Induction of birth in the bandicoot (Isoodon macrourus) with prostaglandin and oxytocin

As in eutherians, maturation of the fetal pituitary and adrenal glands together with an increase in prostaglandin and mesotocin or oxytocin production initiates birth in marsupials. in this study, prostaglandin (Lutalyse) or oxytocin (Syntocinon) were administered to pregnant bandicoots at 05:00 h on the calculated day of birth and the resultant effects were filmed for analysis. The administration of prostaglandin caused the bandicoot to adopt the birth position several minutes after injection (n = 2). However, the bandicoot did not give birth for several hours. Birth occurred at a similar time of day to that observed for untreated bandicoots (n = 7), between 08:00 h and 12:00 h. After an injection of oxytocin, the bandicoot assumed the birth position and birth occurred within several minutes. The young were alive while still connected to their allantoic stalks. However, they were unable to attach to the teats and did not survive (n = 4). The induced young were the colour of venous blood and died soon after the umbilicus was separated, indicating that the cardiopulmonary system of these neonates was underdeveloped and inadequate to maintain life. The results from this study demonstrate that prostaglandin is required to prepare the bandicoot for birth, and mesotocin is required for contraction of the uterus and for birth to occur.

Role of PGF(2 alpha) and oxytocin in parturition in the brushtail possum (Trichosurus vulpecula)

Maturation of the fetal pituitary and adrenal glands allows the secretion of cortisol, which in turn leads to an increase in prostaglandin and mesotocin production. The production of prostaglandin and mesotocin results in an increase in uterine contractions and initiates birth in marsupials. The major metabolite of PGF(2alpha), 13,14-dihydro-15-keto-prostaglandin F-2alpha (PGFM), has been found in the plasma of the possum at the time of birth and administration of PGF(2alpha) to female possums induced the adoption of the birth position. Evidence that mesotocin is an integral hormone of birth in the tammar wallaby indicates that both PGF(2alpha) and mesotocin or oxytocin are required for marsupial birth. The presence of PGF(2alpha) receptors in the uterus and corpus luteum of the possum, and the in vitro uterine responsiveness to PGF(2alpha) or oxytocin, were examined. PGF(2alpha) receptors were not observed in possum uteri and the inability of PGF(2alpha) to cause contractions indicates that PGF(2alpha) is not involved directly in contraction of the uterus at parturition. The presence of oxytocin and mesotocin receptors in the uterus of possoms and the ability of oxytocin to induce uterine contraction in vitro supports the view that mesotocin is required for expulsion of the young from the uterus. Low numbers of PGF(2alpha) receptors were found in the possum corpus luteum at birth, indicating an involvement of PGF(2alpha) in regression of the corpus luteum.

Zur klinischen Bedeutung von Geschwistererfahrungen - hat die Geschwistererfahrung einen Einfluss auf seelische Erkrankungen?

