Framing postpartum hemorrhage as a consequence of human placental biology: an evolutionary and comparative perspective

Animal models of postpartum hemorrhage

Postpartum hemorrhage (PPH)-heavy bleeding following childbirth-is a leading cause of morbidity and mortality worldwide. PPH can affect individuals regardless of risks factors and its incidence has been increasing in high-income countries including the United States. The high incidence and severity of this childbirth complication has propelled research into advanced treatments and alternative solutions for patients facing PPH; however, the development of novel treatments is limited by the absence of a common, well-established and well-validated animal model of PPH. A variety of animals have been used for in vivo studies of novel therapeutic materials; however, each of these animals differs considerably from the anatomy and physiology of a postpartum woman, and the methods used for achieving a postpartum hemorrhagic condition vary widely. Here we critically evaluate the various animal models of PPH presented in the literature and propose additional and alternative methods for modeling PPH in in vivo studies. We highlight how current animal models successfully or unsuccessfully mimic the anatomy and physiology of a postpartum woman and how this may impact treatment development. We aim to equip researchers with the necessary background information to select appropriate animal models for their research related to PPH solutions, while supporting the goals of refinement, reduction and replacement (3Rs) in preclinical animal studies.

Birth, love, and fear: Physiological networks from pregnancy to parenthood

Pregnancy and childbirth are among the most dramatic physiological and emotional transformations of a lifetime. Despite their central importance to human survival, many gaps remain in our understanding of the temporal progression of and mechanisms underlying the transition to new parenthood. The goal of this paper is to outline the physiological and emotional development of the maternal-infant dyad from late pregnancy to the postpartum period, and to provide a framework to investigate this development using non-invasive timeseries. We focus on the interaction among neuroendocrine, emotional, and autonomic outputs in the context of late pregnancy, parturition, and post-partum. We then propose that coupled dynamics in these outputs can be leveraged to map both physiologic and pathologic pregnancy, parturition, and parenthood. This approach could address gaps in our knowledge and enable early detection or prediction of problems, with both personalized depth and broad population scale.

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Giving birth and caring for offspring are dynamic processes that can instill both love and fear.

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Maternal physiology continuously integrates fetal, social, and environmental cues.

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The result is coupled change in hormonal, autonomic nervous, and emotional output.

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Coupling may allow internal state to be assessed from peripheral autonomic markers.

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Such markers may identify healthy or pathologic pregnancy, parturition, and parenting, and enable creation of real-world tools.

Recurrence of postpartum hemorrhage, maternal and paternal contribution, and the effect of offspring birthweight and sex: a population-based cohort study

Purpose

This study examines individual aggregation of postpartum hemorrhage (PPH), paternal contribution and how offspring birthweight and sex influence recurrence of PPH. Further, we wanted to estimate the proportion of PPH cases attributable to a history of PPH or current birthweight.

Methods

We studied all singleton births in Norway from 1967 to 2017 using data from Norwegian medical and administrational registries. Subsequent births in the parents were linked. Multilevel logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CI) for PPH defined as blood loss > 500 ml, blood loss > 1500 ml, or the need for blood transfusion in parous women. Main exposures were previous PPH, high birthweight, and fetal sex. We calculated adjusted population attributable fractions for previous PPH and current high birthweight.

Results

Mothers with a history of PPH had three- and sixfold higher risks of PPH in their second and third deliveries, respectively (adjusted OR 2.9; 95% CI 2.9–3.0 and 6.0; 5.5–6.6). Severe PPH (> 1500 ml) had the highest risk of recurrence. The paternal contribution to recurrence of PPH in deliveries with two different mothers was weak, but significant. If the neonate was male, the risk of PPH was reduced. A history of PPH or birthweight ≥ 4000 g each accounted for 15% of the total number of PPH cases.

Conclusion

A history of PPH and current birthweight exerted strong effects at both the individual and population levels. Recurrence risk was highest for severe PPH. Occurrence and recurrence were lower in male fetuses, and the paternal influence was weak.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00404-021-06374-3.

