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Determinants of nutrient adequacy for lactating and pregnant mothers in a rural area of Bangladesh

Rafiqul Huda Chaudhury
Bangladesh Institute of Development Studies, Dhaka, Bangladesh

INTRODUCTION

Adequate diets for pregnant and lactating mothers deserve special attention. The extra nutritional requirements of pregnant and lactating women ( 1 ) need to be met not only in their own interests, but also for the well-being of their children. In most developing countries the nutrition of a child during the first year of life depends to a great extent on ingestion of breast milk. There is evidence to suggest that satisfactory lactation performance is influenced by the nutritional status of the mother and by the adequacy of her diet (1-8). Maternal nutritional status may affect not only the quantity of breast milk and the length of time she is able to lactate, but also the supply of certain nutrients such as vitamins (9).

Maternal nutrition is also a major determinant of an infant's birth weight. An undernourished pregnant woman is likely to give birth to an underweight child (10) whose health risks are increased as a consequence. A nutritionally inadequate diet also exposes a pregnant woman to a higher risk of morbidity and death. The importance of adequate nutrition for pregnant and lactating mothers is evident and calls for evaluating the extent to which these extra needs are met in a given population. Unfortunately, there is very little information on the dietary intake of pregnant and lactating mothers in Bangladesh. This study attempts to provide such information for a rural area of the country. It evaluates the extent to which these nutritional needs are fulfilled relative to the needs of other members of the family, and also studies the determinants of nutrient intake of pregnant and lactating mothers.

MATERIALS AND METHODS

The data were collected from 572 members of 108 households in the village of Muyiarchar (approximately 220 miles north-east of Dhaka) in the Sylhet District. The sample included 50 per cent of the households of the village, selected to include a representative number of each socio-economic group classified on the basis of land holding and income. Households were selected from each socio-economic stratum, with a probability equal to their proportion in each group.

There were 106 women in the reproductive age group (1544.99 years). Of these, 30 were lactating and 25 were pregnant. The data collected included daily consumption of rice, wheat, fish, milk, meat, pulses, eggs, vegetables, and fruits per person and the sources and costs of food consumed. Information was obtained for each member of the household once a month over a period of one year by 24-hour recall interview. Interviewers, mostly teachers from a nearby elementary school, were locally recruited and trained.

Along with the collection of data on food consumption, we have also obtained information on time allocation for every member of the household five years of age or older. This helped in estimating nutritional requirements, based on the type of activities in which individuals were engaged along with other considerations. Individual food intake was converted into nutrient intake by employing the Indian Food Composition Tables (11).

Average caloric requirements and safe levels of protein intake are estimated for every member of each household in order to assess whether a person consumes more or less than or an amount equal to his/her average requirement. Calorie and protein estimates are based on the recommendations of the Joint FAO/WHO/UNU Expert Consulation on Energy and Protein Requirements (1). The estimate of calorie requirement is provided on the basis of actual information on rest/sleeping and physical activity of a person. This is because human energy requirements consist of two components: basic energy demands for resting metabolic function, and all other energy costs, mainly physical activity.

To arrive at an estimate of caloric need for physical activities and rest/sleep, the following steps are taken. Physical activities are grouped into three categories, light, moderate, and heavy, on the basis of personal experience for actual time in minutes for each of these activities per day per person. We then calculate the energy required per person per day for each of these kinds of activities for males and females separately, as per recommendations of the FAO/ WHO/UNU joint report (1). To this is added the energy needed for sleep/rest (i.e., BMR) per person per minute. This was estimated on the basis of the individual's actual weight.

A final adjustment is made to allow sufficient energy for pregnancy and lactation. The extra allowance is 285 calories per day for a pregnant woman. In Bangladesh, breast-feeding commonly extends beyond the second year of life and may be as long as four years 112). On the basis of actual milk production of lactating mothers obtained from rural areas of Bangladesh, we added 500 calories for mothers who have children two years old or younger.