Im Mittelpunkt der Arbeit steht die Frage, ob bei psychogenen Störungen Geschwistererfahrungen klinische Relevanz haben und ob die erfahrene Geschwisterposition und –konstellation auch im Erwachsenenalter psychodynamisch wirksam ist. Die Arbeit gliedert sich in drei Teile. Im ersten Teil werden in einem metatheoretischen Vorgehen psychoanalytische Konzepte, psychoanalytische Entwicklungstheorien aus der Objekt- und Selbstpsychologie und empirische Forschungsergebnisse zur Geschwisterbeziehung vorgestellt. Darauf aufbauend werden Annahmen formuliert, welche psychodynamischen Konflikte sich in einer pathologischen Entwicklung als psychische Störungen im Erwachsenenalter manifestieren können.Im zweiten Teil der Arbeit werden acht Einzelfälle psychoanalytischer Behandlungen von erwachsenen Patienten unterschiedlicher Geschwisterpositionen und -konstellationen dargestellt, die die in Teil 1 beschriebenen pathogenen Geschwistereinflüsse illustrieren. In den untersuchten Einzelfällen ist die erfahrene Geschwisterposition der Patienten konfliktbesetzt und psychodynamisch wirksam gewesen. Dabei haben die Erfahrungen mit den primären Objekten die Basis für die pathologische Beziehungsdynamik der Geschwister gebildet. Den dritten extra-klinisch empirischen Teil der Arbeit stellt eine explorative Pilotstudie dar, die ebenfalls das Ziel verfolgt, persistierende Geschwisterkonflikte in ihren langandauernden Effekten zu explorieren. Es handelt sich um eine Dokumentenanalyse von 215 Patientenakten aus einer psychosomatischen Klinik. Aus den Akten werden als Variablen ICD - und OPD - Diagnosen als auch inhaltsanalytisch ermittelte psychodynamische Konflikte herausgefiltert und mit den Variablen Geschwisterposition und –konstellation korreliert. Dabei wird erstens der Frage nachgegangen, ob es in den Akten von psychisch erkrankten Patienten zwischen Einzel- und Geschwisterkindern Unterschiede in Bezug auf die Diagnosen und hinsichtlich der formulierten psychodynamischen Konflikte gibt. Zweitens geht es um eine weitergehende Exploration dieser Variablen in Bezug auf die erfahrene Geschwisterposition bzw. –konstellation. Es zeigt sich, dass die ICD-10 Diagnostik aufgrund ihres deskriptiven Charakters und ihrer psychiatrischen Orientierung wenig brauchbar ist, diesbezügliche Hypothesen zu formulieren. Im Unterschied zur ICD-10 ergibt sich in Bezug auf die OPD-Diagnostik, besonders aber in Hinsicht auf die psychodynamischen Konflikte ein differenzierteres Bild. So sind z.B. Parentifizierung am häufigsten von Einzelkindern und Erstgeborenen benannt worden. Gleichzeitig berichten Patienten, die mit Geschwistern aufgewachsen sind, am stärksten von erlebtem emotionalem Mangel in der Familie. Unter Dominanzkonflikten leiden die Patienten am meisten, die als jüngstes Kind aufgewachsen sind. Bei Patienten mit der jüngsten und mittleren Geschwisterposition ist als weiteres Beispiel auffallend oft Altruismus ermittelt worden. Fazit der Arbeit ist, dass ungelöste Geschwisterkonflikte langandauernde Effekte haben können und dass - im Gegensatz zur Birth-Order-Forschung - die Variable der Geschwisterposition unter Berücksichtigung geschlechtsspezifischer Aspekte als ein intra- und interpsychisches dynamisches Geschehen begriffen werden kann.

Kvinnors erfarenheter av framfödandet vid planerad hemförlossning

Background: The prevalence of sphincter rupture during childbirth has increased in Sweden from half percent to three percent from 1973 to 1993. Women who undergo planned home birth have sphincter injuries to a smaller extent than women who undergo planned hospital births. Objective: The purpose of this study was to describe women’s experience of the last stages of delivery during planned home birth. Design: Inductive content analysis of 150 randomly selected delivery reports. The delivery reports were gathered as a reply to an open question in a previously conducted survey.Findings: The woman´s confidence in the natural birthing process emerged as the overall theme of the delivery reports. Fourteen subcategories and five categories emerged during the analysis process: experience of support, physical experience, psychological experience, experience of birthplace and birth position and the woman’s awareness during birth. Conclusion: The support from the surrounding people was very important for the women and they felt calm and secure in the home environment. The women often gave birth in a birthing position that led to a reduced risk of perineal tears. Many risk factors for sphincter injuries were eliminated for the women who went thru planned home birth. For example the women often had experiences of prior deliveries and further no medical instruments were used during late stages of delivery in planned home births.

