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1.
Nature ; 546(7656): 129-132, 2017 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-28569799

RESUMO

X-ray free-electron lasers enable the investigation of the structure and dynamics of diverse systems, including atoms, molecules, nanocrystals and single bioparticles, under extreme conditions. Many imaging applications that target biological systems and complex materials use hard X-ray pulses with extremely high peak intensities (exceeding 1020 watts per square centimetre). However, fundamental investigations have focused mainly on the individual response of atoms and small molecules using soft X-rays with much lower intensities. Studies with intense X-ray pulses have shown that irradiated atoms reach a very high degree of ionization, owing to multiphoton absorption, which in a heteronuclear molecular system occurs predominantly locally on a heavy atom (provided that the absorption cross-section of the heavy atom is considerably larger than those of its neighbours) and is followed by efficient redistribution of the induced charge. In serial femtosecond crystallography of biological objects-an application of X-ray free-electron lasers that greatly enhances our ability to determine protein structure-the ionization of heavy atoms increases the local radiation damage that is seen in the diffraction patterns of these objects and has been suggested as a way of phasing the diffraction data. On the basis of experiments using either soft or less-intense hard X-rays, it is thought that the induced charge and associated radiation damage of atoms in polyatomic molecules can be inferred from the charge that is induced in an isolated atom under otherwise comparable irradiation conditions. Here we show that the femtosecond response of small polyatomic molecules that contain one heavy atom to ultra-intense (with intensities approaching 1020 watts per square centimetre), hard (with photon energies of 8.3 kiloelectronvolts) X-ray pulses is qualitatively different: our experimental and modelling results establish that, under these conditions, the ionization of a molecule is considerably enhanced compared to that of an individual heavy atom with the same absorption cross-section. This enhancement is driven by ultrafast charge transfer within the molecule, which refills the core holes that are created in the heavy atom, providing further targets for inner-shell ionization and resulting in the emission of more than 50 electrons during the X-ray pulse. Our results demonstrate that efficient modelling of X-ray-driven processes in complex systems at ultrahigh intensities is feasible.


Assuntos
Cristalografia/métodos , Elétrons , Lasers , Proteínas/química , Raios X , Iodo/química , Cinética , Fótons , Conformação Proteica , Eletricidade Estática , Fatores de Tempo
2.
Faraday Discuss ; 237(0): 224-236, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-35678517

RESUMO

In this paper we study the out-of-equilibrium dynamics associated with photoinduced charge-transfer (CT) in cyanide-bridged Co-Fe Prussian blue analogue nanocrystals. In these coordination networks, the structural trapping of the photoinduced CT polaron involves local electronic and structural reorganizations. Femtosecond X-ray and optical absorption spectroscopies show that the local structural trapping process occurs on similar timescale for particles with 11 nm and 70 nm sizes. The local photoinduced spin transition, elongating the Co-N bonds and driving the CoIIIFeII → CoIIFeIII CT, activates coherent lattice torsion modes. The elastic deformation waves, launched by these bond elongations, drive macroscopic volume expansion and breathing of the particles. The timescale of this macroscopic deformation depends strongly on the size of the particle, which is more evidence of the multiscale nature of photoinduced phenomena in molecular materials.

3.
Phys Rev Lett ; 127(9): 093202, 2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34506178

RESUMO

The interaction of intense femtosecond x-ray pulses with molecules sensitively depends on the interplay between multiple photoabsorptions, Auger decay, charge rearrangement, and nuclear motion. Here, we report on a combined experimental and theoretical study of the ionization and fragmentation of iodomethane (CH_{3}I) by ultraintense (∼10^{19} W/cm^{2}) x-ray pulses at 8.3 keV, demonstrating how these dynamics depend on the x-ray pulse energy and duration. We show that the timing of multiple ionization steps leading to a particular reaction product and, thus, the product's final kinetic energy, is determined by the pulse duration rather than the pulse energy or intensity. While the overall degree of ionization is mainly defined by the pulse energy, our measurement reveals that the yield of the fragments with the highest charge states is enhanced for short pulse durations, in contrast to earlier observations for atoms and small molecules in the soft x-ray domain. We attribute this effect to a decreased charge transfer efficiency at larger internuclear separations, which are reached during longer pulses.

