bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mode of Delivery in Multiple Birth of Higher Order
Authors: Feingold M. , Cetrulo C. , Peters M. , Chaudhury A. , Shmoys S. , Geifman O. 
Published: July 2016

AbstractA retrospective review of triplets delivered at a Boston perinatal center from 1977 to 1986 was performed. Comparison was made between this group (study group) and previously published data on triplets in our institution (control group). Since 1977 there was a more liberal use of abdominal delivery. Cesarean sections (CS) of all triplets with malpresentation was our protocol. Of the 15 sets of triplet pregnancies in the study group, 11 were delivered by CS and 4 by vaginal delivery, vs only 1 CS in the control group wich consisted also of 15 triplets. The corrected mortality rate in the study group was lower than in the control group (2.6% vs 7.1%) but did not reach statistical significance. Apgar scores at 1 and 5 minutes were significantly higher in the study group (P < 0.002). Apgar scores for the third triplet were also higher in the study group (P < 0.05). In comparing the combined mortality and morbidity between the study group and the control group, no difference was found in the first triplet, but those of the second and third triplets were significantly lower in the study group. Of interest is the finding that the combined mortality and morbidity was not different statistically among the first, second, and third triplets in the study group, while in the control group an increase from the first to the third triplet was noted (21%, 31%, and 43%, respectively). A more liberal approach toward abdominal delivery of pregnancies of higher fetal number is advocated.
A New Method for Representing Mental Growth
Authors: Wilson Ronald S. 
Published: July 2016

AbstractA new method is described for plotting the growth in mental development from birth to adolescence. Using data from a large sample of twins followed since birth, a dimension of mental growth was constructed by arraying all tests in order of difficulty, then computing the average gain from age to age. The gain was expressed in standard-deviation units, which reflected the upward shift in the score distribution from time X to time X + 1. When cumulated over ages, the scores generated a mental growth curve for the sample as a whole, as well as for each case individually. The curves displayed a very rapid gain in mental growth over the first 24 months of life, with the complexity of mental functions advancing by nearly 20 standard deviations from birth to two years. Thereafter the gain progressively tapered off until reaching a final increment of 0.5 SD gain between 15 years and adulthood. At this point, the terminal level of mental growth reached an average value of 31 SD units, with a spread of individual differences equal to ± 3 SD units. The scores at each age represented a combination of base level plus gain from the preceding age, and during infancy the gain scores were large in relation to base. At later ages, however, the gain scores were comparatively small, both in absolute terms and in relation to base. These characteristics help explain the typical low-order correlations obtained among mental test scores during infancy, vs the progressively larger correlations obtained at later ages.
Developmental Research of Twin's Temperament
Authors: Matheny Adam P. 
Published: July 2016

AbstractIn the Louisville Twin Study, pairs of 3- and 4-year-old twins were provided with standardized competitive or cooperative tasks in a laboratory setting. Some tasks required a pair of twins to share toys; other fostered a more competitive engagement between the twins. Behavioral ratings identified temperament and social components at both ages, and between the two ages, there were transformations in the links between the components. Parental ratings of the twins' temperament at the same ages were moderately correlated with the laboratory observations, but the pattern of the relations changed from one age to the next. The combined sets of measures were subjected to twin analyses for 43 pairs of twins. The results are discussed in terms of the similarity of MZ and DZ pairs for the dimensions of temperament and the transformations of temperament.
Longitudinal Research on Temperament in Twins
Authors: Torgersen Anne Mari 
Published: July 2016

AbstractThe changing influence of genetic factors of temperamental individuality has been studied longitudinally in a group of 44 same-sexed twin pairs at four different ages from infancy to puberty. Previous results showed that genetic factors seemed to play an important role in the development of temperamental characteristics when the twins were in infancy and at six years of age. The present report shows that when the within-pair differences in temperament are studied again at age 15 years, the similarity of identical pairs is even higher than at earlier ages. When shared and nonshared stress in the twin pairs was assessed at this age, some interactions were found between within-pair differences in temperament, stress and zygosity.
Multivariate Analysis of Genetic and Environmental Influences for Longitudinal Height and Weight Data
Authors: Fischbein S. , Pedersen N.L. 
Published: July 2016

AbstractA multivariate analysis of genetic and environmental influences on longitudinal height and weight data from a Swedish twin sample is presented. For height in boys, genetic correlations of all ages with the first time point decrease during puberty and increase afterwards. A more linear pattern is evident for the girls. For weight in boys, genetic and environmental correlations are similar to the ones for height. Genetic correlations for girls are stable with age, while environmental correlations peak at 13.5 years and decrease drastically thereafter. The patterns for height and weight in boys suggest that a new set of genes may be turned on during puberty and turned off again afterwards. The pattern found for weight in girls indicates that a simple additive genetic model is not appropriate. It is necessary, however, to apply the model to actual data from several time points to recognize the inadequacy of the model.
Early Influences on the School Social Adjustment of Twins
Authors: Hay D.A. , O'Brien P.J. 
Published: July 2016

