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The onset of menarche signals the start of women‘s reproductive life and is determined by genetics, race, environmental, nutritional habits, socioeconomic status, and exercise. The present study is primarily aimed at determining the mean menarcheal age of adolescent girls from Hausa and Igbo ethnic groups living in rural and urban regions. The study also compared the mean anthropometric dimensions of menstruating and non-menstruating girls. The study also examined the prevalence of premenstrual syndromes among these designated ethnic groups. A total of 800 secondary school girls participated in the study. Four hundred are from Hausa and four hundred from Igbo ethnic groups. One hundred and fifty out of the four hundred from each ethnic group reside in the rural region while another one hundred and fifty from each ethnic group reside in the urban region. The remaining two hundred subjects will constitute the non-menstruating group with hundred from each ethnic group of which fifty are residents of rural region and the remaining fifty from urban region. This cross-sectional study was conducted on girls aged 11-18 years old. Relevant data were collected through a self-administered questionnaire after which certain anthropometric measurements including weight, height, mid upper arm, waist, hip, chest, neck, thigh circumferences, waist-hip, waist-chest and waist-height ratios. There is statistical significant difference in the mean age at menarche of adolescent girls from Hausa and Igbo ethnic groups. The mean age at menarche was 13.54 ± 0.90 years, the mean menarcheal age of school girls from Hausa ethnic group was 13.65 ± 0.92 years while that of school girls from Igbo ethnic group was 13.44 ± 0.87 years. Similarly, the mean menarcheal age of girls from Hausa (rural, urban) and Igbo (rural, urban) ethnic groups were respectively (13.83 ± 0.95, 13.48 ± 0.86, t = -3.33, p <
0.01) years and (13.52 ± 0.87, 13.35 ± 0.88, t = -1.66, p > 0.05) years. The mean of the various anthropometric dimensions were significantly higher among the menstruating girls than the non-menstruating students (p < 0.001). Concerning birth order, first born girls reach menarche earlier than later born for girls from Hausa and Igbo ethnicity (F = 16.73, p < 0.01) and (F = 26.90, p < 0.01) respectively. Also, girls from small family size reach menarche earlier than their counterparts from large family size for girls from Hausa and Igbo ethnic groups (F = 12.13, p < 0.01) and (F = 37.72, p < 0.01) respectively. Parents‘ educational background also showed statistical significant influence on mean age at menarche. Girls whose any or both parents has tertiary educational background reach menarche earlier than girls whom neither of their parents has any form of formal education. Though paternal education showed statistical significant influence (F = 2.81, p = 0.04) while maternal educational background did not show statistical significant influence (F = 2.24, p = 0.08). Menarcheal age showed statistical significant inverse correlation with weight, BMI, chest and hip circumference (p < 0.05). Linear regression models for estimating menarcheal age from anthropometric and socio-demographic variables of girls from each ethnic group were generated. All subjects in this study reported at least one premenstrual syndrome or the other with varying degree of severity. There is however, no predilection in the incidence and severity of premenstrual syndrome based on ethnicity. The mean menstrual cycle length of most participants is 24 – 29 days (χ2 = 7.75, p = 0.02) while most participants reported a mean length of menstrual flow of
4 – 5 days (χ2 = 49.22, p < 0.01).
