Análisis de la tasa de cesáreas en el Hospital Universitario Materno-Infantil La Paz de Madrid (2010-2018) a través de la clasificación de Robson / Analysis of the Caesarean section rate at the La Paz Maternal-Child University Hospital in Madrid (2010–2018) through the Robson classification

Introducción: La necesidad de racionalizar y optimizar el uso de las cesáreas es un reto internacional en salud pública. Para ello, la OMS recomienda el uso de la clasificación Robson, que permite comparar las tasas de cesárea en función del perfil materno-fetal. El objetivo de este trabajo es evaluar la tasa de cesárea en el Hospital Universitario Materno-Infantil La Paz de Madrid entre 2010 y 2018 por medio de la clasificación Robson. Material y métodos: La población analizada corresponde a los datos de los 41.037 partos registrados en el programa Obstetricia del Hospital Universitario Materno-Infantil La Paz de Madrid de 2010 a 2018. Por medio del programa SPSS, se evalúa el cambio temporal en a) el porcentaje de partos (vaginales y por cesárea) respecto al total de nacimientos, b) la tasa de cesárea respecto a los partos vaginales y c) la contribución relativa a la tasa global de cesárea. Resultados: Las más elevadas contribuciones parciales a la tasa global de cesárea correspondieron a nulíparas con parto inducido, con cesárea previa, nulíparas con parto espontáneo y con gestaciones múltiples. El grupo de las nulíparas con parto inducido fue el único que registró un aumento significativo de su contribución a la tasa total de cesárea (30,4% en 2018). Conclusiones: Los resultados de este trabajo indican que el reto en salud pública es seguir evaluando la relación entre inducción del parto y riesgo de cesárea intraparto, particularmente en mujeres nulíparas, el grupo que registra la más alta tasa relativa de cesárea y en aumento significativo.(AU)

Introduction: The need to rationalise and optimise the use of caesarean sections is an international public health challenge. To this end, the WHO recommends the use of the Robson classification, which allows comparison of caesarean section rates according to the maternal-fetal profile. The aim of this study is to evaluate the rate of caesarean section in the Hospital Universitario Materno-Infantil La Paz in Madrid between 2010 and 2018 using the Robson classification. Material and methods: The population analysed corresponds to data from the 41,037 deliveries registered in the Obstetrics programme of the Hospital Universitario Materno-Infantil La Paz of Madrid from 2010 to 2018. Using SPSS software, the temporal change in (a) the percentage of deliveries (vaginal and caesarean) with respect to total births, (b) the caesarean rate with respect to vaginal deliveries and (c) the relative contribution to the overall caesarean rate is evaluated. Results: The highest partial contributions to the overall caesarean section rate were made by nulliparous women with induced labour, previous caesarean section, nulliparous women with spontaneous labour and multiple gestations. The group of nulliparous with induced labour was the only one with a significant increase in its contribution to the overall caesarean section rate (30.4% in 2018). Conclusions: The results of this work indicate that the challenge in public health is to further assess the relationship between induction of labour and risk of intrapartum caesarean section, particularly in nulliparous women, the group with the highest and significantly increasing relative caesarean section rate.(AU)

Phase-field modelling of the dynamics of Z-ring formation in liposomes: Onset of constriction and coarsening.

We propose a model for the dynamics of the formation of rings of FtsZ on tubular liposomes which produce constriction on the corresponding membrane. Our phase-field model is based on a simple bending energy that captures the dynamics of the interplay between the protein and the membrane. The short-time regime is analyzed by a linear dispersion relation, with which we are able to predict the number of rings per unit length on a tubular liposome. We study numerically the long-time dynamics of the system in the non-linear regime where we observe coarsening of Z-rings on tubular liposomes. In particular, our numerical results show that, during the coarsening process, the number of Z-rings decreases as the radius of tubular liposome increases. This is consistent with the experimental observation that the separation between rings is proportional to the radius of the liposome. Our model predicts that the mechanism for the increased rate of coarsening in liposomes of larger radius is a consequence of the increased interface energy.

Curvature multiphase field model for phase separation on a membrane.

We propose a model to describe the physical mechanisms by which chemical substances separate in the vicinity of a membrane. We assume that the adsorption of the different components of a complex liquid on a membrane is governed by interactions that couple them to the spontaneous curvature of the membrane. This problem is relevant to many fields in science, as cell constriction and division, micelles with cosurfactants, holometamorphosis, and morphogenesis in general.

