bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation of Antepartum Uterine Activity and Cervical Change in Twin Gestation
Authors: Newman R. B. , Ellings J. M. , O'Reilly M. M. , Brost B. C. , Miller M. C. , Gates D.
Published: July 2016

Objective. To determine the correlation between quantitative measurements of antepartum uterine activity and cervical change twin gestations.

Methods. Forty women from our Twin Clinic constituted the study group. Participants had a cervical examination each week between 20 and 37 weeks gestation and a cervical score (CS) was calculated as follows: CS = cervical length (cms)-cervical dilation (cms) at the internal os. The women also performed blinded home uterine activity monitoring (HUAM) for a mean of 7.0+3.0 hrs/wk (+SD). Uterine activity was expressed as mean number of contractions/hour/week gestation based on the average of three independent reviewers. CS was determined by a single clinician unaware of the HUAM recordings. A significant change in the CS was defined as a reduction of at least 0.5 from the preceding week. Correlation coefficients were used to determine the association between uterine activity and change in the cervical score.

Results. Twin pregnancy was characterized by a rise from 0.2 + .03 contractions/hr at 20 weeks to 3.2 + 2.4 contractions/hr at 37 weeks gestation. CS fell from a mean of 2.6 + 0.2 at 20 weeks to −2.1 + 0.9 at 37 weeks gestation. There was a significant negative correlation (−0.317, p<.0001) between increasing uterine activity and decreasing CS. There were significantly more (p <.002) contractions during the 7 days preceding a significant reduction in CS (3.3 + 3.5 contractions/hr) than when the CS was unchanged (1.6±1.5 contractions/hr).

Conclusions. In twin gestations, an increasing frequency of uterine contractions is strongly correlated with quantifiable cervical change between 20-37 weeks gestation. Persistent daytime contraction frequencies of >3/hr represent a risk factor for cervical dilation and/or effacement.
The Twinning Rates and Epidemiological Characteristics of Births in Southeast Uttar Pradesh, India
Authors: Sharma K.
Published: July 2016

Birth statistics over a period of 5 years were analyzed to study epidemiological characteristics of twinning in Southeast Uttar Pradesh, India. The data revealed higher incidence of breech twins (11.84% of all cotwins) as compared to breech single births (2.18%). But the perinatal mortality and caesarean section rates were similar in both twin and singleton pregnancies. The cumulative twinning rate over the studied period was 11.70 per 1000 live births. The MZ and DZ twinning rates were estimated respectively as 3.67 and 8.03 per mill. The mean maternal age of sampled mothers was 26.42 years with one standard deviation of 5.30 years. The twinning rate for mothers over 35 years of age was about four times higher than that in mothers younger than 20 years. Incidently, the twinning rate was the highest at parity four and a non-linear curve could more appropriately be fitted to the series of data. Seasonal variations were observed for both twin and singleton births. The highest frequency of births was observed from August through October. But seasonal index for twinning rate showed a clear bimodal distribution with peaks in April (223) and September (167).
Maternal and Neonatal Variables in Twins: an Epidemiological Approach
Authors: Campana M. A. , Roubicek M. M.
Published: July 2016

Population studies on human twinning are scarce in Argentina. In order to analyze frequencies and certain maternal and neonatal variables related to twin births, we studied a series of 69.678 consecutive newborns with 500 g of weight and over, which occurred at a public hospital in the province Buenos Aires, during 14 years (1982-1995). The frequency of twin births (10 per 1000 deliveries) and sex ratio were similar to other studies reported in Caucasian population. Maternal age and order of gravity/parity were positively correlated with twinning rates, more markedly so in dissimilar sex-pairs. Stillbirths and neonatal deaths were more frequent in twins than in singletons, but less frequent when comparing groups of same weight. Congenital malformations were not found to be significantly more frequent in twins than in the total newborn population. However, their occurrence, predominantly in like-sexed pairs and the concordance for defect type in doubly affected same-sex pairs, suggests that monozygotic twinning carries an increased risk for malformation.
Cognitive Development and Behaviour in Very Low Birthweight Twins at Four Years
Authors: Dezoete J.A. , MacArthur B.A.
Published: July 2016

This study included two groups of 37 children, one of twins and the other singletons at 4 years of age. All subjects had birthweights under 1500 grams and individuals in the groups were matched for birth date, gender and birthweight. Except when parental socio-economic status was taken into account, no significant differences between twins and singletons were observed on any of the results ofThe Stanford-Binet Intelligence Scale, nor were there any when the twins and singletons were divided into groups with birthweights < 1000 grams and 1000 to 1499 grams. When cognitive scores were analysed in relation to socio-economic status, there were significant differences in the whole population between subjects in the high and low socioeconomic status groups, with higher mean scores for the former. Comparison of the twins and singletons with parents in the lower socio-economic status group did not produce any significant differences but in the case of the upper socio-economic status group the singletons scored significantly better that the twins in Quantitative Reasoning and on the Composite Score. No significant differences were demonstrated in the clinical assessment of speech, language or behaviour. So far as general life considerations and health were concerned only one significant difference was found and this was for the number of siblings born subsequently, with more born in the singleton families. This study did not provide support for the view that singletons and twins differ significantly in the areas considered.
Reducing Fetal Deaths in Multiple Births: Optimal Birthweights and Gestational Ages for Infants of Twin and Triplet Births
Authors: Luke B.
Published: July 2016