4.
J Fish Biol ; 92(6): 1915-1928, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29624674

RESUMO

Membranous organelles, acid glycoconjugates and lipids were characterized in the digestive tract mucosa of Hemisorubim platyrhynchos by cytochemistry techniques. Two types of mucous-secreting cells were observed in the digestive tract epithelium: goblet cells in the oesophagus and intestine and epithelial cells in the stomach. These cells had a Golgi apparatus more developed than the other cell types. The cytochemical analysis revealed that secretory granules are reactive to acid glycoconjugates, varying in reaction intensity according to the region of the digestive tract. Acid glycoconjugate reactions were also observed in oesophageal epithelial cell microridges and in enterocyte microvilli. In the digestive tract, acid glycoconjugates act to protect the epithelial surface, increasing mucous viscosity, which facilitates the passage of food, prevents the binding of parasites and facilitates their removal. Through lipid staining, a coated membrane was observed around each secretory granule of the oesophageal and intestinal goblet cells, while gastric epithelial cells granules were fully reactive. Oxynticopeptic cells of the gastric glands showed lipid droplets in the cytoplasm and also in the mitochondrial matrix, which act as an energy reserve for these cells that have a high energy demand. Enterocytes showed a well-developed smooth endoplasmic reticulum, especially in the apical region of the cell, being related to absorption and resynthesis of lipids.


Assuntos
Peixes-Gato/anatomia & histologia , Mucosa Esofágica/ultraestrutura , Mucosa Gástrica/ultraestrutura , Mucosa Intestinal/ultraestrutura , Animais , Células Epiteliais , Epitélio , Esôfago , Trato Gastrointestinal , Histocitoquímica , Intestinos , Muco , Estômago
5.
Nat Mater ; 15(6): 601-5, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27159018

RESUMO

Measuring how the magnetic correlations evolve in doped Mott insulators has greatly improved our understanding of the pseudogap, non-Fermi liquids and high-temperature superconductivity. Recently, photo-excitation has been used to induce similarly exotic states transiently. However, the lack of available probes of magnetic correlations in the time domain hinders our understanding of these photo-induced states and how they could be controlled. Here, we implement magnetic resonant inelastic X-ray scattering at a free-electron laser to directly determine the magnetic dynamics after photo-doping the Mott insulator Sr2IrO4. We find that the non-equilibrium state, 2 ps after the excitation, exhibits strongly suppressed long-range magnetic order, but hosts photo-carriers that induce strong, non-thermal magnetic correlations. These two-dimensional (2D) in-plane Néel correlations recover within a few picoseconds, whereas the three-dimensional (3D) long-range magnetic order restores on a fluence-dependent timescale of a few hundred picoseconds. The marked difference in these two timescales implies that the dimensionality of magnetic correlations is vital for our understanding of ultrafast magnetic dynamics.


Assuntos
Irídio/química , Campos Magnéticos , Simulação de Dinâmica Molecular , Estrôncio/química , Supercondutividade
6.
BJOG ; 124(9): 1346-1354, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28220656

RESUMO

OBJECTIVE: To evaluate the extent to which stillbirths affect international comparisons of preterm birth rates in low- and middle-income countries. DESIGN: Secondary analysis of a multi-country cross-sectional study. SETTING: 29 countries participating in the World Health Organization Multicountry Survey on Maternal and Newborn Health. POPULATION: 258 215 singleton deliveries in 286 hospitals. METHODS: We describe how inclusion or exclusion of stillbirth affect rates of preterm births in 29 countries. MAIN OUTCOME MEASURES: Preterm delivery. RESULTS: In all countries, preterm birth rates were substantially lower when based on live births only, than when based on total births. However, the increase in preterm birth rates with inclusion of stillbirths was substantially higher in low Human Development Index (HDI) countries [median 18.2%, interquartile range (17.2-34.6%)] compared with medium (4.3%, 3.0-6.7%), and high-HDI countries (4.8%, 4.4-5.5%). CONCLUSION: Inclusion of stillbirths leads to higher estimates of preterm birth rate in all countries, with a disproportionately large effect in low-HDI countries. Preterm birth rates based on live births alone do not accurately reflect international disparities in perinatal health; thus improved registration and reporting of stillbirths are necessary. TWEETABLE ABSTRACT: Inclusion of stillbirths increases preterm birth rates estimates, especially in low-HDI countries.


Assuntos
Saúde Global/estatística & dados numéricos , Nascimento Prematuro/epidemiologia , Natimorto/epidemiologia , Estudos Transversais , Feminino , Inquéritos Epidemiológicos , Humanos , Gravidez , Organização Mundial da Saúde
7.
Faraday Discuss ; 194: 621-638, 2016 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-27711803

RESUMO

The ultra-bright femtosecond X-ray pulses provided by X-ray Free Electron Lasers (XFELs) open capabilities for studying the structure and dynamics of a wide variety of biological and inorganic systems beyond what is possible at synchrotron sources. Although the structure and chemistry at the catalytic sites have been studied intensively in both biological and inorganic systems, a full understanding of the atomic-scale chemistry requires new approaches beyond the steady state X-ray crystallography and X-ray spectroscopy at cryogenic temperatures. Following the dynamic changes in the geometric and electronic structure at ambient conditions, while overcoming X-ray damage to the redox active catalytic center, is key for deriving reaction mechanisms. Such studies become possible by using the intense and ultra-short femtosecond X-ray pulses from an XFEL, where sample is probed before it is damaged. We have developed methodology for simultaneously collecting X-ray diffraction data and X-ray emission spectra, using an energy dispersive spectrometer, at ambient conditions, and used this approach to study the room temperature structure and intermediate states of the photosynthetic water oxidizing metallo-protein, photosystem II. Moreover, we have also used this setup to simultaneously collect the X-ray emission spectra from multiple metals to follow the ultrafast dynamics of light-induced charge transfer between multiple metal sites. A Mn-Ti containing system was studied at an XFEL to demonstrate the efficacy and potential of this method.