TABLE OF CONTENTS
Title Page ——————————————————————————————- i
CERTIFICATION ——————————————————————————- iii
ACKNOWLEDGEMENT ———————————————————————- iv
DEDICATION ———————————————————————————— vi
Table of Contents —————————————————————————— vii List of Tables ———————————————————————————— xi List of Figures ———————————————————————————- xiv List of Appendices —————————————————————————– xv Abstract —————————————————————————————– xvi 1.0 Introduction ——————————————————————————1 1.1 Background of Study ——————————————————————–1 1.2 Statement of Research Problem —————————————————— 4 1.3 Justifications —————————————————————————– 5 1.4 Significance of Study ——————————————————————– 5 1.5 Study Hypothesis ———————————————————————— 6
1.6 Aims and Objectives of Study ——————————————————— 6
1.6.1 Aims of Study —————————————————————————– 6 1.6.2 Objectives of Study ———————————————————————– 6
1.7 Enugu State ——————————————————————————- 7
1.7.1 Climate and Vegetation of Enugu State ———————————————— 8 1.7.2 Nsukka ————————————————————————————- 9
1.8 Kaduna State —————————————————————————– 9
1.8.1 Zaria ————————————————————————————– 10 1.8.2 Drainage ———————————————————————————- 11 1.8.3 The Climate of Zaria ——————————————————————– 11 1.8.4 Natural Vegetation ———————————————————————- 12 2.0 Literature Review ——————————————————————— 13 2.1 Assessment of Menarcheal Age —————————————————– 13 2.2 Neuroendocrinology of Puberty —————————————————– 14
2.3 Factors Associated with Menarcheal Age —————————————– 14
2.3.1 Urban Versus Rural Environment —————————————————–14 2.3.2 Ethnic Differences in the Timing of Menarche ————————————–16 2.3.3 Socioeconomic Influences on Menarche ———————————————-20 2.3.4 Nutrition ———————————————————————————- 21 2.3.5 Body Mass Index, Weight, Height and Menarche ———————————–22 2.3.6 Month of Birth, Birth Order and Family Size —————————————- 24 2.3.7 Physical Activities ———————————————————————- 25
2.3.8 Father Absence ————————————————————————– 26 2.3.9 Genetic Control of Menarche ———————————————————- 27 2.3.10 Family Heredity ————————————————————————- 29 2.3.11 Family Dysfunction and Child Sexual Abuse —————————————- 30 2.3.12 Exposure to Tobacco Smoke ———————————————————– 31 2.3.13 Birth Weight —————————————————————————– 32 2.3.14 Environmental Influences on Menarche ———————————————- 32 2.3.15 Diseases ———————————————————————————- 34 2.3.16 Age at Menarche and Body Growth and Configuration —————————- 35 2.3.17 Temperature and Humidity ———————————————————— 36 2.3.18 Association between Puberty and Age at Menarche ——————————– 37 2.3.19 Declines in Menarcheal Age during the Last Century —————————— 38
2. 3.20 Health Implications of Early or Late Menarche ————————————- 39
2.4 Defining the Menstrual Cycle ——————————————————- 41
2.5 Phases of the Menstrual Cycle —————————————————— 42
3.0 Materials and Methods ————————————————————— 50
3.1 Research Participants —————————————————————- 50
3.2 Study Area —————————————————————————— 52
3.3 Methodology —————————————————————————- 54
3.4 Data Collection Technique ———————————————————- 56
3.5 Sampling Size Determination ——————————————————- 56
3.6 Anthropometry ———————————————————————— 56
3.7 Ethical Approval ———————————————————————– 58
3.10.1 Inclusion and Exclusion Criteria ——————————————————- 58 3.10.2 Inclusion Criteria ———————————————————————— 58 3.10.3 Exclusion Criteria ———————————————————————– 58 3.11 Statistical Analyses ———————————————————————58 4.0 Results ———————————————————————————– 60 4.1 Analyses of Study Population ——————————————————– 60 4.2 Anthropometric Variables and Menarcheal Age ——————————– 60 4.3 Socio-Demographic Variables ——————————————————- 75 4.4 Correlation between Anthropometric Variables ——————————– 81 5.0 Discussion —————————————————————————— 117 6.0 Summary, Conclusion and Recommendations ———————————– 99 6.1 Summary ——————————————————————————– 99 6.2 Conclusion —————————————————————————– 100 6.3 Recommendations ——————————————————————- 100 6.4 Contributions to Knowledge ——————————————————- 101 References —————————————————————————– 103
1.1 BACKGROUND OF STUDY
The onset of puberty is marked by the development of breast tissue, and menarche is a late event in puberty. The age that menarche occurs varies and is dependent on the interaction between genetic and environmental factors. In the 19th century factors that were thought to exert an influence on the physical maturation of girls were climate (particularly the mean annual temperature), ethnic origin, social status, urban or rural residence, physical activity, education, sexual stimulation, housing, inheritance, and health status (Heidi, 1986). Studies carried out in the 20th century documented other factors associated with the age at menarche, e.g. season and month at birth, physique, birth order, family income, occupation and education of parents and family size (Heidi, 1986).
