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1.
Thymus size and head circumference at birth and the development of allergic diseases 总被引:1,自引:0,他引:1
C. S. Benn D. L. Jeppesen H. Hasselbalch A. B. Olesen† J. Nielsen B. Björkstén‡ I. Lisse P. Aaby 《Clinical and experimental allergy》2001,31(12):1862-1866
BACKGROUND: The positive association between a large head circumference at birth and total serum IgE levels has been suggested to be due to negative associations between head circumference at birth and thymus development and between thymus development and total serum IgE levels. OBJECTIVES: To examine the associations between head circumference and thymus size at birth and the development of allergic disease. METHODS: The size of the thymus was assessed by sonography during the first week of life in 149 healthy term infants. Information on birth characteristics and mode of delivery was collected at delivery. The presence of allergic disease was assessed 5 years later by mailed questionnaires, which were returned by 85% of the eligible families. RESULTS: At birth, head circumference was positively associated with thymus size (P < 0.001). In all, 27 (23%) of the children had developed at least one allergic disease. Multivariate analysis revealed that both parental allergy (Prevalence Ratio and 95% CI) = 3.18 (1.49-6.78)) and caesarean delivery (2.62 (1.48-4.64)) were independently correlated with allergic disease, whereas thymus size was not. CONCLUSIONS: Our study does not support that a large head circumference is associated with a small thymus size, nor that a small thymus size is associated with allergic disease. Whether thymus size at birth is related to total serum IgE levels still remains to be elucidated. 相似文献
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Simten Genc Cagdas N. Emeklioglu Basak Cingillioglu Erhan Akturk H. Turhan Ozkan Veli Mihmanl 《Croatian medical journal》2021,62(2):130
AimTo examine the characteristics of pregnancies at a very advanced age and the effect of parity on adverse obstetric outcomes.MethodsWe retrospectively reviewed the records of women who gave birth at the Obstetrics and Gynecology Department of Okmeydanı Training and Research Hospital between January 2012 and December 2019. Overall, 22 448 of women were younger than 40 and 593 were aged 40 and older. Women aged 40 and older were divided into the primiparous (52 or 8.77%) and multiparous group (541 or 91.23%).ResultsSignificantly more women aged 40 and older had a cesarean section. The most common indications for a secondary cesarean delivery in both age groups were a previous cesarean procedure or uterine operation. The most frequent indication for primary cesarean section in both groups was fetal distress. Cesarean section rates due to non-progressive labor, fetal distress, and preeclampsia were significantly more frequent in primiparous women compared with multiparous women aged 40 and older. In primiparous women, fetal birth weight was lower and preeclampsia/gestational hypertension frequency were higher.ConclusionSince primiparity was a risk factor for lower fetal birth weight and preeclampsia/gestational hypertension in the age group of 40 years and above, more attention should be paid to the follow-up and treatment of these patients.Due to social and economic problems, career priority, and prolonged education, an increasing number of women choose to give birth at an advanced age. Their choice is facilitated by the availability and efficacy of contraceptive methods and assisted reproductive technology (ART) (1). Still, the rate of nulliparity at advanced age increases, while the parity rate decreases (2).The International Federation of Gynecology and Obstetrics (FIGO) uses the term “advanced maternal age” for pregnancies at the age of 35 and over, and the term “very advanced maternal age” for pregnancies at the age 40 and over. In these pregnancies, chronic diseases and medical problems are more common and these women constitute a high-risk patient group (3).Most studies have shown that the advanced maternal age increases the risk of hypertension, gestational diabetes mellitus, postpartum hemorrhage, premature birth, cesarean procedure, intrauterine growth retardation, and perinatal mortality (4,5). However, studies comparing the outcomes in primiparous and multiparous women pregnant at an advanced maternal age are scarce, and the evidence for some of the outcomes is conflicting. Therefore, the aim of our study is to examine the characteristics of pregnancies at a very advanced maternal age and to assess the effect of parity on negative obstetric outcomes. 相似文献
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《Explore (New York, N.Y.)》2020,16(5):310-317