Assuntos
Cristalografia por Raios X , Elétrons , Lasers , Catálise , Raios X
8.
BJOG ; 123(3): 427-36, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26259689

RESUMO

OBJECTIVE: To generate a global reference for caesarean section (CS) rates at health facilities. DESIGN: Cross-sectional study. SETTING: Health facilities from 43 countries. POPULATION/SAMPLE: Thirty eight thousand three hundred and twenty-four women giving birth from 22 countries for model building and 10,045,875 women giving birth from 43 countries for model testing. METHODS: We hypothesised that mathematical models could determine the relationship between clinical-obstetric characteristics and CS. These models generated probabilities of CS that could be compared with the observed CS rates. We devised a three-step approach to generate the global benchmark of CS rates at health facilities: creation of a multi-country reference population, building mathematical models, and testing these models. MAIN OUTCOME MEASURES: Area under the ROC curves, diagnostic odds ratio, expected CS rate, observed CS rate. RESULTS: According to the different versions of the model, areas under the ROC curves suggested a good discriminatory capacity of C-Model, with summary estimates ranging from 0.832 to 0.844. The C-Model was able to generate expected CS rates adjusted for the case-mix of the obstetric population. We have also prepared an e-calculator to facilitate use of C-Model (www.who.int/reproductivehealth/publications/maternal_perinatal_health/c-model/en/). CONCLUSIONS: This article describes the development of a global reference for CS rates. Based on maternal characteristics, this tool was able to generate an individualised expected CS rate for health facilities or groups of health facilities. With C-Model, obstetric teams, health system managers, health facilities, health insurance companies, and governments can produce a customised reference CS rate for assessing use (and overuse) of CS. TWEETABLE ABSTRACT: The C-Model provides a customized benchmark for caesarean section rates in health facilities and systems.


Assuntos
Cesárea/estatística & dados numéricos , Modelos Estatísticos , Adulto , Estudos Transversais , Feminino , Humanos , Internacionalidade , Gravidez , Valores de Referência
9.
J Synchrotron Radiat ; 22(3): 626-33, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25931078

RESUMO

Multiplexing of the Linac Coherent Light Source beam was demonstrated for hard X-rays by spectral division using a near-perfect diamond thin-crystal monochromator operating in the Bragg geometry. The wavefront and coherence properties of both the reflected and transmitted beams were well preserved, thus allowing simultaneous measurements at two separate instruments. In this report, the structure determination of a prototypical protein was performed using serial femtosecond crystallography simultaneously with a femtosecond time-resolved XANES studies of photoexcited spin transition dynamics in an iron spin-crossover system. The results of both experiments using the multiplexed beams are similar to those obtained separately, using a dedicated beam, with no significant differences in quality.

10.
BJOG ; 121 Suppl 1: 32-9, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24641533

RESUMO

OBJECTIVE: To assess the proportion of severe maternal outcomes resulting from indirect causes, and to determine pregnancy outcomes of women with indirect causes. DESIGN: Secondary analysis of the WHO Multicountry Survey on Maternal and Newborn Health. SETTING: A total of 359 health facilities in 29 countries in Africa, Asia, Latin America, and the Middle East. SAMPLE: A total of 314 623 pregnant women admitted to the participating facilities. METHODS: We identified the percentage of women with severe maternal outcomes arising from indirect causes. We evaluated the risk of severe maternal and perinatal outcomes in women with, versus without, underlying indirect causes, using adjusted odds ratios and 95% confidence intervals, by a multilevel, multivariate logistic regression model, accounting for clustering effects within countries and health facilities. MAIN OUTCOME MEASURES: Severe maternal outcomes and preterm birth, fetal mortality, early neonatal mortality, perinatal mortality, low birthweight, and neonatal intensive care unit admission. RESULTS: Amongst 314 623 included women, 2822 were reported to suffer from severe maternal outcomes, out of which 20.9% (589/2822; 95% CI 20.1-21.6%) were associated with indirect causes. The most common indirect cause was anaemia (50%). Women with underlying indirect causes showed significantly higher risk of obstetric complications (adjusted odds ratio, aOR, 7.0; 95% CI 6.6-7.4), severe maternal outcomes (aOR 27.9; 95% CI 24.7-31.6), and perinatal mortality (aOR 3.8; 95% CI 3.5-4.1). CONCLUSIONS: Indirect causes were responsible for about one-fifth of severe maternal outcomes. Women with underlying indirect causes had significantly increased risks of severe maternal and perinatal outcomes.


