Biomedical subjects

Akio Asaka

Publications and source records attributed to Akio Asaka.

5 recordsLinked to original sources

PubMed2005

Comparison of obstetric and birthweight characteristics between the two largest databases of Japanese twins measured in childhood.

The purpose of this study is to compare obstetric and birthweight data of twin children from the two largest databases in Japan to estimate the difference between them in sample collection. The first group consisted of 1131 twin-pair school applicants, and the second group consisted of members' children from several maternal associations devoted to twins and included 951 pairs. All data were gathered by questionnaire. The mean birth years of the twins in these two databases were 1979 and 1995 respectively. The percentage of mothers treated with ovulation-stimulating drugs or in-vitro fertilization was markedly higher in the maternal associations group. Gestational age was around 1 week less in the maternal associations group, whereas birthweight according to gestational weeks and intrapair relative birth weight difference as a percentage according to zygosity showed little difference between both groups. We conclude that the obstetric and birthweight feature data from both groups should be considered to construct twin growth charts based on the methods of sample selection.

Adolescent↗

PubMed2004

Characteristics of a Japanese adult twin database of high school graduates.

This paper profiles a unique cohort of adult Japanese twins. The database contains more than 700 twin pairs, aged 18 to 66 years, who are all graduates of the secondary school attached to the faculty of education of the University of Tokyo. This school was established in 1948, when the study of twins was burgeoning in Japan, and about 10 to 20 pairs of twins have been admitted there every year to participate in studies on twins in education and in related projects. The zygosity of all twins was determined carefully on the basis of various sources. Data from the perinatal period to adulthood were linkable using ID numbers. Follow-up surveys in the field of medical genetics were performed in 1985, 1989 and 1999. For the third survey, which was sent and received exclusively by mail, the distribution and collection process was also assessed in detail. The response rate was around 40%, which statistically was influenced mainly by previous participation and sex. The limitation of this cohort is its selection bias concerning socioeconomic status and its imbalance in favor of monozygotic pairs.

Adolescent↗

PubMed2004

Zygosity diagnosis in young twins by questionnaire for twins' mothers and twins' self-reports.

The present study deals with the determination of zygosity in twins of childhood age by simple questionnaire. The subjects were 224 twin pairs and their mothers, consisting of 159 monozygotic and 65 same-sex dizygotic pairs, identified by genetic markers including DNA samples. Mothers of twins responded to 19 questionnaire items dealing with twin similarity in 16 items about physical features and 3 items about the degree of similarity and frequency of being mistaken (confusion of identity) when twins were about 1 year of age. The twins themselves responded to three questionnaire items dealing with only confusion of identity items. The results of stepwise logistic regression analysis were as follows: the total accuracy of the mothers' questionnaire was 91.5% when using only the items dealing with confusion of identity. This accuracy was slightly lower than that obtained by twins' self-reports dealing with nearly the same question items of confusion of identity, answered by both twins separately with 93.3% accuracy. The total accuracy of mothers' questionnaire responses rose to 95.1% when we used all 19 items. In addition to "the frequency of being mistaken", two physical features, namely "shape of fingers" and "shape of eyebrow", were very informative. In conclusion, twin zygosity can be estimated by the use of the mothers' simple questionnaire with sufficient accuracy even in very young twins about 1 year of age.

Female↗

PubMed2004

Zygosity misclassification of twins at birth in Japan.

Though twinning rates have been rapidly increasing in Japan, the problem of zygosity misclassification at birth has been paid little attention. By analyzing four independent samples, the authors found that at a constant rate about 25-30% of monozygotic twins were misclassified as dizygotic twins at birth. This percentage is in very good accordance with that of monozygotic twins having dizygous placenta. Generally the obstetricians informed twins' parents about their children's zygosity. The number of placentas, as informed by obstetricians, was very strongly associated with zygosity. Concluding, even now many monozygotic twins in Japan may be misclassified as dizygotic at birth by obstetricians based solely on the number of placenta.

Female↗

PubMed2002

[Reference birthweight for multiple births in Japan].

PURPOSE: Intrauterine growth curves of twins, that is, birth weights according to gestational age, were calculated from birth certificate data. METHODS: Multiple births were identified by birthplace, ages of the parents, gestational age, and year and month of birth. There were 49,240 twin births in Japan between 1988 and 1991. Of these, 32,232 livebirth-livebirth pairs, 679 livebirth-stillbirth pairs, and 278 stillbirth-livebirth pairs were included in this analysis. There were also 1894 triplet live births from 744 sets of triplets and 206 quadruplet live births analyzed. For all, access was made to the database of birth certificates in the form of magnetic tapes giving birthweights in hundred gram categories. RESULTS: For all gestational ages, median birthweights of males were ca. 0.05 kg-0.1 kg larger than female values. Compared to singleton births in Japan, median birthweights of twins remained ca. 0.15 kg smaller until gestational age of 34 weeks, the difference then increasing to ca. 0.5 kg at 42 weeks of gestation. As for birth order, mean birthweight of the first twin was larger than that of the second and the standard deviation was larger for the second. Birthweights of twins from multiparous mothers were greater than those from primiparous mothers. Among the multiple births, median birthweight for gestational age was found to be greatest in twins, lower in triplets and lowest in quadruplets. In triplets, the 50th centile for boys was 0.08 kg larger than for girls. DISCUSSION: With regard to perinatal growth, the fetus is affected more or less by the limitation of uterine expansion in the late gestational weeks. Reference birthweights for exclusive use for multiple births are different from that for singletons.

Birth Order↗