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| ORIGINAL ARTICLE |
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| Year : 2016 | Volume
: 23
| Issue : 3 | Page : 121-126 |
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An assessment of sexual maturation among school girls in Abakaliki Metropolis, Ebonyi State, South-East Nigeria
Onyinye Uchenna Anyanwu1, Roland Chidi Ibekwe2, Ada Rosemary C Nwokocha3, Chidozie Bede Ibe3
1 Department of Pediatrics, Federal Teaching Hospital, Abakaliki, Nigeria
2 Department of Pediatrics, Federal Teaching Hospital, Abakaliki; Department of Paediatrics, University of Nigeria, Enugu Campus, Nigeria
3 Department of Paediatrics, University of Nigeria, Enugu Campus; Department of Pediatrics, University of Nigeria Teaching Hospital, Enugu, Nigeria
| Date of Web Publication | 12-Sep-2016 |
Correspondence Address:
Onyinye Uchenna Anyanwu
Department of Pediatrics, Federal Teaching Hospital, Abakaliki
Nigeria
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/1117-1936.190348
Background: Sexual maturation is an important milestone which starts between 8 and 14 years in girls. However, varying ages of onset of sexual maturation have been reported in different environments, with more recent studies showing earlier ages of onset in girls. There is therefore need to describe the sexual maturation of girls in each environment.
Subjects and Methods: A cross-sectional study of 6–18-year-old school girls in Abakaliki. One thousand one hundred and fifty-five girls were selected through multi-staged sampling. They were interviewed, and sexual maturation was assessed using breast and pubic hair development.
Results: Pubic hair development occurred earliest at a mean age of 9.87 ± 2.19 years. Breast development followed at a mean age of 10.53 ± 2.38 years. The mean age for menarche was 12.82 ± 1.29 years, which chronologically occurred between sexual maturity rating stages 3 and 4. Overweight/obesity was found to be correlated with an earlier age of onset of sexual maturation (P < 0.05). Participants belonging to the upper socioeconomic class also had earlier age of onset of sexual maturation (P < 0.05). Compared with earlier studies, positive secular trend for earlier maturation was found using pubic hair development, breast development and menarche as markers of onset of maturation.
Conclusions/Recommendations: Against the background of the present findings of a continuing secular trend of earlier sexual maturation in Igbo girls, there is a need to provide relevant information to parents/guardians and to reduce puberty-related anxiety. This will go a long way in improving quality of parental support for adolescents during this crucial period. Keywords: Abakaliki, school girls, sexual maturation
How to cite this article:
Anyanwu OU, Ibekwe RC, Nwokocha AC, Ibe CB. An assessment of sexual maturation among school girls in Abakaliki Metropolis, Ebonyi State, South-East Nigeria. Niger Postgrad Med J 2016;23:121-6 |
How to cite this URL:
Anyanwu OU, Ibekwe RC, Nwokocha AC, Ibe CB. An assessment of sexual maturation among school girls in Abakaliki Metropolis, Ebonyi State, South-East Nigeria. Niger Postgrad Med J [serial online] 2016 [cited 2023 Mar 29];23:121-6. Available from: https://www.npmj.org/text.asp?2016/23/3/121/190348 |
| Introduction | |  |
Sexual maturation can be defined as a series of events that occur sequentially to transform an immature child into a sexually mature adult capable of performing reproductive functions.[1],[2] It is associated with breast and pubic hair development as well as the onset of menstruation (menarche) in girls.[3] The process of sexual maturation is a response to reproductive hormones produced by the ovaries and adrenal glands, following the relevant central stimulation by the hypothalamus and pituitary glands.[4]
The development or non-development of these characteristics in girls poses a lot of challenges psychosocially to children and their parents/guardians. Understanding the age of onset and factors affecting development of sexual maturation in girls will reduce anxiety in the child, her parents/guardians and the health-care provider since knowing the normal will help appreciate abnormal sexual maturation.
Onset of sexual maturation varies in different races and countries.[2],[3],[4],[5],[6] Therefore, it is pertinent that every country should have records of the ages of onset of sexual maturation in their environment. In addition, such assessments should be updated periodically for comparison with the previous reference data.