The safe allowance for protein was made on the basis of FAO/WHO/UNU recommendations (1). This was calculated by taking the average safe protein allowance per kilogram of body weight in a particular age/sex group times average weight in kilograms of a person in the corresponding age/sex group. In addition to this, allowance was made for pregnancy and lactation. A pregnant woman is allotted 5.6 grams of protein. We added 17 grams of protein (per day, per person) for mothers who have children one year old or younger and 11 grams for mothers with children between the ages of one and two years. All protein estimates were corrected for 70 per cent utilization

TABLE 1. Mean Nutrient Adequacy Ratios of Females 1544.9 Years Old by Pregnancy and Lactation Status

a. "Lactating-l" refers to women who have children one Year old or younger; "lactating-l!" refers to women who have children two years old or younger.
b. Mean calorie/protein intake (actual) per person per day divided by the mean of the recommended daily allowance, times 100.

Dependent Variables

Two dependent variables were employed to measure whether a person consumed more or less than or the equivalent of his/her need: mean nutrient adequacy ratios (NAR), the ratios of an individual's nutrient (calorie/ protein) intake divided by the recommended daily allowance of calories and protein respectively, times 100; observed-to-expected ratios, a measurement of whether a person is consuming more or less than or the equivalent of what his/her consumption would be expected to be if available nutrients were distributed according to relative need within the household. To find the latter ratios, we first obtained the percentage distribution of calorie/protein need for each member of the household and applied the percentage distribution to total observed intake of the household to obtain the expected calorie/protein consumption for each member of the household if foods were distributed wholly according to estimated need. Finally, we obtained the ratio of observed to "expected" consumption for each member of the household based on estimated requirements. This provides a measurement of intra-familial distribution of food.

RESULTS

Mean Nutrient Adequacy Ratios

Table 1 presents data on nutrient adequacy ratios by pregnancy and/or lactation status of female members 1544.99 years old in the household. The table shows that a woman who is neither pregnant nor lactating fares much better in meeting estimated calorie and protein requirements than those who are pregnant or lactating Among the pregnant and/or lactating women, the average intake of those who are pregnant and also lactating falls short of their calorie requirement, and lactating women barely satisfy calorie requirement. However, the average intake of pregnant women is adequate to meet presumed calorie requirements. By more recent estimated allowances (1), every adult woman consumes enough protein to meet requirement irrespective of her lactation and/or pregnancy status.

We have so far looked at the zero-order relationship between lactation and/or pregnancy status and nutrient intake of adult women 15-44.99 years old. In order to determine the net effect of lactation and/or pregnancy status on nutrient intake, it is necessary to control for those variables (education of mother, family size, expenditure on food, morbidity, labour force participation status) that are expected to affect nutrient intake. The net effect is determined through the dummy variable regression technique. Here, each dummy variable represents a single subclass of a factor. An individual is assigned a value of unity if she belongs to the subclass and zero if she does not. Each subclass of the variable is considered as a separate regressor.

TABLE 2. Adjusted Effect of Pregnancy and Lactation Status on Calorie and Protein Adequacy Ratios for Females 15-44.99 Years Old^a: Regression Analysis (OLS)

a. Adjusted for the effect of the following variables: pregnancy and lactation status, education of mother, education of head of household, family size, number of minutes engaged in productive activities per day, number of minutes lost due to sickness per day, expenditure (intake) on food per day. The variances explained by all these factors are 81.28 for the calorie adequacy ratio and 92.90 for the protein adequacy ratio.

b. See table 1, note a.

c Mean calorie intake (actual) per person per day divided by the mean of the recommended daily allowance for calories, times 100.

d. Mean protein intake (actual) per person per day divided by the mean of the recommended daily allowance for protein, times 100.

FIG. 1. Calorie Observed-to-Expected Ratio for Females 1544.99 Years Old (see table 3). The dotted line indicates the expected consumption of calories if calories were distributed according to relative need within the household.

FIG. 2. Protein Observed-to-Expected ratio for Females 1544.99 Years Old (see table 3). The dotted line indicates the expected consumption of protein if protein were distributed according to relative need within the household.

Each factor, for example, pregnancy/lactation status (a), is then converted into a set of regression variables (e.g. a', a2, a3 ) equivalent to the number of subclasses minus one. One subclass has to be dropped for inverting the matrix. The omitted variable becomes the "standard reference," and the remaining coefficient estimates are interpreted by comparison with it. The use of dummy variable regression does not involve making any assumptions about the linearity of the effect. The relationship between the dependent (mean nutrient adequacy ratio/observed-to-expected ratios) and the independent variables (pregnancy and/or lactation status) is analysed by ordinary least squares. The net effect of pregnancy and/or lactation status on mean nutrient adequacy ratios is presented in table 2.

