parturition. Yet, our knowledge of the complex and redundant hormonal pathways controlling uterine contractile activity leading to delivery of the neonate remains incomplete. Finally, we introduce recent animal studies using a novel class of drugs, Selective Progesterone Receptor Modulators, targeting progesterone signaling to prevent premature myometrial contractions.

Acupressure application to relieve postpartum uterus pain during breastfeeding: A randomized controlled study

OBJECTIVE

Postpartum uterus pain while breastfeeding is a situation that can affect mother-infant bonding negatively and is a matter of concern for women. The purpose of this study is to investigate the effectiveness of acupressure application in reducing postpartum uterus pain during breastfeeding.

METHODS

This prospective randomized controlled trial was carried out at a maternity hospital in northwestern Turkey between March and August 2022. The sample of the study included 125 multiparous women who were in the 6th to 24th hours after vaginal delivery. The participants were randomly divided into acupressure and control groups. Visual Analog Scale (VAS) was used to evaluate postpartum uterine pain.

RESULTS

While the VAS scores of the acupressure and control groups were similar before breastfeeding, the scores of the acupressure group at the 10th and 20th minutes of breastfeeding were lower (respectively, p = 0.038 and p = 0.011). In the intragroup comparisons, compared to their values before breastfeeding, the pain score of the acupressure group decreased at a statistically highly significant degree at the 20th minute of breastfeeding (p<0.001), whereas the score of the control group increased at a statistically highly significant degree at the 10th and 20th minutes (p<0.001).

CONCLUSION

It was concluded that acupressure can be an effective nonpharmacological method in reducing uterus pain while breastfeeding in the postpartum period.

Maternal and newborn plasma oxytocin levels in response to maternal synthetic oxytocin administration during labour, birth and postpartum - a systematic review with implications for the function of the oxytocinergic system

BACKGROUND

The reproductive hormone oxytocin facilitates labour, birth and postpartum adaptations for women and newborns. Synthetic oxytocin is commonly given to induce or augment labour and to decrease postpartum bleeding.

AIM

To systematically review studies measuring plasma oxytocin levels in women and newborns following maternal administration of synthetic oxytocin during labour, birth and/or postpartum and to consider possible impacts on endogenous oxytocin and related systems.

METHODS

Systematic searches of PubMed, CINAHL, PsycInfo and Scopus databases followed PRISMA guidelines, including all peer-reviewed studies in languages understood by the authors. Thirty-five publications met inclusion criteria, including 1373 women and 148 newborns. Studies varied substantially in design and methodology, so classical meta-analysis was not possible. Therefore, results were categorized, analysed and summarised in text and tables.

RESULTS

Infusions of synthetic oxytocin increased maternal plasma oxytocin levels dose-dependently; doubling the infusion rate approximately doubled oxytocin levels. Infusions below 10 milliunits per minute (mU/min) did not raise maternal oxytocin above the range observed in physiological labour. At high intrapartum infusion rates (up to 32 mU/min) maternal plasma oxytocin reached 2-3 times physiological levels. Postpartum synthetic oxytocin regimens used comparatively higher doses with shorter duration compared to labour, giving greater but transient maternal oxytocin elevations. Total postpartum dose was comparable to total intrapartum dose following vaginal birth, but post-caesarean dosages were higher. Newborn oxytocin levels were higher in the umbilical artery vs. umbilical vein, and both were higher than maternal plasma levels, implying substantial fetal oxytocin production in labour. Newborn oxytocin levels were not further elevated following maternal intrapartum synthetic oxytocin, suggesting that synthetic oxytocin at clinical doses does not cross from mother to fetus.

CONCLUSIONS

Synthetic oxytocin infusion during labour increased maternal plasma oxytocin levels 2-3-fold at the highest doses and was not associated with neonatal plasma oxytocin elevations. Therefore, direct effects from synthetic oxytocin transfer to maternal brain or fetus are unlikely. However, infusions of synthetic oxytocin in labour change uterine contraction patterns. This may influence uterine blood flow and maternal autonomic nervous system activity, potentially harming the fetus and increasing maternal pain and stress.

