Effects Of Birth Year Research Articles

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Type 1 Diabetes and Pregnancy

To examine changes in perinatal mortality and birth weight of babies born to mothers with pregestational type 1 diabetes over 40 years in a single teaching hospital clinic. This was a retrospective survey of cases from the combined diabetes and obstetrics antenatal clinic at the Royal Infirmary of Edinburgh and Simpson Memorial Maternity Pavilion, Edinburgh, Scotland. Birth weight, standardized birth weight, and perinatal mortality were obtained from 643 singleton babies born after 28 weeks of gestation to mothers with pregestational type 1 diabetes between 1960 and 1999. There was a dramatic improvement in perinatal mortality rate, falling from 225 (per 1,000 total births after 28 weeks of gestation) in the 1960s to 102 in the 1970s, 21 in the 1980s, and 10 in the 1990s (P < .001 for effect of birth year). In contrast, standardized birth weight (adjusted for sex, gestational age, and parity), which was significantly higher than the background population (+1.41 standard deviations above the population norm, P < .001) showed no significant change over time. Changes in diabetic management and obstetric practice over the 40 years of our survey have resulted in enormous improvements in the outlook for offspring of mothers with diabetes. Somewhat surprisingly this has not been associated with a reduction in overgrowth of the fetus. II-2.

Prevalence and genetic parameters for hip dysplasia in Italian population of purebred dogs

This paper aimed to assess the prevalence of hip dysplasia (HD) in some breeds of dogs widely diffused in Italy and to estimate heritability of HD in German Shepherd and Boxer Italian populations. Data consisted of radiographic findings taken on 32,900 dogs (18,665 females and 14,225 males) of 7 breeds (German Shepherd; Boxer; Labrador Retriever; Golden Retriever; Rottweiler; Dobermann; Cane Corso) screened at an age of 17.9 ± 7.0 months. Radiographs of the coxofemoral joints, taken by 478 veterinarians, were scored for HD grade by a single veterinarian panelist according to a grading procedure based on a 5-class linear system (from A, no signs of dysplasia, to E, severe dysplastic hip changes). Logistic regression analysis was used for studying the relationships between selected explanatory variables with the outcome of the diagnosis for HD. Variance components, direct and maternal heritability have been estimated for German Shepherd and Boxer dogs using a REML animal model procedure. Prevalence of HD (hip joint graded C or worse) for the pool of breeds involved approached 22%, with large differences among breeds. In dogs diagnosed as dysplastic, the mild form (grade C) was largely prevalent for all breeds. When compared to the German Shepherd, the Cane Corso exhibited a significantly higher risk, whereas the Dobermann, Labrador and Rottweiler showed a significantly lower risk of being affected by HD. The probability of being diagnosed as dysplastic increased with the increasing of the age of dogs at screening and with the decreasing of experience of x-raying veterinarians. The effect of birth year of dogs on the outcome of the HD diagnosis was significant, but evidenced an inconsistent trend through years. Heritability estimates approached 0.24 and 0.15 for Boxers and German Shepherds, respectively, whereas maternal heritability was close to 0.03 for both breeds. Results from this study demonstrated that HD is fairly prevalent in some breeds of dogs commonly found in Italy, and its reduction should be a goal in breeding schemes of purebred dogs. Age at screening and experience of the x-raying veterinarians are disturbance factors to be considered in screening programs for HD. Heritability estimates for HD was low, but additive genetic variance seems enough for conjecturing selection programs aimed to decrease hip joints disease. Given the low heritability values, current selection schemes based on phenotypic records seem ineffective, whereas the use of breeding values estimated under BLUP animal model procedures should be recommended for gaining genetic progress of Italian dog populations.

Genetic and phenotypic parameters of body weight and wool production in Iranian Moghani sheep

In spite of the fact that there are many sheep breeds in Iran, few studies have been established with respect to their economical traits. Moghani sheep is one of the best Iranian meat type breeds with a 5.5 million population. Some specifications of this breed include Resistance to weather conditions, big body size and ability to producing heavy lambs. The aim of this research was to survey the environmental effects and estimates of genetic parameters for birth weight (BW), average daily gain from birth to three mounts of age (ADG1), three months age weight (TRW), average daily gain from three to six months age (ADG2), six months age weight (SIW), nine months age weight (NIW), yearly weight (twelve months age weight or TWW), lamb fleece weight (LFW) and yearly greasy fleece weight in mature sheep (YFW). The effect of birth year, ewe’s gestation period (or age for yearling greasy fleece weight), birth type and sex as fixed effect and sires (nested in years) as random effect on aforesaid traits were studied.

Effets du milieu et génétiques sur la croissance des agneaux Timahdite et croisés au Maroc