It is considered that during the 20th century the dramatic improvement of socioeconomic conditions and general health of the populations in the industrialized countries resulted in an earlier onset of puberty in children. The most reliable marker of the positive secular changes in pubertal development was the fall of the age at menarche. It has been estimated that during most of the 20th century age at menarche has been fallen by about 3 months per decade (Tanner, 1989), although there are reports from industrialized countries that it has been leveling off or that it shows an upward trend (Lindgren et al., 1991; Dann and Roberts, 1993). Whatever the factors that
influence pubertal maturation and age at menarche are, they interrelate and thus the onset of menarche cannot be attributed to a single factor. Menarche heralds the beginning of a female‘s reproductive life and its timing is an indicator of the start of regular exposure to endogenous oestrogen and other hormones. It is the onset of menstruation and is one of the milestones in women‘s lives. Although it is a late marker of puberty, it is a well validated indicator and an easily remembered event when compared to other events in the process of female sexual maturity (Herman-Giddens et al., 1997;Parent et al., 2003). Adolescence is a transition period from childhood to adult life during which pubertal development and sexual maturation takes place. During puberty, hormonal, psychological, cognitive and physical changes occur simultaneously and interactively making physiological development a challenge adolescents have to face, with emotional, social and behavioral dimensions. Mean age at menarche varies from population to population according to different factors like nutritional status, socio-economic status, geographical and environmental conditions and most of the females experience it when they are 10 to 16 year old (Frédéric et al., 2001; Kaplowitz, 2006). Genetic factors perhaps account for approximately 10-15% variation in age at menarche (Gray, 1993). Generally, better nourished girls have been found to attain menarche earlier than undernourished girls (WHO, 2003).
Menstrual disorders like delayed menarche, premenstrual symptoms and dysmenorrhoea create a great anxiety among the adolescent females and their families, thus it is very important to know menstrual cycle pattern and variation for clinical
evaluation and patient education (Adam, 2002;Diaz et al., 2006). Investigating the age of menarche and menstrual problems among adolescent is of much importance so as to provide health planners and caregivers with fundamental data necessary for interventions. Studying age at menarche is not derived by academic interest, but rather by the huge public health implications which might be caused by changes in the mean age at menarche. Early age at menarche has been linked to several adverse health effects during childhood such as eating disorders (Striegel-Moore et al., 2001) and depression (Kaltiala-Heino et al.,2003); and during adulthood such as type 2 diabetes (Lakshman et al., 2008; Dreyfus et al., 2012; Stockl et al., 2012), metabolic syndrome (Stockl et al., 2011), breast cancer (Petridou et al.,1996; Hadjisavvas et al., 2010), cardiovascular disease and overall mortality (Jacobsen et al., 2007; Jacobsen et al., 2009; Lakshman et al., 2009) and rheumatoid arthritis (Karlson et al., 2004). It is therefore a clinically relevant and widely used measure in anthropological and epidemiological studies, considered as an outcome, predictor, effect modifier or mediator. Estimating age at menarche is also critical for patient education and may guide the clinical evaluation to identify deviations from normal (Diaz et al., 2006). Age at menarche appears to have been declining in recent decades in western industrialized countries (Whincup et al., 2001; Parent et al., 2003;Herman-Giddens, 2007;Cabanes et al., 2009; Lehmann et al., 2010) because of several plausible factors one of which is the increasing rates of childhood obesity which has been postulated to be the prime factor (Kaplowitz et al., 2001; Ahmed et al., 2009; Walvoord, 2010).
