The objective of this study was to evaluate the association between maternal factors, including rates of gestational weight gain before and after 24 weeks' gestation, and adequacy of intrauterine growth for gestational age at birth of triplets, as a mean Z-score of the triplet set. The study design was a retrospective, anonymous, pilot telephone survey of mothers of triplets and an historical cohort analysis of their prenatal weight gain records. The statistical analyses performed included multiple regression analysis to formulate a model for mean triplet Z-score (a measure of birthweight-for-gestational age) and analysis of variance to confirm and simplify the components of this model. Factors significant in the final model and their beta coefficients included weeks' gestation (-0.124, p <0.0001), rate of gain before 24 weeks' gestation (0.606, p = 0.005), and induced conception (−0.404, p = 0.01). Rate of gain > 1.5 lbs/week before 24 weeks was significant in the analysis of variance (p = 0.009). Better intrauterine growth for gestational age is achieved in triplet gestations with maternal weight gains of >1.5 lbs/week before 24 weeks' gestation.

In 184 autopsies of death newborns, stillborn infants and aborted fetuses (mostly with congenital malformations), 57 (30.98%) umbilical cord anomalies were discovered (38 M and 19 F): 19 cases with knots (10.32%), 17 with arterial agenesis (9.2%,), 8 with focal fibrosis of Wharton's jelly (4.34%), 7 with varices and thrombosis (3.8%0), and6 (3.25%) with other anomalies. Thirtyone of the fetuses were born from first pregnancy, 32 were stillborn and 26 premature.

Nineteen women attending a special multiple pregnancy antenatal clinic with a triplet pregnancy were randomly allocated to either bed rest in hospital from 24 weeks gestation onwards until delivery, or to continue conventional outpatient management. Conclusions are limited by the trial size, but the study suggests that routine hospitalization for bed rest decreases the incidence of preterm delivery and light-for-gestational age infants and reduces the need for intensive neonatal care. Although still compatible with change variation, the observations, if confirmed in a larger randomized study, would have considerable implications for clinical practice. The policy needs further evaluation in a large multicentred collaborative study.

We consider three alternative parametric models to describe genetic and environmental influences on smoking initiation and smoking persistence. Under the single liability dimension model, the same genetic and environmental influences which determine smoking initiation also influence smoking persistence. Under the independent liability dimensions model, independent initiation and persistence dimensions determine onset of smoking, and persistence in those who become smokers. The combined model also postulates separate initiation and persistence dimensions, but allows for the possibility that some smokers are so low on liability to smoke on the initiation dimension that they become ex-smokers for this reason. Reanalyses of London twin data published by Eaves and Eysenck support the single liability dimension model. We discuss the difficulty of reconciling this finding with the hypothesis that nicotine dependence is a major determinant of smoking persistence, but caution that sample sizes in the London twin study were small.

It has been suggested that the surviving cotwin and the mother are seriously affected when intrautrine fetal death of one monozygotic twin occurs. Several authors have reported brain damage in the surviving twin coexisting in utero with dead monozygotic cotwin. Most of such instances are monochorionic and show vascular communication between paired twins in the placenta. In a total of 133 pairs of monochorionic twins, death of one twin during pregnancy occurred in 33 cases (24.8%). Of 33 surviving twins, 8 babies suffered from porencephaly, cerebral palsy and other abnormalities. More unfavorable prognosis was recognized when a cotwin died in the latter half of pregnancy, while when a monozygotic cotwin died in the early stage of pregnancy, the surviving twin uneventfully grew to term in most cases.

A study of perinatal mortality in twins has been carried out concurrently in Ibadan, Nigeria, and Aberdeen, Scotland. In both areas perinatal mortality rates have been found to be four times higher in twins than in singletons, reaching up to 310 per 1000 in the monochorionic group in Ibadan. Moreover, rates have been found to increase considerably with maternal age and parity.