AbstractThe birth of twins is often accompanied by complications which may affect both twins equally (eg, prematurity) or which may establish differences between the twins (eg, one coming home from hospital first). Parents' ratings of behaviour may reflect and even perpetuate the influence of such variables and it is of interest to see if people less familiar with the twins' history can observe any long-term effects. In the La Trobe Twin Study teachers routinely complete the Bristol Social Adjustment Guide, an assessment of social maladjustment in children aged 5-16 years. Extreme prematurity and problems at delivery were generally associated with the Underreaction syndrome - the child who is unforthcoming, withdrawn and depressed. Withdrawal, depression and maladaptive behaviour to classroom peers were much more common among those twins discharged from hospital after the cotwin. A major mediating factor was that the parents admitted to greatly preferring the one to come home first. These raise questions both about the practice of bringing twins home separately (which occurred in 21% of the cases) and about intervening variables in studies of personality and temperament.
Prospects for Detecting Genotype × Environment Interactions in Twins with Breast Cancer
Authors: Martin N.G. , Eaves L.J. , Heath A.C. 
Published: July 2016

AbstractWe consider a study of MZ and DZ twin pairs ascertained because one or both twins have a disease. Genotypes at a major locus are known and putative environmental risk factors have been measured for all individuals. The power of the study to estimate the effect on liability of the measured and residual genetic and environmental effects (Gm, Gr, Em, Er) and all two-way interactions between them (except Gr × Er) is estimated by simulation. If liabilities can be indexed on a continuous scale (eg, blood pressure as an index of liability to hypertension), then a study of 600 MZ and 600 DZ pairs would have sufficient power to detect quite subtle interaction effects, even if ascertainment is greatly biased toward MZ twins. If liabilities cannot be measured and only affection status is known, then the power of the study would be much lower, although not impracticably so. There appears to be no advantage in augmenting the twins with a sample of control individuals who have been drawn at random from the population regardless of disease status, at least for the case we have considered in which the disease threshold on the liability scale is assumed to be known without error. The argument is developed in terms of the utility of the design for research into breast cancer.
Constrained Maximum Likelihood Analysis of Familial Resemblance of Twins and Their Parents
Authors: Boomsma D.I. , Molenaar P.C.M. 
Published: July 2016

AbstractWhen the univariate twin design is extended by including parents of twins, it is possible to assess additive genetic effects in the presence of assortative mating and genotype-environment correlation, the effects of parental influence, as well as the extent of residual shared environmental influences. The analysis of data obtained in such an extended twin design can be carried out by means of constrained maximum likelihood confirmatory factor analysis. Specifically, the structural model underlying this design can be represented as a LISREL model with nonlinear constraints. This representation offers the possibility to consider extended multivariate twin designs involving common genetic and environmental factors. The proposed method will be illustrated with applications to simulated and real data.
Spectral Analysis of Twin Time Series Designs
Authors: Molenaar P.C.M. , Boomsma D.I. 
Published: July 2016

AbstractThe genetic analysis of physiological time series has to accommodate the presence of autocorrelation. This can be accomplished by means of orthogonal transformation of the series, thus enabling the use of standard genetic analysis techniques for the sequence of uncorrelated transforms. In view of the oscillatory character which typifies various physiological time series, it is customary to invoke spectral techniques for the analysis of these series. It can be shown that spectral analysis is an orthogonal transformation that asymptotically resembles principal component analysis. Consequently, standard genetic analysis methods for the uncorrelated spectral transforms may be used. This approach will be illustrated with simulated and real (heart rate) data for univariate twin time series. Furthermore, it will be indicated that the proposed analysis can be readily generalized to multivariate time series.
The Vietnam Era Twin (VET) Registry: Method of Construction
Authors: Eisen S. , True W. , Goldberg J. , Henderson W. , Robinette C.D. 
Published: July 2016

AbstractA Vietnam Era (1964-1975) Twin Registry of American male-male veterans born between 1939 and 1955 has been developed to provide a study sample for research evaluating the impact of Vietnam service on the medical and psychosocial aspects of health. In preparation for developing the Registry, several alternative sources of twins and methods for identifying twins were investigated. A computerized database of veterans discharged from the military after 1967 was selected as the source because it contains about 50% of the total Vietnam era veteran population, is reasonably unbiased, and provides a feasible method for identifying twins. Twins were identified using an algorithm which involved matching entries on the database for same last name, different first name, same date of birth, and similar social security number. Twin status was confirmed by review of military records. The registry, now complete, is composed of 7,400 twin pairs. It will be an important resource for future research projects.
Do Breech Presentations in Twins and Singletons Run Different Risks?
Authors: Buekens P. , Lagasse R. , Puissant F. , Leroy F. 
Published: July 2016

