ABSTRACT
The present cross sectional study investigated the growth and sexual maturation of adolescents of Jukun and Kuteb ethnic groups of Taraba State. The aim of the study was to assess growth and sexual maturation of the Jukun and Kuteb adolescents. The mean menarcheal age of the respondents was estimated, while also assessing their nutritional status. Results of the growth parameters and anthropometric measurements of the adolescents showed no statistical significant difference based on ethnicity, but there was statistical significant difference based on sex in most of the variables. The plotted growth curves of BMI, height and weight of the population with international references showed that the boys had lower values than the reference population, while the girls from both ethnic groups had values similar, and in some cases such as BMI higher than the reference population. The nutritional assessment of the population also showed that the prevalence of stunting, thinness and overweight among boys and girls was 22.4%,11.7 % and 1.1 % in boys, and 2.9%, 1.1 % and 3.9 % in girls respectively. Results of the study showed late maturation among the adolescents, especially among males. The mean age at onset of sexual maturation in pubic hair was 11.77 ± 0.87 for Jukun boys and 11.88 ± 1.42 for Kuteb boys. For females, it was 11.25 ± 0.90 for Jukun girls and 11.50±1.14 for Kuteb girls.Age at onset of breast development for females was 11.17 ± 1.04 (Jukun) and 11.12 ± 1.11 (Kuteb) respectively. For males, age at entry of genital development was 11.65± 0.86 (Jukun) and 11.65 ± 1.43 (Kuteb). Age at completion of sexual development in PH and BS for females was 17.68± 1.43 and 17.63± 1.43 (Jukun); 17.80 ± 1.59 and 17.44 ± 1.68 (Kuteb) respectively. For males it was 18.09± 1.40 and 18.23± 1.31 (Jukun), 18.21± 1.25 and 18.13 ± 1.38 (Kuteb). Comparison of the sexual maturity rating with height and weight of this study population showed that girls were shorter than the boys in both PHS and GS_BS stages except during PHS 1. Boys tend to be weightier than girls in stage 5 of PHS and GS_BS only, the girls had
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higher values in the other stages. The girls of this study also had BMI and % body fat values significantly higher than the boys at each stage of the PHS and GS_BS. The Hand and Foot anthropometry showed that boys from the two ethnic groups showed statistically significant higher values than their female counterparts. Linear regression models for estimating sexual maturity rating from anthropometric variables of adolescents from each ethnic group were generated.The present study showed that the age at onset of maturation for pubic hair and genital/breast stage was early and compared favorably with other studies, but there was late maturation into adult size in both the boys and girls.
TABLE OF CONTENTS
Title Page———————————————————————————————- i Declaration——————————————————————————————- ii Certification—————————————————————————————— iii Acknowledgement ———————————————————————————- iv Dedication ——————————————————————————————- v Table of Contents———————————————————————————– vi List of Tables—————————————————————————————- x List of Figures————————————————————————————– xii List of Appendices——————————————————————————— xiii Abstract——————————————————————————————— xiv 1.0 INTRODUCTION ———————————————————————- 1 1.1 Background of the Study————————————————————– 1 1.2 Statement of the Problem————————————————————– 5 1.3 Justification—————————————————————————— 6 1.4 Aims and Objectives——————————————————————- 6 1.4.1 Aims of the Study ———————————————————————— 6 1.4.2 Objectives of the Study —————————————————————– 6 1.5 Significance——————————————————————————- 7 1.6 Study Hypothesis———————————————————————— 7
