Twin and singleton births in Ghana--a case-control study.

A retrospective study involving 623 twin and 1246 singleton births was conducted to compare the two groups with regard to selected maternal, fetal and labor and delivery characteristics and outcomes. Maternal age and parity were significantly higher for twins. The risks of preterm delivery, arrival in the labor ward in second stage of labor, cesarean births and postpartum haemorrhage were significantly higher in twin than in singleton births. In vaginal deliveries twin mothers were significantly less likely to have had episiotomies or perineal lacerations. There was no difference in the duration of the third stage of labor or in the incidence of retained placentae. Antepartum haemorrhage was a less likely indication for cesarean delivery among twins, while there was no significant difference in the likelihood of severe pre-eclampsia/eclampsia being an indication. Singleton babies were significantly heavier than twins. The incidences of malpresentation, low birth weight, stillbirths and of admission of live births to the neonatal intensive care unit were significantly higher in twins. There was no difference in the rate of instrumental vaginal delivery, or in the route of delivery of fetuses presenting by the breech. There is the need for detailed study of the incidences of antepartum haemorrhage and hypertensive diseases in twin and singleton pregnancies and of the factors determining the mode of delivery when such complications arise. Labor and delivery should also be examined to determine any differences between the two groups, especially in the first and second stages.     

Maternal age and birth weight characteristics of twins born to nulliparous mothers: a population study.

In order to examine birth weight characteristics of twins delivered to nulliparous mothers in relation to maternal age, we used a population-based cohort of Israeli twins delivered between 1993-98 to select all 4793 (37.6%) nulliparas who delivered twins. Maternal age was subdivided as less than 20 years, 20-24, 25-29, 30-34, 35-39, and 40 years or more. We counted the frequencies of each total twin birth weight (twin A + twin B) in each of three categories (less than 3000, 3000-4999, and more than 5000 g) and the frequency of very low birth weight (VLBW, less than 1500 g) neonates in each of the six maternal age categories. There were significantly more nulliparas in the twin population at age groups less 30 years and significantly less at ages 30 years or more. We found a highly significant inverse correlation between the proportion of nulliparas and maternal age group, decreasing from 71.8% at less than 20 years to 18.6% at age 35-39 years (% nulliparas = 85 - 13.7 x age group, Pearson R2 = 0.98). However, this trend changed abruptly to the observed figure of 25.9% nulliparas aged 40 years or more instead of the expected 2.8%. We failed to reveal any significant difference in birth weight characteristics between the maternal age groups (all p > 0.05, all confidence intervals included 1.0). The more than tenfold deviation of the observed from the predicted frequency of nulliparas aged 40 years or more suggests that a different relationship between parity and age occurs at this age group. Maternal age of nulliparas is not associated with different birth weight characteristics of their twins.     

The Italian Twin Project: from the personal identification number to a national twin registry.

The unique opportunity given by the "fiscal code", an alphanumeric identification with demographic information on any single person residing in Italy, introduced in 1976 by the Ministry of Finance, allowed a database of all potential Italian twins to be created. This database contains up to now name, surname, date and place of birth and home address of about 1,300,000 "possible twins". Even though we estimated an excess of 40% of pseudo-twins, this still is the world's largest twin population ever collected. The database of possible twins is currently used in population-based studies on multiple sclerosis, Alzheimer's disease, celiac disease, and type 1 diabetes. A system is currently being developed for linking the database with data from mortality and cancer registries. In 2001, the Italian Government, through the Ministry of Health, financed a broad national research program on twin studies, including the establishment of a national twin registry. Among all the possible twins, a sample of 500,000 individuals are going to be contacted and we expect to enrol around 120,000 real twin pairs in a formal Twin Registry. According to available financial resources, a sub sample of the enrolled population will be asked to donate DNA. A biological bank from twins will be then implemented, guaranteeing information on future etiological questions regarding genetic and modifiable factors for physical impairment and disability, cancers, cardiovascular diseases and other age related chronic illnesses.     

A gerontological cohort study of aged twins: the Osaka University Aged Twin Registry.

