Kitae Sohn

The influence of birth season on height: Evidence from indonesia

OBJECTIVES Literature on the effect of birth month on height has generally considered regions in temperate climates. However, because many climatic conditions there change with seasons, it is difficult to isolate potential causes. This study estimated the effect of birth month and season on terminal height by analyzing the population of a country with only a few factors driving its climate. MATERIALS AND METHODS The sample was derived from nationally representative data of the Indonesian population. We considered 9,262 men and 10,314 women 20-50 years of age. We applied cosinor analysis to a time series of height by birth month. We then applied a more flexible approach by regressing height on a series of dummy variables for birth month (and, subsequently, season) and birth year fixed effects by sex. RESULTS There was no statistically significant difference in height by birth month. However, although weakly significant, men born in the dry season (June-September) were 2.3 mm shorter than those born in the wet season (the remaining months). The corresponding figure for women was 2.6 mm, a statistically significant difference. DISCUSSION We eliminated some potential factors previously suggested in the literature, including insolation, the position of our planet with respect to the sun, food availability, and maternal workload. We speculate that babies born in the dry season were affected in the third trimester by the high disease burden that characterizes the wet season.

Is leg length a biomarker of early life conditions? Evidence from a historically short population

While one group (Positive Group) has argued that leg length is a more accurate biomarker of early life conditions than height, another group (Negative Group) has challenged this argument. Analyzing Indonesian data, we attempt to reconcile these contrasting arguments.

Gender Discrimination in Earnings in Indonesia: A Fuller Picture

This article analyses data from the 2007 Indonesia Family Life Survey in order to decompose the gender gap in earnings into explained and unexplained gaps, not only at the mean but also across the entire distribution. Women earned about 30% less than men, in both paid work and self-employment. The explained gap accounts for only about a quarter of the gap in paid work but for about half of the gap in self-employment. When the decomposition is made across the earnings distribution, the total gap decreases with earnings in both paid work and self-employment, and both conditional and unconditional on characteristics. In both employment sectors, the explained gap remains similar across the distribution, and therefore the unexplained gap drives the decrease in the total gap. The unconditional decomposition across the distribution provides great insight into the dynamics that are obscured in results derived from decomposition at the mean.

Biological standards of living: age at menarche vs height.

Abstract Background Researchers typically use height to understand the growth environment, but recent evidence suggests that height does not reflect it well; height can even be misleading. Aim This study compared age at menarche and height to assess which better reflected the growth environment. Subjects and methods This study employed the Indonesian Family Life Survey to extract information on age at menarche from 7831 women and height from 7946 men, both aged 15–49 and born in 1944–1983. It drew on GDP per capita in childhood to represent the growth environment. The means of the two anthropometrics by birth decade were calculated. The trends in the two were then compared and each was regressed on the growth environment and a time trend. Results Between 1944–1953 and 1974–1983, the mean age at menarche decreased from 14.5 to 13.9, while height increased from 160.9 cm to 162.6 cm. Despite the expected broad trends, age at menarche was more closely related to the growth environment than height in graphs, correlation coefficients and regression results. Conclusion The results recommend using more than one anthropometric to investigate changes in the biological standards of living.

Is age at menarche a good predictor of future body fat? The case of a developing country

ABSTRACT Age at menarche has been proposed to serve as a predictor of future body fat for the developed world. Our aim in this study is to determine whether this is also the case for a developing country—Indonesia. We analyze nationally representative data, concerning 9,543 women aged 15–62 in 2007–2008, and find that the relationship between age at menarche and body mass index is negative and statistically significant. The size of the relationship, however, is negligible. It thus appears that age at menarche is not a good predictor of future body fat in Indonesia and possibly other developing countries.