1.7 Study Location———————————————————————– 7 1.7.1 Topography of the study————————————————————- 7 1.7.2 Climate——————————————————————————— 8
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1.8 Definition of Terms——————————————————————— 10 2.0 LITERATURE REVIEW———————————————————– 14 2.1 Adolescent Growth and Sexual Maturation————————————- 14 2.2 Course of Physical Growth——————————————————— 16 2.2.1 Changes in body size —————————————————————— 16 2.2.2 Changes in body proportion ———————————————————- 19 2.2.3 Changes in body fat makeup——————————————————— 20 2.2.4 Skeletal growth————————————————————————- 20 2.3 Indicators of Biological Maturation———————————————- 23 2.3.1. Sexual maturity————————————————————————- 24 2.3.2 Somatic or morphological maturity———————————————— 26 2.3.3 Interrelationships among maturity indicators————————————- 28 2.4 Processes of Sexual, Reproductive and Cognitive Maturation————- 29 2.4.1 Hormonal changes and growth spurts———————————————- 29 2.4.2 Menarche, semenarche and the stages of sexual maturation——————– 31 2.4.3 Reproductive maturation————————————————————- 34 2.4.4 Brain growth and maturation——————————————————– 35 2.5 Factors Affecting Growth———————————————————- 37 2.6.1 Heredity——————————————————————————– 37 2.6.2. Nutrition——————————————————————————– 38 2.6.3 Infectious disease——————————————————————— 47 2.6.4 Physical Activity———————————————————————- 48 2.6.5 Emotional Well-Being————————————————————— 53
3.0 MATERIAL and METHODS—————————————————- 55
3.1 Materials —————————————————————————– 55
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3.2 Research Participants————————————————————– 55 3.3 Methodology————————————————————————- 55 3. Data Collection Technique——————————————————– 57 3.5.1 Anthropometric Assessment ——————————————————– 57 3.5.2 Nutritional Status Assessment —————————————————— 58 3.5.3 Sexual Maturation Assessment —————————————————– 58 3.6 Sampling Size Determination—————————————————– 61 3.7 Ethical Approval——————————————————————– 61 3.8 Inclusion and Exclusion Criteria————————————————- 62 3.8.1 Inclusion criteria———————————————————————- 62 3.8.2 Exclusion criteria———————————————————————- 62 3.9 Statistical Analysis—————————————————————— 62 4.0 RESULTS—————————————————————————– 63 4.1 Analysis of Study Population—————————————————– 63 4.2 Growth and Anthropometric Variables—————————————- 63 4.3 Growth Charts———————————————————————– 64 4.4 Hand and Foot Anthropometry————————————————– 64 4.5 Sexual Maturation Rating——————————————————– 65 4.6 Nutritional Assessment————————————————————- 67 4.7 Correlations of Anthropometric Variables———————————— 68 4.8 Linear Regression Model ——————————————————— 69 5.0 DISCUSSION———————————————————————– 109
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6.0 SUMMARY, CONCLUSION and RECOMMENDATIONS————– 117 6.1 Summary—————————————————————————— 117 6.2 Conclusion ————————————————————————— 119 6.3 Recommendation——————————————————————– 120 REFERENCES ———————————————————————- 121 APPENDICES———————————————————————— 143
CHAPTER ONE
1.0 INTRODUCTION 1.1 BACKGROUND OF THE STUDY Growth and physical maturation are dynamic processes encompassing a broad spectrum of cellularand somatic changes. Traditionally, the assessmentof growth has placed its 31 on stature,but changes in body proportions and body composition are essential elements of the growth process.Growth standards have been developed for each ofthese parameters and aid in the identification ofchildren with normal growth, variations of normalgrowth and development, and the broad spectrum ofabnormal growth states (Rogol et al., 2002).Tanner et al., (1995)has proposed that children be measured accurately to identify individuals or groups of individuals within a community who require special care, to identify illnesses that influence growth, or to determine an ill child’s response to therapy.