We describe subject recruitment and research results from the Osaka University Aged Twin Registry (OUATR). The research focus of OUATR is the genetic and environmental contributions to physical-cognitive-mental aging which we examined in Japanese twins in later adulthood. Within this large-scale registry (12,000 pairs) of oriental twins born between 1900 and 1935, approximately 10% of participants are MZ twins reared apart from early childhood. Two hundred and fifty pairs have had comprehensive medical examinations, including various blood chemical panels, lymphocyte subtests, WAIS (Wechsler Adult Intelligence Scale), and urine analysis. The future foci of this study are primarily on longevity, decline of cognitive functions with aging, bio-physiological functions, lifestyle and behavior genetics, and psycho-spiritual functions.     

Smell-recognition of newborns by women who are not mothers

Women without children held an unrelated infant in their armsfor 1 hr and then were tested for infant-smell-recognition.Most were successful. This indicates that the ability to identifyinfants by thier odor is a more general human skill than previouslyrealized.     

The Danish Twin Registry: 127 birth cohorts of twins.

The Danish Twin Registry is the oldest national twin register in the world, initiated in 1954 by ascertainment of twins born from 1870 to 1910. During a number of studies birth cohorts have been added to the register, and by the recent addition of birth cohorts from 1931 to 1952 the Registry now comprizes 127 birth cohorts of twins from 1870 to 1996, with a total of more than 65,000 twin pairs included. In all cohorts the ascertainment has been population-based and independent of the traits studied, although different procedures of ascertainment have been employed. In the oldest cohorts only twin pairs with both twins surviving to age 6 have been included while from 1931 all ascertained twins are included. The completeness of the ascertainment after adjustment for infant mortality is high, with approximately 90% ascertained up to 1968, and complete ascertainment of all liveborn twin pairs since 1968. The Danish Twin Registry is used as a source for large studies on genetic influence on aging and age-related health problems, normal variation in clinical parameters associated with the metabolic syndrome and cardiovascular diseases, and clinical studies of specific diseases. The combination of survey data with data obtained by linkage to national health related registers enables follow-up studies both of the general twin population and of twins from clinical studies.     

Reproductive hormone genes in mothers of spontaneous dizygotic twins: an association study

There are important genetic influences on the tendency to dizygotic (DZ) twinning and it is a plausible hypothesis that these reside in one or more of the genes coding for the major reproductive hormones. We used Southern analysis of DNA from 50 young (<32) mothers of DZ twins, who also had a family history of DZ twinning, and 50 controls, to examine allele frequencies of five restriction fragment length polymorphisms (RFLPs) in four hormone genes coding for follicle stimulating hormone (FSH), chorionic gonadotropin (CGB), inhibin _B and gonadotropin releasing hormone (GnRH). Comparison of allele frequencies revealed no significant differences between DZ twin mothers and controls. However this does not rule out the role of these genes in the hereditary tendency of multiple ovulation in humans, since absence of linkage disequilibrium does not imply absence of linkage.     

Weight growth in infants born to mothers who smoked during pregnancy.

OBJECTIVE--To determine whether maternal smoking during pregnancy causes impairment in growth after birth. DESIGN--Longitudinal study. SETTING--Six medical university centres of six towns of north, central, and south Italy. SUBJECTS--12,987 babies (10,238 born from non-smoking mothers, 2276 from mothers smoking one to nine cigarettes a day, and 473 from mothers smoking > or = 10 cigarettes a day) entered the study. MAIN OUTCOME MEASURES--Difference in weight gain between children born to smoking mothers and those born to non-smoking mothers. Weight was measured at birth and at 3 and 6 months of age. Maternal smoking habit was derived from interview on third or fourth day after delivery. RESULTS--Compared with children born to mothers who did not smoke during pregnancy, the birth weights of children born to mothers who smoked up to nine cigarettes a day were 88 g (girls) and 107 g (boys) lower; in children born to mothers who smoked > or = 10 cigarettes a day weights were 168 g and 247 g lower. At six months of age for the first group the mean weight for girls was 9 g (95% confidence interval -47 g to 65 g) higher and for boys 64 g (-118 g to -10 g) lower than that of children born to mothers who did not smoke. The corresponding figures for the second group were 28 g (-141 g to 85 g) lower for girls and 24 g (-136 g to 88 g) lower for boys. CONCLUSIONS--The deficits of weight at birth in children born to mothers who smoked during pregnancy are overcome by 6 months of age. These deficits are probably not permanent when smoking habit during pregnancy is not associated with other unfavourable variables (such as lower socioeconomic class).     