Assuntos
Cuidados Críticos/estatística & dados numéricos , Centros de Saúde Materno-Infantil , Trabalho de Parto Prematuro/mortalidade , Complicações Cardiovasculares na Gravidez/mortalidade , Complicações Infecciosas na Gravidez/mortalidade , Complicações Neoplásicas na Gravidez/mortalidade , Adolescente , Adulto , África/epidemiologia , Anemia/mortalidade , Ásia/epidemiologia , Estudos Transversais , Dengue/mortalidade , Feminino , Infecções por HIV/mortalidade , Humanos , Mortalidade Infantil , Recém-Nascido de Baixo Peso , Recém-Nascido , América Latina/epidemiologia , Malária/mortalidade , Mortalidade Materna , Centros de Saúde Materno-Infantil/normas , Oriente Médio/epidemiologia , Razão de Chances , Gravidez , Prevalência , Fatores de Risco , Organização Mundial da Saúde , Adulto Jovem
11.
BJOG ; 121 Suppl 1: 66-75, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24641537

RESUMO

OBJECTIVE: To illustrate the variability in the use of antibiotic prophylaxis for caesarean section, and its effect on the prevention of postoperative infections. DESIGN: Secondary analysis of a cross-sectional study. SETTING: Twenty-nine countries participating in the World Health Organization Multicountry Survey on Maternal and Newborn Health. POPULATION: Three hundred and fifty-nine health facilities with the capacity to perform caesarean section. METHODS: Descriptive analysis and effect estimates using multilevel logistic regression. MAIN OUTCOME MEASURES: Coverage of antibiotic prophylaxis for caesarean section. RESULTS: A total of 89 121 caesarean sections were performed in 332 of the 359 facilities included in the survey; 87% under prophylactic antibiotic coverage. Thirty five facilities provided 0-49% coverage and 77 facilities provided 50-89% coverage. Institutional coverage of prophylactic antibiotics varied greatly within most countries, and was related to guideline use and the practice of clinical audits, but not to the size, location of the institution or development index of the country. Mothers with complications, such as HIV infection, anaemia, or pre-eclampsia/eclampsia, were more likely to receive antibiotic prophylaxis. At the same time, mothers undergoing caesarean birth prior to labour and those with indication for scheduled deliveries were also more likely to receive antibiotic prophylaxis, despite their lower risk of infection, compared with mothers undergoing emergency caesarean section. CONCLUSIONS: Coverage of antibiotic prophylaxis for caesarean birth may be related to the perception of the importance of guidelines and clinical audits in the facility. There may also be a tendency to use antibiotics when caesarean section has been scheduled and antibiotic prophylaxis is already included in the routine clinical protocol. This study may act as a signal to re-evaluate institutional practices as a way to identify areas where improvement is possible.


Assuntos
Antibioticoprofilaxia , Cesárea , Medicina de Emergência/métodos , Adulto , África/epidemiologia , Ásia/epidemiologia , Cesárea/efeitos adversos , Cesárea/métodos , Cesárea/mortalidade , Estudos Transversais , Esquema de Medicação , Procedimentos Cirúrgicos Eletivos , Feminino , Pesquisas sobre Atenção à Saúde , Humanos , Recém-Nascido , América Latina/epidemiologia , Mortalidade Materna , Bem-Estar Materno , Centros de Saúde Materno-Infantil , Oriente Médio/epidemiologia , Gravidez , Complicações Infecciosas na Gravidez/tratamento farmacológico , Fatores de Risco , Organização Mundial da Saúde
12.
BJOG ; 121 Suppl 1: 49-56, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24641535

RESUMO

OBJECTIVE: To assess the association between advanced maternal age (AMA) and adverse pregnancy outcomes. DESIGN: Secondary analysis of the facility-based, cross-sectional data of the WHO Multicountry Survey on Maternal and Newborn Health. SETTINGS: A total of 359 health facilities in 29 countries in Africa, Asia, Latin America, and the Middle East. SAMPLE: A total of 308 149 singleton pregnant women admitted to the participating health facilities. METHODS: We estimated the prevalence of pregnant women with advanced age (35 years or older). We calculated adjusted odds ratios of individual severe maternal and perinatal outcomes in these women, compared with women aged 20-34 years, using a multilevel, multivariate logistic regression model, accounting for clustering effects within countries and health facilities. The confounding factors included facility and individual characteristics, as well as country (classified by maternal mortality ratio level). MAIN OUTCOME MEASURES: Severe maternal adverse outcomes, including maternal near miss (MNM), maternal death (MD), and severe maternal outcome (SMO), and perinatal outcomes, including preterm birth (<37 weeks of gestation), stillbirths, early neonatal mortality, perinatal mortality, low birthweight (<2500 g), and neonatal intensive care unit (NICU) admission. RESULTS: The prevalence of pregnant women with AMA was 12.3% (37 787/308 149). Advanced maternal age significantly increased the risk of maternal adverse outcomes, including MNM, MD, and SMO, as well as the risk of stillbirths and perinatal mortalities. CONCLUSIONS: Advanced maternal age predisposes women to adverse pregnancy outcomes. The findings of this study would facilitate antenatal counselling and management of women in this age category.