ObjectiveThis research was conducted to determine the effects of labor dance on perceived birth pain, birth satisfaction, and neonatal outcomes.DesignThis is an experimental study. Data were collected under three groups during the active phase of labor: the dance practitioner midwife group (DPMG, comprising 40 pregnant women), the dance practitioner spouse/partner group (DPSG, comprising 40 pregnant women) and the control group (CG, comprising 80 pregnant women).SettingThis study was conducted between 1 April 2017 and 31 October 2017 in Turkey.ParticipantsThis study was administered on pregnant women volunteers with no risk during the active phase of labor.InterventionsDuring the active phase, pregnant women in DPMG danced with the midwife; pregnant women in DPSG, on the other hand, danced with their spouses/partners throughout the active phase. When vaginal dilatation reached 4 cm and 9 cm, labor pain was measured by employing the visual analog scale (VAS). In the postpartum phase, newborn babies’ first, fifth, and tenth minute Apgar scores and oxygen saturation levels were measured and registered. In the first hour after delivery, the Mackey Birth Satisfaction Scale was administered. CG, on the other hand, received only the routine procedures offered in the hospital.FindingsThe mean scores of VAS 1 and VAS 2 in DPSG and DPMG were lower than in CG. The fifth and tenth minute Apgar scores and the first, fifth, and tenth minute oxygen saturation levels of the newborns in the experimental groups, as well as the level of birth satisfaction, were significantly higher than in CG.Key conclusionsThe study showed a positive effect of labor dancing on the labor process. 相似文献
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J. Lampi D. Canoy D. Jarvis A.‐L. Hartikainen L. Keski‐Nisula M.‐R. Järvelin J. Pekkanen 《Clinical and experimental allergy》2011,41(7):987-993
Background Cross‐sectional studies have shown an association between the farming environment and a decreased risk of atopic sensitization, mainly related to contact with farm animals in the childhood. Objective Investigate the association of a farming environment, especially farm animal contact, during infancy, with atopic sensitization and allergic diseases at the age of 31. Methods In a prospective birth cohort study, 5509 subjects born in northern Finland in 1966 were followed up at the age of 31. Prenatal exposure to the farming environment was documented before or at birth. At age 31, information on health status and childhood exposure to pets was collected by a questionnaire and skin prick tests were performed. Results Being born to a family having farm animals decreased the risk of atopic sensitization [odds ratio (OR) 0.67; 95% confidence interval (CI) 0.56–0.80], atopic eczema ever (OR 0.77; 95% CI 0.66–0.91), doctor‐diagnosed asthma ever (OR 0.74; 95% CI 0.55–1.00), allergic rhinitis at age 31 (OR 0.87; 95% CI 0.73–1.03) and allergic conjunctivitis (OR 0.86; 95% CI 0.72–1.02) at age 31. There was a suggestion that the reduced risk of allergic sensitization was particularly evident among the subjects whose mothers worked with farm animals during pregnancy, and that the reduced risk of the above diseases by farm animal exposure was largely explained by the reduced risk of atopy. Having cats and dogs in childhood revealed similar associations as farm animals with atopic sensitization. Conclusion and Clinical Relevance Contact with farm animals in early childhood reduces the risk of atopic sensitization, doctor‐diagnosed asthma and allergic diseases at age 31. Cite this as: J. Lampi, D. Canoy, D. Jarvis, A.‐L. Hartikainen, L. Keski‐Nisula, M.‐R. Järvelin and J. Pekkanen, Clinical & Experimental Allergy, 2011 (41) 987–993. 相似文献
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Cezary Wojtyla Paulina Wojtyla-Buciora Michal Ciebiera Stanisaw Orzechowski Andrzej Wojtyla 《Archives of Medical Science》2021,17(2):352
IntroductionSmoking during pregnancy is a risk factor for adverse pregnancy outcomes. Data on the correlation between passive maternal smoking and pregnancy outcomes remain limited. We investigated the effect of active smoking and environmental tobacco smoke (ETS) during pregnancy on neonatal birthweight, including the risk for low birthweight (LBW).Material and methodsThe study was conducted between 2010 and 2012. A group of 8625 women were surveyed during postpartum hospitalization. Outcome measures included mean birthweight of newborns. Additionally, odds ratios with confidence intervals were calculated to investigate the risk for LBW in active and passive smoking groups of mothers.ResultsLower birthweight (46 g – 307 g; p < 0.05) and a higher risk for LBW (OR = 1.35, 95% CI: 1.05–1.75; p < 0.05) were observed in all infants born to smoking mothers. A negative effect of ETS in pregnancy on the reduction of mean birthweight was also found. Additionally, we analyzed the cumulative effect of active and passive smoking on neonatal birthweight. A statistically significant reduction in neonatal weight at birth was found in a group of women who smoked actively and passively during pregnancy (130 g; p < 0.05).ConclusionsSmoking is associated with decreased birthweight and in a group of active smoking mothers increased risk for LBW. This effect is dose-dependent and is also present in a group of women who smoked before pregnancy. There is also a cumulative effect of active smoking and ETS causing decreased neonatal birthweight and increased risk for low birthweight. 相似文献