Menarcheal age is the most widely used indicator of sexual maturation and can be used as an indicator of female health, growth and development, and the capacity to reproduce (Rees 1993;Aksglaede et al., 2009; Gohlke and Woelfle, 2009; Biro et al., 2010; Gaudineau et al., 2010). Onset of maturation and age at menarche, are influenced by several factors, e.g. genetics, ethnicity, height, weight, body mass index (BMI), and socioeconomic circumstances (Mul et al., 2001; Fredriks et al., 2000; Anderson and Must, 2011; Aksglaedeet al., 2009; Gohlke and Woelfle, 2009). Several studies from various developed countries worldwide have shown a systematic decrease in median age at menarche in the past 160 years (Rees, 1993; Fredriks et al., 2000). In Europe the median age at menarche decreased with 2 to 3 months per decade from 16.5years in 1840 to about 13.0 years in the 1960s, with 0.5 years variation between countries (Cabanes et al., 2009; Gohlke and Woelfle,2009). In Scandinavian countries the secular trend in age at menarche and stature has stopped, and possibly even reversed in the past three decades (Liestol and Rosenberg, 1995; Gaudineau et al., 2010).
1.2 STATEMENT OF RESEARCH PROBLEM
To our knowledge as at the time of writing this thesis, no previous study has been conducted to compare the menarchecal age of rural and urban girls between the Igbo and Hausa ethnic groups in Nigeria.There is no previous study with adequate methodology to compare and ascertain whether age at menarche has declined over the last few decades between the Hausa and Igbo ethnic groups in Nigeria due to the influence of variation in anthropometric parameters, ethnicity, and socio-demographic factors. The present study attempts to answer the following questions. What is the mean age of menarche among rural and urban girls of Hausa and Igbo ethnic groups, girls
from which ethnic group have lower or higher age at menarche with regard to selected anthropometric parameters,geographical location and social background.
The increasing breast cancer incidence worldwide follows trends toward earlier age at menarche and higher rates of obesity. Age at menarche and obesity has been identified as risk factors for breast cancer. For each 1-year delay in menarche, the risk of breast cancer decreases by around 5%, and this menarcheal effect may be stronger in premenopausal than in postmenopausal women, indicating a time dependent effect. Menarche is a clinically relevant and widely used measure in anthropological and epidemiological studies, considered as an outcome, predictor, effect modifier or mediator. Several studies have indicated that women who have an early menarche are at increased risk for breast cancer (Walvoord, 2010). According to Steingraber (2007), researchers have speculated that with early menarche a woman‘s lifetime exposure to oestrogen is increased, and exposure to oestrogen increases the risk of breast carcinogenesis.
1.4 SIGNIFICANCE OF STUDY
Menstrual disorders like delayed or early menarche, premenstrual symptoms and dysmenorrhoea create a great anxiety among adolescent girls and their families, thus it is of enormous significant to know the age at menarche for girls‘ clinical evaluation, education and identification of deviations from normal. Investigating the age of menarche and menstrual problems among adolescent is also important so as to provide health planners and caregivers with fundamental data necessary for interventions. The
knowledge of age at menarche in a given population is a pressing need of the society as no law about the age at marriage, consensual sex, abortion, family planning, rape and other aspects of female reproductive life can be made without it. With emergence of acquired immune deficiency syndrome as one of major threat to mankind and teenage pregnancies as one of the major social problems, an urgent need is felt, in developed as well as developing countries to make the adolescents aware of it.
1.5 STUDY HYPOTHESES This study sets out to test the following hypotheses:
i. There will be difference in age at menarche due to anthropometric variables, ethnicity, and socio-demographic factors.
ii. There will be difference in anthropometric variables between menstruating and non-menstruating girls.
iii. There will be no difference in the incidence of premenstrual syndrome between girls from both ethnic groups.
1.6 AIMS AND OBJECTIVES OF STUDY
1.6.1 Aims of Study
The present cross-sectional study is primarily aimed to investigate the influence of socio-demographic factors on average age at menarche among Nigerian secondary schoolgirls from Enugu and Kaduna States of Nigeria.