Assuntos
Idade Materna , Mortalidade Materna , Centros de Saúde Materno-Infantil , Mortalidade Perinatal , Nascimento Prematuro/epidemiologia , Natimorto/epidemiologia , Adulto , África/epidemiologia , Ásia/epidemiologia , Estudos Transversais , Aconselhamento Diretivo , Feminino , Pesquisas sobre Atenção à Saúde , Humanos , Recém-Nascido , América Latina/epidemiologia , Centros de Saúde Materno-Infantil/organização & administração , Centros de Saúde Materno-Infantil/normas , Pessoa de Meia-Idade , Oriente Médio/epidemiologia , Gravidez , Resultado da Gravidez , Nascimento Prematuro/prevenção & controle , Prevalência , Fatores de Risco , Organização Mundial da Saúde
13.
BJOG ; 121 Suppl 1: 101-9, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24641540

RESUMO

OBJECTIVE: To evaluate how the effect of maternal complications on preterm birth varies between spontaneous and provider-initiated births, as well as among different countries. DESIGN: Secondary analysis of a cross-sectional study. SETTING: Twenty-nine countries participating in the World Health Organization Multicountry Survey on Maternal and Newborn Health. POPULATION: 299 878 singleton deliveries of live neonates or fresh stillbirths. METHODS: Countries were categorised into very high, high, medium and low developed countries using the Human Development Index (HDI) of 2012 by the World Bank. We described the prevalence and risk of maternal complications, their effect on outcomes and their variability by country development. MAIN OUTCOME MEASURES: Preterm birth, fresh stillbirth and early neonatal death. RESULTS: The proportion of provider-initiated births among preterm deliveries increased with development: 19% in low to 40% in very high HDI countries. Among preterm deliveries, the socially disadvantaged were less likely, and the medically high risk were more likely, to have a provider-initiated delivery. The effects of anaemia [adjusted odds ratio (AOR), 2.03; 95% confidence interval (CI), 1.84; 2.25], chronic hypertension (AOR, 2.28; 95% CI, 1.94; 2.68) and pre-eclampsia/eclampsia (AOR, 5.03; 95% CI, 4.72; 5.37) on preterm birth were similar among all four HDI subgroups. CONCLUSIONS: The provision of adequate obstetric care, including optimal timing for delivery in high-risk pregnancies, especially to the socially disadvantaged, could improve pregnancy outcomes. Avoiding preterm delivery in women when maternal complications, such as anaemia or hypertensive disorders, are present is important for countries at various stages of development, but may be more challenging to achieve.


Assuntos
Cesárea/estatística & dados numéricos , Parto Obstétrico/estatística & dados numéricos , Eclampsia/mortalidade , Pré-Eclâmpsia/mortalidade , Complicações Cardiovasculares na Gravidez/mortalidade , Complicações Infecciosas na Gravidez/mortalidade , Nascimento Prematuro/epidemiologia , Adolescente , Adulto , África/epidemiologia , Anemia/mortalidade , Ásia/epidemiologia , Cesárea/mortalidade , Estudos Transversais , Parto Obstétrico/mortalidade , Feminino , Idade Gestacional , Pesquisas sobre Atenção à Saúde , Humanos , América Latina/epidemiologia , Oriente Médio/epidemiologia , Gravidez , Complicações Cardiovasculares na Gravidez/prevenção & controle , Complicações Infecciosas na Gravidez/prevenção & controle , Resultado da Gravidez , Gravidez de Alto Risco , Fatores de Risco , Natimorto , Organização Mundial da Saúde , Adulto Jovem
14.
BJOG ; 121 Suppl 1: 40-8, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24641534