Previous studies from Nigeria [2],[4] on the same subject were carried out more than two decades ago, and they reported variations in the sexual maturation feature which had the earlier onset, breast development and appearance of pubic hair. No study has been carried out within Abakaliki. Before 1996, Abakaliki was essentially rural. With the creation of Ebonyi State and Abakaliki as its capital, it became upgraded to an urban area. Since then, the city has evolved from a rural area to a metropolis with changing lifestyles and socioeconomic status of its inhabitants. Empirical observations of earlier development of sexual maturation in girls, following complaints by anxious parents, in addition to the absence of similar studies in Abakaliki therefore, were considered a valid justification of the present study.
The study aims at determining the age of development of female secondary sexual characteristics and its association with socioeconomic status of parents as well as body mass index (BMI). It hopes to provide information that will help physicians counsel patients and their anxious parents who may notice their daughters developing earlier or later than expected.
| Subjects and Methods | | |
Study design
This was a cross-sectional descriptive study of 6–18-year-old primary and secondary school girls in Abakaliki, Ebonyi State, Nigeria.
Sample size determination
The sample size was determined as 1214 of 6162 girls enrolled in 2012–2013 session,[7] using the formulae [8]n = z2pq/d2 (for infinite population) and  .
Selection of participants
Participants were selected by a multi-staged sampling method. Primary and secondary schools in the Metropolis were stratified into the two local government areas (LGAs) (Ebonyi and Abakaliki LGAs) and further into public and private schools in each LGA. One school was selected from each stratum randomly giving a total of eight schools (four primary, four secondary). Participants were systematically selected from each of the selected schools pro rata depending on the school population, number of classes and number of class arms. The number of girls from each school was selected proportionally.
Selection within classes was done by simple random sampling using the class register. The number selected from each class was done proportionally according to each class population. This was done in an attempt to capture various ages of subjects. Girls with known or suspected chronic illnesses (chronic illnesses affect sexual maturation)[9],[10],[11] were excluded from the study.
Ethical considerations
Ethical approval was obtained from Research and Ethics' Committee, Federal Teaching Hospital, Abakaliki (FETHA/REC/VOL1/2012/017), and Education Board of the State Ministry of Education, Ebonyi State. Informed consent was obtained from school authorities and parents/guardians while assent was obtained verbally from all participants after explaining the nature of the study.
Method
A pilot study was done to assess appropriateness of study tools and to provide training opportunity for three female research assistants before commencing the study. Primary researcher and assistants were females so that the participants being females would feel more at ease during their physical examinations. The study was done between February and August 2013. Socioeconomic stratification was done using mother's education and father's occupation. Participants were stratified into upper, middle, and lower socioeconomic classes using the criteria by Olusanya et al.[12] Age was obtained from school records. Birth certificates/immunisation certificates were also viewed. Age at menarche was obtained during the individual participants' interview.
A well-calibrated stadiometer (SECA ® stadiometer, model 217, SECA Corp., Hamburg, Germany) was used to measure heights to the nearest 0.1 cm. Heights were measured in Frankfurt plane without foot- or head-wear. Two measurements were made, and the mean was obtained. Where a difference of >0.2 cm was obtained, another measurement was taken.
A well-calibrated standing weighing scale (SECA ® Precision Weighing Balances, Bradford, USA) was used to measure weights in kilograms to the nearest 100 g in minimal clothing (underwear and blouse). Two measurements were made, and the mean was obtained. Where a difference of >200 g was obtained, a third weight was taken.