The objective of this study was to determine the birthweight and gestational age associated with the lowest fetal mortality for twins and triplets. The study design was a population-based analysis of all live births and fetal deaths in the US between 1983-88. Fetal mortality was compared by categories of birthweight and gestational age, for twins and triplets versus singletons, and within each plurality by the lowest rate compared to all other rates as relative risks ± 95% Cls. The overall versus lowest fetal death rate per 1,000 conceptions for singletons was 4.3 versus 0.9 at 3700-4000 g and 40-41 weeks; for twins, 15.5 versus 3.3 at 2500-2800 g and 36-37 weeks; and for triplets, 21.0 versus 5.2 at 1900-2200 g at 34-35 weeks. Beyond these plurality-specific lowest ranges, the risk of fetal death increased, more for twins than singletons, and most for triplets. To conclude, fetal death rates can be reduced by 75-80% with attainment of birthweight and gestational age within a plurality-specific ideal range.
The “Equal Environments Assumption” in MZ-DZ Twin Comparisons: an Untenable Premise of Psychiatric Genetics?
Authors: Pam A. , Kemker S.S. , Ross C.A. , Golden R.
Published: July 2016

The comparison of MZ-DZ twins in behavioral genetics has produced what seems like irrefutable evidence for the heritability of many psychiatric disorders. But such research depends on the validity of the EEA – the “equal environments assumption” – as an underlying premise. In this paper, several empirical studies which support the EEA are critically reviewed in terms of methodology and the way data has been processed in a mathematical model called “path analysis”. It turns out that studies investigating the EEA appear to be largely inadequate in terms of technique, as well as biased in the inferences drawn. Further, the “heritability” estimate – often taken to mean the influence of trait – specific genes – is merely a statistical abstraction derived from a matrix of correlations; this estimate encompasses many buried environmental effects so that “heritability” does not correspond to any underlying DNA structure. In conclusion, many MZ-DZ pedigree studies have dubious scientific value, given the non-viable premise of the EEA, as well as the misleading operational definition of what has been called “heritability”.
Embryologic Development and Monozygotic Twinning
Authors: Hall J.G. , Lopez-Rangel E.
Published: July 2016

In 1875, Sir Francis Galton was the first to propose that by comparing the concordance of a specific trait or disorder in monozygotic (MZ) twins (assumed to be genetically identical) and dizygotic (DZ) twins (which were assumed to be as similar or as different as any other pair of sibs), it would be possible to distinguish between environmental and heritable effects. DZ twins are derived from the fertilization of two eggs by two sperm. MZ twins are the result of the fertilization of one egg by one sperm that then divides to form two embryos.

Genetic research has made amazing progress since 1875. Advances in molecular DNA techniques and developmental genetics have made it possible to differentiate unequivocally between MZ and DZ twins [1, 14]. It is in this new light that this manuscript will review the recent knowledge about twins and the twinning process.

The incidence of DZ twins differs between population [11, 18]. A DZ twin birth in North America is estimated to occur 9–11 times in every 1000 live births or 1 in 100 births; i.e. 1 in every 50 people is a DZ twin.

The DZ twinning rate is closely related to maternal age, parity, height, weight and gonadotropin levels. An increased DZ twinning rate is seen with increasing maternal age and peaks around 35–39 years; higher parity is also associated with a higher DZ twinning rate [19]. Tall heavy women are more likely to give birth to DZ twins than short thin women. A higher incidence of DZ twins has also been reported with the use of new reproductive techniques.
Imprinting and Transgenerational Modulation of Gene Expression; Human Growth as a Model
Authors: Pembrey M.
Published: July 2016

It is proposed that transgenerational modulation of gene expression might be possible, if the metabolic response of the parent to some physiological or social stress modified imprint setting. Transcription regulators could theoretically mediate this process. The nature of imprinted genes poised, as it were, between a transcriptionally active and silent state, makes them good candidates for incorporation into the evolution of transgenerational adaption systems where coordinated changes in gene expression over the generations is a selective advantage. The coordination of human fetal (head) growth with the existing size of the mother's pelvis is suggested as just such a circumstance. The reduced birth weight of Dutch babies where their grandmothers suffered acute starvation in mid pregnancy, supports the notion of transgenerational adaption to nutrition, as does the secular change (increase) in child growth over the last century. The recent indication that there may be functional polymorphism in the imprinting of the human IGF2 and IGF2R genes suggests these ideas could be explored using association studies at the population and individual level.
Aneuploid Correction and Confined Placental Mosaicism
Authors: Simoni G. , Sirchia S. M. , Fraccaro M.
Published: July 2016

Uniparental disomy (UPD) can be caused by various genetic mechanisms such as gamete complementation, chromosome duplication in a monosomic zygote or postzygotic aneuploid correction. This latter mechanism has been recently well documented in human reproduction and seems to be strictly related to placental mosaicism. We have therefore studied some aspects of confined placental mosaicism (CPM) which are useful to clarify one of the most common sources of UPD in humans.

Abnormal distribution of chromosomes in postzygotic mitotic cell divisions may result in a mosaic condition with two or more cell lines showing different chromosome constitutions. The effects on fetal phenotype and pregnancy development depend on the chromosomes involved, the distribution of the abnormal cells among tissues and on the precise stage at which chromosome mutation occurs.