Clinical anophthalmia: an epidemiological study in northeast Italy based on 368,256 consecutive births.

We describe an epidemiological and clinical study of Clinical Anophthalmia in a population of consecutive live and stillborns enrolled in a hospital based registry of congenital malformations in Northeast Italy during the period from 1981 to 1989; 22 cases were detected among 368,256 births yielding a birth prevalence of 0.60 per 10,000 (95% CI 0.34-0.84); 20 cases were associated with at least one other major malformation. Malformation syndrome, association, or sequence was diagnosed in 13, while a non-recognizable multiple defect pattern was observed in 7/20 (35%). A chromosomal anomaly was present in eight syndromic cases. No significant trend over time, nor space or time clusters, were detected. As most CAn cases are associated with other anomalies recognizable by ultrasound, a decreasing trend in its prevalence at birth is expected in the future.     

Similarity of social security numbers among twins: data from the Virginia Twin Registry.

At least two twin registries in the United States have been or are being assembled using the similarity of Social Security Numbers in computerized records to help identify possible twin pairs. While the success of such enterprises depends directly on a high probability of twinness given Social Security Numbers, there are theoretical and practical reasons to study the probability of Social Security Number similarity given twinness. For example, the number of twin pairs with similar Social Security Numbers obviously determines the maximum number of twin pairs that can be discovered by similarity algorithms. To study this issue, we examined the similarity of known Social Security Numbers in twin pairs from the Virginia Twin Registry by age, sex, race, and zygosity of the pair. We found that similarity between the Social Security Numbers of twin pairs varies markedly by age, and MZ twin pairs have significantly more similar Social Security Numbers than DZ pairs at all ages. Among older twins, there are also significant differences by sex and race. For younger twins, algorithms that identify putative twin pairs on the basis of the similarity of their Social Security Numbers hold the promise of being able to identify a large proportion of all true twin pairs. Such algorithms will be substantially less successful, however, in identifying a large proportion of older twin pairs.     

Challenges in recruiting older twins for the Sri Lankan twin registry.

The National Twin Registry of Sri Lanka was established in 1997 as a volunteer register. To extend it to a population-based register, we examined the effectiveness of tracing older twins by inspecting birth records and recruiting them by postal invitation and in-person contact. Birth records at a divisional secretariat reported from 2 maternity hospitals between the years of 1954-1970 were scrutinised to identify a random sample of twins. These hospitals had the highest twin delivery rates for the whole country. We identified 620 twins and a questionnaire was mailed to them. Research assistants visited a cohort of non-respondents (71) in the postal survey. These 620 twins were identified after perusing 20700 birth records. The twinning rate was estimated at 29.95 ([620/20700] x 1000) twins per 1000 registered births (CI 27.63-32.27). In the postal survey, 37 (12%) responded and 62 letters were returned (20%). Both twins were still alive in 20 pairs, one was still alive in 15 pairs, and both twins were dead in 2 pairs. During field visits, 42 (59.2%) addresses were located. Information was available on 16 twin pairs. Both twins were alive in 8 pairs, one each in 4 pairs, and both were dead in 4 pairs and at least one twin was traced in 10 pairs (14%). Both the postal and the field survey gave a low yield. This finding is different from tracing younger twins born between 1985-1997 by using the same methods. Migration, urbanization and development in the country might have affected tracing older twins from the birth record addresses, which were decades old.     

Prenatal and postnatal prevalence of Turner's syndrome: a registry study.