Intervenções benéficas durante o parto para a prevenção da mortalidade materna

O caráter multifatorial das complicações e da mortalidade materna torna difícil e demorada a tarefa de seu controle a longo prazo. A atenção profissional à mulher gestante e/ou parturiente representa seguramente elemento chave para a obtenção de bons resultados, tanto maternos quanto perinatais. Partindo-se do pressuposto de que atenção médica profissional ao parto de maneira adequada tem a capacidade de diminuir a ocorrência de complicações associadas à morbidade e mortalidade materna, são apresentadas resumidamente as evidências sobre algumas intervenções incluídas nesta atenção. São enfocadas as evidências derivadas de estudos realizados com extremo rigor metodológico e científico, os ensaios controlados randomizados, sobre intervenções capazes de reduzir as complicações e a mortalidade materna. Estas principais intervenções referem-se basicamente a: atenção institucional ao parto, atendimento profissional capacitado, utilização de parteiras tradicionais em determinados contextos, uso de tecnologias apropriadas incluindo o partograma, local do parto, posição para o parto, uso de episiotomia, tipo de parto, uso de ocitócicos na fase ativa do parto, realização de esforços de puxo no período expulsivo, manejo da dequitação e profilaxia da hemorragia puerperal. Ainda que o efeito de prevenir mortes seja difícil de ser avaliado pela baixa freqüência, sua utilização de forma racional e padronizada, por meio de manuais e normatizações de condutas de serviços, tem um efeito positivo sobre a qualidade da atenção ao nascimento. Isso faz parte do contexto técnico e humano do direito que toda mulher tem ao melhor atendimento possível nesse momento tão especial de sua vida.

Codeine and breastfeeding: cases and STIS position

Codeine is commonly used in North America in the postpartum period for pain associated with episotomyand caesarean section. Analgesic properties of codeine are mainly due to its metabolisation intomorphine (5-10%) via CYP2D6. This enzyme is subject to genetic variability, which can alter theamount of active narcotic excreted into breastmilk. A recent case report highlighted this issue, reportingfatal consequences in a newborn whose mother was taking codeine for episiotomy-related pain (1-2). New-born's blood (post-mortem) and mother's milk showed high morphine concentrations. Genotypeanalysis classified the mother as a CYP2D6 ultrarapid metabolizer, a genotype associated withenhanced formation of morphine from codeine. The authors concluded "clinical and laboratory picturewas consistent with opioid toxicity leading to neonatal death". Subsequent comments expressed reasonnabledoubts on this conclusion, though (3-4). Since, anxiety increased about the safety of codeineduring breastfeeding and genetic screening was proposed as a prevention strategy.STIS position:? Codeine with paracetamol is not a usual pain prescription in the postpartum period in Switzerland.This markedly reduces codeine use during lactation in our country, and may partly explain why webarely collected 3 codeine exposures through breastmilk in 15 years at the STIS (all reported afterabove case's publication and without side effects).? Other centrally acting analgesics are not considered safer (5) than codeine during lactation andrequire close observation for somnolence in both the mother and the infant in case of repeated maternaldosage. A lack of monitoring was salient in the case reported above (1).? If the incidence of CYP2D6 polymorphism (1-10% of individuals in Western Europe) (6) can beconsidered of clinical significance, it is not the exclusive predisposing factor to toxic effects. Healthynewborns can be particularly sensitive to even usual doses of narcotic analgesics because of immaturedrug disposition (7). Conditions leading to impaired clearance or increased susceptibility inthe infant (e.g. preterm birth, metabolic diseases) represent further risk factors for opioid toxicity,regardless of the molecule.In conclusion, when prescribed on a large scale, codein can be rarely associated with adverse drugreactions in breastfed infants (8-9). However, other central acting analgesics cannot be considered asinvariably safer. Therefore, paracetamol and well documented NSAID should be used in 1st choiceduring lactation. In case of severe pain, codeine (with paracetamol) remains an acceptable choice butrequires close monitoring, and breastfeeding mothers should be educated regarding risks related toaccumulation in the newborn. Finally, it is doubtful whether CYP2D6 genetic screening would preventall toxic effects, as other risk factors exist for opioids toxicity