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Objective : The purpose of this study is to construct the cross-sectional head circumference growth curves, intended for clinical use, for the Japanese from birth to 18 years of age. Subjects and methods : Two sets of the national survey data on head circumference and height were utilized for the study: (1) The 1990 data collected by the Japanese Ministry of Health and Welfare on children below 7 years of age ( n = 16 621, 8511 males, 8110 females). (2) The 1992-1994 data collected by the Research Institute of Human Engineering for Quality Life on children from 7 to 18 years of age ( n = 10 183, 5610 males, 4573 females). We used the LMS method to obtain the 3rd, 10th, 25th, 50th, 75th, 90th and 97th percentile values for each age and gender. Results and conclusions : The results showed a persistent positive secular trend in head circumference in Japanese children of both genders. Comparison of these data with those of recent Caucasian studies revealed ethnic difference in head circumference, with Japanese having relatively larger head circumference for height as compared with Caucasians. 相似文献
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The cross-sectional head circumference growth curves for Japanese from birth to 18 years of age: the 1990 and 1992-1994 national survey data 总被引:1,自引:0,他引:1
OBJECTIVE: The purpose of this study is to construct the cross-sectional head circumference growth curves, intended for clinical use, for the Japanese from birth to 18 years of age. SUBJECTS AND METHODS: Two sets of the national survey data on head circumference and height were utilized for the study: (1) The 1990 data collected by the Japanese Ministry of Health and Welfare on children below 7 years of age (n = 16 621, 8511 males, 8110 females). (2) The 1992-1994 data collected by the Research Institute of Human Engineering for Quality Life on children from 7 to 18 years of age (n = 10 183, 5610 males, 4573 females). We used the LMS method to obtain the 3rd, 10th, 25th, 50th, 75th, 90th and 97th percentile values for each age and gender. RESULTS AND CONCLUSIONS: The results showed a persistent positive secular trend in head circumference in Japanese children of both genders. Comparison of these data with those of recent Caucasian studies revealed ethnic difference in head circumference, with Japanese having relatively larger head circumference for height as compared with Caucasians. 相似文献
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The splenium (posterior ⅕) of the corpus callosum is sexually dimorphic in the adult rat brain. In the present study we examined the role of developmental hormones and cryoanesthesia (which is normally used during the performance of neonatal hormone manipulations) on the gross size of the splenium in male and female rats. There was a sex difference in splenial size (male > female) among nonhormonally manipulated animals, p = .0007. While neonatal castration was ineffective in altering the size of the male splenium, testosterone injections in females were found to increase the size of the splenium relative to oil-injected females, p = .05. The effect of developmental testosterone was further observed: Sex ratio (males to females) of the litter correlated with splenial area in females, r = .55, p = .03. Duration of cryoanesthesia negatively correlated with splenial area in males, r = −.81, p = .03, with a similar trend in females. © 1998 John Wiley & Sons, Inc. Dev Psychobiol 33: 295–303, 1998 相似文献
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Event-related potentials (ERPs) from 134 children were obtained at 3 and 8 years of age and recorded to a series of consonant-vowel speech syllables and their nonspeech analogues. The HOME inventory was administered to these same children at 3 and 8 years of age and the sample was divided into 2 groups (low vs. high) based on their HOME scores. Discriminant functions analyses using ERP responses to speech and non-speech analogues successfully classified HOME scores obtained at 3 and 8 years of age and discriminated between children who received low vs. high levels of stimulation for language and reading. 相似文献
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H.G. Dahlen H.P. Kennedy C.M. Anderson A.F. Bell A. Clark M. Foureur J.E. Ohm A.M. Shearman J.Y. Taylor M.L. Wright S. Downe 《Medical hypotheses》2013
There are many published studies about the epigenetic effects of the prenatal and infant periods on health outcomes. However, there is very little knowledge regarding the effects of the intrapartum period (labor and birth) on health and epigenetic remodeling. Although the intrapartum period is relatively short compared to the complete perinatal period, there is emerging evidence that this time frame may be a critical formative phase for the human genome. Given the debates from the National Institutes of Health and World Health Organization regarding routine childbirth procedures, it is essential to establish the state of the science concerning normal intrapartum epigenetic physiology. EPIIC (Epigenetic Impact of Childbirth) is an international, interdisciplinary research collaboration with expertise in the fields of genetics, physiology, developmental biology, epidemiology, medicine, midwifery, and nursing. We hypothesize that events during the intrapartum period – specifically the use of synthetic oxytocin, antibiotics, and cesarean section – affect the epigenetic remodeling processes and subsequent health of the mother and offspring. The rationale for this hypothesis is based on recent evidence and current best practice. 相似文献
12.