Association between anesthetic method and postpartum hemorrhage in Korea based on National Health Insurance Service data

Background

Postpartum hemorrhage (PPH) is a major cause of maternal mortality and the risk factors for PPH differ among studies. In this large-scale study, we investigated whether the anesthetic method used was associated with PPH after cesarean section.

Methods

We extracted data on cesarean sections performed between January 2008 and June 2013 from the National Health Insurance Service database. The anesthetic methods were categorized into general, spinal and epidural anesthesia. To compare the likelihood of PPH among deliveries using different anesthetic methods, crude and adjusted odds ratios (ORs) and 95% confidence intervals were calculated using logistic regression analysis.

Results

Data from 330,324 cesarean sections were analyzed, and 21,636 cases of PPH were identified. Univariate analysis showed that general and epidural anesthesia increased the risk of PPH compared to spinal anesthesia. The OR for PPH was highest for morbidly adherent placenta, followed by placenta previa, placental abruption, and hypertension. When other clinical covariates were controlled for, general and epidural anesthesia still remained significant risk factors for PPH compared to spinal anesthesia.

Conclusions

This study showed that general and epidural anesthesia elevated the risk of PPH compared to spinal anesthesia during cesarean section. Since we could not consider the potential bias of group differences in indications, more in-depth clinical trials are needed to validate our findings. Obstetric factors such as placental abnormalities had high odds ratios and thus are more important than the choice of anesthetic method, which should be based on the patient's clinical condition and institutional resources.

Using shear wave elastography to assess uterine tonicity after vaginal delivery

This study aims to evaluate the feasibility and clinical interest of shear wave elastography, by quantitatively estimating the baseline stiffness of the myometrium before and after placental expulsion. We conducted a prospective cohort study of women at term, without known risk factors for postpartum hemorrhage, who gave birth via spontaneous labor in our tertiary center. Myometrium tonicity was evaluated based on measurements of shear wave speed (SWS) in the anterior uterine corpus. All data points were collected by a single operator. Measurements were carried out at three different time points: after fetal delivery (T1), after placental delivery (T2) and 30 min after placental delivery (T3). Our primary objective was to assess the feasibility of this new imaging technique. Ten valid SWS measurements obtained at each of the three different time points were considered as a positive primary outcome. Our secondary objectives were to evaluate the difference in median myometrial shear wave velocity between each time point, as well as to determine the correlation between myometrial shear wave velocity and patients’ characteristics. 38 women were recruited during the study period, of whom 34 met the study criteria. 1017 SWS measurements were obtained. The median time to perform measurements was 16 s for one value, and 2 min 56 s for ten. For 11 women (32%) it was not possible to achieve ten SWS at T1 as placental expulsion immediately followed the birth of the newborn. One patient experienced placental retention and only measurements at T1 were performed. For all other patients, we were successfully able to obtain all measures as intended. There was no difference in the mean shear wave speed between the three time points. After adjustments for confounders, we observed a significant correlation for total blood loss (correlation coefficient = − 0.26, p < 0.001, units of oxytocin (correlation coefficient = − 0.34, p = 0.03), and newborn weight (correlation coefficient = − 0.08, p = 0.001). It is feasible to assess uterine tonicity by shear wave imaging, after placental expulsion. We did not observe a variance in uterine tonicity between the three time points. Women who had higher blood loss, received more units of oxytocin and/or those with newborns of a higher weight exhibited lower shear wave speed measures.