Postpartum Hemorrhage and its Associated Factors Among Women who Gave Birth at Yirgalem General Hospital, Sidama Regional State, Ethiopia

Background

Globally, postpartum hemorrhage (PPH) is one of the leading causes of maternal mortality. In developing countries, it accounts for more than 30% of all maternal deaths. So, understanding its burden in the health care setting is significant. Thus, this study aimed to assess the magnitude of PPH and its associated factors among women who gave birth at Yirgalem General Hospital, Sidama Region, Ethiopia.

Methods

A cross-sectional study was conducted from March 12 to 26, 2020 among randomly selected 298 women. Data were collected using an interviewer-administered, structured, and pretested questionnaire. EpiData version 3.1 and SPSS version 20 were used to enter and analyze the data, respectively. Descriptive statistics, bivariable, and multivariable logistic regression analysis were done. Adjusted odds ratio with 95% confidence interval (CI) was used to measure the presence and strength of association between the independent and the outcome variables. A P-value ≤.05 was considered to declare statistical significance.

Result

The magnitude of PPH was 9.4% [95% CI: 6.0, 12.8]. Prolonged labor (≥24 h) [AOR = 3.4, 95% CI: 1.1, 9.9], giving birth by cesarean section [AOR = 5.8, 95% CI: 1.1, 22.0], and instrumental vaginal delivery [AOR = 3.7, 95% CI: 1.1, 12.7], and having a history of the uterine atony [AOR = 4.8, 95% CI: 1.4, 16.6] during their last delivery were factors significantly associated with PPH.

Conclusion

The magnitude of PPH was high. Healthcare professionals should manage the progress of labor and take all necessary measures at right time. Also, giving attention to the safety of delivery-related procedures and early related potential risks is crucial.

Physiology and Pathology of Contractility of the Myometrium

Uterine atony is a serious obstetrical complication since it is the leading cause of postpartum hemorrhage. Postpartum hemorrhage (PPH) is one of the 5 major causes of postpartum mortality; therefore, it requires immediate medical intervention, independent of whether delivery occurs normally or with a cesarean section. While in the past years most cases of postpartum hemorrhage were caused due to uterine atony following vaginal delivery, in recent years most PPH cases indicate a significant association with cesarean delivery. There are several methods used in order to avoid such a life-threatening complication, ranging from risk assessment to prevention, and finally medical intervention and management, if such an event occurs. In this scientific paper emphasis is given on the so-called "uterotonic" agents that are currently used, including oxytocin among others. It is, therefore, important to be familiar with these agents as well as understand the physiological mechanism by which they work, since they are used in everyday practice, not only for managing but also for preventing PPH. There are several potential questions that arise from the use of such "uterotonic" agents, and most specifically of oxytocin. Maybe one of the most important issues is the determination of optimal dosing of oxytocin in order to avoid PPH after a cesarean section.

The evolutionary biology of endometriosis

We provide the first analysis and synthesis of the evolutionary and mechanistic bases for risk of endometriosis in humans, structured around Niko Tinbergen's four questions about phenotypes: phylogenetic history, development, mechanism and adaptive significance. Endometriosis, which is characterized by the proliferation of endometrial tissue outside of the uterus, has its phylogenetic roots in the evolution of three causally linked traits: (1) highly invasive placentation, (2) spontaneous rather than implantation-driven endometrial decidualization and (3) frequent extensive estrogen-driven endometrial proliferation and inflammation, followed by heavy menstrual bleeding. Endometriosis is potentiated by these traits and appears to be driven, proximately, by relatively low levels of prenatal and postnatal testosterone. Testosterone affects the developing hypothalamic-pituitary-ovarian (HPO) axis, and at low levels, it can result in an altered trajectory of reproductive and physiological phenotypes that in extreme cases can mediate the symptoms of endometriosis. Polycystic ovary syndrome, by contrast, is known from previous work to be caused primarily by high prenatal and postnatal testosterone, and it demonstrates a set of phenotypes opposite to those found in endometriosis. The hypothesis that endometriosis risk is driven by low prenatal testosterone, and involves extreme expression of some reproductive phenotypes, is supported by a suite of evidence from genetics, development, endocrinology, morphology and life history. The hypothesis also provides insights into why these two diametric, fitness-reducing disorders are maintained at such high frequencies in human populations. Finally, the hypotheses described and evaluated here lead to numerous testable predictions and have direct implications for the treatment and study of endometriosis. Lay summary: Endometriosis is caused by endometrial tissue outside of the uterus. We explain why and how humans are vulnerable to this disease, and new perspectives on understanding and treating it. Endometriosis shows evidence of being caused in part by relatively low testosterone during fetal development, that 'programs' female reproductive development. By contrast, polycystic ovary syndrome is associated with relatively high testosterone in prenatal development. These two disorders can thus be seen as 'opposite' to one another in their major causes and correlates. Important new insights regarding diagnosis, study and treatment of endometriosis follow from these considerations.