Association of socioeconomic position with health behaviors and mortality

CONTEXT: Previous studies may have underestimated the contribution of health behaviors to social inequalities in mortality because health behaviors were assessed only at the baseline of the study. OBJECTIVE: To examine the role of health behaviors in the association between socioeconomic position and mortality and compare whether their contribution differs when assessed at only 1 point in time with that assessed longitudinally through the follow-up period. DESIGN, SETTING, AND PARTICIPANTS: Established in 1985, the British Whitehall II longitudinal cohort study includes 10 308 civil servants, aged 35 to 55 years, living in London, England. Analyses are based on 9590 men and women followed up for mortality until April 30, 2009. Socioeconomic position was derived from civil service employment grade (high, intermediate, and low) at baseline. Smoking, alcohol consumption, diet, and physical activity were assessed 4 times during the follow-up period. MAIN OUTCOME MEASURES: All-cause and cause-specific mortality. RESULTS: A total of 654 participants died during the follow-up period. In the analyses adjusted for sex and year of birth, those with the lowest socioeconomic position had 1.60 times higher risk of death from all causes than those with the highest socioeconomic position (a rate difference of 1.94/1000 person-years). This association was attenuated by 42% (95% confidence interval [CI], 21%-94%) when health behaviors assessed at baseline were entered into the model and by 72% (95% CI, 42%-154%) when they were entered as time-dependent covariates. The corresponding attenuations were 29% (95% CI, 11%-54%) and 45% (95% CI, 24%-79%) for cardiovascular mortality and 61% (95% CI, 16%-425%) and 94% (95% CI, 35%-595%) for noncancer and noncardiovascular mortality. The difference between the baseline only and repeated assessments of health behaviors was mostly due to an increased explanatory power of diet (from 7% to 17% for all-cause mortality, respectively), physical activity (from 5% to 21% for all-cause mortality), and alcohol consumption (from 3% to 12% for all-cause mortality). The role of smoking, the strongest mediator in these analyses, did not change when using baseline or repeat assessments (from 32% to 35% for all-cause mortality). CONCLUSION: In a civil service population in London, England, there was an association between socioeconomic position and mortality that was substantially accounted for by adjustment for health behaviors, particularly when the behaviors were assessed repeatedly.

Systematic review protocol to define classical IgE-associated diseases from birth to adolescence: the MeDALL study

BACKGROUND: Classical disease phenotypes are mainly based on descriptions of symptoms and the hypothesis that a given pattern of symptoms provides a diagnosis. With refined technologies there is growing evidence that disease expression in patients is much more diverse and subtypes need to be defined to allow a better targeted treatment. One of the aims of the Mechanisms of the Development of Allergy Project (MeDALL,FP7) is to re-define the classical phenotypes of IgE-associated allergic diseases from birth to adolescence, by consensus among experts using a systematic review of the literature and identify possible gaps in research for new disease markers. This paper describes the methods to be used for the systematic review of the classical IgE-associated phenotypes applicable in general to other systematic reviews also addressing phenotype definitions based on evidence. METHODS/DESIGN: Eligible papers were identified by PubMed search (complete database through April 2011). This search yielded 12,043 citations. The review includes intervention studies (randomized and clinical controlled trials) and observational studies (cohort studies including birth cohorts, case-control studies) as well as case series. Systematic and non-systematic reviews, guidelines, position papers and editorials are not excluded but dealt with separately. Two independent reviewers in parallel conducted consecutive title and abstract filtering scans. For publications where title and abstract fulfilled the inclusion criteria the full text was assessed. In the final step, two independent reviewers abstracted data using a pre-designed data extraction form with disagreements resolved by discussion among investigators. DISCUSSION: The systematic review protocol described here allows to generate broad,multi-phenotype reviews and consensus phenotype definitions. The in-depth analysis of the existing literature on the classification of IgE-associated allergic diseases through such a systematic review will 1) provide relevant information on the current epidemiologic definitions of allergic diseases, 2) address heterogeneity and interrelationships and 3) identify gaps in knowledge.