As shown in Fig. 1, when the mutational event occurs in the blastocyst, prior to the differentiation of embryonic and chorionic compartments, the mosaicism is found in both the placental and fetal tissues. In contrast, when the chromosome mutation occurs at a later stage, after embryonic and chorionic compartment separation, the abnormal cells may be confined to the placenta or to the embryo, and are not necessarily found in both.
The IPW Gene is Imprinted and is not Expressed in the Prader-Willi Syndrome
Authors: Wevrick R. , Kerns J.A. , Francke U.
Published: July 2016

Since the original description of the Prader-Willi syndrome (PWS) in 1956 [1], and the recognition of the involvement of the proximal region of chromosome 15 in this disorder [2], understanding of the molecular basis of the genetic defect in PWS has progressed rapidly. A set of clinical criteria has been defined [3], although the diagnosis on clinical grounds alone remains difficult in the first year of life. Research has focussed both on improving the diagnostic molecular and cytogenetic tests for PWS and on identifying and defining the functions of genes whose expression is altered in this neurobehavioral disorder. Furthermore, this region is known to be subject to genomic imprinting effects, so that expression of genes involved in PWS is expected to be exclusively from the paternal allele.

A critical step in the definition of the region containing such genes was the identification of a subset of unusual patients affected with either PWS or the Angelman syndrome, which also involves a gene or genes in the proximal region of chromosome 15. These unique patients, who have chromosome 15 translocations or deletions, helped to narrow the critical region to an interval containing less than 500 kb of DNA [4-6] (Fig. 1). As will be discussed, below, regulatory elements exist in this 500 kb region which alter the expression of genes located outside this interval [7, 8].
A New Case of Beckwith-Wiedemann Syndrome with an 11p15 Duplication of Paternal Origin [46,XY,-21,+der(21), t(11;21)(p15.2;q22.3)pat]
Authors: Krajewska-Walasek M. , Gutkowska A. , Mospinek-Krasnopolska M. , Chrzanowska K.
Published: July 2016

We present a new case of 11p15 duplication (trisomy 11p15) in a boy [46,XY,-21,+der(21), t(11;21)(p15.2;q22.3)] suffering from Beckwith-Wiedemann syndrome (BWS), whose phenotypically normal father carries a balanced translocation between chromosomes 11 and 21[46,XY, t(11;21)(p15.2;q22.3)]. The paternal grandmother has the same balanced translocation and is also clinically normal. BWS was suspected when the boy was 6 months old because of gigantism, macroglossia, visceromegaly, ear lobe creases and abdominal distention. Apart from the characteristic BWS phenotype, the boy has other features which are almost exclusively observed in 11p trisomy (high forehead with frontal upsweep of hair, wide central nose bridge, slightly beaked nose, chubby cheeks and severe mental retardation). So far, at least eight cases of 11p15 duplication have been described as patients with BWS. In six of these, the duplication was due to inheritance of a translocated or rearranged paternal chromosome. This was also the case in our patient. In the two other previously published cases, the 11p15 duplications were de novo, but in one of these, DNA analysis has subsequently shown that the duplication was of paternal origin. We discuss our observations in relation to the above-mentioned previous cases of 11p15 duplication and the possible role of genomic imprinting in the etiology of BWS.
A Case of Angelman Syndrome Arising as a Result of a De Novo Robertsonian Translocation
Authors: Ramsden S. , Gaunt L. , Seres-Santamaria A. , Clayton-Smith J.
Published: July 2016

A male child has been identified with Angelman syndrome. He has been shown to carry a de novo Robertsonian 15/15 translocation where both chromosome 15s have been derived from the father. Consequently the disease in this instance is due to paternal uniparental disomy.
The Childhood Growth of Twin Children
Authors: Luke B. , Leurgans S. , Keith L. , Keith D.
Published: July 2016

The objective of this study was to assess the childhood growth of twin children in terms of the effects of intrauterine growth retardation (IUGR) and discordancy at birth on the incidence and severity of stunting and discordancy in current height and weight. The study was part of a cross-sectional field project conducted at the Annual Twins Days Festival in Twinsburg. Ohio, USA, during 1990, 1991, and 1993, and including all twin children between 2 and 12 years of age. Mothers of twins were interviewed regarding their children's birthweights and gestational age; the twin children were measured for their current heights and weights. The study population included 990 twin children, including 555 boys and 435 girls, of which there were 254 boy pairs and 194 girl pairs. Birthweight for gestational age and current weight and height were each converted into Z-scores and characterized as severe (Z-score <−2,0), or moderate IUGR or stunting (Z-score > −2.0 and < −1.2). For the present study discordancy in birthweight, and current height and weight was calculated for like-gender twin pairs. Only twin children with severe IUGR at birth showed an increased risk of stunting in their current height or weight, and this risk was only for moderate, not severe, stunting. Boy twins with severe IUGR at birth were at increased risk of moderate stunting in their current weight (OR 2.67, 95% CI 1.55, 4.58, P = 0.002), while girl twins with severe IUGR at birth were at increased risk of moderate stunting in their current height (OR 4,09, 95% CI 1.49, 10.99, p = 0.003). Among like-gender twin pairs, there were no differences in mean or categories of birthweight or current weight discordancy, but boy twin pairs did show a significantly greater proportion of current weight discordancy compared to girl twin pairs (p = 0.005). Overall, there was a significant tendency for differences in height and weight between like-gender twin pairs to disappear over time, with the effect being greater for boy twin pairs. We conclude from these findings that twin children tend to overcome growth retardation and discordancy present at birth, and although children who had severe IUGR or discordancy at birth were more likely to have some residual moderate stunting or discordancy in height or weight, they still tended to be within normal values for their gender and current age.
Mutations in Fucosidosis Gene: a Review
Authors: Tiberio G. , Filocamo M. , Gatti R. , Durand P.
Published: July 2016