The genetical analysis of covariance structures is used to explore the genetical and environmental intercorrelations of impulsiveness and sensation seeking factors and their conformity to Eysenck's principal personality dimensions. The independent dimensions of psychoticism, extraversion, neuroticism, and lie scale are not found to give a very satisfactory account of the genetical factor structure. In particular, it is clear that impulsiveness and sensation seeking are not simple reflections of extraversion.

Some health related psychosocial correlates of the Eysenck neuroticism scale were examined in a questionnaire study of 1501 monozygotic (MZ) and 3455 dizygotic (DZ) male twin pairs representing the adult male twin population in Finland. In analyses of the individuals, 34% of the variance in neuroticism was associated to: psychological variables (stress of daily activities, life satisfaction, quality of sleep, and extroversion – the explanatory rate of this variable set was 30%), psychotropic drugs (5%), alcohol use (4%), and smoking (2%). Neuroticism was also associated to social, life change, and medical variables. In pairwise analyses, the heritability estimate (h2) was 0.54 for pairs living together and 0.39 for pairs living apart. It seems that heritability estimates are confounded by the closer intrapair relationship between members of MZ than DZ pairs. In pairwise analyses, 23% of the intrapair difference of neuroticism in MZ pairs was associated to intrapair differences in the aforementioned variables. The following explanatory rates were found: psychological variables, 21%; psychotropic drugs, 2%; alcohol use, 2%; and smoking, 1%. Neuroticism of pairs discordant for background variables showed similar intrapair differences as between individuals in the following variables: service vs farming work, use of alcohol, use of antacids, hypertension, heavy physical work, quality of sleep, changes of workplace for negative reasons, smoking, and use of tranquillizers. It appears that in Finland environmental factors explain at least 61% of the variability in neuroticism, and that factors determining neuroticism are also associated to health related behavior such as smoking, use of alcohol and psychotropic drugs.

Data on five tests of general and specific cognitive abilities, cognitive styles, and creativity, obtained from members of 60 identical and 63 fraternal Russian adolescent twin pairs, are presented. All tests are adaptations of standardized instruments widely used outside of the Soviet Union. Identical and fraternal twin correlations for general cognitive ability yielded a lower estimate of heritability (0.29) than generally found in other countries worldwide (0.52) although the twin correlations themselves are fairly comparable to figures from other countries and cultures — 0.83 and 0.69 for Russian identical and fraternal twin pairs, respectively, vs 0.86 and 0.60 for non-Russian identical, and fraternal twin pairs. Twin correlations for other cognitive-related abilities assessed were also comparable to correlations obtained outside the Soviet Union with the exception of creativity which yielded higher within-pair resemblance than reported in previous twin studies.

It is commonly, but incorrectly, assumed that the presence of genotype × environment covariance must necessarily reduce the heritability (h2) as estimated from twin data, when the formula used to obtain h2 makes no assumption about G × E covariance or assumes that it is zero. But, in fact, G × E covariance does not always reduce the genetic variance, and it can be shown under some conditions, an increase in the G × E covariance implies a greater genetic variance. The effect of G × E covariance on h2 as estimated from data on MZ and DZ twins, depends jointly upon the degree of assortative mating and the degree of environmental correlation between MZ twins and between DZ twins. A method, based on the solution of a pair of simultaneous quadratic equations, is proposed for estimating the range of h2 from twin data under varying assumed values for assortative mating, the environmental correlations between MZ and DZ twins, and the G × E covariance. The solution of three simultaneous equations permits direct estimation of the genetic variance, environmental variance, and G × E covariance, under varying reasonable assumed values for assortative mating and the MZ and DZ environmental correlations. Examples of the method are based on intelligence tests scores of MZ and DZ twins.

It is shown that the recent secular decline in DZ twinning rates in Italy was not solely due to secular changes in birth order or maternal age.

The extent of the decline differed in different maternal age-parity categories. It seemed to be greater in younger women than older ones for constant parity. The data gave no clear support to the suggestion that the decline is associated with social class.

It seems that this secular decline in Italy has not been greatly affected by the use of ovulation-inducing drugs.