New era of trophoblast research: integrating morphological and molecular approaches

Many pregnancy complications are the result of dysfunction in the placenta. The pathogenic mechanisms of placenta-mediated pregnancy complications, however, are unclear. Abnormal placental development in these conditions begins in the first trimester, but no symptoms are observed during this period. To elucidate effective preventative treatments, understanding the differentiation and development of human placenta is crucial. This review elucidates the uniqueness of the human placenta in early development from the aspect of structural characteristics and molecular markers. We summarise the morphogenesis of human placenta based on human specimens and then compile molecular markers that have been clarified by immunostaining and RNA-sequencing data across species. Relevant studies were identified using the PubMed database and Google Scholar search engines up to March 2020. All articles were independently screened for eligibility by the authors based on titles and abstracts. In particular, the authors carefully examined literature on human placentation. This review integrates the development of human placentation from morphological approaches in comparison with other species and provides new insights into trophoblast molecular markers. The morphological features of human early placentation are described in Carnegie stages (CS), from CS3 (floating blastocyst) to CS9 (emerging point of tertiary villi). Molecular markers are described for each type of trophoblast involved in human placental development. We summarise the character of human trophoblast cell lines and explain how long-term culture system of human cytotrophoblast, both monolayer and spheroid, established in recent studies allows for the generation of human trophoblast cell lines. Due to differences in developmental features among species, it is desirable to understand early placentation in humans. In addition, reliable molecular markers that reflect normal human trophoblast are needed to advance trophoblast research. In the clinical setting, these markers can be valuable means for morphologically and functionally assessing placenta-mediated pregnancy complications and provide early prediction and management of these diseases.

Care of Infants in the Past: Bridging evolutionary anthropological and bioarchaeological approaches

The importance of care of infants and children in palaeoanthropological and human behavioural ecological research on the evolution of our species is evident in the diversity of research on human development, alloparental care, and learning and social interaction. There has been a recent surge of interest in modelling the social implications of care provision for people with serious disabilities in bioarchaeology. However, there is a lack of acknowledgement of infant and child care in bioarchaeology, despite the significant labour and resources that are required, and the implications this has for health outcomes within societies. Drawing on the recent proliferation of studies on infancy and childhood in evolutionary anthropology and bioarchaeology, this paper presents ways the subdisciplines may draw on research developments from each field to advance a more holistic understanding of the evolutionary, social and health significance of infant and children care in the past.

Cooperation and conflict in human pregnancy

For many humans living today, obstetric care begins early in pregnancy, and most babies are born in hospitals. These are precautionary measures. Medical complications during the brief nine months of pregnancy are such a common part of human experience that we rarely ask ourselves why gestation does not always proceed as smoothly and reliably as the lifelong beating of our heart or filtration of blood by our kidneys. The birth of a healthy child is central to reproductive fitness and must have been subject to strong natural selection. Why then should placentas be less reliable organs than hearts or kidneys? Why should maternal hearts and kidneys be more subject to catastrophic failures during pregnancy than at other times? A crucial contrast distinguishes obstetrics from cardiology and nephrology. The coordinated activities of heart and kidneys take place within an individual comprised of genetically largely identical cells, whereas pregnancy involves an interaction between genetically-distinct individuals whose cooperation is obviated by evolutionary conflicts of interest.

Placenta Accreta in an Oragnutan (Pongo abelii) and a Chimpanzee (Pan troglodytes)

Placenta accreta is defined as abnormal adherence of the placenta to the uterine wall. Placenta accreta is recognized as a common problem in human medicine, but has apparently not been reported previously in great apes, despite similarity in their reproductive biology. A 36-year-old multiparous female Sumatran orangutan (Pongo abelii) and a 20-year-old nulliparous female chimpanzee (Pan troglodytes), with gross uterine and histological uterine vascular changes that are characteristic of placenta accreta, are presented.