The beginning of biological growth and development during adolescence is signified by the onset ofpuberty, which is often defined as the physical transformation of a child into an adult (Kaplowitz et al., 2001). A myriad ofbiological changes occur during puberty including sexual maturation, increases in height andweight, completion of skeletal growth accompanied by a marked increase in skeletal mass, andchanges in body composition (Marshal, 1978; Sisk and Foster, 2004). The succession of these events during puberty is consistent amongadolescents (Hazenet al., 2008, Mei et al., 2008), however, there may be a great deal of deviation in the age of onset, duration, andtempo of these events between and within individuals (Rogolet al., 2000; Gasser et al., 2000). For this reason, adolescents of the samechronological age can vary greatly in physical appearance. This has direct relevance for thenutrition requirements of adolescents (Stang and Story, 2005).
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Puberty occurs through a long process and begins with a surge in hormone production, which in turn causes a number of physical changes (Cooney, 2010). It is the stage of life in which a child develops secondary sex characteristics (for example, a deeper voice and larger adam’s apple in boys, and development of breasts and more curved and prominent hips in girls) as his or her hormonal balance shifts strongly towards an adult state. This is triggered by the pituitary gland, which secretes a surge of hormonal agents into the blood stream, initiating a chain reaction. The male and female gonads are subsequently activated, which puts them into a state of rapid growth and development; the triggered gonads now commence the mass production of the necessary chemicals. The testes primarily release testosterone, and the ovaries predominantly dispense estrogen. The production of these hormones increases gradually until sexual maturation is met. Some boys may develop gynecomastia due to an imbalance of sex hormones, tissue responsiveness or obesity (Nydick et al., 1961; Slap, 2001).
One of the hallmarks of puberty is the adolescent growth spurt. As puberty approaches, growth velocity slows to a nadir (―preadolescent dip‖) before its sudden acceleration during midpuberty. The timing of the pubertal growth spurt in girls is typically at Tanner breast stage 3 and does not reach the magnitude of that in boys (Bogin, 2001; Archibald et al., 2003). Girls average a peak height velocity of 9 cm/y at age 12 and a total gain in height of 25 cm during the pubertal growth period (Kelch and Beitins, 1994). Boys, on average, attain a peak height velocity of 10.3 cm/y 2 years later than girls, during Tanner genital stage 4, and gain 28 cm in height (Kelch and Beitins, 1994). The longer duration of prepubertal growth in boys, combined with a greater peak height velocity, results in an average adult height difference of 13 cm
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between men and women. After a period of decelerating height velocity, growth virtually ceases because of epiphyseal fusion, typically at a skeletal age of 15 years in girls and 17 years in boys (Tanner, 1989; Bogin, 1999).
Puberty is also a time of significant weight gain; 50% of adult body weight is gained during adolescence. In boys, peak weight velocity occurs at about the same time as peak height velocity and averages 9 kg/y. In girls, peak weight gain lags behind peak height velocity by ≈6 mo and reaches 8.3 kg/y at ≈12.5 y of age (Tanner, 1989). The rate of weight gain decelerates in a manner similar to height velocity during the later stages of pubertal development.
Body fat (most of which lies just beneath the skin) increases in the last few weeks of prenatallife and continues to do so after birth, reaching a peak at about 9 months of age. This earlyrise in ―baby fat‖ helps the infant keep a constant body temperature. Starting in the secondyear and continuing into middle childhood, most toddlers slim down (Fomon and Nelson, 2002). At birth, girls have slightly more body fat than boys, a difference that persists into theearly school years and then magnifies. Around age 8, girls start to add more fat on theirarms, legs, and trunk; they continue to do so throughout puberty, while the arm and leg fatof adolescent boys decreases (Siervogel et al., 2000).The changes in the distribution of body fat (central compared with peripheral, subcutaneous compared with visceral, and upper compared with lower body) results in the typical android and gynoid patterns of fat distribution of the older adolescent and adult (Johnston, 1992).