Tools, techniques, and future opportunities for characterizing the mechanobiology of uterine myometrium

The myometrium is the smooth muscle layer of the uterus that generates the contractions that drive processes such as menstruation and childbirth. Aberrant contractions of the myometrium can result in preterm birth, insufficient progression of labor, or other difficulties that can lead to maternal or fetal complications or even death. To investigate the underlying mechanisms of these conditions, the most common model systems have conventionally been animal models and human tissue strips, which have limitations mostly related to relevance and scalability, respectively. Myometrial smooth muscle cells have also been isolated from patient biopsies and cultured in vitro as a more controlled experimental system. However, in vitro approaches have focused primarily on measuring the effects of biochemical stimuli and neglected biomechanical stimuli, despite the extensive evidence indicating that remodeling of tissue rigidity or excessive strain is associated with uterine disorders. In this review, we first describe the existing approaches for modeling human myometrium with animal models and human tissue strips and compare their advantages and disadvantages. Next, we introduce existing in vitro techniques and assays for assessing contractility and summarize their applications in elucidating the role of biochemical or biomechanical stimuli on human myometrium. Finally, we conclude by proposing the translation of "organ on chip" approaches to myometrial smooth muscle cells as new paradigms for establishing their fundamental mechanobiology and to serve as next-generation platforms for drug development.

Incidence, severity, and determinants of uterine contraction pain after vaginal delivery: a prospective observational study

BACKGROUND

Postpartum uterine contraction pain has not been studied sufficiently. We aimed to assess the incidence, intensity, and risk factors for postpartum uterine contraction pain.

METHODS

Women with singleton pregnancies who delivered vaginally were enrolled in this prospective, observational, single-institution study. We determined the numerical rating scale (NRS) score (0 to 10-point) for uterine contraction pain at 6, 12, 24, and 48 h after delivery. Generalized mixed modeling was used to identify the risk factors for significant postpartum uterine contraction pain (NRS score ≥3). We compared the incidence and severity of postpartum uterine contraction pain between nulliparous and multiparous women.

RESULTS

Two hundred and sixty-five nulliparous and 139 multiparous women were included. Forty-seven percent (188/404; 95% confidence interval [CI] 41.7% to 51.4%) of women presented with significant uterine contraction pain within 48 h of delivery. The generalized mixed model showed that nulliparous women had a lower risk of significant postpartum uterine contraction pain compared with multiparous women (odds ratio [OR] 0.33, 95% CI 0.17 to 0.61; P<0.001). Women with a history of dysmenorrhea had higher risk of significant postpartum uterine contraction pain (OR 1.77, 95% CI 1.12 to 2.79; P=0.014). Both nulliparous and multiparous women reported more intense uterine contraction pain while breastfeeding (P<0.001).

CONCLUSIONS

Postpartum uterine contraction pain is common and severe in some women. Parity and history of dysmenorrhea are significant risk factors for significant postpartum uterine contraction pain.

Physiologic childbirth and active management of the third stage of labor: A latent class model of risk for postpartum hemorrhage

BACKGROUND

Postpartum hemorrhage (PPH) is a threat to maternal mortality worldwide. Evidence supports active management of third stage labor (AMTSL) for preventing PPH. However, trials of AMTSL include women at varying risk levels, such as women undergoing physiologic labor and those with labor complications. Counseling women about their risk for PPH and AMTSL is difficult as many women who appear low-risk can still have PPH.

METHODS

This study uses outcomes of 2322 vaginal births from a hospital midwifery service in the United States to examine risks for PPH and effectiveness of AMTSL. Using a latent class analysis approach, physiologic birth practices and other risk factors for PPH were analyzed to understand if discrete classes of clinical characteristics would emerge. The effect of AMTSL on the PPH outcome was also considered by class.

RESULTS

A four-class solution best fit the data; each class was clinically distinct. The two largest Classes (A and B) represented women with term births and lower average parity, with higher rates of nulliparity in Class B. Class A women had more physiologic birth elements and less labor induction or labor dysfunction compared with Class B. PPH and AMTSL use was higher in Class B. In Class B, AMTSL lowered risk for PPH. However, in Class A, AMTSL was associated with higher risk for PPH and delayed placental delivery (>30 minutes).

DISCUSSION

AMTSL may not be as beneficial to women undergoing physiologic birth. Further study of the etiology of PPH in these women is indicated to inform preventive care.