RESUMO

OBJECTIVE: To investigate the risk of adverse pregnancy outcomes among adolescents in 29 countries. DESIGN: Secondary analysis using facility-based cross-sectional data of the World Health Organization Multicountry Survey on Maternal and Newborn Health. SETTING: Twenty-nine countries in Africa, Latin America, Asia and the Middle East. POPULATION: Women admitted for delivery in 359 health facilities during 2-4 months between 2010 and 2011. METHODS: Multilevel logistic regression models were used to estimate the association between young maternal age and adverse pregnancy outcomes. MAIN OUTCOME MEASURES: Risk of adverse pregnancy outcomes among adolescent mothers. RESULTS: A total of 124 446 mothers aged ≤24 years and their infants were analysed. Compared with mothers aged 20-24 years, adolescent mothers aged 10-19 years had higher risks of eclampsia, puerperal endometritis, systemic infections, low birthweight, preterm delivery and severe neonatal conditions. The increased risk of intra-hospital early neonatal death among infants born to adolescent mothers was reduced and statistically insignificant after adjustment for gestational age and birthweight, in addition to maternal characteristics, mode of delivery and congenital malformation. The coverage of prophylactic uterotonics, prophylactic antibiotics for caesarean section and antenatal corticosteroids for preterm delivery at 26-34 weeks was significantly lower among adolescent mothers. CONCLUSIONS: Adolescent pregnancy was associated with higher risks of adverse pregnancy outcomes. Pregnancy prevention strategies and the improvement of healthcare interventions are crucial to reduce adverse pregnancy outcomes among adolescent women in low- and middle-income countries.


Assuntos
Serviços de Saúde do Adolescente , Cesárea/estatística & dados numéricos , Parto Obstétrico/estatística & dados numéricos , Eclampsia/mortalidade , Centros de Saúde Materno-Infantil , Gravidez na Adolescência , Gravidez não Planejada , Infecção Puerperal/mortalidade , Adolescente , Serviços de Saúde do Adolescente/organização & administração , África/epidemiologia , Ásia/epidemiologia , Cesárea/mortalidade , Criança , Estudos Transversais , Parto Obstétrico/mortalidade , Países em Desenvolvimento , Eclampsia/prevenção & controle , Feminino , Pesquisas sobre Atenção à Saúde , Acessibilidade aos Serviços de Saúde , Humanos , Recém-Nascido de Baixo Peso , Recém-Nascido , América Latina/epidemiologia , Idade Materna , Centros de Saúde Materno-Infantil/organização & administração , Oriente Médio/epidemiologia , Gravidez , Resultado da Gravidez , Gravidez na Adolescência/prevenção & controle , Infecção Puerperal/prevenção & controle , Serviços de Saúde Reprodutiva , Fatores de Risco , Organização Mundial da Saúde , Adulto Jovem
15.
BJOG ; 121 Suppl 1: 76-88, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24641538

RESUMO

OBJECTIVE: We aimed to determine the prevalence and risks of late fetal deaths (LFDs) and early neonatal deaths (ENDs) in women with medical and obstetric complications. DESIGN: Secondary analysis of the WHO Multicountry Survey on Maternal and Newborn Health (WHOMCS). SETTING: A total of 359 participating facilities in 29 countries. POPULATION: A total of 308 392 singleton deliveries. METHODS: We reported on perinatal indicators and determined risks of perinatal death in the presence of severe maternal complications (haemorrhagic, infectious, and hypertensive disorders, and other medical conditions). MAIN OUTCOME MEASURES: Fresh and macerated LFDs (defined as stillbirths ≥ 1000 g and/or ≥28 weeks of gestation) and ENDs. RESULTS: The LFD rate was 17.7 per 1000 births; 64.8% were fresh stillbirths. The END rate was 8.4 per 1000 liveborns; 67.1% occurred by day 3 of life. Maternal complications were present in 22.9, 27.7, and 21.2% [corrected] of macerated LFDs, fresh LFDs, and ENDs, respectively. The risks of all three perinatal mortality outcomes were significantly increased with placental abruption, ruptured uterus, systemic infections/sepsis, pre-eclampsia, eclampsia, and severe anaemia. CONCLUSIONS: Preventing intrapartum-related perinatal deaths requires a comprehensive approach to quality intrapartum care, beyond the provision of caesarean section. Early identification and management of women with complications could improve maternal and perinatal outcomes.


Assuntos
Cesárea/mortalidade , Eclampsia/mortalidade , Mortalidade Materna/tendências , Centros de Saúde Materno-Infantil , Mortalidade Perinatal/tendências , Pré-Eclâmpsia/mortalidade , Adolescente , Adulto , África/epidemiologia , Ásia/epidemiologia , Estudos Transversais , Diagnóstico Precoce , Eclampsia/prevenção & controle , Feminino , Pesquisas sobre Atenção à Saúde , Humanos , Recém-Nascido , América Latina/epidemiologia , Bem-Estar Materno , Centros de Saúde Materno-Infantil/organização & administração , Centros de Saúde Materno-Infantil/normas , Oriente Médio/epidemiologia , Pré-Eclâmpsia/prevenção & controle , Gravidez , Prevalência , Organização Mundial da Saúde , Adulto Jovem
16.
BJOG ; 121 Suppl 1: 89-100, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24641539