Data on susceptibility to motion sickness were collected on a sample of 535 individuals divided into eight groups. The prevalence of motion sickness among Tibetans and Northeast Indians (28%) was slightly higher than Northwest Indians (26%). Generally speaking, females (27.3%) were more susceptible than males (16.8%). Among different groups, the highest incidence of susceptibility to motion sickness (SMS) was recorded in schizophrenic patients (30%), while the lowest in rowers (zero percent). Ears and eyes are the most potent receptors of provocative motion that causes sickness. Individuals with greater spatial and motor control, reflected in sports like rowing, athletics and professions like armed and paramilitary forces, were less susceptible to motion sickness.

The SMS was significantly higher in individuals who suffered from spatial disorientation (35.05%), migraine (26.31%), gastrointestinal disorders (26.82%) and those who were more sensitive to unpleasant odours (24.64%) and preferred sweet flavours (24.48%) than their counterparts. These correlates have been utilized to explain the genesis of sickness using threshold model. Genetic and environmental pathways are strongly advocated. Past episodes of motion sickness acted as a strong psychological attribute in determining further episodes. The roadway buses and trucks proved more effective passive transportation types that caused sickness. The voluntary stabilization of the head and neck movements and gaze control proved very effective natural measures adopted by 38% subjects to avoid or limit motion sickness. About 50% of susceptible individuals became less susceptible or fully acclimatized to motion sickness due to habituation. The mean age at acclimatization was 21.98 ± 5.93 years.

Scurvy, now regarded as a nutritional disorder due to the lack of the trace food constituent, vitamin C, is shown to be the end result of a typical genetic disease. This genetic disease syndrome has been named Hypoascorbemia. Its primary cause is the hereditary lack of — or defect in — the gene controlling the synthesis of the enzyme, L-gulonolactone oxidase. This is a mammalian liver enzyme, the last one in the series for converting glucose into ascorbic acid. Man is one of the few mammals that lacks this enzyme and hence is unable to sythesize his own ascorbic acid. The gene defect occurred during the course of evolution by a conditional lethal mutation. The replacement of the present vitamin C theory regarding the etiology of scurvy by this genetic concept gives important new viewpoints to the quantitative aspects of ascorbic acid in human physiology and also provides new rationales for the use of high levels of ascorbic acid in normal physiology and in the therapy of clinical entities other than scurvy.

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.

The incidence of twinning in Western Nigeria is very high, being 45‰ (Nylander, 1969a), as compared with 11-12‰ in Caucasian populations (Registrar General, 1967). A recent study of twinning in Ibadan, in which zygosity of individual twin pairs was determined, has shown that the pattern of placentation and zygosity in this population is also very different from that in Caucasian populations.

As many as 1475 consecutive newborn twin pairs delivered in three hospitals in Ibadan between March 1967 and April 1969 were investigated.

The placentae of the twins were examined macroscopically by the author personally to determine the form (whether single, fused, double or separate) and the membrane relationships (whether monochorionic or dichorionic) as shown in Figs. 1 and 2. The membrane relationship was confirmed by histological examination.

Cord blood samples were collected from each twin pair and studied for (1) ABO, Rh (using antisera, C, c, D, E, e), MNSs and Gonzales blood groups and (2) G6PD electrophoretic pattern. Other blood groups like Fya, k and Jk, used initially, were discontinued later, because the gene frequencies in this population are such that they are uninformative for zygosity determination.

Samples of the placenta of each twin were sent in refrigerated containers to the Galton Laboratory, London University, for placental enzyme studies — phosphoglucomutase and peptidase (Hopkinson and Harris, 1968; Lewis and Harris, 1967).

Factors presumed to influence intrauterine growth were analyzed among 192 twin pairs. Mean birthweight was considerably reduced compared to single pregnancies, and a high proportion of twins were growth retarded (12.4%). One fifth of the twin pairs presented an intrapair birthweight difference exceeding 20%. DZ twins were sligthly heavier than the MZ, while dichorionic twins had a somewhat higher birthweight than the monochorionic. The intrapair weight differences were greater in twins with fused dichorionic placentae than in those with separate ones. The umbilical cord insertion seemed to influence intrauterine growth. Fetuses with velamentously or marginally inserted cords presented more frequently retarded growth than twins with centrally inserted umbilical cords. Though a total of 13 cases of twin transfusion syndromes were observed, these were not characterized by great intrapair weight differences.

