The pattern of differentials in undemutrition between boys and girls is interesting; in terms of stunting overall mean z-scores for the two sexes are similar but the percentage of children stunted is slightly higher among girls than boys; the differentials are not statistically significant. The pattern of sex differentials in stunting by age is interesting: prevalence of stunting increases (or mean z-scores decline) with age among both sexes but the rate of increase is greater for the girls than the boys. As a result sex differentials in stunting observed in the young ages change in favour of boys after 18-23 months of age (see Figure 5.3 and Table 5.4). For instance the sex ratio of stunting at 3-5 months is 166 per 100 girls. This ratio drops consistently over the rest of the age group: 133 at 6-11 month and 116 at 12-17 months. After 18-23 months the sex ratio of stunting reaches a level below 100.
Sex differentials in wasting show similarities with those observed in stunting but the pattern of differentials by age group is less clear: at young ages girls are less affected than boys by wasting. The relative advantage that girls enjoy tends to reverse after 24 months of age. The prevalence estimates of wasting for the two sexes
■— G ir ls
18-23
12-17 24-29 30-36
Age of child
Figure 5.3 Percentage of children aged 3-36 months stunted by age and sex.
B o ys —^ G irls
18-23
12-17 24-29 30-36
Age of child
Table 5.4 Prevalence of stunting and wasting by sex of child and age, Sri Lanka, SLDHS, 1987
Indicator/
Sex of child All 3-5 6-11 12-17 18-23 24-29 30-36
Mean z-score Length for age
All -1.36 -0.53 -1.15 -1.47 -1.51- -1.43 -1.77
Boys -1.36 -0.71 -1.25 -1.49 -1.56 -1.38 -1.55
Girls -1.36 -0.30 -1.01 -1.44 -1.47 -1.52 -1.99
Weight for age
All -1.64 -0.54 -1.41 -1.84 -1.77 -1.86 -1.98
Boys -1.66 -0.73 -1.50 -1.88 -1.82 -1.83 -1.84
Girls -1.62 -0.31 -1.29 -1.80 -1.72 -1.89 -2.13
Weight for length
All -0.98 -0.23 -0.67 -1.24 -1.24 -1.09 -1.12
Boys -1.01 -0.33 -0.75 -1.27 -1.26 -1.09 -1.14
Girls -0.95 -0.11 -0.58 -1.20 -1.22 -1.10 -1.10
per cent undernourished Length for age
All 27.1 7.1 15.4 27.6 33.9 28.9 38.2
Boys 26.0 8.8 17.3 29.6 33.7 27.6 29.9
Girls 28.4 5.3 13.0 25.4 34.4 30.5 47.4
Weight for age
All 37.2 3.8 21.4 43.0 41.0 46.0 47.9
Boys 37.1 3.8 24.0 47.3 44.4 44.4 39.6
Girls 37.4 4.0 18.2 38.4 37.5 48.5 56.6
Weight for length
All 11.5 1.3 3.2 19.6 19.1 10.4 9.2 Boys 11.4 1.3 4.6 22.3 17.4 8.2 9.1 Girls 11.5 1.3 1.3 16.8 20.6 13.2 9.7 Number of children Boys 1051 116 193 199 173 206 164 Girls 915 96 159 177 171 148 165
show that boys have an early peak (see Figure 5.4), perhaps a reflection of earlier
weaning of boys than of girls (as discussed in Chapter 6). Sex differentials in
underweight broadly conform with those observed in stunting.
Although the overall differentials between the sexes were not statistically significant, statistical tests (chi square statistics for per cent undernourished and 't' statistics for mean z-scores) were performed to examine whether the differences
observed in nutrition between various age groups are in fact statistically significant. The results are presented in Table 5.5. For both stunting and underweight lower nutritional levels observed among the boys were statistically significant during infancy. At age group 30-36 the differentials were also significant; boys showed a relative advantage over girls. For wasting, differentials were not significant except for the female advantage observed in the second half of the first year. Sex differentials in stunting and wasting among the children differentiated by the mother's education, residential type and religion of the mother were minor and not statistically significant (Appendix Table 5.3).
Table 5.5 Statistical significance of relationships between nutritional status expressed in terms of mean z-scores between boys and girls by individual age of children
Indicator/
Characteristic All 3-5 6-11 12-17 18-23 24-29 30-36
Length for age
Boys vs Girls NS * * NS NS NS ★
Weight for age
Boys vs Girls NS * * NS NS NS *
Weight for length
Boys vs Girls NS NS * NS NS NS NS
NS = Not statistically significant * = Significant at p < 0.05
It has been hypothesized that under environmental stress conditions boys are less protected from morbidity, poorer growth and mortality than girls. Frequently cited examples in support of this hypothesis come from Greulich and others (discussed in Stinson, 1985) who studied the growth pattem of children who survived the atomic bombing in Nagasaki and Hiroshima, Japan. They found that, among the survivors, growth and maturation were poorer among boys than among girls. Similar evidence was also reported from Leningrad in the food shortage period during the Leningrad siege (Antonov, 1971 cited in Stinson, 1985).
growth, morbidity, and mortality to test the hypothesis that males are less buffered than girls against the effects of the environment, and found sufficient evidence in favour of
the hypothesis during prenatal growth. The evidence on growth under postnatal
environmental stress, however, did not consistently show poorer growth among boys.
The main reason for the inconsistency in the results, according to Stinson, is the possible effect of sex bias in the postnatal period in favour of sons. In some countries, mainly in South Asia, there is evidence of sex preference in caring for and rearing of children: for instance in Bangladesh, Chen, Huq, and D'Sousa (1981) observed intra family food allocations in favour of boys; while Sen and Sengupta (1983) found in two Indian villages poorer growth among girls than boys due to parental care and feeding behaviour in favour of sons. In Sri Lanka Nadarajah (1983) suspects that the higher mortality among girls than boys that existed in the past was possibly due to son preference:
preference for sons does not necessarily mean that female children are deliberately ill treated or neglected. They may be subject to relative and probably unconscious neglect compared to male children (Nadarajah,
1983:233).
The differential pattern of growth observed between boys and girls may be a reflection of the advantage that girls inherited from the prenatal period continuing through infancy during which period breastfeeding is carried out without much discrimination between the sexes. After infancy girls experience a more rapid decline in nutritional status than boys possibly because of the intentional or unintentional feeding practices in favour of boys. As is discussed in Chapter 6 there is a pattern, although the statistical significance is weak, of earlier weaning of boys than girls.