Flower development as an interplay between dynamical physical fields and genetic networks.

In this paper we propose a model to describe the mechanisms by which undifferentiated cells attain gene configurations underlying cell fate determination during morphogenesis. Despite the complicated mechanisms that surely intervene in this process, it is clear that the fundamental fact is that cells obtain spatial and temporal information that bias their destiny. Our main hypothesis assumes that there is at least one macroscopic field that breaks the symmetry of space at a given time. This field provides the information required for the process of cell differentiation to occur by being dynamically coupled to a signal transduction mechanism that, in turn, acts directly upon the gene regulatory network (GRN) underlying cell-fate decisions within cells. We illustrate and test our proposal with a GRN model grounded on experimental data for cell fate specification during organ formation in early Arabidopsis thaliana flower development. We show that our model is able to recover the multigene configurations characteristic of sepal, petal, stamen and carpel primordial cells arranged in concentric rings, in a similar pattern to that observed during actual floral organ determination. Such pattern is robust to alterations of the model parameters and simulated failures predict altered spatio-temporal patterns that mimic those described for several mutants. Furthermore, simulated alterations in the physical fields predict a pattern equivalent to that found in Lacandonia schismatica, the only flowering species with central stamens surrounded by carpels.

Dynamics of reaction-diffusion systems in a subdiffusive regime.

In this paper, we examine the dynamics of reaction-diffusion systems with fractional time derivatives. It is shown that in these conditions diffusion is anomalous, in the sense that the mean-square displacement r2 approximately tgamma, where gamma<1, a situation known as subdiffusion. We study the conditions for the appearance of a diffusion-driven instability and show that the restrictive conditions for a Turing instability are relaxed. This implies that systems whose kinetics are not of the activator-inhibitor kind can have a Turing instability and a modulated final state. We demonstrate our results with numerical calculations in two dimensions using a generic Turing model.

Soliton behaviour in a bistable reaction diffusion model.

We analyze a generic reaction-diffusion model that contains the important features of Turing systems and that has been extensively used in the past to model biological interesting patterns. This model presents various fixed points. Analysis of this model has been made in the past only in the case when there is only a single fixed point, and a phase diagram of all the possible instabilities shows that there is a place where a Turing-Hopf bifurcation occurs producing oscillating Turing patterns. In here we focus on the interesting situation of having several fixed points, particularly when one unstable point is in between two equally stable points. We show that the solutions of this bistable system are traveling front waves, or solitons. The predictions and results are tested by performing extensive numerical calculations in one and two dimensions. The dynamics of these solitons is governed by a well defined spatial scale, and collisions and interactions between solitons depend on this scale. In certain regions of parameter space the wave fronts can be stationary, forming a pattern resembling spatial chaos. The patterns in two dimensions are particularly interesting because they can present a coherent dynamics with pseudo spiral rotations that simulate the myocardial beat quite closely. We show that our simple model can produce complicated spatial patterns with many different properties, and could be used in applications in many different fields.

Wave-front dynamics in systems with directional anomalous diffusion.

In this paper we study the solutions of a generalized reaction-diffusion system with a bistable reaction term, and considering directional anomalous diffusion. We use the well-known properties of fractional derivatives to model asymmetric anomalous diffusion, and obtain traveling wave solutions that propagate in a direction that depends on the metastability of the front, the fractional exponent and the asymmetry of the diffusion.

Quasiwetting on spherical solid surfaces by oil-water-amphiphile mixtures.

We study the wetting behavior on spherical walls by ternary mixtures of oil, water, and an amphiphile. We use the Ginzburg-Landau free energy with a single order parameter and find that there are different stable structures of the interface and that a quasiwetting transition is the mechanism involved in the transition among them. We calculate these wetting transitions for two sets of parameters in the bulk free energy which are known to show microemulsion behavior. The surface transitions are thin-thick first-order transitions (continuous transitions are absent), and the phase diagram in surface parameter space is constructed. For the first set of bulk parameters water, oil, and a microemulsion coexist, and we study the first-order transition where the oil phase wets the wall-microemulsion interface and its behavior as the radius of the wall becomes large. Therefore, we recover the known wetting transitions on a planar wall. In the second set of bulk parameters only water and oil coexist, and for some sizes of the solid wall, the oil phase wets the wall-water interface, and the phase behavior is extremely rich. We obtain a coexistence of four surface phases or two triple points followed by three lines of first-order transitions which end at three critical points depending on the radius of the surface. When there are micellar metastable solutions in bulk, the behavior of the thickness of the wetting layer of the oil phase as the radius of the spherical wall gets larger is nonmonotonic. We associate this behavior with the intrinsic micelle structure due to the spontaneous curvature of the model.