Early life, current socioeconomic position and serum lipids in young adulthood of participants in a cohort study initiated in 1978/1979

The association between socioeconomic position (SEP) and serum lipids has been little studied and the results have been controversial. A total of 2063 young adults born in 1978/79 were evaluated at 23-25 years of age in the fourth follow-up of a cohort study carried out in Ribeirão Preto, SP, Brazil, corresponding to 31.8% of the original sample. Total serum cholesterol (TC), triglycerides, high-density cholesterol (HDL cholesterol) and low-density cholesterol (LDL cholesterol) were analyzed according to SEP at birth and during young adulthood. SEP was classified into tertiles of family income and a cumulative score of socioeconomic disadvantage was created. TC was 11.85 mg/100 mL lower among men of lower SEP in childhood (P < 0.01) but no difference was found in women, whereas it was 8.46 lower among men (P < 0.01) and 8.21 lower among women of lower SEP in adulthood (P < 0.05). Individuals of lower SEP had lower LDL and HDL cholesterol, with small differences between sexes and between the two times in life. There was no association between SEP and triglyceride levels. After adjustment of income at one time point in relation to the other, some associations lost significance. The greater the socioeconomic disadvantage accumulated along life, the lower the levels of TC, LDL and HDL cholesterol (P < 0.05). The socioeconomic gradient of TC and LDL cholesterol was inverse, representing a lower cardiovascular risk for individuals of lower SEP, while the socioeconomic gradient of HDL cholesterol indicated a lower cardiovascular risk for individuals of higher SEP.

Risk factors for birth-related perineal trauma: a cross-sectional study in a birth centre

Aim and objectives. To identify maternal, newborn and obstetric factors associated with birth-related perineal trauma in one independent birth centre. Background. Risk factors for birth-related perineal trauma include episiotomy, maternal age, ethnicity, parity and interventions during labour including use of oxytocin, maternal position at time of birth and infant birth weight. Understanding more about these factors could support the management of vaginal birth to prevent spontaneous perineal trauma, in line with initiatives to reduce routine use of episiotomy. Design. Cross-sectional study. Methods. Data were retrospectively collected from one independent birth centre in Brazil, during 20062009. The dependent variable (perineal trauma) was classified as: (1) intact perineum or first-degree laceration, (2) second-degree laceration and (3) episiotomy (right mediolateral or median). Results. There were 1079 births during the study period. Parity, use of oxytocin during labour, position at time of giving birth and infant birth weight were associated with second-degree lacerations and episiotomies. After adjusting for parity, oxytocin, maternal position at the expulsive stage of labour and infant birth weight influenced perineal outcomes among primiparae only. Conclusions. Although the overall rate of episiotomies in this study was low compared with national data, it was observed that younger women were most vulnerable to this intervention. In this age group in particular, the use of oxytocin as well as semi-upright positions at the time of birth was associated with second-degree lacerations and episiotomies. Relevance to clinical practice. The use of upright alternative positions for birth and avoidance of use of oxytocin could reduce the risk of perineal trauma from lacerations and need to perform episiotomy.

Position-dependent activity of α-fetoprotein enhancer element III in the adult liver is due to negative regulation

α-Fetoprotein (AFP) transcription is activated early in hepatogenesis, but is dramatically repressed within several weeks after birth. AFP regulation is governed by multiple elements including three enhancers termed EI, EII, and EIII. All three AFP enhancers continue to be active in the adult liver, where EI and EII exhibit high levels of activity in pericentral hepatocytes with a gradual reduction in activity in a pericentral-periportal direction. In contrast to these two enhancers, EIII activity is highly restricted to a layer of cells surrounding the central veins. To test models that could account for position-dependent EIII activity in the adult liver, we have analyzed transgenes in which AFP enhancers EII and EIII were linked together. Our results indicate that the activity of EIII is dominant over that of EII, indicating that EIII is a potent negative regulatory element in all hepatocytes except those encircling the central veins. We have localized this negative activity to a 340-bp fragment. This suggests that enhancer III may be involved in postnatal AFP repression.

