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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 16  |  Issue : 1  |  Page : 29-35

Does settlement and season of birth influence body size? A cross-sectional study of school children and adolescents in Republic of Niger


1 Department of Anatomy, Faculty of Medicine, Ahmadu Bello University, Zaria, Nigeria
2 Department of Anatomy, Faculty of Medical Sciences, Federal University, Lafia, Nigeria

Date of Web Publication9-Aug-2017

Correspondence Address:
Monday Nwankwo
Department of Anatomy, Faculty of Medical Sciences, Federal University, Lafia
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jeca.jeca_40_16

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  Abstract 

Background: The objective of the present study was to examine the effect of season of birth and settlement on body dimensions of children and adolescents from Niger Republic. The study group comprises 1547 boys and 1660 girls from Niger Republic.
Materials and Methods: The study was conducted in rural, urban, and semi-urban regions in the Southeast Region of Niger Republic. Data were collected with structured questionnaire followed by anthropometric measurements of stature and weight. Others are head, hip, waist, leg, and mid-upper arm circumference (MUAC). Biceps, triceps, subscapular, and supra-iliac skinfolds were also measured. Statistical analyses included Student's t- test, one-way analysis of variance.
Results: Birth weight, weight, stature, and body mass index showed little sexual dimorphism across various age groups. There were significant differences in all anthropometric variables based on settlements (P < 0.01) except menstrual cycle and duration (P > 0.05). Individuals residing in semi-urban area have significantly higher body dimensions than those from the other two settlements except for stature, weight, and MUAC. Individuals born in dry season have higher body dimensions than their counterparts born in wet season. Marked significant differences in body dimensions based on the season of birth were observed among boys than girls.
Conclusion: The present study reveals difference in body sizes based on settlements while the magnitude of the impact of season of birth is more among boys than girls.

Keywords: Adolescents, anthropometrics, birth, season, settlement


How to cite this article:
Katiella AK, Danborno B, Nwankwo M. Does settlement and season of birth influence body size? A cross-sectional study of school children and adolescents in Republic of Niger. J Exp Clin Anat 2017;16:29-35

How to cite this URL:
Katiella AK, Danborno B, Nwankwo M. Does settlement and season of birth influence body size? A cross-sectional study of school children and adolescents in Republic of Niger. J Exp Clin Anat [serial online] 2017 [cited 2018 May 21];16:29-35. Available from: http://www.jecajournal.org/text.asp?2017/16/1/29/212640




  Introduction Top


A substantial body of empirical evidence shows that settlements have a significant influence on later body size. Individuals living in urban areas have better anthropometric dimensions than those living in rural settlements (Bielicki, 1986; Eveleth and Tanner, 1990; Peña Reyes et al., 2003; Malina et al., 1981; Eiben et al., 2005). Several studies in developing countries have shown that body size parameters, such as weight and stature, are significantly higher among those living in urban areas than those living in rural areas (Von Braun et al., 1993; Menon et al., 2001; Sahn and Stifel, 2003; Wang, 2003; Smith et al., 2005; Fotso, 2007). These parameters are important for monitoring of nutritional status of both children and adolescents. Therefore, disparity in these parameters means difference in nutritional status. Understanding the relative significance of these determinants of nutritional status coupled with whether they are different based on settlements is key in designing better response programs and policies to target the needs of different populations (Lisa et al., 2005).

The difference in body sizes between residents of rural and urban areas may be due to the fact that urban centers have on average greater availability of social amenities, good sanitary conditions, and better socioeconomic status (SES).

Seasonal variations during prenatal period may have long-term phenotypic effects (Cameron and Demerath, 2002). For instance, malnourished fetus (Barker, 1995) and those with hormonal deficiency (Manning and Bundred, 2000) are at the risk of having many diseases later in life. This process is known as fetal programming and involves methylation of DNA and histone proteins through organized membrane receptors and finally to delay in growth (Waterland and Michels, 2007). Changes in a factor required for programming early in life with season will lead to individuals born at certain season being disadvantaged.

Anthropometric dimension differences have also been impacted by the season of birth. In particular, there is a large body of evidence showing that individuals born in winter and spring compared to those born in summer and spring tend to be heavier and longer (Tustin et al., 2004; McGrath et al., 2005; McGrath et al., 2006; Puch et al., 2008). These differences continue up to adulthood.

Several studies have linked season of birth to various biological parameters such as growth (Weber et al., 1998), reproduction (Huber et al., 2004; Cagnacci et al., 2005), neurological disorders (Joinson and Nettle, 2005), dyslexia (Livingston et al., 1993), and longevity (Flouris et al., 2009; Lerchl, 2004). Regarding academic performance, it has been reported that summer-born children have poor academic performance (Martin et al., 2004).

In summary, urban dwellers have higher anthropometric parameters than those from rural area. Winter- and spring-born infants are heavier, taller, and have better academic performance than summer- and autumn-born infants.