RESUMO

OBJECTIVE: To describe the mode and timing of delivery of twin pregnancies at ≥34 weeks of gestation and their association with perinatal outcomes. DESIGN: Secondary analysis of a cross-sectional study. POPULATION: Twin deliveries at ≥34 weeks of gestation from 21 low- and middle-income countries participating in the WHO Multicountry Survey on Maternal and Newborn Health. METHODS: Descriptive analysis and effect estimates using multilevel logistic regression. MAIN OUTCOME MEASURES: Stillbirth, perinatal mortality, and neonatal near miss (use of selected life saving interventions at birth). RESULTS: The average length of gestation at delivery was 37.6 weeks. Of all twin deliveries, 16.8 and 17.6% were delivered by caesarean section before and after the onset of labour, respectively. Prelabour caesarean delivery was associated with older maternal age, higher institutional capacity and wealth of the country. Compared with spontaneous vaginal delivery, lower risks of neonatal near miss (adjusted odds ratio, aOR, 0.63; 95% confidence interval, 95% CI, 0.44-0.94) were found among prelabour caesarean deliveries. A lower risk of early neonatal mortality (aOR 0.12; 95% CI 0.02-0.56) was also observed among prelabour caesarean deliveries with nonvertex presentation of the first twin. The week of gestation with the lowest rate of prospective fetal death varied by fetal presentation: 37 weeks for vertex-vertex; 39 weeks for vertex-nonvertex; and 38 weeks for a nonvertex first twin. CONCLUSIONS: The prelabour caesarean delivery rate among twins varied largely between countries, probably as a result of overuse of caesarean delivery in wealthier countries and limited access to caesarean delivery in low-income countries. Prelabour delivery may be beneficial when the first twin is nonvertex. International guidelines for optimal twin delivery methods are needed.


Assuntos
Cesárea/mortalidade , Parto Obstétrico/mortalidade , Centros de Saúde Materno-Infantil , Gravidez de Gêmeos , Natimorto/epidemiologia , Adolescente , Adulto , África/epidemiologia , Ásia/epidemiologia , Cesárea/efeitos adversos , Estudos Transversais , Parto Obstétrico/efeitos adversos , Feminino , Idade Gestacional , Pesquisas sobre Atenção à Saúde , Humanos , Recém-Nascido , América Latina/epidemiologia , Centros de Saúde Materno-Infantil/organização & administração , Oriente Médio/epidemiologia , Razão de Chances , Guias de Prática Clínica como Assunto , Gravidez , Resultado da Gravidez , Fatores de Tempo , Gêmeos , Organização Mundial da Saúde , Adulto Jovem
17.
BJOG ; 121 Suppl 1: 110-8, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24641541

RESUMO

OBJECTIVE: To develop and test markers of neonatal severe morbidity for the identification of neonatal near-miss cases. DESIGN: This is a database analysis of two World Health Organization cross-sectional studies: the Global Survey on Maternal and Perinatal Health (WHOGS) and the Multicountry Survey on Maternal and Newborn Health (WHOMCS). SETTING: The WHOGS was performed in 373 health facilities in 24 countries (2004-2008). The WHOMCS was conducted in 359 health facilities in 29 countries (2010-2011). POPULATION: Data were collected from hospital records of all women admitted for delivery and their respective neonates. METHODS: Pragmatic markers (birthweight <1750 g, Apgar score at 5 minutes <7, and gestational age <33 weeks) were developed with WHOGS data and validated with WHOMCS data. The diagnostic accuracy of neonatal characteristics and management markers of severity was determined in the WHOMCS. RESULTS: This analysis included 290 610 liveborn neonates from WHOGS and 310 436 liveborn neonates from WHOMCS. The diagnostic accuracy of pragmatic and management markers of severity for identifying early neonatal deaths was very high: sensitivity, 92.8% (95% CI 91.8-93.7%); specificity, 92.7% (95% CI 92.6-92.8%); positive likelihood ratio, 12.7 (95% CI 12.5-12.9); negative likelihood ratio, 0.08 (95% CI 0.07-0.09); diagnostic odds ratio, 163.4 (95% CI 141.6-188.4). A positive association was found between the frequency of neonatal near-miss cases and Human Development Index. CONCLUSION: Newborn infants presenting selected markers of severity and surviving the first neonatal week could be considered as neonatal near-miss cases. This definition and criteria may be seen as a basis for future applications of the near-miss concept in neonatal health. These tools can be used to inform policy makers on how best to apply scarce resources for improving the quality of care and reducing neonatal mortality.