The results of the dummy variable regression analysis uphold the earlier findings Pregnancy and/or lactation has a depressing effect on the nutrient adequacy ratio of an adult woman. The nutrient adequacy ratios of women who are pregnant and lactating are the lowest, followed by lactating or pregnant women. The difference in mean nutrient adequacy ratio of the lactating and/or pregnant women is significantly lower than those of non-pregnant, non-lactating women.

Observed-to-Expected Ratios {Calorie and Protein) for Females 15-44.99 Years Old by Pregnancy and/or Lactation Status

TABLE 3. Unadjusted Calorie and Protein Observed-to-Expected Ratios for Females 15-44.99 Years Old by Pregnancy and Lactation Status

a. see table 1, note a.

b. This ratio measures whether a person is consuming more or less than or the equivalent of his/her expected consumption if available calories and protein were distributed according to relative need within the household,

These ratios measure whether a woman is consuming more or less than or the equivalent of her expected consumption if available calories and protein were distributed according to relative need within the household. The data are presented in table 3 and figures 1 and 2, which show that the ratios of observed to expected consumption of calories and protein are higher for non-lactating and non-pregnant women than for pregnant and/or lactating women. In other words, the former consume more calories and protein than their relative need, while the latter consume less than their relative need.

Women who are both pregnant and lactating consume far less than their relative needs. These findings still hold true when allowance is made for the effect of other variables (table 4). The table also shows that an adult woman's chances of obtaining calories and protein as percentage of need decline if she is pregnant and/or lactating. The observed to expected consumption of calories and protein for the lactating and/or pregnant women is significantly lower than that of non-pregnant and non-lactating women.

Determinants of Nutrient Intake by Lactating and Pregnant Women

We have also examined the factors affecting nutrient intake and nutrient adequacy ratios of pregnant and lactating women. The variables considered to affect nutrient intake of pregnant and lactating women are: education, family size, morbidity, participation in the labour force, and expenditure on food per day. The ordinary least-square regression technique was employed to determine the effect of each independent variable on nutrient intake and nutrient adequacy ratios. The results are presented in tables 5 and 6.

TABLE 4. Adjusted Effect of Pregnancy and Lactation Status on Calorie and Protein Observed-to-Expected Ratios for Females 15-44.99 Years Old^a

a. Adjusted for the same variables as in table 2. The variances explained by these factors are 68.00 for the calorie ratio and 88.08 for the protein ratio.

b. See table 1, note a. c. See table 3, note b.

TABLE 5. Determinants of Nutrient Intake and Nutrient Adequacy Ratios of Pregnant Women: Regression Analysis (OLS)

Figures in parentheses are "t" values.
a. See table 1, note b.
b. Significant at .0001 1 ever.
c. Significant at .05 level.

TABLE 6. Determinants of Nutrient Intake and Nutrient Adequacy Ratios of Lactating Women: Regression Analysis (OLS)

Figures in parentheses are "t" vales.
a. See table 1, note b.
b. Significant at .0001 level.
c. Significant at .05 level.

From these tables it is evident that economic position measured in terms of per capita expenditure on food per day is the most important factor positively affecting calorie and protein intake and nutrient adequacy of pregnant and lactating mothers. No other variable is found to be statistically significant. It indicates that improvement in income over and above other factors can be expected to enhance the nutrient intake of pregnant and/or lactating mothers.

DISCUSSION AND CONCLUSIONS

The findings in this study are that the calorie and protein intakes relative to estimated requirements of pregnant and lactating women are far below those of non-pregnant, non-lactating women. The observed to expected consumption of calories and protein (i.e., consumption relative to need) is higher for non-pregnant and non-lactating than for pregnant and/or lactating women. Among the latter, those who are both lactating and pregnant have an average caloric intake much less than their requirement. Women who are only lactating are slightly better off. The average intake of pregnant women appears to satisfy both their calorie and protein needs (see figs. 1 and 2).

The finding that the diets of lactating and pregnant women are inadequate has serious implications for their children. Satisfactory fulfillment of nutrient requirements of a preschool child (0-4.99 years) also depends on the adequacy of a mother's nutrient intake relative to her need, as verified by data of the present study. Breast-feeding is the most important source of nutrients for infants in Bangladesh because it is almost universally practiced and extends beyond the second year of life. However, the lactation performance of poorly nourished mothers is not likely to be satisfactory in terms of meeting a child's nutrient needs, thus rendering the child more susceptible to infection (13, 14). This situation calls for improving the nutrient intake of lactating and/or pregnant women.