Fucosidosis is an autosomal recessive disorder caused by a deficiency of alpha-L-fucosidase. Up to now 79 cases have been described and several others identified but not yet published. The higher incidence of the disease is in Italy, where nearly 20 patients have been identified. Fourteen disease-causing mutations have been detected and four of them, Q422X, G60D, E375X, P141fs are present in more than 70% of the forty patients studied. In Italian patients, only seven mutations have been described and P141fs and G60D mutations are present in more than 50% of the cases. The P141fs mutation is absent in other ethnic groups. It has been impossible to establish genotype-phenotype correlation so far and the clinical variability of the disease cannot be explained only by genetic heterogeneity.
Twin-to-twin Transfusion Syndrome Type III - Case Report of an Intrauterine Death in Monochorionic Pregnancy
Authors: Biskup I. , Malinowski W.
Published: July 2016

The acute form of twin-to-twin transfusion syndrome is caused by rapid transfer of blood from one of the twins to another via placental anastomoses. Usually, this only occurs during the second stage of labour as a result of a sudden relative rise of blood pressure in one of the fetal circulations. This can result in the sudden intrauterine death of a fetus (or both, as in our case). Currently, there is no reliable means of identifying such an at-risk pregnancy by means of ultrasound antenatally. We would classify this as TTTS Type III.
Laterality Effects In Twins
Authors: Meshkova T.A.
Published: July 2016

The laterality effects in 10 symmetrical EEG derivations in twins (20 MZ and 20 DZ pairs with a mean age of 20.5 years) were examined. The quantitative and qualitative analyses gave the following results: (1) cotwins in the MZ and DZ pairs differed particularly in the intensity of asymmetry for EEG parameters — one was more asymmetrical than the other; (2) among the MZ twins there were no “mirror” pairs (opposite asymmetry of the EEG), even where opposite-handedness existed. For example, a right-handed twin had an asymmetrical EEG, while the other, a left-hander, had a symmetrical one; (3) the most asymmetrical EEG was in the temporal derivations showing a more active left hemisphere; and, (4) there was no evidence of genetic influence in the intensity of EEG asymmetry.
Twinning Rates in Japan, 1951-1990
Authors: Imaizumi Y.
Published: July 2016

Twinning rates in all of Japan for 1951-1968 and 1974-1990 were analyzed using data from vital statistics of Japan. The twinning rate per 1,000 births was 6.43 in 1951 and remained nearly constant until 1968, then decreased to 5.79 in 1974 and gradually increased to 7.00 in 1990. The MZ twinning rate increased slightly up to 1966, but decreased thereafter, whereas the DZ rate declined over the entire period. As for maternal age, the DZ rate increased up to the age group 35-39 and decreased thereafter. The same tendency is seen in the MZ rate, but the maternal age effect is less marked than in DZ twins. The same tendency is also seen in the overall rate for 1975-1985. As for geographical variations, the MZ and DZ rates were computed in each prefecture for 1955-1959 and in 1974. The DZ rate increased from a low level in the southwest of Japan to a high level in the northeast for both periods, whereas the MZ rate was rather constant in 1974 throughout Japan. As for seasonal variation, the highest rates per 1,000 births for MZ(4.56) and DZ(2.20) twins were seen in April, with the lowest rate in September (3.69) for MZ twins and in July (1.71) for DZ twins.
Intrapair Differences of Physical Aging and Longevity in Identical Twins
Authors: Hayakawa K. , Shimizu T. , Ohba Y. , Tomioka S. , Takahasi S. , Amano K. , Yura A. , Yokoyama Y. , Hayakata Y.
Published: July 2016

The genetic and environmental contributions to physical aging (hair graying, balding, presbyopia) and longevity (age at death) were examined by within-pair comparison in monozygotic (MZ) and dizygotic (DZ) twins in later adulthood. Physical aging was investigated on 135 pairs of adult twins aged over 50. Hair graying and hair loss (baldness) showed significantly higher rates of concordance in the MZ twins than in the DZ twins. The intrapair difference of the degree of hair graying was negligible in 79%, slight in 15% and striking in 5% among the MZ pairs; while negligible in 40%, slight in 50% and striking in 10% among the DZ pairs. The intrapair difference of the degree of hair loss was negligible in 92%, slight in 8% (and striking in none) among the MZ pairs; while negligible in 69%, slight in 25% and striking in 6% among the DZ pairs. The age at onset of presbyopia showed a slightly higher rate of concordance in the MZ than in the DZ pairs. Longevity (age at death) was surveyed on 184 pairs of twins who died at over 40 years of age. The intrapair difference of longevity was 6.65 ± 5.6 years (maximum 18.0; minimum 0.04) in the MZ pairs, and 8.66 ± 7.2 years (maximum 18.6; minimum 2.9) in the DZ pairs. The MZ pairs showed a slightly smaller within-pair difference of longevity than the DZ pairs.
Risk Factors for Cognitive Aging in Adult Twins
Authors: Hayakawa K. , Shimizu T. , Ohba Y. , Tomioka S.
Published: July 2016