OBJECTIVE--To study prevalence of Turner''s syndrome in Denmark and to assess validity of prenatal diagnosis. DESIGN--Study of data on prenatal and postnatal Turner''s syndrome in Danish Cytogenetic Central Register. SUBJECTS--All registered Turner''s syndrome karyotypes (100 prenatal cases and 215 postnatal cases) during 1970-93. MAIN OUTCOME MEASURES--Prevalence of Turner''s syndrome karyotypes among prenatally tested fetuses and Turner''s syndrome among liveborn infants. RESULTS--Among infant girls, prevalence of Turner''s syndrome was 32/100,000. Among female fetuses tested by amniocentesis, prevalence of Turner''s syndrome karyotypes was 176/100,000 (relative risk of syndrome, 6.74 compared with prevalence among untested pregnancies). Among female fetuses tested by chorion villus sampling, prevalence of syndrome karyotypes was 392/100,000 (relative risk, 16.8). We excluded prenatal tests referred because of results of ultrasound scanning: among fetuses tested by amniocentesis revised relative risk was 5.68, while revised relative risk among fetuses tested by chorion villus sampling was 13.3. For 29 fetuses with prenatal diagnosis of possible Turner''s syndrome, pregnancy was allowed to continue and 24 children were live born. Thirteen of these children were karyotyped postnatally, and diagnosis of Turner''s syndrome had to be revised for eight, seven being normal girls and one boy. This gives tentative predictive value of amniocentesis in diagnosing Turner''s syndrome of between 21% and 67%. There was no significant relation between mother''s age and risk of Turner''s syndrome. CONCLUSIONS--Discrepancy between prenatal and postnatal prevalence of Turner''s syndrome challenges specificity of prenatal examination in diagnosing Turner''s syndrome.     

Parental consanguinity as a cause for increased incidence of births defects in a study of 238,942 consecutive births.

The risk for birth defects in the offspring of first-cousin matings has been estimated to increase sharply compared to non consanguineous marriages. As a general decline in the frequency of consanguineous marriages was observed in this century, one wonders whether consanguinity is still a factor in the appearance of birth defects in developed countries. Based on our registry of congenital anomalies we tried to answer to this question. In the population studied in North-Eastern France a consanguineous mating was known in 1.21% of the cases with congenital anomalies, vs. 0.27% in controls, (p < 0.001). The frequency of the malformations recorded paralleled the degree of consanguinity: out of 89 malformed children, 51 were seen in first-cousins mating (10.3 times more frequent than in offspring of non consanguineous couples), 17 in second-cousins marriages and 18 in more distant relatives mating. Three were uncle-niece marriage. Excluding known mendelian conditions these numbers were 73, 36, 17 and 17 respectively and the corresponding relative risk were 3.68, 3.01, 3.41 and 4.89 respectively. Therefore there is a negative dose-response effect between level of inbreeding and risk of congenital malformations. Consanguineous mothers were more often pregnant than non consanguineous mothers (p < 0.01) and they had more stillbirths than non consanguineous mothers. These results show that consanguinity is still a factor of birth defects and they must be taken into account for genetic counseling of inbred marriages, in developed countries.     

Stress and coping among mothers of twins in rural southwestern Nigeria.

High rates of twinning have been reported in Africa. This study sought to learn whether mothers of twins experience different stress levels than those who have only singletons. Both twin mothers (101) and singleton mothers (101) were interviewed. Using a scale of 15 stressors the researchers found that the mean stress score was significantly higher for twin mothers than singleton mothers. Higher stress scores were also associated with parity and perceptions of problems in caring for children and inversely related to perceived levels of social support. Confronting stressors or simply accepting them were the two main ways that mothers coped with their problems.     

Perceived Parenting Self-Efficacy (PMP S-E) of mothers who are breastfeeding hospitalised preterm neonates

Breastfeeding is a complex task for many mothers but may be particularly difficult when coping with the birth of a preterm. In the following article the task of breastfeeding a preterm neonate is identified as one facet of the parenting process and the many problems encountered when breastfeeding are highlighted. Research is presented which investigates whether breastfeeding a preterm neonate mediates mothers' Perceived Parenting Self-Efficacy (PMP S-E) whilst in hospital. The findings from this study suggest that not only do mothers who are breastfeeding their preterm neonate have a lower self-efficacy than non-breastfeeding mothers, but they also require further support in all aspects of parenting. The authors discuss these results in terms of self-efficacy theory and suggest that they may have implications for Neonatal Health Psychologists practice particularly with regard to the facilitation of breastfeeding within the neonatal unit.