RESUMO
OBJECTIVES: We examined whether and when differences in body size disappear over time and whether twins attain normal final height and body mass index (BMI). STUDY DESIGN: Height, weight, and BMI data of twins at ages 1, 4, and 18 years were compared with data from their nontwin siblings. Second, twin and sibling data were compared with population standards. In addition to height, weight, and BMI, data on body proportions at age 18 years were analyzed. RESULTS: At the age of 18 years, twins were as tall as their siblings but were significantly leaner. Compared with children from the general population, adolescent twins attained the same height and BMI. Birth weight was shown to have a considerable effect on height in adolescent twins. CONCLUSIONS: Twins attained normal final height compared with siblings and children from the general population. No differences in BMI were shown between 18-year-old twins and children from the general population, whereas the siblings of twins had increased BMI values compared with the general population.
Assuntos
Desenvolvimento do Adolescente/fisiologia , Tamanho Corporal/fisiologia , Desenvolvimento Infantil/fisiologia , Irmãos , Gêmeos/fisiologia , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Países BaixosRESUMO
OBJETIVOS: avaliar a prevalência de nascimentos gemelares em Pelotas, RS, em três períodos da última década e a influência de alguns fatores sobre este processo. MÉTODOS: estudo de corte transversal (série temporal), baseado no banco de dados do Programa de Monitorização de Defeitos Congênitos, onde se encontram registrados todos os nascimentos ocorridos nos cinco hospitais da cidade de Pelotas, nos anos de 1993, 1997 e 2003. RESULTADOS: a taxa média de gêmeos por mil nascimentos foi de 8,95ë (monozigóticos=2,20ë e dizigóticos=6,76ë ). A taxa de triplos ficou em 0,07ë . A taxa total de nascimentos gemelares, assim como de gêmeos monozigóticos e dizigóticos sofreu elevação no período. A média de idade (27,53 anos) e da ordem gestacional (2,35) das mães de gêmeos foi significativamente mais elevada do que das mães de únicos (26,03 anos e 2,14) respectivamente. Verificaram-se números aproximados de partos gemelares e únicos nos diferentes grupos de renda materna analisados. CONCLUSÕES: as mães com idade maior ou igual a 30 anos foram responsáveis pelo aumento da taxa de gêmeos em Pelotas. A média mais elevada de ordem gestacional em mães de gemelares descartou o uso significativo de técnicas de reprodução assistida.
OBJECTIVES: to evaluate the prevalence of twin births in Pelotas, Rio Grande do Sul, Brazil, during three periods, and the influence of a number of factors on this occurrence. METHODS: a cross-cutting (multiple time series) study was carried out, using the database of the Congenital Defect Monitoring Program, which registers all of the births occurring in the five hospitals of the city of Pelotas, for the years 1993, 1997 and 2003. RESULTS: the mean prevalence of twin births per thousand births (ë )t was 8.95ë (monozygotic=2.20ë and dizygotic=6.76ë ). The prevalence of triplets was 0.07ë . The total prevalence for twin births, in the case of both monozygotic and dizygotic twins rose over the period studied. The mean age of the mother (27.53 years) and the order in the series of gestations (2.35) were significantly higher in cases of twin births than in cases of the birth of a single infant (26.03 years and 2.14 respectively). CONCLUSIONS: mothers aged >30 years were responsible for the increase in the prevalence of twin births in Pelotas. The higher mean position in a sequence of gestations among mothers of twins ruled out the significance of the use of fertility treatment techniques.
Assuntos
Humanos , Feminino , Gravidez , Recém-Nascido , Adulto , Coeficiente de Natalidade , Gravidez Múltipla/estatística & dados numéricos , Idade Materna , Brasil/epidemiologia , Estudos Transversais , Gêmeos/fisiologia , Renda , Prevalência , Fatores SocioeconômicosAssuntos
Peso ao Nascer , Desenvolvimento Fetal , Idade Gestacional , Gêmeos , Ultrassonografia Pré-Natal , Adulto , Feminino , Humanos , Recém-Nascido , Masculino , Valor Preditivo dos Testes , Gravidez , Gêmeos/fisiologiaRESUMO
A female spider monkey (Ateles belzebuth belzebuth) that gave birth to twins was studied during 13 months, and her activity budget and diet were compared to those of females with single offspring and females with no offspring to assess selective pressures that could influence litter size. We recorded qualitative information on the development and social interactions of the twins and three other single infants. Emi, the female that had the twins, had the highest proportion of resting time and the lowest proportion of feeding and moving time compared to other adult females and males. Emi also had the lowest average daily travel distance and relied more heavily on flowers and leaves than other group members who included a higher proportion of fruits in their diets. These results suggest that twins are energetically costly to spider monkeys because of the direct energy allocated into raising and carrying the twins and, also, because these costs have direct effects in the ability of a mother to obtain high-quality resources (e.g., fruits). The twins had a slower rate of physical and social development as well as a smaller body size compared to same-aged singletons by the end of the study. Thus, the extended periods of maternal care and the costs associated with rearing and carrying offspring are some of the factors that influence the evolution and maintenance of a litter size of one in most anthropoid primates.