Cognitive costs of reproduction: life-history trade-offs explain cognitive decline during pregnancy in women

Life-history theory predicts that access to limited resources leads to trade-offs between competing body functions. Women, who face higher costs of reproduction when compared to men, should be especially vulnerable to these trade-offs. We propose the 'cognitive costs of reproduction hypothesis', which states that energy trade-offs imposed by reproduction may lead to a decline in maternal cognitive function during gestation. In particular, we hypothesize that the decline in cognitive function frequently observed during pregnancy is associated with the allocation of resources between the competing energetic requirements of the mother's brain and the developing foetus. Several distinctive anatomical and physiological features including a high metabolic rate of the brain, large infant size, specific anatomical features of the placenta and trophoblast, and the lack of maternal control over glucose flow through the placenta make the occurrence of these trade-offs likely. Herein, we review several lines of evidence for trade-offs between gestation and cognition that are related to: (i) energy metabolism during reproduction; (ii) energy metabolism of the human brain; (iii) links between energy metabolism and cognitive function; and (iv) links between gestation and cognitive function. We also review evidence for the important roles of cortisol, corticotropin-releasing hormone and sex hormones in mediating the effects of gestation on cognition, and we discuss possible neurophysiological mechanisms underlying the observed effects. The evidence supports the view that energy trade-offs between foetal growth and maternal endocrine and brain function lead to changes in maternal cognition, and that this phenomenon is mediated by neuroendocrine mechanisms involving the hypothalamic-pituitary-adrenal axis, brainstem nucleus locus coeruleus and hippocampus.

Lotus birth, a holistic approach on physiological cord clamping

BACKGROUND

The positive effects of delayed cord clamping (DCC) has been extensively researched. DCC means: waiting at least one minute after birth before clamping and cutting the cord or till the pulsation has stopped. With physiological clamping and cutting (PCC) the clamping and cutting can happen at the earliest after the pulsation has stopped. With a Lotus birth, no clamping and cutting of the cord is done. A woman called Clair Lotus Day imitated the holistic approach of PCC from an anthropoid ape in 1974. The chimpanzee did not separate the placenta from the newborn.

AIM

The aim of this case report is to discuss and learn a different approach in the third stage of labour.

METHOD

Three cases of Lotus birth by human beings were observed. All three women gave birth in an out-of-hospital setting and had ambulant postnatal care.

FINDINGS

The placenta was washed, salted and herbs were put on 2-3h post partum. The placenta was wrapped in something that absorbs the moisture. The salting was repeated with a degreasing frequency depending on moistness of the placenta. On life day six all three Lotus babies experiences a natural separation of the cord. All three Lotus birth cases were unproblematic, no special incidence occurred.

CONCLUSIONS

One should differentiate between early cord clamping (ECC), delayed cord clamping (DCC) and physiological cord clamping (PCC). Lotus birth might lead to an optimisation of the bonding and attachment. Research is needed in the areas of both PCC and Lotus birth.

The role of invasive trophoblast in implantation and placentation of primates

We here review the evolution of invasive placentation in primates towards the deep penetration of the endometrium and its arteries in hominoids. The strepsirrhine primates (lemurs and lorises) have non-invasive, epitheliochorial placentation, although this is thought to be derived from a more invasive type. In haplorhine primates, there is differentiation of trophoblast at the blastocyst stage into syncytial and cellular trophoblast. Implantation involves syncytiotrophoblast that first removes the uterine epithelium then consolidates at the basal lamina before continuing into the stroma. In later stages of pregnancy, especially in Old World monkeys and apes, cytotrophoblast plays a greater role in the invasive process. Columns of trophoblast cells advance to the base of the implantation site where they spread out to form a cytotrophoblastic shell. In addition, cytotrophoblasts advance into the lumen of the spiral arteries. They are responsible for remodelling these vessels to form wide, low-resistance conduits. In human and great apes, there is additional invasion of the endometrium and its vessels by trophoblasts originating from the base of the anchoring villi. Deep trophoblast invasion that extends remodelling of the spiral arteries to segments in the inner myometrium evolved in the common ancestor of gorilla, chimp and human.