Monozygotic (MZ) and dizygotic (DZ) twins in later adulthood were studied in order to examine genetic and environmental contributions to the decline of cognitive performance. In this study, 118 twin pairs took a comprehensive medical examination at a university hospital. Cognitive function was measured by the Wechsler Adult Intelligence Scale (WAIS). The intraclass correlation coefficients on Digit Span (D) and Digit Symbol (DS) subtests of the WAIS did not show any significant difference between MZ and DZ twins although Block Design (BD) showed a significant difference. The values of the intraclass correlation coefficients were mostly around 0.5 and showed significant within-pair similarity of test scores. The mean score of D, DS and BD declined with advancing age. The intraclass correlation coefficients for D, DS and BD were around 0.2 in the MZ twins reared apart, and around 0.6 in the MZ twins reared together. These results indicated a significant environmental influence on cognitive aging in later adulthood.
Twinning and the r/K Reproductive Strategy: A Critique of Rushton's Theory
Authors: Allen G. , Eriksson A.W. , Fellman J. , Parisi P. , Vandenberg S.G.
Published: July 2016

The theory of r selection, favoring population growth, as opposed to K selection, favoring more efficient utilization of resources, has in recent years been applied by Rushton to contrast human ethnic groups in terms of their r/K reproductive strategies, suggesting the existence of a continuum from r groups, producing many offspring but providing little parental care, to K groups, producing few offspring but providing much parental care. Rushton's theory, which is largely based on ethnic differences in twinning rates, is here critically examined. It is pointed out that twinning rate differences are not necessarily genetic in origin since various environmental factors clearly play a role, and also that twinning, as a mode of reproduction, is not necessarily an r strategy, considering the high prenatal and perinatal selection to which it has been, and still is, associated. Moreover, Rushton misinterprets a number of relevant aspects related to the biology of twinning. The claim that ethnic differences in twinning rates provide evidence for an r/K typology in human populations with respect to reproductive strategies does not appear to be warranted.
Triplet Pregnancy: A 10-Year Review of 105 Cases at Harare Maternity Hospital, Zimbabwe
Authors: Crowther C.A. , Hamilton R.A.
Published: July 2016

During the 10-year period, 1975-1984, 105 triplet pregnancies were delivered at Harare Maternity Hospital, Zimbabwe, among 286,338 pregnancies in the Greater Harare Unit, giving an incidence of triplets of 1:2,727. The mean gestational age at delivery was 32.5 wk with 81 women (77.1%) delivering before 37 wk. Primigravidas delivered at a significantly earlier mean gestational age (P < 0.05) and had a higher perinatal mortality (P < 0.001) compared with grand multigravidas. Of the 315 babies, 277 (87.9%) weighed < 2500 g. The overall perinatal mortality rate was 327‰, with a pernital mortality rate of 146‰ for infants weighing ≥ 1000 g. Women hospitalised for bed rest during the antenatal period had fewer perinatal deaths compared with those diagnosed during the antenatal period, but not hospitalised for bed rest (P < 0.02). No difference was found in the mean gestational age at delivery or the mean birth weights between these two groups. Among infants ≥ 28 wk gestation there were fewer perinatal deaths in triplets delivered by cesarean section compared with triplets delivered vaginally (P < 0.0004). This suggests that cesarean section may offer the optimal mode of delivery in triplet pregnancy.
Evaluation of Zygosity Diagnosis in Twin Pairs Below Age Seven by Means of a Mailed Questionnaire
Authors: Bønnelykke B. , Hauge M. , Holm N. , Kristoffersen K. , Gurtler H.
Published: July 2016

The mothers of a consecutive series of 125 same sexed pairs of twins aged 6 months to 6 1/2 years completed a mailed questionnaire concerning the physical similarity of the twin partners. Zygosity diagnoses were first determined blindly on the basis of the answers given by the mothers, who did not know the result of the blood group test when fullfilling the questionnaire. Next, the results were compared with the zygosity determination based on examination of erythrocyteserum- and enzyme-groups. It turned out that a few simple questions distinguished well enough between MZ and DZ pairs, with a frequency of misclassification of 4%, leaving 5% as unclassifiable. It is concluded that twin zygosity can be estimated by a simple questionnaire with sufficient accuracy even in very young twin pairs. This has relevant implications for more extensive twin studies where the use of a wide spectrum of serological characters would imply too high expenses.
Decline of the Twinning Rate in Brazil
Authors: de Moraes M.H. Baena , Beiguelman B. , Krieger H.
Published: July 2016