Muscle accumulates slowly throughout infancy and childhood, with a dramatic rise atadolescence. Both sexes gain muscle at puberty, but this increase is 150 % greater inboys, who develop larger skeletal muscles, hearts, and lung capacity (Rogol et al.,
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2002). Also, the number of red blood cells—and therefore the ability to carry oxygenfrom the lungs to the muscles—increases in boys but not in girls. Altogether, boys gain farmore muscle strength than girls, contributing to their superior athletic performance duringthe teenage years (Ramos et al., 1998). Growth in a number of dimensions shows asignificant familial resemblance. Adult stature, tempoof growth, timing and rate of sexual development,skeletal maturation, and dental development are allsignificantly influenced by genetic factors (Sinclair, 1978), withestimates of genetic transmissibility ranging from 41 % to 71 % (Tanner, 1989). Twin studies have shown that theaverage difference in height between monozygotictwins is only 2.8 cm, compared with 12 cm fordizygotic twins of the same sex. Adult stature is bestcorrelated with mid-parental height calculations, butthe polygenic model of inheritance results in greatervariation in size of children born to parents ofdisparate heights compared with those born to parents both of average height (Smith, 1977, Sheehy et al 2000; Estourgie-van Burk et al., 2006).The overall contribution of heredity to adult sizeand shape varies with environmental circumstances,and the two continuously interact throughout theentire period of growth (Oyhenart et al., 2008). Children with similar genotypes,who would reach the same adult height underoptimal conditions, may be differently affected byadverse circumstances. Thus, the interaction betweengenetic makeup and the environment is complex andnon-additive (Tanner, 1994; Euling, 2008).
The secular trend in height and adolescent development is further evidence for the significant influence of environmental factors on an individual‘sgenetic potential for linear growth. Since the turn ofthe century, children in average economic conditionshave increased in height approximately 1 to 2 cm perdecade (Euling et al.,
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2008).The secular gain appears earlyin life, increases over childhood and early adolescence,and then declines as mature body sizeis reached. This pattern suggests that the largersize of today‘s children is mostly due to a fasterrate of physical development. Consistent with thisview, age of first menstruation declined steadilyfrom 1900 to 1970, by about 3 to 4 months perdecade. Although evidence on boys is sparse,they, too, show signs of having reached pubertyearlier in recent decades. The gain in adult stature, however, hasbeen less, indicating that, in part the trend towardgreater size during childhood is the result of earliermaturation and adult height achievement (Tanner, 1994).Improved health and nutrition are largelyresponsible. As developing nations make socioeconomicprogress, they also show secular gains (Ji and Chen, 2009). Secular trends are smaller forlow-income children, who have poorer diets andare more likely to suffer from growth-stuntingillnesses. In regions with widespread poverty, famine, and disease, either no secular changeor a secular decrease in body size has occurred (Barnes-Josiah and Augustin, 1995; Cole et al., 2000).In most industrialized nations, the secular gain in height has slowed, and the trend toward earlier first menstruation (menarche) has stopped or undergone a slightreversal. But in the United States and a few European countries, soaring rates of overweightand obesity are responsible for a modest, continuing trend toward earlier menarche(Parent et al., 2003; Kaplowitz, 2008). 1.2 STATEMENT OF THE PROBLEM
The secular trend in growth patterns has been extensively studied. While this exist for some, there is paucity of data on Jukun and Kuteb ethnic groups. Hence there is a need to generate growth reference values for all ethnic groups and this study location in particular. Furthermore, there are very few if nonexistent sexual maturation studies that have been carried out or published in Nigeria.