Exacerbated venous thromboembolism in mice carrying a protein S K196E mutation

Protein S (PS) acts as an anticoagulant cofactor for activated protein C in regulation of blood coagulation. The K196E mutation in PS is a race-specific genetic risk factor for venous thromboembolism with a prevalence of ∼2% within the Japanese population. To evaluate the thrombosis risk of the PS-K196E mutation, we generated PS-K196E knockin mice and heterozygous PS-deficient mice. We analyzed their thrombotic states, comparing with mice carrying the factor V Leiden mutation (FV-R504Q), a race-specific genetic risk for venous thrombosis in whites. PS-K196E mice grew normally but had decreased activated protein C cofactor activity in plasma. Purified recombinant murine PS-K196E showed the same decreased activated protein C cofactor activity. A deep vein thrombosis model of electrolytic inferior vena cava injury and pulmonary embolism models induced by infusion of tissue factor or polyphosphates revealed that PS-K196E mice, heterozygous PS-deficient mice, and FV-R504Q mice were much more susceptible to venous thrombosis compared with wild-type mice. Transient middle cerebral artery ischemia-reperfusion injury model studies demonstrated that both PS-K196E mice and heterozygous PS-deficient mice had cerebral infarction similar to wild-type mice, consistent with human observations. Our in vitro and in vivo results support a causal relationship between the PS-K196E mutation and venous thrombosis and indicate that PS-K196E mice can provide an in vivo evaluation system to help uncovering racial differences in thrombotic diseases.

Is oxytocin a maternal-foetal signalling molecule at birth? Implications for development

The neuropeptide oxytocin was first noted for its capacity to promote uterine contractions and facilitate delivery in mammals. The study of oxytocin has grown to include awareness that this peptide is a neuromodulator with broad effects throughout the body. Accumulating evidence suggests that oxytocin is a powerful signal to the foetus, helping to prepare the offspring for the extrauterine environment. Concurrently, the use of exogenous oxytocin or other drugs to manipulate labour has become common practice. The use of oxytocin to expedite labour and minimise blood loss improves both infant and maternal survival under some conditions. However, further investigations are needed to assess the developmental consequences of changes in oxytocin, such as those associated with pre-eclampsia or obstetric manipulations associated with birth. This review focuses on the role of endogenous and exogenous oxytocin as a neurochemical signal to the foetal nervous system. We also examine the possible developmental consequences, including those associated with autism spectrum disorder, that arise from exogenous oxytocin supplementation during labour.

Genetic contribution to postpartum haemorrhage in Swedish population: cohort study of 466,686 births

OBJECTIVE

To investigate the familial clustering of postpartum haemorrhage in the Swedish population, and to quantify the relative contributions of genetic and environmental effects.

DESIGN

Register based cohort study.

SETTING

Swedish population (multi-generation and medical birth registers).

MAIN OUTCOME MEASURE

Postpartum haemorrhage, defined as >1000 mL estimated blood loss.

PARTICIPANTS

The first two live births to individuals in Sweden in 1997-2009 contributed to clusters representing intact couples (n = 366,350 births), mothers with separate partners (n = 53,292), fathers with separate partners (n = 47,054), sister pairs (n = 97,228), brother pairs (n = 91,168), and mixed sibling pairs (n = 177,944).

METHODS

Familial clustering was quantified through cluster specific tetrachoric correlation coefficients, and the influence of potential sharing of known risk factors was evaluated with alternating logistic regression. Relative contributions of genetic and environmental effects to the variation in liability for postpartum haemorrhage were quantified with generalised linear mixed models.

RESULTS

The overall prevalence of postpartum haemorrhage after vaginal deliveries in our sample was 4.6%. Among vaginal deliveries, 18% (95% confidence interval 9% to 26%) of the variation in postpartum haemorrhage liability was attributed to maternal genetic factors, 10% (1% to 19%) to unique maternal environment, and 11% (0% to 26%) to fetal genetic effects. Adjustment for known risk factors only partially explained estimates of familial clustering, suggesting that the observed shared genetic and environmental effects operate in part through pathways independent of known risk factors. There were similar patterns of familial clustering for both of the main subtypes examined (atony and retained placenta), though strongest for haemorrhage after retained placenta.

CONCLUSIONS

There is a maternal genetic predisposition to postpartum haemorrhage, but more than half of the total variation in liability is attributable to factors that are not shared in families.