Influence of analytical and biological variation on the clinical interpretation of seminal parameters.

Quality assurance in semen analysis has been questioned recently in this journal. Based on the limited capacity of seminal parameter in the determination of fertility, the authors advocated abandoning methods of quality assurance in semen analysis for clinical situations. In this article, we explore arguments as to why quality assurance in semen analysis for clinical use is not 'a waste of time'. Imprecision and within-subject biological variations are the two major components involved in the dispersion of seminal parameter results obtained by analysis of a semen sample from an individual. As within-subject biological variation is constant across geography, time and population, imprecision is a very important factor in the quality of laboratory test results. We analyse this influence on various seminal parameters and observe that there is an amount of error that can be tolerated without invalidating the medical usefulness of seminal parameter determination. However, there is a maximum allowable analytical error above which the medical usefulness of seminal parameter results is invalidated. The level of performance required to facilitate clinical decision-making is termed quality specification. We comment on different strategies to define the maximum allowable analytical error.

Dynamics of growth in a three-component mixture with competing interactions.

We study numerically the dynamics, in two dimensions, of phase separation in ternary mixtures with dipolar interactions which lead to the formation of modulated phases. We distinguish three different modulated phases: a hexagonal phase of droplets, a lamellar phase, and a hexagonal phase of bubbles. Inside the crystal structures an additional phase separation occurs "coloring" the texture. The dynamics in the droplet phase mixes the two kinds of droplets of different composition. The lamellar phase does not evolve toward parallel lamellae, and the phase separation inside the channels proceeds until they reach a grain boundary. The hexagonal bubble phase is never formed due to the phase separation that forms an interface of bubbles which blocks the contact between the two phases. In its place we find an unsuspected lamellar phase.

Spinodal decomposition, power laws, and wetting at a triple point.

We study numerically the dynamics of phase separation in ternary mixtures at a triple point. For the full range of compositions and for different interaction parameters, the long time growth is in accord with a universal law. The early time behavior is governed by the structure of the spinodal region, including the possibility of a two step separation and decomposition originating at a surface and propagating into the bulk. The appearance of the domains is governed by the wetting properties of the mixture and the growth of a wetting layer follows again the universal law; a result that we can interpret with a simple phenomenological model.

Secular trend and intrapopulational variation in age at menopause in Spanish women.

Menopause is associated with the general ageing process and marks the end of follicular depletion, a process that begins in the intrauterine stage and lasts throughout the lifetime of women until their reproductive senescence. Controversy persists about whether the age at menopause is sensitive to the ecological determinants prevailing during the lifecycle or whether it has a predominantly genetic component that would allow groups of women to be characterized with respect to particular menstrual characteristics manifested throughout their fertile life. By contrast, there is a definite secular trend in age at menarche in populations that have registered improvements in their environment: sexual maturation is closely associated with the general processes of growth and development. These aspects were analysed in a sample of Spanish women, mothers and daughters, born between 1883 and 1941. The results show (a) indications--although not conclusive--of a secular trend in the age at menopause, (b) a possible association between the age at menopause of mothers and their daughters, and (c) an association at the individual level between age at menarche, particular characteristics of ovarian function (fetal loss) and age at menopause. The reproductive ageing process therefore seems to result from the expression of the influence of ecological conditions in which the lifecycle of the women develops and of a degree of heritability that affects not only the age at menopause but also a range of characteristics of ovarian function.

Lifetime dietary change and its relation to increase in weight in Spanish women.