The present study examined the relation between settlements, season of birth and body size in 5–18-year-old children and adolescents from Niger Republic. The present study provides some advantages such as body size composition assessment by grouping individuals into age categories and the influence of settlement and season of birth on anthropometric profiles.


  Materials and Methods Top


Demographics of study population

Niger is among the developing countries in Sub-Saharan Africa with a population of 11.5 million with a per capita national gross income of USD 415.4. A total of 3207 made up of 1660 girls and 1547 boys of primary and secondary school children and adolescents aged 5–18 years from randomly selected primary and secondary schools in Diffa Region of Niger Republic participated in the study in 2011. Participants were recruited from rural, urban, and semi-urban settlements of Diffa Region, and data were collected using predesigned questionnaires.

Questionnaires and consent

The questionnaires and participation consent form were administered to the participants a day before their anthropometric measurements were taken. Only participants whose parents or guardians signed the consent form were included in the study. The study was conducted after the approval of Health Research Ethics, Committee of Ahmadu Bello University Teaching Hospital, Zaria, Nigeria. Necessary permissions were also obtained from authorities of participating schools. Questions pertaining to demographics of the participants were answered by parents in the questionnaires.

Anthropometrics

The anthropometric measurements taken by trained assistants included weight, height, mid-upper arm circumference (MUAC), head circumference, hip circumference, waist circumference, leg circumference, biceps, triceps, subscapular, and supra-iliac skinfolds. The training was performed before the beginning of the study. Measurements of individuals were taken in duplicates. All anthropometric measurements were taken using standard techniques (Lohman et al., 1988; Gibson, 1990). Height was measured to the nearest 1 mm, using a stadiometer. Weight was measured to the nearest 100 g, using a mechanical scale. Skinfold measurements were taken using Lange calipers manufactured by Beta Technology, Inc., Santa Cruz, CA. The maximum acceptable difference between the measurements was 0.5 cm for height and circumferences, 10 g for weight and 0.3 mm for skinfold measurements. Triceps skinfold was measured on the back of the right arm over the triceps muscle, midway between the elbow and the acromion process of the scapula. The subscapular skinfold was measured on the right side, just below the inferior angle of the scapula. The subscapular skinfold was picked up on a diagonal, inclined inferolaterally approximately at 45° at the horizontal plane in the natural cleavage lines of the skin. Biceps skinfold was measured on the posterior aspect of the arm over the belly of the muscle, 10 mm above the level used to mark the triceps. The supra-iliac skinfold was measured in line with the natural angle of the iliac crest taken in the anterior axillary line immediately superior to the iliac crest. All measurements of skinfold were made on the right side of the individuals with the caliper placed perpendicular to the skinfold, and halfway between the crest and the base of the fold.

Statistical analysis

The studied variables were subjected to normality using the Shapiro–Wilk test to determine the distributions. Descriptive results were expressed as mean ± standard deviation for parametric and geometric mean at 95% confidence interval for nonparametric variables. To estimate differences in anthropometric variables among participants based on settlements, one-way analysis of variance followed by Tukey post hoc multiple comparisons was used. To estimate differences between genders and season of birth, Student's t-test or Mann–Whitney U-test if nonparametric was used. Statistical analyses were conducted using Statistical Package for Social Sciences for Windows version 22 (IBM SPSS Inc., Chicago, Illinois, USA). Statistical significance was set to a two-sided P < 0.05.


  Results Top


The results of comparison of birth weight, weight, height, and body mass index (BMI) are shown in [Table 1]. The birth weight of girls aged 13 years was significantly higher than that of their male contemporaries. Further, girls aged 12, 14, and 15 years are significantly heavier than boys while boys aged 18 years are significantly heavier than their female cohorts. Height indicates significant difference at ages 9, 15, 17, and 18 years between boys and girls. Pertaining to BMI, it indicates significant difference at ages 9, 10, 12, 13, 14, 15, 16, and 17 years. Girls have significantly higher BMI at all these ages compared to boys.
Table 1: Descriptive statistics of body dimensions of female and male individuals according to age

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Descriptive statistics for urban, semi-urban, and rural individuals are presented in [Table 2]. There was statistical significant difference in body dimensions according to settlements. Individuals from rural center are heavier, taller, have higher MUAC, menarcheal age, and menstrual cycle than those from other settlements (P< 0.01). Urban individuals had slightly higher birth weight, and more days of menstrual flow (P< 0.01). Individuals from semi-urban settlement (1312) had significantly higher head, hip, waist, and leg circumferences, BMI and skinfolds (P< 0.01).
Table 2: Distribution of birth weight and anthropometric measures according to Settlements–Niger

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Descriptive statistics for boys and girls born in dry and wet seasons are summarized in [Table 3]. The mean anthropometric dimensions were significantly higher among the girls born in dry season than boys born in the same season (P< 0.01). The difference in birth weight, height, and head circumference, between the boys and girls were not significant. Among the girl and boy born in wet season, females showed statistically significant higher values for all variables except for birth weight, in which the boys were heavier at birth than the girls (P< 0.01).
Table 3: Wet and dry season distribution of birth weight and relevant anthropometric measures of Nigerien children and adolescents

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The results showed that there was no significant difference in anthropometric dimensions among girls according to the season of birth. Girls born in dry season have mean higher anthropometric dimensions than their counterparts born in wet season except for birth weight; waist circumference, cycle length. The means of the anthropometric parameters of girls born in dry and wet seasons compete favorably, while data revealed a significant difference in anthropometric dimensions of boys based on the season of birth. Boys born in dry season have significantly higher body dimensions than those born in wet season.