Is socioeconomic position early in life associated with physical activity during adulthood following the accumulation of risk model with additive effects?

L'activité physique améliore la santé, mais seulement 4.8% des Canadiens atteignent le niveau recommandé. La position socio-économique est un des déterminants de l'activité physique les plus importants. Elle est associée à l’activité physique de manière transversale à l’adolescence et à l’âge adulte. Cette thèse a tenté de déterminer s'il y a une association à long terme entre la position socio-économique au début du parcours de vie et l’activité physique à l’âge adulte. S'il y en avait une, un deuxième objectif était de déterminer quel modèle théorique en épidémiologie des parcours de vie décrivait le mieux sa forme. Cette thèse comprend trois articles: une recension systématique et deux recherches originales. Dans la recension systématique, des recherches ont été faites dans Medline et EMBASE pour trouver les études ayant mesuré la position socio-économique avant l'âge de 18 ans et l'activité physique à ≥18 ans. Dans les deux recherches originales, la modélisation par équations structurelles a été utilisée pour comparer trois modèles alternatifs en épidémiologie des parcours de vie: le modèle d’accumulation de risque avec effets additifs, le modèle d’accumulation de risque avec effet déclenché et le modèle de période critique. Ces modèles ont été comparés dans deux cohortes prospectives représentatives à l'échelle nationale: la 1970 British birth cohort (n=16,571; première recherche) et l’Enquête longitudinale nationale sur les enfants et les jeunes (n=16,903; deuxième recherche). Dans la recension systématique, 10 619 articles ont été passés en revue par deux chercheurs indépendants et 42 ont été retenus. Pour le résultat «activité physique» (tous types et mesures confondus), une association significative avec la position socio-économique durant l’enfance fut trouvée dans 26/42 études (61,9%). Quand seulement l’activité physique durant les loisirs a été considérée, une association significative fut trouvée dans 21/31 études (67,7%). Dans un sous-échantillon de 21 études ayant une méthodologie plus forte, les proportions d’études ayant trouvé une association furent plus hautes : 15/21 (71,4%) pour tous les types et toutes les mesures d’activité physique et 12/15 (80%) pour l’activité physique de loisir seulement. Dans notre première recherche originale sur les données de la British birth cohort, pour la classe sociale, nous avons trouvé que le modèle d’accumulation de risque avec effets additifs s’est ajusté le mieux chez les hommes et les femmes pour l’activité physique de loisir, au travail et durant les transports. Dans notre deuxième recherche originale sur les données canadiennes sur l'activité physique de loisir, nous avons trouvé que chez les hommes, le modèle de période critique s’est ajusté le mieux aux données pour le niveau d’éducation et le revenu, alors que chez les femmes, le modèle d’accumulation de risque avec effets additifs s’est ajusté le mieux pour le revenu, tandis que le niveau d’éducation ne s’est ajusté à aucun des modèles testés. En conclusion, notre recension systématique indique que la position socio-économique au début du parcours de vie est associée à la pratique d'activité physique à l'âge adulte. Les résultats de nos deux recherches originales suggèrent un patron d’associations le mieux représenté par le modèle d’accumulation de risque avec effets additifs.

Socioeconomic position, cognitive function, and clustering of cardiovascular risk factors in adolescence: Findings from the Mater University Study of Pregnancy and its outcomes