AbstractWe have compared breech twins and breech single births in a population recorded between 1974 and 1978 in 10 Belgian maternity centers. In 190 twin pregnancies, 38 first and 65 second twins were delivered in breech presentation. These twins were compared to 853 singleton breeches, of which 95 delivered by cesarean section were excluded. Data were stratified according to birthweight. No significant difference between twins and singletons was found in terms of perinatal mortality rates. However, Apgar scores below 7 at 5 minutes were significantly less numerous among first twins than among singletons. Therefore, first twins in breech presentation might be at lower risk of fetal distress. This difference should be taken into account in the management of first twins presenting by the breech.
Fetal Alcohol Syndrome in Twin Pregnancy
Authors: Chasnoff Ira J. 
Published: July 2016

AbstractIn recent years, it has been realized that some infants of frankly alcoholic mothers escape the stigmata of fetal alcohol syndrome (FAS) and others have only a few of the characteristics. These infants are thought to display fetal alcohol effects (FAE). The controversy regarding the amount of alcohol a woman can safely drink during pregnancy and the effects of timing and individual physiology on producing FAS vs FAE in the infant are important questions which can perhaps be partially answered through examining twin pregnancies and offspring. Data are presented regarding the long-term growth and development of a set of dizygotic twins, one with FAS and one with FAE, delivered to a mother who drank moderate amounts of alcohol during pregnancy. The variation in the degree of abnormality found in dizygotic twins exposed to similar amounts of alcohol at the same time during gestation indicates that differences in fetal susceptibility to ethanol dysmorphogenesis are of prime importance to the expression of the fetal alcohol syndrome.
Umbelical Waveforms in Twin Pregnancy
Authors: Giles W.B. , Trudinger B.J. , Cook C.M. 
Published: July 2016

AbstractContinuous wave Doppler ultrasound was used to study the twin fetus in 76 multiple pregnancies. The technique is not difficult and allowed the identification of the small for gestional age twin in both intrauterine growth failure and twin to twin transfusion syndrome.
Cotwin Closeness in Monozygotic and Dizygotic Twins: A Biasing Factor in IQ Heritability Analysis?
Authors: Tambs K. , Sundet J. M. , Berg K. 
Published: July 2016

AbstractFor 98 pairs of MZ twins, four measures indicating degree of cotwin closeness were correlated with absolute differences between IQ scores within pairs. In two different twin samples (40 MZ vs 40 DZ pairs and 169 MZ vs 174 DZ pairs, respectively), means and standard deviations in the closeness variables were obtained for MZ and DZ pairs. Whereas MZ cotwins were clearly closer than DZ cotwins, the relation between cotwin closeness and similarity in IQ seemed rather weak and ambiguous. “Years lived together in childhood home” were positively related to similarity in IQ (P < 0.01), whereas subjective feeling of closeness in contact tended to be negatively related to similarity in IQ.
The Northwestern University Twin Study XV: Rationales for a Standard of Care in Compromised Twin Pregnancies
Authors: Minogue J.P. , Tamura R.K. , Keith L.G. 
Published: July 2016

AbstractCurrent antenatal technologies have improved the obstetrician's ability to assess fetal well-being as well as to diagnose fetal compromise. These technologies have given rise to very difficult ethical issues in the management of compromised twin pregnancies: for example, a choice must be made between putting a healthy twin at risk due to preterm delivery for the sake of a compromised cotwin or of allowing the compromised twin to die in order to buy time for the healthy twin. Though each case is unique, good medical practice requires a standard of care by which consistent patient management can be proposed. In the pluralistic environment of Northwestern Memorial Hospital, our staff has favored a standard of care based on patient autonomy. This approach demands: 1) a practitioner who offers a thorough explanation of the diagnosis and possible treatment approaches; 2) time for the patient and her partner to assimilate this information and test treatment options against their personal value system; 3) a third, but disinterested, party to facilitate patient understanding and value clarification; 4) a practitioner either willing to support the patient's decisions or refer her to another practitioner who will.
Estimated Fetal Weight in Twin Pregnancy: How Good Are We?
Authors: Campbell D.M. , Smith A.P. , Wilson A.W. 
Published: July 2016