INTRODUCTION: Changes in dietary patterns and a decrease in physical activity have occurred in Western countries. These are factors in the variation in body composition observed in populations, characterized by a progressive accumulation of fat with age and a consequent increase in the risk of suffering from common chronic illnesses such as obesity, cardiovascular disease and cancer. OBJECTIVE: To investigate weight gain throughout the life-cycle and its relation to modifications in dietary patterns, analyzing the causes of these modifications and their implications for patterns of adult overweight and obesity. DESIGN: Cross-sectional sample of Spanish women from a socio-economically disadvantaged class. SUBJECTS: 1037 healthy perimenopausal women (age: 45-65 y). MEASUREMENTS: Juvenile body mass index (BMI), current BMI, food frequency questionnaire, retrospective food habits. RESULTS AND CONCLUSIONS: Of these women, 48.8% had changed their dietary habits during their lifetime. A change in diet due to migration or marriage occurred at approximately 20 years of age and was characterized by an increased frequency of consumption of foods rich in protein and complex carbohydrates, while a change due to illness occurred at around 50 years of age and was characterized by a decrease in the consumption of these types of food. The change in dietary behavior due to migration was associated with weight gain. Weight gain was also inversely associated with BMI during youth; women who in their youth had a BMI<18.5 kg/m2 gained an average of 21.4 kg, compared with those with a BMI>27 kg/m2 in their youth, who gained an average of 5.4 kg. International Journal of Obesity (2000)24, 14-19

Turing patterns on a sphere.

We address the problem of pattern formation on the surface of a sphere using Turing equations. By considering a generic reaction-diffusion model, we numerically investigate the patterns formed under different conditions on the parameter values. Our results show that a closed surface with curvature, as a sphere, imposes geometrical restrictions on the shape of the pattern. This is important in some biological systems where curvature plays an important role in guiding chemical, biochemical, and embryological processes.

A two-dimensional numerical study of spatial pattern formation in interacting Turing systems.

For many years Turing systems have been proposed to account for spatial and spatiotemporal pattern formation in chemistry and biology. We extend the study of Turing systems to investigate the rô1e of boundary conditions, domain shape, non-linearities, and coupling of such systems. We show that such modifications lead to a wide variety of patterns that bear a striking resemblance to pigmentation patterns in fish, particularly those involving stripes, spots and transitions between them. Using the Turing system as a metaphor for activator-inhibitor models we conclude that such a mechanism, with the aforementioned modifications, may play a rô1e in fish patterning.

Determinants of contraceptive use in Morocco: stopping behaviour in traditional populations.

The determinants of modern contraceptive use in traditional populations are analysed in married women aged 30-44 living in the province of Marrakech (Morocco). Women who have never used contraception have smaller family sizes than those who do: the number of live children (or live births) is the variable with maximum predictive power on contraceptive use, while child mortality is the main inhibiting factor. The probability of contraceptive use increases with female age at marriage and decreases with the woman's age, indicating a generational change in reproductive behaviour. The socioeconomic variables education, employment and residence, have no significant independent predictive character on contraceptive use, although the interaction between education and residence does. The paper evaluates the hypothesis that traditional populations in the initial phase of their demographic transition resort to modern contraception in order to stop childbearing, when they have reached a desired number of children, rather than to space births or reduce their fertility.

PIP: The authors conclude that the determinants of contraceptive use among the rural population in Marrakech province, Morocco, were multiple and interrelated in complex ways. Birth control was a consequence of changes at both the individual and social levels. Findings indicate that women who had never used contraception had smaller family sizes than those women who used contraception. Contraceptive users had a significantly higher number of live births and living children. Child mortality was significantly greater among noncontracepting women. Contraceptive users had a significantly longer reproductive period than nonusers, which was attributed to a longer delay in the last live birth. Logistic models show that significant independent predictors of contraceptive use were the number of live births, the number of children who died before the age of 5, the age of the mother, the type of marriage, and the age at first marriage. The probability of access to contraceptives decreased with under-5 mortality, female age, marriage age, and increases in polygynous unions. This model explained 63.9% of the variance. Although residence and educational level did not significantly increase the fit of the model, the probability of contraceptive use did increase in relation to urban residence and a basic educational level. The number of live children was a predictor of contraceptive use but the best predictor of contraceptive use was family size (65.8%). The probability of contraceptive use increased among women with three or more children. Female education had no independent predictive impact on contraceptive use. Contraceptive use increased among women in polygynous unions, regardless of residence or schooling.