The twinning rate during a twenty-year period (1965-1985) was investigated at five-year intervals in four Brazilian hospitals. During this period the twinning rate has decreased significantly (from 10.68‰ to 8.11‰), being highly negatively correlated with the five-year intervals (r = −0.97). This change was due mainly to the decline in dizygotic twinning, since the incidence of DZ twins has fallen from around 7‰ in 1965 to around 3.6‰ in 1985. The detected decline in DZ twinning seems to be due to the remotion of the fertility advantage of the more fecundable DZ twin-prone women by the introduction of effective birth control at the present, while some other mechanisms are causing the decline irrespective of the type of twinning.
Analisi delle Dinamiche del Travaglio e del Parto Gemellare Mediante l'Uso di un Programma Computerizzato
Authors: Valle A. , Reina S. , Casini M.
Published: July 2016

Lo studio dei fenomeni dinamici del travaglio e del parto gemellare suggerisce che l'azione uterina inefficace è un fenomeno frequente; l'uso dell'ossitocina per accelerare il travaglio è controverso, soprattutto per la relativa difficoltà di monitorare en-trambe i gemelli in maniera soddisfacente. Inoltre, non esiste consenso su quale sia l'in-tervallo di tempo ideale tra il parto del primo gemello e quello del secondo. Uno dei motivi principali delle divergenze di opinioni su quale debba essere la condizione ottimale del travaglio e del parto gemellare, è la relativa bassa incidenza della gravidanza gemellare, fenomeno che, all'interno di ogni singola unità ostetrica, spesso impedisce una analisi statisticamente significativa dei dati. Recentemente è stato proposto un programma computerizzato (PartoSoft) che, oltre alla raccolta e alla analisi statistica dei dati, permette la visualizzazione e la stampa del partogramma costruito dal computer sulla base degli eventi del travaglio e del parto precedentemente immessi nella banca dati. Il programma prevede una immissione dati specifica per il travaglio ed il parto gemellare. Con la modalità “partogramma multiplo” è possibile visualizzare e quindi studiare contemporaneamente decine di curve relative ad altrettanti travagli gemellari. In questa maniera si possono correlare le modalità di travaglio e parto a numerosi parametri clinici: parità, dilatazione cervicale all'inizio del travaglio, stato delle membrane, uso dell'ossitocina, situazione e presentazione, tipo di analgesia, indicatori di benessere alla nascita (punteggio di Apgar, equilibrio acido-base sui funicoli ombellicali) e pesi alla nascita con percentili.

L'adozione di questo programma su scala nazionale permetterebbe la centralizzazione e l'analisi dei dati relativi ai 6000-7000 travagli e parti gemellari che si verificano ogni anno in Italia permettendo di rispondere in modo scientifico ai numerosi quesiti ancora irrisolti.
Incidence and Neonatal Mortality of Twins: Italy 1981-90
Authors: Pugliese A. , Arsieri R. , Patriarca V. , Spagnolo A.
Published: July 2016

The aims of this study were: 1) to study the characteristics of birth and neonatal mortality (NM) rates of twins as compared to singletons in recent years in Italy; 2) to evaluate NM rate differences among twins and singletons by birthweight: 3) to calculate the cause-specific NM rates among singletons and twins. Data concerning all live-born infants were obtained from the birth and death records of the Italian Institute of Statistics (ISTAT) for the years 1981, 1985, 1989 and 1990 and were analyzed by the Statistics Office of the Italian National Institute of Health. Between 1981 and 1990 the incidence of twins increased from 18.3 to 19.1 per thousand livebirths. This increase was mainly related to twins resulting from multiple pregnancies, thus, the proportion of twins weighing < 1500g also increased from 67 to 77 per thousand. Twins accounted for 10% of overall neonatal mortality in 1981 and 14% in 1990. Between 1981 and 1990 in the Centre-South of Italy the crude NM rates showed a greater decrease among singletons than among twins, while in the North the decrement involved both singletons and twins. The birthweight-specific NM rate showed a steady improvement in survival for twins rather than for singletons in the 1500-2499g weight range. Taking each cause of death in 1989-90, NM rates were considerably higher for twins compared to singletons, Twin mortality risks due to newborn respiratory distress syndrome (RDS) and asphyxia were respectively 11 and 8 times that of singletons. The comparison between twin NM rates in the three geografical areas and in relation to the cause of death indicated a greater incidence of RDS and asphyxia in the Centre-South than in the North.

This study offers indications on the planning of perinatal care in order to improve twin survival in the Centre and South of Italy, particularly with regard to the prevention and care of asphyxia-RDS.
Genetic and Environmental Effects on Blood Cells
Authors: Colletto G.M.D. Dal , Fulker D.W. , Barretto O.C. de O. , Kolya M.
Published: July 2016

In a sample of 105 concordant sex MZ and DZ twin pairs, the following characteristics were measured: red cell count, haemoglobin concentration, package cell volume, mean cell volume, mean cell haemoglobin, mean cell haemoglobin concentration, reticulocytes, platelets, white cell count and the six types of leucocytes, lymphocytes, monocytes, band and segmented neutrophils, eosinophils and basophils. The statistical model employed in the univariate twin analysis allows for three sources of variation: genetic (h2), shared environmental (c2) and specific environmental influences (e2). A genetic component was significant for red cell count, haemoglobin and mean cell haemoglobin (0.64, 0.60 and 0.46 respectively), with heritable variation suggested for package cell volume, mean cell volume, mean cell haemoglobin, lymphocytes and monocytes. Shared environmental variation was only present for neutrophils.
Conjoined Twins - An Epidemiological Study Based on 312 Cases
Authors:   The International Clearinghouse for Birth Defects Monitoring Systems
Published: July 2016