The BMI was calculated, from the formula, weight/height 2 (kg/m 2). All individual BMIs were converted to percentiles using the WHO 2007 reference growth charts.[13]
Physical examinations were conducted in well-illuminated rooms and in privacy using the school clinics, and where there was none, a room provided by the school authorities was used. Sexual maturity status using breast and pubic hair development was determined according to the stages of maturity by Marshall and Tanner.[14]
Tanner's sexual maturation staging
The Tanner's sexual maturity rating (SMR) scale is discussed briefly:
- Stage 1 (SMR1 P1 and P2) is the pre-pubertal stage, where the breast has a flat appearance with only the papilla raised while pubic hair consists of fine and downy lanugo in the genital area [14]
- Stage 2 (SMR2 P2 and B2) signifies onset of puberty. The breast bud is present such that the areola is elevated above the chest wall. There is sparse pubic hair growth, spread on the midline mainly along the labia majora. The hair is coarser in texture and darker in colour than the downy lanugo seen at SMR1
- In stage 3 (SMR3 P3 and B3), the breast tissue extends beyond the areola causing the elevation of the breast along with the areola, but the contour of the areola is the same as the rest of the breast. Further, characteristic of this stage is hair growth at the pubic region; the hair noticeably is more coarse and pigmented [14]
- Stage 4 (SMR4 P4 and B4) is the penultimate maturational stage. The areola forms a separate contour from the rest of the breast creating what is referred to as the 'mound on the mound' appearance while the pubic hair forms a triangle over the pubis [14]
- Stage 5 (SMR5 P5 and P5) is the final stage, and changes consist of the adult pattern where the areola flattens down assuming the contour of the rest of the breast, and the pubic hair extends beyond the triangle up to the abdomen and down the thighs.[14]
Participants who showed signs of puberty at <8 years or those with no sign of puberty by 14 years were referred to paediatric endocrinology unit of Federal Teaching Hospital, Abakaliki, for further evaluation.
Data analysis
It was done using SPSS version 20.0 (IBM SPSS Statistics for Windows, Version 20.0, IBM Corp., Armonk, NY, USA). Results were expressed in frequencies and means while the t-test was used for comparison of means. Correlations between BMI and age of sexual maturation were done using Pearson product moment correlation (r). All calculations were based on a significant level of P < 0.05.
| Results | | |
Participants' mean age was 11.97 ± 3.52 years and 50.9% were of lower socioeconomic class. Those in primary schools constitute 59.6% (mean age 9.83 ± 2.57 years) while 40.4% (mean age 15.13 ± 2.04 years) were in secondary schools. Six (8.6%) 6-year olds and 30 (30%) 7-year olds were pubertal (B2). Two (2%) 14-year olds were pre-pubertal (breast development stage 1 [B1]). Similarly, 18 (25.7%) 6-year olds and 50 (50%) 7-year olds were pubertal (pubic hair development stage 2 [P2]) while 4 (4.1%) 14-year olds were pre-pubertal (P1).
Four hundred and seventy-six (69.2%) primary school participants and 463 (99.1%) secondary school girls were pubertal using pubic hair development (P2) (χ2 = 164.20; df = 1; P < 0.001). In addition, 385 (56%) primary and 459 (98.3%) secondary school participants were pubertal using breast development (B2) (χ2 = 253.30; df = 1; P < 0.001) [Table 1]. | Table 1: Sexual maturation of participants in primary and secondary schools
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Mean age for P2 was 9.87 ± 2.19 years (range = 6–15 years). B2 occurred at 10.53 ± 2.38 years (range = 6–15 years). The mean ages increased for both pubic hair and breast development from SMR2 to 5 [Table 2]. Four hundred and two (34.8%) participants had attained menarche. The mean age for menarche was 12.82 ± 1.3 years, which falls midway of the maturational period for both breast and pubic hair development (between Stages 3 and 4). The mean age of girls in the various SMR stages and at menarche (M) is represented in a chronological order in [Table 1]. By 13 years, 70.6% (n = 402) of participants had attained menarche. | Table 2: Chronological representation of the mean ages of participants in each pubertal stage
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[Table 3] shows significant difference between the mean age of attainment of P2 for the upper and middle socioeconomic classes as well as with the lower class (P < 0.05). A similar finding was made of breast development (P < 0.001). The age of menarche was 11.55 ± 1.09 and 13.48 ± 1.07 years for participants in upper and lower socioeconomic classes, respectively [Table 4]. | Table 3: Association between socioeconomic class and onset of sexual maturity (P2 and B2)