AbstractUltrasonic assessment of fetal weight derived from multiple measurements of the fetus has become accepted in clinical practice as being useful in singleton pregnancies. Several different formulae for estimating fetal weight have been derived from differing measurements of the fetus, such as biparietal diameter, trunk circumference, and femur length. To date, there has been no attempt to evaluate such a technique in multiple pregnancy. This study aims to see whether the formulae derived for singleton pregnancy are applicable to twin pregnancies. Estimated fetal weight will be derived by mathematical modelling from ultrasonic measurements made within a week of delivery and the results compared with the actual birthweight to give an indication of how good such estimated fetal weights are. Factors to be considered in the analysis include whether there are differences between Twin I and Twin II, differences of presentation with twins and differences by gestation at delivery.
Simultaneous Genetic Analysis of Longitudinal Means and Covariance Structure Using the Simplex Model: Application to Repeatedly Measured Weight in a Sample of 164 Female Twins
Authors: Fischbein S. , Molenaar P.C.M. , Boomsma D.I. 
Published: July 2016

AbstractThe simultaneous analysis of means and covariance structures is applied to longitudinal twin data. Body weight was measured on six occasions in a sample of young female MZ and DZ twins. When average body weight at the first measurement occasion, as well as the increments in weight at later occasions, are specified in the genetic part of the model that also adequately explains the covariance structure, a good fit is obtained. In this application the increase in body weight at each occasion is weighted by the square root of the genetic variance innovation terms that represent the new genetic variance entering into the process.
Genetic Influences on Neonatal Temperament
Authors: Riese M.L. 
Published: July 2016

AbstractThe genetic contribution to temperament was assessed during the neonatal period in 172 newborn infants from 47 pairs of monozygotic (MZ) and 39 pairs of same-sex dizygotic (DZ) twins. Zygosity was not related to the neonatal temperament variables. Examination of the scores for twin concordance indicated significant within-pair concordance in temperament ratings, but MZ twins were not more like each other than DZ twins. The results suggested that neonatal temperament was influenced by environmental factors. Further analyses indicated that neonatal temperament was influenced by perinatal variables such as birth weight, 1- and 5-minute Apgar scores, and number of days spent in the hospital. It was concluded that there was no clear pattern of genetic influence on neonatal temperament, and that nonshared environmental factors were an important source of variance for temperament during this period.
Permissiveness-Restrictiveness for Twins and Controls in Two Educational Settings: The Swedish Compulsory School and the Israeli Kibbutz
Authors: Fischbein S. , Guttman R. , Nathan M. , Esrachi A. 
Published: July 2016

AbstractIn a previous longitudinal twin project a model was developed for studying heredity-environment interaction. One important environmental dimension in this model is permissiveness-restrictiveness. The purpose of the present study has therefore been to investigate perceived and imposed restrictiveness at the societal and classroom level and possible interactional effects on pupil behavior. Results are reported from grade 4 to grade 6 in Israeli kibbutzim and Swedish compulsory school. One major finding is that no systematic differences have been found between twins and controls in the two countries. In both Swedish schools and Israeli kibbutzim permissiveness-restrictiveness will vary depending upon perspective (perceived or imposed) and upon content (type of subject or rule-breaking activity). Preliminary within-pair comparisons for the Swedish twins are reported for different types of test results. In agreement with the model, logical abstract thinking as well as reading and mathematics achievement seem to be less influenced by hereditary factors in a restrictive educational setting than in a permissive one.
What Information Should the Multiple Birth Family Receive Before, During and After the Birth?
Authors: Hay D.A. , Gleeson C. , Davies C. , Lorden B. , Mitchell D. , Paton L. 
Published: July 2016

AbstractAdvances in the management of the multiple pregnancy and delivery must be accompanied by corresponding improvements in service access outside key centres and especially in the information families receive about what may happen during or after the pregnancy. A major review of birthing services in Victoria has focussed attention on four areas where the quality of information is often inadequate. 1) Prepregnancy and the standard of counselling about the incidence of multiples as a result of fertility drugs and in vitro fertilization procedures and about problems which may accompany a multiple birth. 2) Antenatal: At what stage of the pregnancy should parents be told of the multiple pregnancy and how should monitoring of the mother and procedures such as bedrest take into account what are often conflicting demands within the family? 3) Perinatal: Families are frequently illprepared for a cesarean delivery and for the procedures for premature multiples. The problem is often compounded by separation of the mother from one or both twins. While bereavement services are improving, much still needs to be learned about handling congenital abnormalities in one or more multiples. 4) Postnatal: Irrespective of the level of prenatal advice, families greatly underestimate the workload with multiples. The resulting stress contributes to the incidence of postnatal depression, child abuse and divorce now being reported from multiple birth families. Some suggestions are made from social psychology and genetic counselling about how families can best handle risk information to achieve the goal of neither under- nor overestimating the risks at these different stages of the multiple pregnancy.