Assuntos
Mortalidade Infantil , Nascido Vivo/epidemiologia , Serviços de Saúde Materna/estatística & dados numéricos , Adolescente , Adulto , África/epidemiologia , Índice de Apgar , Ásia/epidemiologia , Biomarcadores , Estudos Transversais , Feminino , Idade Gestacional , Pesquisas sobre Atenção à Saúde , Humanos , Recém-Nascido de Baixo Peso , Recém-Nascido , América Latina/epidemiologia , Oriente Médio/epidemiologia , Valor Preditivo dos Testes , Gravidez , Reprodutibilidade dos Testes , Organização Mundial da Saúde , Adulto Jovem
18.
BJOG ; 120(13): 1622-30; discussion 1630, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23924217

RESUMO

OBJECTIVE: To investigate the risk of adverse pregnancy outcomes and caesarean section among adolescents in low- and middle-income countries. DESIGN: Secondary analysis using facility-based cross-sectional data from the World Health Organization (WHO) Global Survey on Maternal and Perinatal Health. SETTING: Twenty-three countries in Africa, Latin America, and Asia. POPULATION: Women admitted for delivery in 363 health facilities during 2-3 months between 2004 and 2008. METHODS: We constructed multilevel logistic regression models to estimate the effect of young maternal age on risks of adverse pregnancy outcomes. MAIN OUTCOME MEASURES: Risk of adverse pregnancy outcomes among young mothers. RESULTS: A total of 78 646 nulliparous mothers aged ≤24 years and their singleton infants were included in the analysis. Compared with mothers aged 20-24 years, adolescents aged 16-19 years had a significantly lower risk of caesarean section (adjusted OR 0.75, 95% CI 0.71-0.79). When the analysis was restricted to caesarean section indicated for presumed cephalopelvic disproportion, the risk of caesarean section was significantly higher among mothers aged ≤15 years (aOR 1.27, 95% CI 1.07-1.49) than among those aged 20-24 years. Higher risks of low birthweight and preterm birth were found among adolescents aged 16-19 years (aOR 1.10, 95% CI 1.03-1.17; aOR 1.16, 95% CI 1.09-1.23, respectively) and ≤15 years (aOR 1.33, 95% CI 1.14-1.54; aOR 1.56, 95% CI 1.35-1.80, respectively). CONCLUSIONS: Adolescent girls experiencing pregnancy at a very young age (i.e. <16 years) have an increased risk of adverse pregnancy outcomes.


Assuntos
Países em Desenvolvimento , Resultado da Gravidez , Adolescente , África , Ásia , Estatura , Índice de Massa Corporal , Desproporção Cefalopélvica/cirurgia , Cesárea/estatística & dados numéricos , Estudos Transversais , Escolaridade , Feminino , Inquéritos Epidemiológicos , Humanos , Recém-Nascido de Baixo Peso , Recém-Nascido , América Latina , Idade Materna , Paridade , Gravidez , Gravidez na Adolescência , Nascimento Prematuro/epidemiologia , Cuidado Pré-Natal/estatística & dados numéricos , Pessoa Solteira , Adulto Jovem
20.
BJOG ; 119(2): 177-86, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21794070

RESUMO

OBJECTIVE: To assess the cost-effectiveness of universal vaccination of 11-year-old girls against human papillomavirus (HPV) infection and increased screening coverage to prevent cervical cancer in Japan where the coverage of Papanicolaou smears is very low. DESIGN: A cost-utility analysis from a societal perspective. SETTING: Japan, 2010. POPULATION: The female Japanese population aged 11 years or older. METHODS: A Markov model of the natural history of cervical cancer was constructed to compare six strategies: i.e. a screening coverage rate of 20, 50 and 80% with and without routine vaccination at age 11. MAIN OUTCOME MEASURES: Cervical cancer incidence, quality-adjusted life years (QALYs), costs and incremental cost-effectiveness ratios. RESULTS: Expanding the coverage of Papanicolaou smears from the current level of 20-50 and 80% yields a 45.5 and 63.1% reduction in cervical cancer incidence, respectively. Impact of combined strategies increases with coverage. Coverages of 20, 50 and 80% showed a 66.1, 80.9 and 86.8% reduction in disease, respectively. The costs of strategies with vaccination are four times higher than the cost of strategies without vaccination. Vaccinating all 11-year-old girls with bivalent vaccines with a Papanicolaou smear coverage rate of 50% is likely to be the most cost-effective option among the six strategies. CONCLUSIONS: The introduction of HPV vaccination in Japan is cost-effective as in other countries. It is more cost-effective to increase the coverage of the Papanicolaou smear along with the universal administration of HPV vaccine.


Assuntos
Detecção Precoce de Câncer/economia , Infecções por Papillomavirus/economia , Vacinas contra Papillomavirus/economia , Neoplasias do Colo do Útero/economia , Criança , Análise Custo-Benefício , Feminino , Humanos , Japão/epidemiologia , Infecções por Papillomavirus/mortalidade , Infecções por Papillomavirus/prevenção & controle , Prognóstico , Anos de Vida Ajustados por Qualidade de Vida , Fatores de Risco , Taxa de Sobrevida , Neoplasias do Colo do Útero/mortalidade , Neoplasias do Colo do Útero/virologia , Vacinação/economia
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