1.6.2 Objectives of Study
The present study is designed to achieve the following objectives:
i. Determine the mean age at menarche of girls from the Igbo and Hausa ethnic groups of Nigeria;
ii. compare the mean age at menarche of girls based on ethnicity and socio-demographic factors;
iii. investigate the influence of certain anthropometric variables on menarche;
iv. investigate the relationship between BMI and age at menarche;
v. compare anthropometric variables of menstruating and non-menstruating girls;
vi. determine the prevalence of premenstrual syndrome in girls from these ethnic groups;
vii. investigate the effect of settlement (urban and rural) on age at menarche and anthropometric variables and indices;
viii. to generate predictive equations for the estimation of menarcheal age and other anthropometric variables.
1.7 ENUGU STATE
Enugu State is one of the 36 States in Nigeria, apart from the Federal Capital Territory, located between latitude 5º 56′ N and 7º 00′ N and longitude 7º 00′ E and 7º55′ E of the Greenwich meridian (fig. 3.1). The State is bounded in the northeast by Ebonyi State, on the north by Benue and Kogi States and to the west by Anambra State from which it was carved out in 1991. In the south it borders with Abia State. Enugu State has a total land area of 7660.166 sq. kilometres with a population of 3,267,837 persons (National population census, 2006) and therefore a population density of 427 persons per square kilometre with an area code of 042. Administratively, Enugu State is divided into 19 Local Government Areas. But politically, there are three zones, namely: Enugu North, Enugu South and Enugu Central. About 85% of the rural population are engaged
in the agricultural sector, characterized largely by smallholding of less than one hectare. Predominant food crops include cassava, yam, maize, rice, pigeon pea, bambara nuts, cocoyam and cowpea. The major perennial tree crops grown are oil palm, citrus, pear and cashew. These are supplemented with small-scale livestock farming such as poultry, small ruminants and indigenous cattle. The State capital is located at the hilly city of Enugu. An old seat of government, Enugu was the capital of the former East Central State from which present Anambra, Enugu, Imo, Abia, and Ebonyi States were carved out. Highly cosmopolitan, Enugu boasts of a couple of industries. The state is called the Coal City State because of the discovery of coal in commercial quantity in Enugu urban in 1909 (Enete and Alabi, 2012). 1.7.1 Climate and vegetation of Enugu State
Enugu state falls within the humid tropical rain forest belt of South-eastern Nigeria. It has two seasons, the raining season and the dry season. The rainy season which is characterized by heavy thunderstorms lasts from April to October with the South Westerly moisture accompanied by air mass moving northwards into the city. The turbulent runoff result in leaching, sheet erosion and eventually gullies (Akabuike, 1990). The mean temperature varies from about 20.30 ºC to about 32.16 ºC in the dry season and rainy season respectively, (Akabuike, 1990). During the dry season the humidity is lower than in the rainy season. Temperature is most often high during the day and low during the night. This results in high evaporation rate during the day. Harmatten which occurs between the months of November and February is always
accompanied by poor visibility mostly at night and early in the morning (Enete and Alabi, 2012). 1.7.2 Nsukka Nsukka area lies between latitude 6º 18′ and 7º 06′ N and longitudes 6º 52′ and 7º 54′ E, and covers a total surface area of approximately 3,961 square kilometers (Noble, 2002). However, the Nsukka urban community is one of the two major urban centres of Enugu State recognized by the state government. It has a population of about 254,422. Before 1960, Nsukka was a relatively unknown town, overshadowed by the then more prosperous Ogurugu, which became a major exporting centre (on account of its location along the River Niger coast) and Ibagwa, which had a flourishing horse market. After 1960, all these changed with the establishment of the University of Nigeria. (Noble, 2002). Nsukka has grown pari pasu with development of the University. A casual look at the settlements will reveal two distinct patterns, namely: one predominantly rural, where indigenes live; and another, essentially cosmopolitan, and mostly inhabited by nonindigenes. The University dominates the landscape of Nsukka, offering employment to most of the inhabitants and constituting its main economic base or its main industry (Noble, J. N. 2002). 1.8 KADUNA STATE
