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9. Outstanding gaps in knowledge, and research recommendations

9.1. There are discrepancies between recommended dietary allowances during pregnancy and lactation and actual consumption levels, particularly in the developing world, but also in industrialized countries. Research is urgently required so that, where necessary, RDAs can be revised after considering metabolic adaptations to a higher efficiency when intake is low or physiological needs become elevated. Climate, work load, and environmental hygiene also need to be taken into account.

9.2. The response of a mother's capacity to produce milk needs to be studied in circumstances where protein deficiency as well as total energy deficiency are limiting factors. There is circumstantial evidence that lactation is more affected in countries where kwashiorkor is the principal form of pre-school child malnutrition.

9.3. More information is required on the range of breast-milk volumes produced by healthy, totally breast-feeding mothers, and mothers with optimal management of their lactations, so that realistic norms can be identified and goals established for maternal supplementation programmes. Such studies should be longitudinal rather than cross-sectional in nature.

9.4. We need to know with much greater certainty for how long breastfeeding alone is adequate for healthy growth, neurological development, and adequate immune competence. The range of biological variability within healthy communities should also be studied; cultural and biological factors limiting breast-feeding and lactational capacity need to be clarified on an objective basis.

9.5. Ways of identifying lactational inadequacy must be devised. Growth-charts for infants who have been successfully fed entirely from the breast should be constructed with a special emphasis on the first six months of life. The current, tentative conclusion is that initially breast-fed children may grow with a higher velocity during the first three months than bottle-fed ones, but then fall away in the second trimester of infancy. This needs to be confirmed.

We need to know more about functional significance of growth faltering and of moderate deficits in linear growth. Do such deficits produce a direct handicap - reduced resistance to infection, for example? Or do the risks result indirectly from a generally deprived environment? Could stunting be regarded as a reasonably successful biological adaptation?

9.6. Hypogalactia should be made a subject for priority research and include investigations into its biological background, lack of response to hormonal stimulus, or, in the case of undernourished women, to dietary supplementation. The possibility of pre-adult and pre-natal causes should be considered as well as post-natal ones. Objective criteria should be developed so that a predisposition towards hypogalactia can be diagnosed or predicted. Methods of treatment should be sought.

9.7. The precise physiological role of suckling behaviour on the mother's capacity for milk production needs to be studied more objectively, with particular reference to the frequency and length of contact at the breast. The optimal level of physical contact between mother and baby for successful long-term breast-feeding should be identified both during the daytime and at night. We need to know with greater precision the extent to which the baby can stimulate a greater milk output as his size and physiological needs grow, and at what point the mother's capacity is truly exceeded rather than limited by social constraints or conventional attitudes.

9.8. Research should be carried out on the timing of the onset of breastfeeding to determine how important commencement almost immediately after birth is to the subsequent success of lactation. It is of major importance that the differences in the initiation of lactation in women under different socioeconomic circumstances be studied. Such studies should be related to the different beliefs and taboos associated with colostnum and to the subsequent establishment of lactation. This is an obvious area for a multi-centre research programme.

9.9. A major multi-centre study needs to be set up whereby the effect of dietary supplementation on the lactational capacity of previously undernourished mothers can be assessed. This study should boost mean intakes as near as possible to current RDAs, care being taken not to affect adversely the customary intake of home food. Centres should be chosen so that correction of protein deficiency as well as energy defiency can be studied. The intervention programme needs to be planned to shed light upon what can be expected from short-term supplementation, such as during a single pregnancy-lactation cycle, as well as over a longer proportion of a mother's reproductive life.

Milk output and nutrient content should be measured at regular intervals, and any changes in the mother's nutritional status, general well-being, and physical activity should also be assessed. The growth of the baby from birth throughout infancy should also be monitored on a regular basis, as should patterns of morbidity both in the baby and the mother. The effect of supplementary feeding in pregnancy on birth-weight should also be assessed.

9.10. Major shortcomings in our knowledge of the fundamental metabolic and endocrine control of pregnancy and lactation should be acknowledged, because they affect the confidence with which practical intervention programmes can be planned to deal effectively with the essential features of maternal undernutrition without leading to impossibly complex and expensive public health programmes.

9.11. Although there is a wealth of subjective and anecdotal information concerning the interaction between lactation and fertility, this subject has received too little scientific consideration, and the collection of objective information from a range of countries is of priority importance. Of associated relevance to the major theme of this report are teenage pregnancies and the biological, sociological, and psychological problems faced by young, immature girls when they attempt to breast-feed.

9.12. New studies are required on the health significance of different intervals of birth-spacing. This investigation needs to be carried out on a representative range of countries and in mothers of differing socio-economic status, as potential hazards are likely to vary substantially with these variables. Such knowledge is vital before the importance of changes in lactational infertility can be interpreted with confidence. In addition, more information is needed about the distribution of infant mortality within the first year of life, and the causes of death at different times.

9.13. The precise role of prolactin and the cascade of hormonal events that terminate lactational infertility need to be clarified. Variations in baseline prolactin concentrations between well-nourished and underfed women need to be investigated in a wider range of countries than has occurred so far, and the causes identified. The relationship between circulating prolactin and breast-milk volume as well as fertility needs to be defined. A multi-centre study to provide answers to these questions could be run in conjunction with those described in recommendations 9.9. and 9.11.

9.14. During the planning and execution of these multi-centre studies, attention must be focused upon the potential translation of the results into primary health-care programmes. Since it is unlikely to be possible for all needy women to be assisted, selective criteria need to be devised for the identification of mothers and children, or preferably families, who are most at risk. Any nutritional programme must be integrated within a wider maternal and child-health framework, with special attention being paid to personal preferences and national policies towards birth-spacing, family planning, and population control. Standards and goals need to be identified for national programmes, and the success of the scheme should be determined by regular surveillance, measuring parameters relevant to both health and national productivity, and development.

9.15. Primary health centres must be organized in such a way that they provide both for the nutritional health and well-being of the mother as well as her child. Doctors, nurses, and health assistants staffing or responsible for such centres need to be trained in maternal and child care as an integrated whole, and not obstetrics and paediatrics as separate specialities.

9.16. Although more research is required (see recommendations 9.13 and 9.14), health workers must be made aware that improving a lactating mother's health and nutritional state may well affect the return of fertility during lactation. Where relevant, family-planning procedures need to be identified to deal with this effect.

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