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1.3 JUSTIFICATION It is universally accepted that anthropometry is the most useful tool for assessing the growth, nutrition status, and risks of poor health and survival of infants and adolescents. This work is designed to assess growth and sexual maturation of adolescents and also link it with some anthropometric measurements. This will generate a baseline data for growth and sexual maturation and also to identify whether a secular trend in sexual maturation occurs among the study population. 1.4 AIMS AND OBJECTIVES OF THE STUDY
1.4.1 Aims of the Study
The aim of this study is to assess physical growth and sexual maturation of Jukun and Kuteb adolescents. 1.4.2 Objectives of the Study The study has been designed with the following objectives:
i. estimate the mean height, weight and Body Mass Index (BMI) of the population and compare it with international values
ii. estimate the mean age at menarche of adolescentgirls from theJukun and Kutebethnic groups
iii. compare the onset of puberty and sexual maturation among the Jukun and Kuteb ethnic groups
iv. assess the nutritional status of adolescents among Jukun and Kuteb ethnic groups
v. generate growth reference values for adolescents among Jukun and Kuteb ethnic groups
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vi. Generate linear regression equation for sexual maturation of adolescents of Jukunand Kuteb using anthropometric variables.
1.5 SIGNIFICANCE The study will establish baseline data of growth pattern and sexual maturation amongst the Jukun and Kuteb ethnic groups. This research work can also be used in planning, evaluation and advocacy that will lead to the implementation of interventions to improve child health and survival. 1.6 STUDY HYPOTHESIS There will be no difference in growth and sexual maturation between the Jukuns and the Kutebs adolescents. 1.7 STUDY LOCATION Takum Local Government is located in Southern part of Taraba State, its headquarters are in the town of Takum, at latitude 70 16 ‗00‘N and 90 59 ‗00‘E. It has a total land mass of 6400 square kilometer and a population of 135,349 at the 2006 census. Takum chiefdom shares boundaries with Benue State to the west, Donga Local government lies to the Northeast, while to the southeast lies Kurmi Local Government. The Federal Republic of Cameroun lies to the south of Takum local Government area. 1.7.1 Topography of the Study Area The area consist mainly of gently undulating land with a few dotted mountainous feature with high land area of about 3000 – 9000mm above sea level the land area below 300 meters above see level, suitable for man habitation and indeed farming is carried out extensively in this area.
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1.7.2 Climate Takum local government enjoys two distinctive climate condition in a year which are dry season and rainy (weet) season the farming starts from mid march to October some time, extend to November. The dry season characterized by the north-east trade with which are the tropical continental and resulting to cold weather, with most sever? Being December January and February are dry and some time dusty. The rainy season is dominated by south west tropical maritime wind and the rainfall over the area range from 1,500mm, with humility rate relatively high. Climate is an important factor that determines the form of any architecture. In Nigeria the Jukun and Kuteb live in northern Savannah type of climate. The rainfall intensity is very high between the months of July and August. As a result though the environment is generally dry, crops are frequently lost through too much rain. It also results in rapid surface run-off, soil erosion and water-logging (Udo, 1970).Dry season is the period of harmattan: a transition period between the wet and the hot seasons. It is a period when there is little or no rainfall (Ati, 2002). Daytime temperatures fluctuate between 16 and 32ºC in November with clear sky of sunshine hours of between 8.9 and 9.5. December to January in Takum is
characterized by the suspension of fine dust particles in the air, due to Harmattan winds which cause surface turbulence.Visibility is poor, disrupting air navigation while sun‘s rays barely reach ground surface. This action reduces night temperatures to 14ºC, with sunshine hours between 8.7 and 9.5. Daytime temperature may drop to 31ºC, giving a variation of 17ºC, the highest in the year. This extreme diurnal temperature range is another characteristic of the Savanna type of climate (Areola et al., 2005).
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Fig. 1.1: Map of Nigeria, showing Takum LGA. Source:Geographic and information systems (GIS)
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1.8 DEFINITION OF TERMS
i. Adolescence: Period of the life span between the time puberty begins and the time adult status is approached, when young people are preparing to take on the roles and responsibilities of adulthoodin their culture.
ii. Adrenarche: Maturation of the adrenal gland that results in secretion of androgens from the adrenal cortex. Regulated by the Hypothalamic-pituitary adrenal axis (HPA) but activated by unknown factors, adrenarche occurs independently of gonadal maturation and breast development.
