Menarchial Age of Secondary School Girls in Urban and Rural Areas of Rivers State, Nigeria



educated on the study to be carried out.
Also, informed consent was obtained from
all the girls and the school authorities before
the study was carried out.

Statistical                               Analysis:

Means, standard deviations and simple
percentage were determined. Z-score was
used to test for significance level, since the
sample size was large. In all cases a 5% level
of error was assumed and 95% level of
confidence accommodated with a critical
value of 1.96 on a two-tailed distribution or
a critical value of 1.64 on a one-tailed
distribution.

Results

There was a statistically significant lower
mean menarchial age in urban school girls
compared to the rural school girls (Z-score
=10.22, Table 1). In both urban and rural
areas, school girls from high socio-economic
class had significantly lower mean
menarchial age compared to their
counterparts from low socio-economic class
(Z score = 13.89 and 7.68, respectively, Table
2). In the rural area, school girls involved in
vigorous sport activity had a higher age of
menarche compared to girls in non-sporting
activity (Z = 9.75, Table 3)

Table 1: Mean menarchial age in urban and rural secondary school girls

Urban

Rural

Z = score

Menarchial age (years)

13.19 ± 1.32

14.22 ± 1.47

10.22*

Values are mean ± S D; *Statistically significant

Table 2: Mean menarchial age (years) of high, middle and low socio-economic class school
girls in the urban and rural areas

High

Middle

Low

High Vs Low Z -
score

Middle Vs Low Z -
score

Urban area

13.06±1.35
(n =218)

13.08±1.27
(n =87)

13.70±1.18

(n =51)

18.89*

7.29*

Rural area

13.98±1.46

(n=61)

14.10±1.59
(n =49)

14.38±1.42
(n -133)

7.68*

-1.54NS

Values are Mean ± SD; *Significant; NS = Not significant

Table 3: Relationship between menarchial age (years) and sporting activity

_________Sporting_________

______Non- sporting______

Z-score

Urban

13.10 ± 1.27 (n = 284)

12.98 ± 1.40 (n = 224)

-1.12 Ns

Rural

14.61 ± 1.34 (n = 211)

14.09 ± 1.57 (n = 140)

____________9.75*____________

Values are Mean ± SD

Discussion

Data from the present study shows a
statistically significant lower mean
menarchial age (13.89 ± 1.37 years) for urban
secondary school girls than the mean value
for the rural school girls (14.22 ± 1.47 years).
This is consistent with the observation of Lin
et al7, that urban Chinese girls had a lower
menarchial age than their rural
counterparts. A number of factors may have
contributed to this difference. Socio-
economic factor was investigated in this
study and it was observed that school girls
from a high socio-economic class had a
statistically significant lower mean age of
menarche compared to those in low Socio-
economic class. Ikechebelu8 had earlier
noted lower age of menarche in girls of high
socio-economic status than those of low
socio-economic class. It seems that the socio-
economic status affects menarchial age, and
this may account for the significant
difference in menarchial age between urban
and rural school girls, since 56.6% (133) of
the rural school girls were within the low



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