The pattern of reproductive life in a Berber population of Morocco.

Reproductive patterns were studied from data collected in 1,450 Berber households in the province of Marrakesh, Morocco in 1984. Women aged 45-49 years had a mean of 8.9 pregnancies to achieve 5.7 living children. Social influences on fertility rates show the importance of tradition, particularly through time-dependent variables such as age at marriage, waiting time to first birth, interbirth intervals, and duration of breastfeeding. Birth control does not appear to affect the tempo of fertility; rather, its main use is to bring the reproductive period to a close. The comparison of two subsamples of women separated by a 25-year interval indicates an actual acceleration of the tempo of fertility by the reduction of waiting time to first birth and of interbirth intervals. The supposed ongoing process of demographic transition is not clearly observed in this population.

PIP: In October 1984, July 1986, and July 1987, data from 1450 Berber households in Amizmiz subdivision, located in the Atlas piedmont and mountains (altitude up to 2500 ft) of Marrakesh Province in Morocco, were studied to learn the population's reproductive patterns. 45-49 year old women had a mean of 8.9 pregnancies and 5.7 living children. These high rates existed despite the government's intense family planning effort since 1968. 40% of all women either currently used or had ever used contraception. 15-19 year old women had the lowest contraceptive use rate, while 25-45 year old women had the highest rate (34% and 60%, respectively). Women mainly used contraception to limit births. Culture still played an important role in fertility, as evidenced by the time-dependent variables of age at marriage, waiting time to first birth, interbirth intervals, and duration of breast feeding. Specifically, women younger than 30 years old married at a younger age (17.66 years vs. 18.03 years), had a shorter first birth interval (14.92 months vs. 22.49 months) and shorter interbirth intervals (27.4 months vs. 31.87 months; p 0.0001), were younger at first birth (18.89 years vs. 19.88 years), and breast fed for a shorter duration (14.92 months vs. 18.26 months; p 0.0001) than women who were older than 40 years old. The acceleration of family constitution among the younger women reflects either individual desires or improvement of fertility via medical intervention, both of which indicate some movement toward more modern societies.

Marriage, age at last birth and fertility in a traditional Moroccan population.

A sample of 842 rural women from Morocco (Amizmiz, Marrakech) was used to examine the relationship between a number of biosocial variables and fertility patterns. For women still in their reproductive years there were significant correlations between family size and woman's age, age at marriage and years of marriage. Among women with completed families, those with early age at marriage ceased childbearing about 10 years before reaching menopause, while women who married later continued to bear children until the end of their fertile life.

PIP: Traditional patterns of fertility control among women who do not use contraception may occur. Relationships between the beginning and end of reproductive life are examined among a traditional population of Moroccan women. The sample population was comprised of 842 married women from 5 out of 10 communes in the highlands of Amizmiz, Marrakech province, Morocco. The rural agricultural population is isolated and predominately illiterate. Event history data were collected on marital and reproductive life. Principal component analysis was used to assess the relationship between spouse age, age at menarche, age at first marriage, waiting time to first birth, maternal ages at first and last birth, number of live births, and years of marriage. Women were grouped as women married before the age of 17 (20.96%), married between 17-20 (57.32%), and married over 20 (12.70%). The influence of breast-feeding patterns on child spacing was also examined. Women tended to have a late age at menarche and early age at menopause (45.02 years). The findings show that final family size is independent of marital duration, but is correlated with maternal age at first and last births. For women under 45 years, differences in family size are explained by duration of marriage, age of both partners, and age at last live birth in the first component. For women over 45 years, there was no relationship between family size and years of marriage in the first component. Marriage age, age at first birth, and family size defined the second component. 50% of women married before the age of 17 had their last child before age 35 years, and 60% of women married over 20 years finished childbearing over the age of 44. When marital disruption is accounted for, the last live birth increases for all 3 age groups but the range in variation is the same (8 years). Breast-feeding patterns show women who marrying past the age of 20 breast feed significantly longer (p.05). The fertility difference of 1.01 live births for women with a marriage age difference of 10 years is significant but low. The final family size follows a pattern suggested by "unnatural" fertility and does not correspond to historical European populations. Child spacing is not derived from lactation or modern contraception. The variability in age at last birth is similar to patterns evident in other developing countries.