Data on conjoined twins have been collected from 14 different malformation monitoring programs around the world. Among over 28 million births, 312 cases were identified. After considering underascertainment in one large program, the best estimate of the incidence based on the sum of induced abortions and births is 1.3 per 100,000 births. The distribution according to type of twinning, the sex distribution (39% males) and the stillbirth rate (47%) are presented. The presence of malformations not directly related to the area of fusion is discussed. In three women, thyroid disease was present and five women had been treated for infertility before conception.
The Definition, Diagnosis, and Management of Growth-Discordant Twins: An International Census Survey
Authors: Blickstein I.
Published: July 2016

In order to establish a protocol considering the definition, diagnosis, and management of growth-discordant twin gestations, a questionnaire was sent to 96 authors of twin-related obstetric articles. The views of the 61 responders comprise this international census survey. The data suggest that a clear cut-off value for discordancy is still needed; however, the data indirectly supported a two-grade definition, namely, mild (> 15% and < 25% birth-weight disparity) and severe (> 25%) growth discordants. Expectant management was advocated by the majority of participants with out-patient follow-up for mild discordants, while severe discordants may preferably be hospitalized. Follow-up should be done by non-stress testing (daily - 2/wk), biophysical profile (1-2/wk), Doppler velocimetry (1/wk - bi-weekly) and sonographic biometry (bi-weekly). The opinions considering termination of pregnancy because of intertwin growth discordancy were divided; however, discordancy per se, was not considered an indication for cesarean delivery. An adapted management flowchart that summarizes the survey's data is presented and may be used as a standard for future investigations.
Higher Order Multiple Births: Natural Wonder or Failure of Therapy?
Authors: Grützner-Könnecke H. , Grützner P. , Grützner B. , Grützner U. , Spalding-Grützner A. , Spalding P.
Published: July 2016

Data of 601 families with triplets and higher multiples have been collected. Since about nine years the number of higher-order births has been increasing enormously. The average pregnancy duration and the average birthweight of these mostly premature children have been declining from year to year. Despite the progress in neonatology, the death rate and the rate of handicapped children is very high. To prevent such disastrous outcomes, treatments for infertility should be performed only by physicians in centers with strong controls. Selective abortions are no regular solution to the problem of higher multiple gestation.
The End of Reproductive Life in Mothers of Twins: Epidemiologic Analysis of a Large Data Base
Authors: Philippe P.
Published: July 2016

A case-control study was conducted on the termination of menstrual life on mothers of twins. It involves a much larger data base and finer analyses, and makes use of the same methodology of a previous study. The time interval between the twin and the last confinement proved to be shorter in twin-bearing mothers than in a matched set of controls with singletons only after blocking of the effect of birth order, and despite the similarity of maternal age at delivery and confinements numbers. Mothers of like-sex twins only appeared to terminate reproductive life earlier than controls. The separate study of maternal age at twin confinement shows that the earlier the twin birth the shorter the menstrual life thereafter. Both like-sex twin births and early maternal age at delivery of a twin pair have the same shortening effect on subsequent menstrual life without clear evidence of additivity of effects as if both occurrences were alternatives with similar biological effects. Comparison of the results of the current study with those of our earlier analysis shows consistency on above results. However, the current study could not reproduce previous results on the role of unlike-sex twins or late maternal age at delivery on time to last confinement; yet, they cannot be discarded. It is suggested that increased power of interaction analyses and tighter matching of controls with respect to sex might improve the conclusions of subsequent studies.
Perinatal Mortality in Twins, Australia, 1973-1980: I
Authors: Doherty John D.H.
Published: July 2016

The perinatal outcome of twin births in Australia is described from 1973 to 1980. Over that period, the perinatal mortality rate declined more slowly in twins that singletons. The stillbirth rate actually increased in twins due to a rise in antepartum deaths. An increasing proportion of monozygotic twins may have contributed to this trend. The overall perinatal mortality rate was 82.85/1,000 for twins and 16.49/1,000 for singletons, giving a relative risk of 5.0.
The Epidemiology of Conjoined Twins in Latin America
Authors: Castilla E.E. , Lopez-Camelo J.S. , Orioli I.M. , Sánchez O. , Paz J.E.
Published: July 2016

Twenty–three cases of symmetrical conjoined twins were registered by the Latin-American Collaborative Study of Congenital Malformations (ECLAMC) in 1,714,952 births, which were observed during the 1967-1986 period in 95 maternity hospitals distributed in eleven Latin-American countries. This results in a birth prevalence rate of about 1/75,000 births. The secular and geographic distribution of this material do not depart from random in spite of one hospital with three cases, and two hospitals with two cases each, within a short time period. These 23 cases include one diprosopus, 3 dicephalus, one ischiopagus, 5 pygopagus, none dipygus, 3 syncephalus, none craniopagus, 9 thoracopagus, one omphalopagus, and none rachipagus. Sex distribution is even, with 12 male and 11 female cases.
The Northwestern University Twin Study. V: Twin Deliveries at Prentice Women's Hospital and Maternity Center, 1978-83
Authors: Keith L.G. , Depp R. , Method M.W. , Wittman R. , Lopez-Zeno J. , Minoque J. , Nearhing R. , Keith D.M.
Published: July 2016