The male-taller norm: Lack of evidence from a developing country

In general, women prefer men taller than themselves; this is referred to as the male-taller norm. However, since women are shorter than men on average, it is difficult to determine whether the fact that married women are on average shorter than their husbands results from the norm or is a simple artifact generated by the shorter stature of women. This study addresses the question by comparing the rate of adherence to the male-taller norm between actual mating and hypothetical random mating. A total of 7954 actually married couples are drawn from the last follow-up of the Indonesian Family Life Survey, a nationally representative survey. Their heights were measured by trained nurses. About 10,000 individuals are randomly sampled from the actual couples and randomly matched. An alternative random mating of about 100,000 couples is also performed, taking into account an age difference of 5 years within a couple. The rate of adherence to the male-taller norm is 93.4% for actual couples and 88.8% for random couples. The difference between the two figures is statistically significant, but it is emphasized that it is very small. The alternative random mating produces a rate of 91.4%. The male-taller norm exists in Indonesia, but only in a statistical sense. The small difference suggests that the norm is mostly explained by the fact that women are shorter than men on average.

The influence of climate on age at menarche: Augmented with the influence of ancestry

Samples representative of South Korea, Indonesia, and Peninsular Malaysia were analyzed and the influence of climate on age at menarche was investigated. The sample size was 24,651 for Korea (birth years 1941-1992), for Indonesia 8331 (birth years 1944-1988) plus 20,519 (birth years 1978-1997), and 2842 for Peninsular Malaysia (birth years 1927-1968). Respondents recalled their age at menarche. The mean age at menarche was calculated for each birth year by country, and for Malaysia, additionally by ancestry. It has been found that mean ages at menarche for the early birth years were much younger in Indonesia than in Korea despite similar levels of socioeconomic conditions (proxied by GDP per capita). For example, for the birth year 1944, the mean age at menarche was 14.45 years for Indonesia and 16.19 years for Korea-a difference of 1.74 years. It was necessary to double the Korean GDP per capita to make the Korean mean age at menarche the same as the Indonesian one. Chinese and Malay women in Peninsular Malaysia were further analyzed, and the results provided indirect evidence that the difference between Korea and Indonesia was not due to ancestry differences. Results in multivariate settings provided consistent results. It has been concluded that climate exerts a significant influence on age at menarche because the relatively easy availability of food in the tropics increases energy intake while the absence of cold weather decreases energy expenditure on maintenance and activity.

Improvement in the biological standard of living in 20th century Korea: Evidence from age at menarche

We used age at menarche to understand improvement in the biological standard of living in South Korea during the 20th century.

Sexual stature dimorphism as an indicator of living standards

Abstract Background: A group of researchers has argued that sexual stature dimorphism (SSD) can serve as an indicator of living standards. This argument is based on evidence that boys’ physical growth is more sensitive to environmental conditions than girls’ physical growth. Because Koreas economic growth in the second half of the 20th century was unprecedentedly rapid, according to their logic, it is likely to see an increasing trend in SSD. Aim: We aimed to determine whether SSD can serve as an accurate indicator of living standards for a population that would exhibit a pronounced trend in SSD, providing that the logic for use of SSD is correct. Subjects and methods: We employed nationally representative Korean men born in 1941–1990 (n = 17 268) and women born in 1941–1991 (n = 22 543) and estimated mean heights by sex and birth years. We then calculated SSD values and charted the trend. Results: Although male height increased faster than female height, the SSD trend was flat for the pooled observations and for sub-groups by socioeconomic status. Conclusion: These results cast doubt on the argument for using SSD as an indicator of living standards.

Sick But Unaware: Hypertension in Indonesia

Discrepancies between self-reported and measured hypertension pose a great risk to health because they prevent timely treatment. Analyzing the Indonesian Family Life Survey, we compared self-reported and measured hypertension to assess the extent of the misclassification of hypertension. Building on this, we estimated factors related to self-reported and measured hypertension. Our results show that different factors were involved in each case, suggesting that they are two different phenomena. More importantly, we estimated factors that increased awareness of hypertension and found that visiting a health facility was a very effective way of increasing awareness of hypertension among hypertensive patients.