Out of 296 mothers of twins interviewed about difficulties encountered while rearing twins, 49% mentioned inadequate sleep, 18% financial strain, 39% emotional disturbance, 22% disturbance in the marital relationship, and 43% lack of time to take care of other children. With the growth of twins, the problems gradually decreased, except for emotional disturbance, the most difficult period being the first year. Only 15% reported leaving the babies in the care of relatives during the day time. Overall, 68.2% felt the support from the father, but 39% of them felt the support was useless; 49% felt support from the mother-in-law, but 43% of them regarded the mother-in-law to be of no help; 36% were supported by their own mothers, but 54% mentioned that they had received little help. One must conclude that social support from relatives was inadequate. Public policy should take this fact into account and provide public health nurses and social workers to help the mothers of twins, especially during the first year.

A nine-year-old girl with short stature was referred to the department of pediatrics at Kyushu University. The clinical diagnosis was Turner syndrome; karyotypic analysis performed on peripheral blood, using GTG techniques, demonstrated a 45,X/47,XYY (17:83) mosaicism. Her twin brother, a phenotypically normal male, had the same karyotype; 45,X/47,XYY (3:97) on peripheral blood. Their skin fibroblast karyotypes showed the same mosaicism, ie. 45,X/47,XYY (41:59 and 31:69 respectively). On eleven biochemical genetic markers the twin pair were concordant, thus the likelihood of monozygosity was 0.99527034. In addition, the analysis of variable number of tandem repeat (VNTR) markers revealed the likelihood of monozygosity to be 0.99944386. The most plausible explanation of the X/XYY mosaicism was nondisjunction of the Y in the first cleavage division of the 46,XY zygote. A disproportionate rate of cell populations with 45,X and 47.XYY in the twinning process of the X/XYY embryo, especially in the germ lines, would result in discordant sex in twin pairs.

Patterns of NOR activity in 640 metaphase spreads from twelve monozygotic (MZ) and eight dizygotic (DZ) twin pairs were studied to evaluate the heritability of this chromosomal heteromorphism. NORs were stained by a modification of the Ag-AS technique and counterstained with quinacrine mustard dihydrochloride to facilitate chromosome identification and assess their value in zygosity determination. In this study, all karyotypes were read blind with respect to zygosity and pair membership.

A discriminant function analysis of pair score differences in MZ and DZ twins revealed that, in our sample, the probability of accurately determining zygosity with NOR scores was 0.93 and with QFQ scores was 0.99. We conclude that NOR and QFQ scores are highly heritable and of great value in zygosity determination.

Data were collected from 687 metaphase spreads on the frequency with which an acrocentric chromosome was found in a satellite association. A significant correlation was found between this frequency and the degree of Ag-AS stain of the NOR. This study, therefore, confirms previous results showing that a high degree of NOR activity is found in those chromosomes most often involved in satellite associations.

The Indian populations of the State of Santa Catarina, Brazil, are found in two places, Duque de Caxias and Xapecó. In the former live Aweikoma (possibly a Caingang subgroup), Caingang and Guarani; in the latter, Caingang and Guarani. The Aweikoma intercross freely with the Caingang, and the Aweikoma/Caingang group thus formed can be compared with the Caingang of Xapecó. The Guarani, on the other hand, are reproductively isolated from both populations. The Aweikoma/Caingang of Duque de Caxias and the Caingang of Xapecó differ from each other in characteristics related to racial composition (degree and amount of non-Indian genes), gene flow, average age of mothers and frequency of stillbirths. On the other hand, they show similarities in a series of demographic variables related to fertility, mortality and inbreeding levels. The index of total selection intensity is practically the same in the two localities.