Many experimental studies of the effects of placental blood flow on growth exist. Nevertheless, few of them deal with the relationship between impaired uterine blood supply, and cranial growth and sex differentiation. The object of the present study was to investigate the impact of intrauterine growth retardation (IUGR) on sexual cranial dimorphism in the newborn rat. Three experimental groups were employed: (a) control; (b) operated (IUGR), in which both uterine vessels were partially bent in the 15th day of gestation; and (c) sham-operated, identical to (b) but without vessel bending. At birth, pups were weighed, and their bodies and craniums, measured. In the cases of asymmetric distributions, data were logarithmically transformed. A multi-way analysis of variance (ANOVA) and LSD post-hoc tests were used to find out differences between experimental groups and sex. Controls had significant sex differences in body and cranial variables. The prenatal growth of IUGR pups was significantly inhibited. Body and facial variables were more affected than the neurocranial ones. Undernutrition produced body and cranial size changes. Since IUGR affected male more than female growth, sex dimorphism was clearly reduced in all variables which were dimorphic in controls. 相似文献
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Effect of very low birth weight and subnormal head size on cognitive abilities at school age 总被引:13,自引:0,他引:13
M Hack N Breslau B Weissman D Aram N Klein E Borawski 《The New England journal of medicine》1991,325(4):231-237
BACKGROUND. We tested the hypothesis that very-low-birth-weight (less than 1.5 kg) infants with perinatal growth failure whose head size is not normal by eight months of age (corrected for prematurity) have significantly poorer growth and neurocognitive abilities at school age than very-low-birth-weight children with a normal head size at eight months. We also hypothesized that these differences would persist even after control for major neurologic impairment and perinatal and sociodemographic risk factors. METHODS. We have followed a cohort of very-low-birth-weight children since their birth during the period 1977 to 1979. At eight to nine years of age 249 children were evaluated with a neurologic examination and tests of intelligence; receptive and expressive language skills; speech, reading, mathematics, and spelling aptitude; visual and fine motor abilities; and behavior. Ages were corrected for premature birth. RESULTS. Among these 249 very-low-birth-weight children, head size was subnormal (less than the mean -2 SD for age) at birth in 30 (12 percent), at term in 57 (23 percent), and at eight months in 33 (13 percent). As compared with the 216 children with normal head sizes, the 33 children with subnormal head sizes at the age of eight months had significantly lower mean birth weights (1.1 vs. 1.2 kg) and higher neonatal risk scores (71 vs. 53) and at the age of eight years had a higher incidence of neurologic impairment (21 percent vs. 8 percent) and lower IQ scores (mean verbal, 84 vs. 98). Even among the children without neurologic abnormalities, a subnormal head size at eight months of age was predictive of poorer verbal and performance IQ scores at eight years of age; lower scores for receptive language, speech, reading, mathematics, and spelling; and a higher incidence of hyperactivity. In multiple regression analyses to control for socioeconomic and neonatal risk factors, intrauterine growth failure, birth weight, and neurologic impairment, a subnormal head size at eight months of age had an independently adverse effect on IQ and on scores for receptive language, speech, reading, and spelling. CONCLUSIONS. In very-low-birth-weight infants, perinatal growth failure, as evidenced by a subnormal head circumference at eight months of age, is associated with poor cognitive function, academic achievement, and behavior at eight years of age. 相似文献
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Becker A Watson W Ferguson A Dimich-Ward H Chan-Yeung M 《The Journal of allergy and clinical immunology》2004,113(4):650-656