Various reasons could be advanced to explain this relative inadequacy of the diet of lactating women, but most important is the lack of resources. It is difficult to meet the extra needs of lactating women and those who are both lactating and pregnant for the majority of rural households in Bangladesh that live below the poverty level unless their income level is improved. This is supported by the finding of positive and significant effects of per capita expenditure on food on nutrient intake and adequacy ratios of pregnant and/or lactating women. These results indicate the importance of developing income-generating programmes, particularly for the rural poor. Educational programmes could raise the awareness of rural people about the higher nutrient needs of pregnant and/or lactating women for the benefit of both the children and their mothers.

ACKNOWLEDGEMENTS

The findings presented here are part of a major study on "Determinants of Intra-familial Distribution of Food and Nutrient Intake in Rural Bangladesh." The financial support received from UNICEF to analyse the data of the present study is gratefully acknowledged. The author is grateful to Professor Nevin Scrimshaw and Professor Lance Taylor at MIT Professor Richard Jolly and Dr. Hossein Ghassemi of UNICEF, and Professor Paul Streeten of Boston University for intellectual and moral support. The author is also thankful to Boston University for providing computer facilities and to Mr. William Marshall, Program Analyst of the university, for his generous help in cleaning and processing the data set used in this study. Mr. Fazlul Karim Chowdbury of Sylhet Government College, who supervised collection of data under the guidance of the author, deserves special thanks for his meticulous work.

REFERENCES

1, Energy and Protein Requirements, report of a Joint FAO/WHO/UNU Expert Consultation, Rome, 5-17 October 1981 (WHO, Geneva, in press).

2. C. Gopalan, "Studies on Lactation in Poor Indian Communities," J. Trop. Pediat., 3: 87 (1958).

3. O. Bassir, "Nutritional Studies on Breast-Milk of Nigerian Women: Supplementing the Maternal Diet with a Protein-Rich Plant Product," Trans. Roy. Soc. Trop. Med. Hyg., 53 (3): 258 11959).

4. C. Gopalan and B. Belavady, "Nutrition and Lactation," Fed. Proc., 20 (part 3, suppl. 7): 177 (1961).

5. C.C. DeSilva, "Common Nutritional Disorders of Childhood in the Tropics," Adv. Pediat., 13: 213 (1964).

6. K.V. Bailey, "Quality and Consumption of Breast Milk in Some New Guinean Populations," J. Trop. Podiat., 11: 35 (1965).

7. B.S. Lindblad and R.J. Rahimtoola, "A Pilot Study of the Quality of Human Milk in a Lower Socio-economic Group in Karachi, Pakistan, "Acta Paediat. Scand., 63: 125 (1974).

8. J.C. Edozien, M.A. Rahimkhan, and C.l. Waslien, "Protein Deficiency in Man: Results of a Nigerian Village Study," J. Nutr., 106: 312 11976).

9. R. Frisch, "Does Malnutrition Cause Permanent Mental Retardation in Human Beings?" Psychiat. Neurol Neurochir., 74:463 (1971).

10. A. Lechtig, J-P. Habicht, H. Delgado, R.E. Klein, C. Yarbrough, and R. Martorell, "Effect of Food Supplementation during Pregnancy on Birth-Weights," Pediatrics, 56: 508 (1975).

11. C. Gopalan, B. V. Rama Sastri, and S.C. Balasubrumanian, Nutritive Value of Indian Foods (National Institute of Nutrition, Hyderabad, India, 1981).

12. L.C. Chen, M. Gesche, and W.H. Mosley, "A Prospective Study of Birth interval Dynamics in Rural Bangladesh," Pop. Studies, 28:277 (1974).

13. M. Sidney Cantor Associates, "Tamil Nadu Nutritional Study: An Operations-Oriented Study of Nutrition as an Integrated System in the State of Tamil Nadu," report to the US Agency for International Development, Contract No. AID/NESA-399, Mission to India (1974).

14. J. Hammer, Essays in Economic Development and Income Distribution, Ph.D. dissertation (Department of Economics, Massachusetts Institute of Technology, Cambridge, Mass., USA, 1979).

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