Two hundred fifty-one twin deliveries between January 1, 1978 and June 30, 1983 at Prentice Women's Hospital and Maternity Center were reviewed. Cases were excluded if birth weight was less than 500 g, if gestational age was less than 26 weeks or if an antenatal fetal demise had occurred. Maternal demographic characteristics, delivery data and infant characteristics are described. The effect of providing care to a high-risk population of mothers in whom approximately 60% either deliver thair infants preterm or with a birth weight of less than 2,500 g is discussed in terms of costs of care.
Perinatal Deaths in Twin Pregnancy: A 22-Year Review
Authors: Lumme R.H. , Saarikoski S.V.
Published: July 2016

Changes in the management of 1120 twin pregnancies delivered in Tampere University Central Hospital during the years 1964-1985 were studied, together with changes in the pattern of perinatal deaths. Perinatal mortality decreased from 7.4% in 1964-68 to 3.5% in 1981-85. There were no significant changes in stillbirths. The decrease of perinatal mortality resulted from a reduction in early neonatal deaths, mainly those due to respiratory distress syndrome. Changes in obstetric management include earlier diagnosis by ultrasound, intrapartum monitoring, and an increase in cesarean section rate from 4% to 32%. There is still a need for a reduction in the number of very early preterm births, and for more effective intrauterine supervision of twin pregnancies.
The Northwestern University Triplet Study. II: Fourteen Triplet Pregnancies Delivered between 1981 and 1986
Authors: Keith L.G. , Ameli S. , Depp O.R. , Hobart J. , Keith D.M.
Published: July 2016

Fourteen triplet deliveries conducted between 1 January 1981 and 30 June 1986 at the principal teaching hospitals of Northwestern University Medical School are reviewed. Maternal demographic characteristics are listed, as are the obstetric outcomes, including mode of delivery, and the fetal outcome. The recent literature of triplet delivery is reviewed.

The rate of triplet delivery in our study was 0.37 per 1,000 live births. About two-thirds of the pregnancies resulted from the use of fertility-inducing agents. Ultrasonic confirmation was available in all cases. The majority of women were delivered by cesarean section (85%). No consistent pattern of presentation was seen. The mean weight of all 42 infants was 1,779 g (± 594). Unlike-sex triplets accounted for most of the sets (77%). The mean 5-min Apgar score of all infants was 9 and had no association with the order of deliveries. The weight differences by sex regardless of birth order were clinically insignificant. Neonatal mortality was 2.3%
The Northwestern University Triplet Study. III: Neonatal Outcome
Authors: Collins J.W. , Merrick D. , David R.J. , Ameli S. , Ogata E.S.
Published: July 2016

Limited data suggest that cesarean section (CS) may be the preferred method of delivery for triplets. Despite this, it is also felt that the third triplet is at great risk at delivery. We reviewed our experience of 14 triplet pregnancies at Northwestern University between 1981 and 1985. All deliveries were attended by neonatal teams in sufficient number to resuscitate each infant. Of the 14 pregnancies, two ended in previable loss. Thirty-six infants were born from 12 pregnancies of a mean gestational age of 33 weeks (28-38 weeks). The overall survival was 97.3%. Two women delivered vaginally. While the first was successful, the second resulted in vaginal delivery of the first two triplets followed by emergency CS for the third. That infant had a cord blood pH of 6.96(BE-19), was resuscitated and survived. All 10 CS were successful. The mean cord blood gas tensions and pH were normal. In addition, Apgar scores, the requirement for mechanical ventilation or supplemental oxygen, and mortality did not differ between the first and thirdborn triplet. These observations suggest that CS was beneficial. Our very low mortality rate supports the concept that CS delivery and aggressive neonatal resuscitation and therapy greatly enhances survival.
Growth Characteristics in Twins and Higher Order Multiple Births
Authors: Buckler J.M.H. , Buckler J.B.
Published: July 2016

Measurements of height and weight have been undertaken on 201 pairs of twins and 46 sets of higher multiples once each at various ages through childhood. The heights of twins are comparable to the overall population of singletons, those of higher multiples are slightly undersized. However, the total group of twins were shorter than expected when compared with the heights of parents and siblings, but this was entirely accounted for by that component of the group who at birth had been very light for dates. The children in all groups of multiples were underweight for their height in comparison with standards of a comparable population and with their own siblings.
The Analysis of Marital Interaction in Cross-Sectional Twin Data
Authors: Heath A.C.
Published: July 2016

The effects on twin data of social interaction between spouses is examined. When social interaction leads to an increase in marital resemblance (eg through reciprocal imitation), the variance of married individuals is increased, compared to the variance of unmarried individuals. Furthermore, the expected correlations between concordant married twin pairs will be lower than the expected correlations between concordant unmarried twin pairs, with the discordant twin correlations being intermediate in value. It is therefore possible, in principle, to detect the effects of marital interaction without using either longitudinal data or data on spouse pairs. However, to be detectable in twin data, marital interaction must be strong, or must exhibit marked asymmetry of effects between males and females. Genotype × environment interaction can also produce heterogeneity of correlation between concordant married, discordant, and concordant unmarried twin pairs, when genetic and environmental effects interact with marital status. However, this will usually produce increased estimates of the genetic component of variance in unmarried twins, whereas marital interaction produces increased genetic variance in married twins.