BACKGROUND: Avoidance of individual risk factors have not been successful in preventing the development of asthma. OBJECTIVE: We sought to determine the effectiveness of a multifaceted intervention program in primary prevention of asthma in high-risk infants. METHODS: We identified 545 high-risk infants on the basis of an immediate family history of asthma. Families were randomized into intervention or control groups. Intervention measures included avoidance of house dust mite, pet allergen, and environmental tobacco smoke. Breast-feeding was encouraged with formula supplementation if necessary, and introduction of solid foods was delayed. RESULTS: At 2 years of age, 19.5% of the children had asthma, and 14.7% had atopy (positive skin test response to one or more common allergens). Significantly fewer children had asthma in the intervention group compared with in the control group (16.3% vs 23.0%), with 60% less persistent asthma at 2 years. There was a 90% reduction for recurrent wheeze in the intervention group compared with that seen in the control group. Exposure to maternal environmental tobacco smoke during pregnancy or the first year was a risk factor for asthma at 2 years of age. A positive skin test response, particularly to food, at 12 months predicted asthma at 2 years. There was no significant difference for atopy between the intervention and control groups, but daycare reduced atopy at 2 years. CONCLUSION: This multifaceted intervention program during a window of opportunity in the first year of life was effective in preventing asthma in high-risk children at 2 years of age. Future studies with this cohort at school age are important. 相似文献
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酒精所致精神障碍患者妻子的心理健康调查 总被引:1,自引:0,他引:1
本文采用SCL-90对酒精所致精神障碍患者妻子的心理健康状况进行研究,结果发现,躯体化、人际关系、抑郁、焦虑、敌对和偏执6个因子均分显著高于国内常模,提示对酒精所致精神障碍患者的妻子进行必要的心理安慰和社会资助不容忽视。 相似文献
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Angie C. Jelin Amanda Mahle Susan H. Tran Teresa N. Sparks Katherine A. Rauen 《American journal of medical genetics. Part A》2023,191(2):323-331
We systematically delineated the prenatal phenotype, and obstetrical and neonatal outcomes of the RASopathy cardio-facio-cutaneous (CFC) syndrome. A comprehensive, retrospective medical history survey was distributed to parents of children with confirmed CFC in collaboration with CFC International, Inc. Data were collected on CFC gene variant, maternal characteristics, pregnancy course, delivery, and neonatal outcomes with the support of medical records. We identified 43 individuals with pathogenic variants in BRAF (81%), MEK1 (14%), or MEK2 (5%) genes. The median age was 8.5 years. Hyperemesis gravidarum, gestational diabetes, gestational hypertension, and preeclampsia occurred in 5/43 (12%), 4/43 (9%), 3/43 (7%), and 3/43 (7%) of pregnancies, respectively. Second and third trimester ultrasound abnormalities included polyhydramnios, macrocephaly, macrosomia, and renal and cardiac abnormalities. Delivery occurred via spontaneous vaginal, operative vaginal, or cesarean delivery in 15/42 (36%), 7/42 (16%), and 20/42 (48%), respectively. Median gestational age at delivery was 37 weeks and median birth weight was 3501 grams. Germline pathogenic vaiants had mutiple congenital consequences including polyhydramnios, renal and cardiac abnormalities, macrosomia, and macrocephaly on second and third trimester ultrasound. Elevated rates of operative delivery and neonatal complications were also noted. Understanding and defining a prenatal phenotype may improve prenatal prognostic counseling and outcomes. 相似文献
17.
Juhn YJ Weaver A Katusic S Yunginger J 《The Journal of allergy and clinical immunology》2005,116(3):510-516
BACKGROUND: To test the hygiene hypothesis, previous studies have assessed the relationship between mode of delivery at birth and asthma incidence, but the results have been inconsistent because of potential selection and ascertainment biases. OBJECTIVE: To assess the relationship between mode of delivery at birth and asthma by following all children born in Rochester, Minn, between 1976 and 1982. METHODS: From the birth certificate, we determined mode of delivery (cesarean section vs vaginal delivery). Asthma status during the first 7 years of life was ascertained from comprehensive medical record reviews. The association between mode of delivery and asthma status was evaluated in a proportional hazards model adjusted for sex, birth weight, maternal education, and maternal age. RESULTS: The cumulative incidence rates of asthma among children who were born by cesarean section and vaginal delivery were 3.2% versus 2.6%, 4.6% versus 4.6%, 4.6% versus 5.8%, and 5.7% versus 6.7% at the 1st, 3rd, 5th, and 7th years of life, respectively. The adjusted hazard ratios for cesarean section in predicting asthma and wheezing episode were 0.93 (95% CI, 0.6-1.4; P=.71) and 0.93 (95% CI, 0.7-1.3; P=.67), respectively. CONCLUSION: Mode of delivery is not associated with subsequent risk of developing childhood asthma or wheezing episodes. Because the effect of mode of delivery on a risk of developing asthma or wheezing episodes varies over time (ie, age), selection of the study subjects according to their ages may have influenced the findings of previous studies with a shorter follow-up period. 相似文献