Gene x environment interactions impact endometrial function and the menstrual cycle: PROGINS, life history, anthropometry, and physical activity

OBJECTIVES

We assessed the impact of a high frequency, functionally significant allelic variant of the progesterone receptor gene (PROGINS) on endometrial function and menstrual cycle characteristics. Further we asked whether PROGINS moderates the impact of life history characteristics, anthropometric measures, and physical activity on endometrial function.

METHODS

Fifty-two women were genotyped for the PROGINS variant, provided life history information, and had anthropometric measurements made. Women monitored their menstrual bleeding for three cycles, performed mid-cycle urinary ovulation tests, and recorded physical activity. A subset of women provided daily saliva samples and had mid-luteal endometrial thickness measurements taken during the third menstrual cycle. Salivary progesterone was assayed using ELISAs. The direct impact of PROGINS on endometrial and menstrual cycle characteristics was determined via independent t-tests with Bonferroni correction. Interactions between PROGINS and covariates were assessed by moderated regression.

RESULTS

PROGINS did not directly impact any indicator of endometrial function. However, PROGINS caused an increase in menstrual cycle length with increasing mid-luteal progesterone levels; the opposite relationship was present in noncarriers (P < 0.05). Additionally, PROGINS interacted with four of six anthropometric measures (BMI, waist circumference, height, and waist-hip ratio) to impact endometrial function, however, interactions between PROGINS and life history variables, or physical activity was limited.

CONCLUSIONS

The gene x environment interactions we report suggest that PROGINS alters endometrial sensitivity to maternal energetic condition. Thus, the possibility of genetically-based variation in sensitivity to energetic stress should be considered in future adaptive models of women's reproduction.

Practices related to postpartum uterine involution in the Western Highlands of Guatemala

BACKGROUND

Guatemala has the third highest level of maternal mortality in Latin America. Postpartum haemorrhage is the main cause of maternal mortality. In rural Guatemala, most women rely on Traditional Birth Attendants (TBAs) during labour, delivery, and the postpartum period. Little is known about current postpartum practices that may contribute to uterine involution provided by Mam- and Spanish-speaking TBAs in the Western Highlands of Guatemala.

METHODS

a qualitative study was conducted with 39 women who participated in five focus groups in the San Marcos Department of Guatemala. Questions regarding postpartum practices were discussed during four focus groups of TBAs and one group of auxiliary nurses.

RESULTS

three postpartum practices believed to aid postpartum uterine involution were identified: use of the chuj (Mam) (Spanish, temazcal), a traditional wood-fired sauna-bath used by Mam-speaking women; herbal baths and teas; and administration of biomedicines.

CONCLUSIONS

TBAs provide the majority of care to women during childbirth and the postpartum period and have developed a set of practices to prevent and treat postpartum haemorrhage. Integration of these practices may prove an effective method to reduce maternal morbidity and mortality in the Western Highlands of Guatemala.

The roles of the immune system in women's reproduction: evolutionary constraints and life history trade-offs

Life history theory posits that, as long as survival is assured, finite resources are available for reproduction, maintenance, and growth/storage. To maximize lifetime reproductive success, resources are subject to trade-offs both within individuals and between current and future investment. For women, reproducing is costly and time-consuming; the bulk of available resources must be allocated to reproduction at the expense of more flexible systems like immune function. When reproducing women contract infectious diseases, the resources required for immune activation can fundamentally shift the patterns of resource allocation. Adding to the complexity of the reproductive-immune trade-offs in women are the pleiotropic effects of many immune factors, which were modified to serve key roles in mammalian reproduction. In this review, we explore the complex intersections between immune function and female reproduction to situate proximate immunological processes within a life history framework. After a brief overview of the immune system, we discuss some important physiological roles of immune factors in women's reproduction and the conflicts that may arise when these factors must play dual roles. We then discuss the influence of reproductive-immune trade-offs on the patterning of lifetime reproductive success: (1) the effect of immune activation/infectious disease on the timing of life history events; (2) the role of the immune system, immune activation, and infectious disease on resource allocation within individual reproductive events, particularly pregnancy; and (3) the role of the immune system in shaping the offspring's patterns of future life history trade-offs. We close with a discussion of future directions in reproductive immunology for anthropologists.