Kaduna metropolis (fig. 3.1) is located at latitude 11º 3′ N and longitude 7º 25′ E. It is the capital city of Kaduna State, a state that shares boundaries with Kano, Zamfara, Katsina, Niger and Bauchi states in northern Nigeria. The town is largely a heterogeneous town, with major ethnic groups being of Hausa, Fulani, Kataf, Gbagyi, Jabba and Kagoro extractions, among many other minor groups (Akinbabijo, 2012). Kaduna State has a total land area of 45,711.188 sq. kilometres with a population of 6,113,503 persons (National population census, 2006) and therefore a population density of 134 persons per sq. kilometer. Kaduna State is divided into 19 Local Government Areas Birni-Gwari, Chikun, Giwa, Igabi, Kajuru, Ikara, Jaba, Kachia, Jema’a, Kaduna North, Kaduna South, Kagarko, Kaura, Kauru, Kubau, Kudan, Lere, Makarfi, Sabon-Gari, Sanga, Soba, Zango-Kataf, and Zaria. 1.8.1 Zaria
Zaria is a Hausa land in northern Kaduna State, in the northern part of Nigeria and is located on latitude 11º04′ north and longitude 7º 43′ east. It is defined by a 15 Km radius from the PZ post office and is well connected by roads and rail with other regions of the country. Distances from Kaduna, Kano, Jos and Sokoto are approximately; 75 Km, 176 Km, 387 Km and 404 km respectively. Zaria is the second principal town in Kaduna state after Kaduna and home to the Ahmadu Bello University, established in 1962 and a host to several other federal government institutions like Federal Institute for Chemical andLeather Research, Federal College of Aviation and Industrial Development Corporation.
The population of Zaria is approximately 975,153 (projections from 2006 national census).It is made up of two Local Government Councils, Zaria Local Government, consisting of two districts; Zaria walled city and Tudun Wada, and Sabon gari Local Government which consists of three districts; Sabon Gari, Samaru, and the Government Reservation Area (Olamdimeji and Ojibo, 2012). 1.8.2 Drainage The Kubanni River has its source from the Kampagi hill in Shika near Zaria. It flows in a Southeast direction through the premises of Ahmadu Bello University. The Samaru stream which is one of the tributaries of Kubanni River has a stream length of 1.05km within an area of 2.28km2 and has drainage density of 0.4605 km/km2 (Yusuf and Shuaib, 2012). 1.8.3 The climate of Zaria
The climate of the study area is a tropical savanna climate, with distinct wet and dry seasons (Aw climate Koppens classification). Zaria experiences six (6) months of rainy season and six (6) months of dry season. The rainy season is from May to late October, while the dry season is from early November to April, this is as a result of the interplay of the two dominant air masses within the region i.e. the tropical continental air messes (cT) and Tropical maritime air masses (mT) (Iguisi and Abubakar, 1998). Climate is an important factor that determines the form of any architecture. In Nigeria the Hausa live in northern Savannah type of climate (Moughtin, 1985). 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 (DURP, 1979). December to January in Zaria 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, and the highest in the year. This extreme diurnal temperature range is another characteristic of the Savanna type of climate (Areola et al., 2006). 1.8.4 Natural vegetation
Nigeria has six Climatic Zones (Bureau for Public Enterprises, 2003-2007); The Mangrove Swamp, Swamp Forest, Rain Forest, Guinea Savanna, Sudan Savanna and Sahel Savanna. The Sudan Savanna approximates in a belt from Latitude 8º north to Latitude 12º north of the Equator, in Nigeria (Anuforom and Okpara, 2004). This region definitely includes Zaria, which is located at latitude 11º 3′ N and longitude 7º 25′ E. The Sudan Savanna is typified by tall tropical ‗savanna‘ grass (Ati, 2002); the elephant grass (Areola et al., 2006). Trees are scattered, typical of wet dry climate. This vegetation is mixed with scrubs and thorny bushes, adapting itself to the climatic rhythm of longer water-drought and shorter summer rain. They are mostly deciduous, shedding their leaves in the dry
season to conserve water which would have been lost by transpiration; lying dormant and searching for ground water. Tallest trees in Zaria are the baobab ‗gingiya‘, palm and cotton trees (Anselem and Ojonigu, 2010).