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BACKGROUND: During the past decade in the UK, only one in six cycles of assisted conception has resulted successfully in a live birth. Assisted hatching (AH) has been proposed to improve outcome. This systematic review of randomized controlled trials addresses primary outcomes of live birth, clinical pregnancy and embryo implantation. METHODS: Trials on post-fertilization disruption of the zona pellucida were identified from the Cochrane Controlled Trials Register, MEDLINE, EMBASE and published bibliographies. Outcomes were analysed using random effects meta-analysis, sensitivity analysis, sub-grouping and meta-regression. RESULTS: Of 23 included trials recruiting 2572 women, only six reported live birth data. AH had no significant effect on live birth (OR 1.21, 95% CI 0.82-1.78). There was a significant benefit of AH on clinical pregnancy (OR 1.63, 95% CI 1.27-2.09), especially in the sub-group of women with previous failure of assisted conception (OR 2.33, 95% CI 1.63-3.34). Meta-regression suggested that AH might be more useful in older women. Implantation data were not considered valid for statistical analysis. The methodological quality of included trials was sub-optimal. CONCLUSIONS: AH probably enhances clinical pregnancy, especially in women with previous failure of assisted conception treatment and in older women; however, trials were of poor quality and so may be biased. Better quality trials reporting live birth are required to confirm any positive effects on the 'take-home-baby rate'. 相似文献
19.
John McGrath Adrian Barnett Darryl Eyles Thomas Burne Carsten B Pedersen Preben Bo Mortensen 《BMC medical research methodology》2007,7(1):1-10
Background
Birth weight and length have seasonal fluctuations. Previous analyses of birth weight by latitude effects identified seemingly contradictory results, showing both 6 and 12 monthly periodicities in weight. The aims of this paper are twofold: (a) to explore seasonal patterns in a large, Danish Medical Birth Register, and (b) to explore models based on seasonal exposures and a non-linear exposure-risk relationship.Methods
Birth weight and birth lengths on over 1.5 million Danish singleton, live births were examined for seasonality. We modelled seasonal patterns based on linear, U- and J-shaped exposure-risk relationships. We then added an extra layer of complexity by modelling weighted population-based exposure patterns.Results
The Danish data showed clear seasonal fluctuations for both birth weight and birth length. A bimodal model best fits the data, however the amplitude of the 6 and 12 month peaks changed over time. In the modelling exercises, U- and J-shaped exposure-risk relationships generate time series with both 6 and 12 month periodicities. Changing the weightings of the population exposure risks result in unexpected properties. A J-shaped exposure-risk relationship with a diminishing population exposure over time fitted the observed seasonal pattern in the Danish birth weight data.Conclusion
In keeping with many other studies, Danish birth anthropometric data show complex and shifting seasonal patterns. We speculate that annual periodicities with non-linear exposure-risk models may underlie these findings. Understanding the nature of seasonal fluctuations can help generate candidate exposures. 相似文献20.
Makri T Yakoumakis E Papadopoulou D Gialousis G Theodoropoulos V Sandilos P Georgiou E 《Physics in medicine and biology》2006,51(19):5023-5033
Seeking to assess the radiation risk associated with radiological examinations in neonatal intensive care units, thermo-luminescence dosimetry was used for the measurement of entrance surface dose (ESD) in 44 AP chest and 28 AP combined chest-abdominal exposures of a sample of 60 neonates. The mean values of ESD were found to be equal to 44 +/- 16 microGy and 43 +/- 19 microGy, respectively. The MCNP-4C2 code with a mathematical phantom simulating a neonate and appropriate x-ray energy spectra were employed for the simulation of the AP chest and AP combined chest-abdominal exposures. Equivalent organ dose per unit ESD and energy imparted per unit ESD calculations are presented in tabular form. Combined with ESD measurements, these calculations yield an effective dose of 10.2 +/- 3.7 microSv, regardless of sex, and an imparted energy of 18.5 +/- 6.7 microJ for the chest radiograph. The corresponding results for the combined chest-abdominal examination are 14.7 +/- 7.6 microSv (males)/17.2 +/- 7.6 microSv (females) and 29.7 +/- 13.2 microJ. The calculated total risk per radiograph was low, ranging between 1.7 and 2.9 per million neonates, per film, and being slightly higher for females. Results of this study are in good agreement with previous studies, especially in view of the diversity met in the calculation methods. 相似文献