Objectives: The objectives of this study were to examine the extent of clustering of smoking, high levels of television watching, overweight, and high blood pressure among adolescents and whether this clustering varies by socioeconomic position and Cognitive function. Methods: This study was a cross-sectional analysis of 3613 (1742 females) participants of an Australian birth cohort who were examined at age 14. Results: Three hundred fifty-three (9.8%) of the participants had co-occurrence of three or four risk factors. Risk factors clustered in these adolescents with a greater number of participants than would be predicted by assumptions of independence having no risk factors and three or four risk factors. The extent of clustering tended to be greater in those from lower-income families and among those with lower cognitive function. The age-adjusted ratio of observed to expected cooccurrence of three or four risk factors was 2.70 (95% confidence interval [Cl], 1.80-4.06) among those from low-income families and 1.70 (95% Cl, 1.34-2.16) among those from more affluent families. The ratio among those with low Raven's scores (nonverbal reasoning) was 2.36 (95% Cl, 1.69-3.30) and among those with higher scores was 1.51 (95% Cl, 1.19-1.92); similar results for the WRAT 3 score (reading ability) were 2.69 (95% Cl, 1.85-3.94) and 1.68 (95% Cl, 1.34-2.11). Clustering did not differ by sex. Conclusion: Among adolescents, coronary heart disease risk factors cluster, and there is some evidence that this clustering is greater among those from families with low income and those who have lower cognitive function.

Is socioeconomic position early in life associated with physical activity during adulthood following the accumulation of risk model with additive effects?

L'activité physique améliore la santé, mais seulement 4.8% des Canadiens atteignent le niveau recommandé. La position socio-économique est un des déterminants de l'activité physique les plus importants. Elle est associée à l’activité physique de manière transversale à l’adolescence et à l’âge adulte. Cette thèse a tenté de déterminer s'il y a une association à long terme entre la position socio-économique au début du parcours de vie et l’activité physique à l’âge adulte. S'il y en avait une, un deuxième objectif était de déterminer quel modèle théorique en épidémiologie des parcours de vie décrivait le mieux sa forme. Cette thèse comprend trois articles: une recension systématique et deux recherches originales. Dans la recension systématique, des recherches ont été faites dans Medline et EMBASE pour trouver les études ayant mesuré la position socio-économique avant l'âge de 18 ans et l'activité physique à ≥18 ans. Dans les deux recherches originales, la modélisation par équations structurelles a été utilisée pour comparer trois modèles alternatifs en épidémiologie des parcours de vie: le modèle d’accumulation de risque avec effets additifs, le modèle d’accumulation de risque avec effet déclenché et le modèle de période critique. Ces modèles ont été comparés dans deux cohortes prospectives représentatives à l'échelle nationale: la 1970 British birth cohort (n=16,571; première recherche) et l’Enquête longitudinale nationale sur les enfants et les jeunes (n=16,903; deuxième recherche). Dans la recension systématique, 10 619 articles ont été passés en revue par deux chercheurs indépendants et 42 ont été retenus. Pour le résultat «activité physique» (tous types et mesures confondus), une association significative avec la position socio-économique durant l’enfance fut trouvée dans 26/42 études (61,9%). Quand seulement l’activité physique durant les loisirs a été considérée, une association significative fut trouvée dans 21/31 études (67,7%). Dans un sous-échantillon de 21 études ayant une méthodologie plus forte, les proportions d’études ayant trouvé une association furent plus hautes : 15/21 (71,4%) pour tous les types et toutes les mesures d’activité physique et 12/15 (80%) pour l’activité physique de loisir seulement. Dans notre première recherche originale sur les données de la British birth cohort, pour la classe sociale, nous avons trouvé que le modèle d’accumulation de risque avec effets additifs s’est ajusté le mieux chez les hommes et les femmes pour l’activité physique de loisir, au travail et durant les transports. Dans notre deuxième recherche originale sur les données canadiennes sur l'activité physique de loisir, nous avons trouvé que chez les hommes, le modèle de période critique s’est ajusté le mieux aux données pour le niveau d’éducation et le revenu, alors que chez les femmes, le modèle d’accumulation de risque avec effets additifs s’est ajusté le mieux pour le revenu, tandis que le niveau d’éducation ne s’est ajusté à aucun des modèles testés. En conclusion, notre recension systématique indique que la position socio-économique au début du parcours de vie est associée à la pratique d'activité physique à l'âge adulte. Les résultats de nos deux recherches originales suggèrent un patron d’associations le mieux représenté par le modèle d’accumulation de risque avec effets additifs.