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At P2 and B2, respectively, 74.2% and 74.7% of participants were of normal weight with mean ages of 10.03 ± 1.99 and 10.37 ± 2.18 years. The underweight participants had a mean age of 11.03 ± 2.58 and 12.56 ± 1.63 years for P2 and B2, respectively. Obese group had mean ages of 6.80 ± 0.45 and 6.67 ± 0.52 years for P2 and B2, respectively (P < 0.05). Eighty-nine per cent of pubertal <7-year olds were overweight/obese. All 14-year olds who were pre-pubertal were underweight. The mean age of menarche for participants was 14.13 ± 1.64, 12.87 ± 1.19, 12.47 ± 1.38 and 9.00 ± 1.16 years for underweight, normal weight, overweight and obese groups, respectively. There was statistically significant difference in the mean ages with that of the obese group being the least (P < 0.001). A correlation coefficient of − 0.51 was obtained for P2 while − 0.63 was obtained for B2 (P < 0.001). At menarche, a correlation coefficient of −0.32 (P < 0.001) was obtained. The mean age at menarche for this study was 12.82 ± 1.29 years. Earlier studies on Igbo girls from 1950 to 1990 suggested a trend of decreasing ages of menarche over the years [Figure 1].[2],[15],[16],[17]
| Discussion | | |
The finding in this study that pubic hair development heralded sexual maturation is similar to reports by Nwokocha [2] and Akenzua and Oronsanye,[18] but contrasts with that of Fakeye and Fagbule [4] and Marshall and Tanner.[14] In their reports,[4],[14] breast development heralded sexual maturation, the reason of which is not very clear. However, it has been shown that adrenal hormones contribute to pubertal development and may initiate pubic hair development even as early as 6 years. Hormonal assay is beyond the scope of this study, but the contribution of adrenal hormones and/or other environmental changes to the observed difference in what feature of sexual maturation occurs earlier among Nigerian girls has not been elucidated. The role of pubertal hormones in sexual maturation of girls, especially in defining the secondary characteristic which appears earlier in girls, should be the subject of subsequent studies.
The mean age (9.87 ± 2.19 years) of onset of puberty using pubic hair development is remarkably earlier than the previous Nigerian studies.[4],[18] This difference may be attributable to the different populations of girls studied. Previous Nigerian authors [4],[18] recruited participants aged 10–16 years from secondary schools. Girls who mature before 10 years may have been missed. Another reason may be that of secular trend which is attributable to better living conditions and increased incidence of obesity among girls. In this study, a significant proportion of the participants were overweight or obese at onset of sexual maturation.
The age of onset of breast development obtained in the current study is comparable to that in Caucasian studies that used similar methodology.[6],[19],[20],[21] It however does not support Herman-Gidden et al.'s [21] postulation that Black girls developed much earlier than Caucasian girls. It therefore appears that the varying ages of onset of breast development in different locale may be due to environmental factors such as nutrition, rather than genetic and/or racial differences. Therefore, the differences can change between generations with substantial changes in diets and dietary patterns.
More than 50% of the participants in primary schools in the current study had attained puberty (69.2% using pubic hair development and 56.0% using breast development). There is therefore need to introduce sexual/pubertal change education in primary schools to help them in dealing with and coping with these dramatic changes. This may justify the need to introduce education on pubertal changes in primary schools.
Socioeconomic class in the current study showed significant association with onset of sexual maturation using breast, pubic hair and menarcheal development. The upper socioeconomic class showed statistically significant earlier ages for onset of sexual maturation using all parameters, than the middle and lower classes. Similar association of socioeconomic class and sexual maturation was made earlier by Nwokocha,[2] who observed earlier age at onset of sexual maturation in the upper socioeconomic class compared to the middle and lower classes. Nwokocha [2] observed that at onset of sexual maturation, there was a good proportion of overweight participants. It is therefore opined that the association of socioeconomic class with sexual maturation may indeed be a reflection of the nutritional status of participants in the upper socioeconomic class.
