Motor development of Japanese twins in childhood as reported by mothers

THYROID DYSFUNCTION IN PREGNANCY: COMPARISON OF OUTCOMES IN INFANTS

The aim of this study was to compare the incidence of mild psychomotor delay in infants whose mothers were treated for thyroid dysfunction regardless of the cause during first trimester of pregnancy with those whose mothers did not use medications prenatally. The sample included 200 infants up to 4 months of age. Half of the infants were examined by a pediatric physiatrist, while the other half were chosen randomly from the primary pediatric clinic. Binary logistic regression was performed to assess the impact of factors on psychomotor delay. The model contained seven independent variables derived from bivariate analyses and clinical relevance. Results showed that the infant's chance of having psychomotor delay was 5.53 times higher if the mother had drug-compensated thyroid dysfunction. Younger gestational age increased the likelihood of delay 2.12 times per each gestational week. The likelihood of psychomotor delay also rose by 1% per 1 g of birth weight reduction. We found strong positive linear correlation between maternal drug-compensated thyroid dysfunction during pregnancy and psychomotor delay in infants, which has not been reported elsewhere. This differentiates an important and common prenatal risk factor and lays the foundation for faster initiation of habilitation of infants at risk. These insights provide a basis for planning the National Screening Program for Neurorisk Infants.

Twin Database of the Secondary School Attached to the Faculty of Education of the University of Tokyo

This article profiles the historical twin databases of the secondary education school attached to the Faculty of Education at the University of Tokyo. The school was established in 1948. Every year, about 50 pairs of twins of all sex and zygosity combinations, aged 11-12 years, take an examination, and about 10-20 pairs are admitted based on the results. Three datasets exist: one for applicants (11-12 years old), one for junior and senior high school students (12-18 years old) and one for graduates (18-85 years old). Linking the records from these three databases should facilitate several important research projects, for example, life course genetic epidemiologic studies and the verification of the so-called developmental origins of health and disease hypothesis.

Places and postures: A cross-cultural comparison of sitting in 5-month-olds

Motor development-traditionally described in terms of age-related stages-is typically studied in the laboratory with participants of Western European descent. Cross-cultural studies typically focus on group differences in age-related stages relative to Western norms. We adopted a less traditional approach: We observed 5-month-olds and their mothers from six cultural groups around the world during one hour at home while they engaged in natural daily activities. We examined group differences in infants' sitting proficiency, everyday opportunities to practice sitting, the surfaces on which sitting took place, and mothers' proximity to sitting infants. Infants had opportunities to practice sitting in varied contexts-including ground, infant chairs, and raised surfaces. Proficiency varied considerably within and between cultural groups: 64% of the sample sat only with support from mother or furniture and 36% sat independently. Some infants sat unsupported for 20+ minutes, in some cases so securely that mothers moved beyond arms' reach of their infants even while infants sat on raised surfaces. Our observations of infant sitting across cultures provide new insights into the striking range of ability, varied opportunities for practice, and contextual factors that influence the proficiency of infant motor skills.

Twin database of the secondary school attached to the Faculty of Education of the University of Tokyo: lifecourse database of twins

This article profiles the historical twin databases of the secondary education school attached to the Faculty of Education at the University of Tokyo. The school was established in 1948. Every year, about 50 pairs of twins of all sex and zygosity combinations and aged 11-12 years take an examination, and about 10-20 pairs are admitted based on the results. Three data sets exist: one for applicants (11-12 years), one for junior and senior high school students (12-18 years), and one for graduates (18-79 years). Record linkage of these three databases should facilitate several important research projects; for example, the lifecourse genetic epidemiologic studies and verification of so-called developmental origin of health and disease hypothesis.

The effect of an increase in the rate of multiple births on low-birth-weight and preterm deliveries during 1975-2008

BACKGROUND

Despite the rapid increase in the rate of multiple births due to the growth of reproductive medicine, there have been no epidemiologic studies of the secular trends in the impact of multiple births on the rates of low-birth-weight and preterm deliveries in Japan.

METHODS

Japanese vital statistics for multiple live births were obtained from the Ministry of Health, Labour and Welfare and reanalyzed. With singletons as the reference group, an analysis was performed of secular trends in relative risk and population attributable risk percent of low-birth-weight (<2500 grams), very-low-birth-weight (<1500 grams), and extremely-low-birth-weight (<1000 grams) deliveries, using 1975-2008 vital statistics, and of preterm deliveries (ie, before 37, 32, and 28 weeks), using 1979-2008 vital statistics.

RESULTS

The rate of multiple births doubled during the past 2 decades, and about 2% of all neonates are now multiples. The population attributable risk percent tended to increase during the same period for all variables, and was approximately 20% in 2008.

CONCLUSIONS

The public health impact of the rapid increase in multiple births remains high in Japan.

Breast-feeding rates and related maternal and infants' obstetric factors in Japanese twins

OBJECTIVES

The aims of the present study are to describe the secular trend of breast-feeding rates in Japanese twins in comparison with the general population, and then to clarify the maternal and infants' obstetric factors associated with breast-feeding in twins.

METHODS

Breast-feeding rates from 0 to 6 full months and related maternal and infant obstetric factors were analyzed using 4,023 Japanese twins, consisting of two different volunteer-based twin samples, age 1-15 years, whose birth year ranged from 1968 to 2003. Data were collected through mailed or hand-delivered questionnaires. Obstetric factors that affect full and partial breast-feeding of twins were confirmed using logistic analyses according to birth order in twin pairs, adjusted by birth year.

RESULTS

The full breast-feeding rates of twins were lower than those of the general population. On the other hand, the combined rates of full and partial breast-feeding were close to those of general population, except for the period 1968-1974. The percentage of concordance pares was around 95% for all months. The most influential factor that negatively correlated with breast-feeding from 0 to 6 months was gestational weeks. Higher maternal age at twin birth and the use of an incubator also prevented breast-feeding in the neonatal period.

CONCLUSIONS

The results of the present study for the first time indicated that full breast-feeding of twins has risen recently in Japan, although the rates are still lower than those of the general population. The importance of the gestational weeks for breast-feeding rates was also shown.