La connaissance des paramètres génétiques pour les caractères de croissance d’intérêt économique est nécessaire à l’évolution des populations ovines au Maroc. Les données sur 544 agneaux de race Timahdite (T) et 756 agneaux D’man x Timahdite (DT), tous nés de 1992 à 1998, ont été utilisées pour estimer les paramètres génétiques des poids des agneaux à la naissance, à 30, 70 et 90 jours, ainsi que des gains de poids journaliers de 10 à 30, 30 à 70 et 30 à 90 jours, pour chaque caractère. Les variances-covariances ont été estimées séparément par la méthode du REML, utilisant un modèle animal qui incluait les effets fixes de l’année de naissance, du sexe, de l’âge de la brebis, du type de naissance ou du mode d’allaitement et de l’interaction année de naissance x sexe, effet génétique direct et effet génétique maternel. Les corrélations génétiques et phénotypiques entre les caractères ont été estimées avec des modèles comportant tous les mêmes effets fixes et seulement les effets génétiques directs additifs. Tous les effets fixes ont eu une influence sur les caractères de croissance. Les estimations des héritabilités directes pour les différents caractères poids et gains de poids journaliers ont été faibles à modérées et ont varié de 0,07 à 0,25 chez les T, et de 0,02 à 0,18 chez les DT. Les héritabilités maternelles ont été de 0,20 à 0,36 chez les DT et de 0,01 à 0,10 chez les T, à l’exception du poids à la naissance (0,53). Pour tous les caractères, les corrélations génétiques directes et maternelles ont été élevées et négatives chez les DT (-0,80 et -1,00) et chez les T (-0,90 et -1,00). Cependant, la précision de telles estimations est faible étant donné la petite taille du fichier des données utilisé dans cette étude. Les estimations des corrélations génétiques et phénotypiques ont été positives pour tous les caractères et particulièrement élevées pour les corrélations génétiques entre les poids et les gains de poids après la naissance à la fois chez les agneaux DT et T montrant l’absence d’antagonismes génétiques entre les différents caractères étudiés.

Oral contraceptive use at a young age and the risk of breast cancer: an Icelandic, population-based cohort study of the effect of birth year.

The possible association between breast cancer and oral contraceptive use before the age of 20 was investigated using Icelandic population-based information from women born after 1944. The design was a nested case-control study within a cohort, using data on duration of oral contraceptive use at young ages. The availability of oral contraceptives before the age of 20 has changed dramatically and is highly dependent on birth years, with 20% and 82% starting before the age of 20 among Icelandic users born in 1945-47 and 1963-67 respectively. The association between total duration of oral contraceptive use and breast cancer was significantly dependent on year of birth. In women born in 1951-67 (based on 81 cases), the relative risk (RR) associated with use for more than 4 years was 2.0 (95% CI 1.1-3.7). The association disappeared when women born in 1945-50 were included (RR 1.1,95% CI 0.8-1.6), adding 123 cases. A significant trend of increased risk with longer duration was present only in the group born after 1950, with RR 0.9, 1.7 and 3.0 for < or = 4 years, >4-8 years and > 8 years of use respectively. The results of this study indicate an association between breast cancer and oral contraceptive use at a young age. They also stress the importance of distinguishing between groups with different opportunities for exposure at young age.

Coresidence Beliefs in American Society. 1973 to 1991

This article examines trends in beliefs about desirability of coresidence between adult children and their parents in U.S. between 1973 and 1991. Despite some clear historic tendencies toward independent living arrangements in population as a whole, data presented from General Social Surveys actually show a significant toward acceptability of coresidence. The decomposition of these trends into intra- and intercohort patterns reveals important intercohort differences. A multivariate analysis, including variables measuring sociodemographic experiences, indicates that about 20% of effects of birth year can be accounted for by these factors, particularly greater kinship contact reported by younger cohorts. The article concludes with a discussion of meaning of these trends. Key Words: cohorts, coresidence beliefs, General Social Surveys, generations, intergenerational relations, living arrangements. Coresidence with extended kin, while often thought to be more prevalent in early America, is a form of household living that is virtually extinct in contemporary society. There is debate about nature of long-term historical patterns in extended kinship coresidence in North America; however, post-World War II patterns in United States indicate a definite rise in primary individual, Census Bureau's term for persons who live alone (e.g., Ruggles, 1987). Increasingly, people are achieving privacy and independence in living arrangements at expense of household-based extended kinship relations and intergenerational responsibilities (Goldscheider & Waite, 1991; Kobrin, 1976a, 1976b; Michael, Fuchs, & Scott, 1980; Santi, 1988). To some extent, similar changes have occurred in Western Europe (e.g., Murphy & Grundy, 1993; van Solinge, 1993). At same time, however, several observers have noted a more recent reversal of trend, with increasing numbers of young adults apparently coresiding with their parents. Data for U.S. indicate that there has been virtually no decline in age of leaving parental home, and those who leave are now more likely to return (Buck & Scott, 1993; Glick & Lin, 1986; Heer, Hodge, & Felson, 1985). The General Social Surveys (GSS) data reported here show a systematic increase in support for intergenerational coresidence, a result that is somewhat surprising given trends toward autonomous living. Indeed, remarking on GSS data through 1986, Glenn (1987) noted that this is the only distinctly profamilistic [he has] discovered in all sample survey data [he has] examined. But, he commented that trend is of uncertain importance because it is not at all certain that persons with elderly parents became more willing, on average, to take their parents into their homes or that parents became more willing to live with their offspring (pp. 119-120). In following analysis, I decompose these trends into two components: cohort turnover and intracohort change. Then, while controlling for several other factors known to be predictive of intergenerational relations, I further analyze contributions of these components. While ambiguity in GSS question, which Glenn noted, still remains, intent of this analysis is to bring clarity to nature of within context of a broader reconnaissance of developing literature on this topic. TRENDS IN RESIDENTIAL NORMS There are several indications of rather substantial changes in residential norms in U.S. over past century. For example, proportion of persons classified as primary individuals by U.S. Bureau of Census has systematically increased (Ruggles, 1988). The Current Population Reports show that fewer than 8% of U.S. households contained persons living alone in 1940s, whereas across recent decades this figure has gradually risen, and in early 1990s it had reached 25% (U. …