This study showed a weak correlation (r = −0.5 and −0.61) between the BMI and the age of onset of maturation, which supports earlier reported studies.[5],[22],[23] Obese girls had the lowest mean age at onset of sexual maturation. It therefore infers that the more overweight a subject is the more likely she is to have early onset of sexual maturation. This finding supports a previous report among Turkish girls by Bundak et al.,[5] who noted earlier onset of puberty among obese and overweight girls when compared with their normal-weight peers. Earlier pubertal onset among overweight girls was postulated by Biro et al.[24] to be due to increased serum leptin levels which potentiate the hypothalamic-pituitary-gonadal axis. All 14-year olds who were pre-pubertal were underweight while all the 6- and 7-year olds participants who were pubertal were either overweight or obese. This further highlights the strong association between BMI and onset of sexual maturation. The effect of obesity on onset of sexual maturation may be explained by the postulation of Soules [25] that metabolic changes rather than gonadal steroids may be the key signal to the brain in initiating gonadotropin release. This postulation was supported by the finding of increased serum levels of basic nutrients such as fat, glucose and amino acids in pubertal animals.[25]
Secular trend of earlier onset of sexual maturation in girls was observed. Two decades ago, Nwokocha [2] conducted a similar study on sexual maturation of Igbo girls in Enugu. Compared to her findings, this study showed earlier age of onset of the various features of sexual maturation in girls. Onset of sexual maturation was earlier by 0.5 years (6 months) and 0.35 years (4 months) for pubic hair and breast development, respectively. Menarche occurred 0.42 years (5 months) earlier than it occurred in the study carried out in 1990.[2] Previous researchers studying menarche in Igbo girls had reported results showing decline with varying rates of 2, 3.5 and 3 months/decade.[2],[15],[16],[17] Comparing the present study with earlier ones using age at menarche, the 5 months decline in the past two decades may be interpreted as a decline by 2.5 months/decade. This falls within the purported decline range of 2–3 months/decade. The findings of a prevalence of 9.9% for overweight and obesity combined among the participants in this study suggest that the observed decline in age at onset of sexual maturation may be a reflection of improved nutritional status, socioeconomic status and preponderance for obesity among the participants. This further supports the speculations that the purported secular trend of earlier onset of sexual maturation which has been reported may not be unrelated to better nutrition and improved standards of living in these girls.[2]
| Conclusions | | |
An earlier onset of sexual maturation occurs in girls studied in keeping with the secular trend. Higher socioeconomic class as well as higher parameters of anthropometric variables favoured earlier maturation in girls. Against the background of the present findings of a continuing secular trend of earlier sexual maturation in Igbo girls, there is a need to provide relevant information to parents/guardians and to reduce puberty-related anxiety. This may contribute to improving quality of parental support for adolescents during this crucial period.
Limitations
This was a cross-sectional study even though a longitudinal study would have been preferred. A longitudinal study to address the research question will require up to 5–10 years of follow-up and enormous financial resources. A longitudinal study has however been commenced on the same subject matter.