iii. Androgens: Sex hormones that have especially high levels in males from puberty onward and aremostly responsible for male primary and secondarysex characteristics
iv. Estradiol The estrogen most important in pubertaldevelopment among girls
v. Estrogens: Sex hormones that have especially high levels in females from puberty onward andare mostly responsible for female primary andsecondary sex characteristics.
vi. Gonadarche: Maturation of the gonads (ovaries in girls) that results in a dramatic increase in sex hormone production (estradiol in girls). Gonadarche is the result of the activation of the Hypothalamus-pituitary-gonadal axis and indicates that puberty has commenced. Gonadarche is less visible in girls than boys.
vii. HPA axis: Hypothalamus-pituitary-adrenal axis. A second signaling pathway involved in puberty. The HPA axis permits the production of steroidal
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hormones from the adrenal glands (which sit atop the kidneys). These hormones include androgens.
viii. HPG axis: Hypothalamus-pituitary-gonadal axis. This signaling pathway regulates the production of sex hormones by sending chemical messages from the hypothalamus in the brain to the pituitary gland and then, in girls, to the ovary. Its activation marks the onset of puberty.
ix. Infant puberty (also known as ―mini puberty‖): The period of early development (from late prenatal life through 3 to 9 months) when the HPG axis is active and prior to its repression during the juvenile period. Sex hormones are produced during infant puberty. Unlike adolescent puberty, infant puberty is not tightly regulated.
x. Insulin resistance: Occurs when increasing amounts of insulin are needed to transport blood glucose into body tissues. The result is hyperinsulinism, often a precursor of type 2 diabetes.
xi. Isolated premature thelarche: Breast development without activation of the HPG axis and in the absence of gonadarche in girls younger than 7. Isolated premature thelarche may or may not raise the risk for true precocious puberty. The self-limiting or progressive nature of this condition is a matter of ongoing debate (Salardi, 1998).
xii. Menarche: Onset of menstruation and a consequence of estradiol stimulation. It is a late stage event in the pubertal process. Along with thelarche, menarche is a consequence of HPG activation.
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xiii. Precocious puberty: Signs of sexual maturation that appear at an age that is more than two standard deviations below the mean. True precocious puberty refers to premature activation of the (HPG) axis that initiates gonadarche and thelarche. True precocious puberty is five times more common in girls than boys. In the past, true precocious puberty was defined as onset of gonadarche and thelarche before age 8, which was considered the lower limit for normal puberty in girls. In 1999 in the United States, these age limits were revised downward to 7 years old for white girls and 6 years old for black girls (Kaplowitz and Oberfield, 1999).
xiv. Premenstrual Syndrome is defined as the cyclical recurrence of symptoms, physical, psychological, and/or behavioural, that occur after ovulation and disappear within a few days of onset of bleeding. These symptoms affect how women function in daily life, often interfering with work, school or personal relationships.
xv. Primary Sex Characteristics:Production of eggs (ova)and sperm and the development of the sex organs
xvi. Pubarche: Appearance of pubic and underarm hair, adult body odour, increased oiliness of skin and hair and, sometimes, acne.
xvii. Puberty: Changes in physiology, anatomy, and physical functioning that develop a person into a mature adult biologically and prepare the body forsexual reproduction.
xviii. Puberty: The time at which the onset of sexual maturity occurs and the reproductive organs become functional. This is manifested in both sexes by
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the appearance of secondary sexual characteristics. These changes are brought about by an increase in sex hormone activity due to the stimulation of the ovaries and testes by pituitary hormones.
xix. Secondary Sex Characteristics:Bodily changes of puberty not directly related to reproduction.
xx. Spermarche:Beginning of development of sperm in boys‘ testicles at puberty.
xxi. Testosterone:The androgen most important inpubertal development among boys
xxii. Thelarche: Onset of breast development, also called ―breast budding.‖ It is a physical consequence of gonadarche and an early visible event in pubertal development.
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