  Discussion Top


The present study documents a descriptive anthropological study that explores the relationship between settlements, season-of-birth, and anthropometric profiles of Nigerien children and adolescents. In the present study, BMI, the circumferences, and the skinfolds of semi-urban children and adolescents were significantly higher than those from the rural and urban settlements. In general, it was expected that the urban settlers should have a higher anthropometric values, but the present study has shown that the semi-urban dwellers instead had higher anthropometric values. The significant differences in anthropometric variables observed in semi-urban settlements may be attributed to socioeconomic factors. Socioeconomic factors are often given by parents' educational level or occupation. It may be then assumed that parents from semi-urban areas possess better parental knowledge as well as financial wherewithal that enable them to ensure optimal development of their children irrespective of their location. Availability of land for farming, relatively low cost of living, and the presence of social amenities may be confounding factors to the observed difference. This explanation is plausible as low and middle class parents are also found in the urban settlements.

No evidence for the season-of-birth effect on birth weight, height, head, and waist circumferences was found in the present study. On the other hand, season of birth showed a significant difference in body weight, BMI, skinfolds, MUA, hip, and leg circumferences. Individuals born in dry season have higher mean anthropometric values than those born in wet season except waist circumference in which those born in wet season have higher waist circumfluence. The study recorded greater season-of-birth effects in boys than in girls. This is consistent with the report of previous studies that boys born in dry season have significantly higher body dimensions than those born in wet season (Henneberg and Louw, 1993; Banegas et al., 2001; Kościński et al., 2004).

Multiple studies have confirmed that males are more sensitive than females to both harsh and conducive environmental factors (Jantz and Jantz, 1999; Padez et al., 2009; Lampl et al., 2010). Harsh environmental factors are reflected in the form of prenatal and infant mortality, childhood infections, and prenatal and postnatal stress-induced influences. Conducive environmental factors are manifested in the form of improvement in living conditions of the child following adequate nutrition. The evidence provided by Stinson in 1985 for greater male than female susceptibility is the most convincing.

The possible mechanism as reported by Benenson, (2005) and Harrison et al., (1989) was that males, unlike females, have only one X chromosome as the phenotypic influence of their mutations are easily masked. In addition, the higher growth rate of the male conceptus at early pregnancy (Mittwoch, 1993; de Zegher et al., 1999) could lead to higher chance of vulnerability to environmental influences (Mittwoch, 1993; Ulijaszek, 1998; de Zegher et al., 1999). Studies by Alonso-Alvarez et al., (2007) and Mougeot et al., (2009) proposed a rather different mechanism which showed that testosterone, a male steroid hormone produced by testes in the male embryo has been reported to elevate the production of reactive oxygen species which in turn leads to oxidative stress. Some authors had suggested that prenatal oxidative stress may increase the risks of developing diabetes or cancer later in life (Luo et al., 2006; Wan and Winn, 2006).

The present study was unable to point out the precise reason why the season-of-birth effect was revealed only in boys, and the effect of settlements of which the researchers believed that each of the above-mentioned mechanisms may explain part of the differences observed. Whatever the reason, the results from the present study on the season-of-birth fit well with previous studies' supposition that males are more sensitive than females to various developmental factors leading to low body composition (Kościński et al., 2004).

More research is needed to determine the reason for the urban/semi-urban difference in anthropometric dimensions.

The magnitude of the season-of-birth effect was moderated by the level of SES and traditionalism; the risk group included the boys coming from the families of low SES and/or low traditionalism. The SES factor embraced education level of both parents, number of books at home, and wealth indices resulting from the declared income and profitability indices of the professions. It may be then assumed that the high-SES parents possess parental knowledge as well as financial means that enable them to assure the optimal development of their child irrespective of his/her birth season. The second risk factor appeared to be low traditionalism, which means here short breastfeeding and low number of siblings.


  Conclusion Top


The present study found that anthropometric profile of Nigerien children and adolescents was influenced by settlements and season of birth. Subjects residing in semi-urban area have significantly higher body dimensions in most of the variables considered than their counterparts in other settlements. Male subjects born in dry season have significantly higher body dimensions than those born in wet season. Female subjects showed less variation in body dimensions based on season of birth. Further studies to investigate the impact of season of birth and settlements are called to verify the results from the present study.

Acknowledgments

The authors owe the participants a great debt for their participation in the study and thank the parents and authorities of the Schools that participated in the study for their cooperation during the study. The authors are also thanking the research assistants for their tireless ferret for participants.[46]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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