Acknowledgements
We acknowledge Mrs. V.N. Egbe and Mrs. G.C. Ngwu of the Ministry of Education, Ebonyi State, and the authorities of the various schools used for this study for your approval which has made this work possible. We appreciate Winifred, Uche and Ezinne our research assistants who worked tirelessly with us during data collection. We also appreciate Chinwe the typist who did most of our clerical work.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
| 1. | Nwokocha AR. Adolescence and associated problems. In: Azubuike JC, Nkanginieme KE, editors. Pediatrics and Child Health in a Tropical Region. 2 nd ed. Owerri: African Educational Services; 2007. p. 84.  |
| 2. | Nwokocha AR. Sexual maturation of Igbo girls in Enugu. Dissertation: National Postgraduate Medical College of Nigeria; 1991. |
| 3. | Kelnar CJ, Butler GE. Puberty and adolescence. In: Forfar JO, Arneil GC, editors. Textbook of Paediatrics. 7 th ed. London: Churchhill Livingstone; 2008. p. 447-50. |
| 4. | Fakeye O, Fagbule D. Age and anthropometric status of Nigerian girls at puberty: Implication for the introduction of sex education into secondary schools. West Afr J Med 1990;9:226-31. |
| 5. | Bundak R, Darendeliler F, Günöz H, Bas F, Saka N, Neyzi O. Puberty and pubertal growth in healthy Turkish girls: No evidence for secular trend. J Clin Res Pediatr Endocrinol 2008;1:8-14. |
| 6. | Ma HM, Du ML, Luo XP, Chen SK, Liu L, Chen RM, et al. Onset of breast and pubic hair development and menses in urban Chinese girls. Pediatrics 2009;124:e269-77. |
| 7. | Ebonyi State Ministry of Education, Statistics and Planning Unit. 2010 School Enrolment: 12-24. |
| 8. | Araoye MO, editor. Sample size determination. In: Research Methodology with Statistics for Health and Social Sciences. Ilorin: Nathadox Publishers; 2004. p. 115-22. |
| 9. | Soliman A, De Sanctis V, Elalaily R. Nutrition and pubertal development. Indian J Endocrinol Metab 2014;18:S39-47. |
| 10. | Chowdhury S. Puberty and type 1 diabetes. Indian J Endocrinol Metab 2015;19 Suppl 1:S51-4. |
| 11. | Aina OF, Fadaka K, Temiye E, Renner JK. Sexual maturation and psychiatric morbidity among persons with sickle cell anaemia in a Nigerian teaching hospital. Int J Psychiatry Med 2010;40:31-43. |
| 12. | Olusanya O, Okpere EE, Ezimokhai M. The importance of social class in voluntary fertility control in a developing country. West Afr J Med1985;4:252-5. |
| 13. | |
| 14. | Marshall WA, Tanner JM. Variations in pattern of pubertal changes in girls. Arch Dis Child 1969;44:291-303. |
| 15. | Akenzua GI, Oronsanye AU. Events of puberty in Nigerian girls. Pediatr Adolesc Gynaecol1985;3:205-34. |
| 16. | Tanner JM, O'keeffe B. Age at menarche in Nigerian school girls, with a note on their heights and weights from age 12 to 19. Hum Biol 1962;34:187-96. |
| 17. | Ellis RW. Age of puberty in the tropics. Br Med J 1950;1:85-9. |
| 18. | Uche GO, Okorafor AE. The age of menarche in Nigerian urban school girls. Ann Hum Biol 1979;6:395-8. |
| 19. | Atay Z, Turan S, Guran T, Furman A, Bereket A. Puberty and influencing factors in schoolgirls living in Istanbul: End of the secular trend? Pediatrics 2011;128:e40-5. |
| 20. | Saffari F, Rostamian M, Esmailzadehha N, Shariatinejad K, Karimzadeh T. Pubertal characteristics in girls of Qazvin Province, Iran. Iran J Pediatr 2012;22:392-8. |
| 21. | Herman-Giddens ME, Slora EJ, Wasserman RC, Bourdony CJ, Bhapkar MV, Koch GG, et al. Secondary sexual characteristics and menses in young girls seen in office practice: A study from the Pediatric Research in Office Settings network. Pediatrics 1997;99:505-12. |
| 22. | Jean RT, Bondy ML, Wilkinson AV, Forman MR. Pubertal development in Mexican American girls: The family's perspective. Qual Health Res 2009;19:1210-22. |
| 23. | Codner E, Unanue N, Gaete X, Barrera A, Mook-Kanamori D, Bazaes R, et al. Age of pubertal events in Chilean school age girls and its relationship with socioeconomic status and body mass index. Rev Med Chil 2004;132:801-8. |
| 24. | Biro FM, Khoury P, Morrison JA. Influence of obesity on timing of puberty. Int J Androl 2006;29:272-7. |
| 25. | Soules MR. Paediatric and adolescent endocrinology. Paediatr Clin North Am 1987;34:1083-103. |
[Figure 1]
[Table 1], [Table 2], [Table 3], [Table 4]
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