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1 From the International Science and Technology Institute, Arlington, VA, and the Department of International Health, Johns Hopkins University, Baltimore.
2 Presented at the symposium Maternal Nutrition: New Developments and Implications, held in Paris, June 11–12, 1998. 3 Reprints not available. Address correspondence to JO Mora, 1820 North Fort Myer Drive, Suite 600, Arlington, VA 22209. E-mail: jmora{at}istiinc.com.
ABSTRACT
In developing countries, the health and nutrition of females throughout their entire life is affected by complex and highly interrelated biological, social, cultural, and health service–related factors. Rather than focusing exclusively on the prenatal period, we describe a life cycle approach to improving maternal nutrition, which goes beyond the traditional provision of nutrition services during pregnancy, by addressing risk factors that are present well before pregnancy, even before childbearing age. This approach involves specific policy initiatives and a "minimum package" program that is targeted at females. Policy actions and the components for effective implementation of the program are described. The prospects and challenges to be overcome—which include translating scientific knowledge into action, removing conceptual and implementational constraints, identifying biologically meaningful indicators for problem identification, and improving understanding of physiologic and social adaptation mechanisms—are discussed, as are persistent problems with health care delivery systems.
Key Words: Prenatal nutrition • developing countries • nutrition strategies • women • adolescent girls • nutritional programs • malnutrition
INTRODUCTION
Good maternal nutrition is important for the health and reproductive performance of women and the health, survival, and development of their children. Malnutrition in women, including pregnant women, is not conspicuous and remains, to a large extent, uncounted and unreported; thus, insufficient attention has been given to the extent, causes, and consequences of malnutrition in women (1). As a result, inadequate resources and efforts have been allocated to improving women's nutrition compared with other nutritional and public health actions (2). The limited available data and the few experiences with programs that do exist come mostly from small-scale efforts to improve nutrition during pregnancy, often through nutritional supplementation to enhance fetal growth and birth weight (3). It was suggested that highly publicized initiatives such as "child survival" and "safe motherhood" have not had the expected effect because too little attention has been given to the nutritional status of women, including mothers (4). This lack of emphasis on women's nutrition is unacceptable given the importance of nutrition to women's health, pregnancy outcome, and child survival; the availability of effective nutrition-related programs; and the increased opportunities for policies and programs that can be implemented through existing health systems, which are expanding and providing better coverage, particularly in prenatal care, in most developing countries.
The situation is not dire, however. By translating and integrating existing biological and socioeconomic knowledge into practical action, a solid basis for policy and program decisions can be developed. The purposes of this article are 1) to review the rationale for improving prenatal nutrition and strategy, policy, and program options and 2) to identify the prospects for and challenges to improving prenatal nutrition in developing countries.
RATIONALE
Some 200 million women become pregnant each year, most of them in developing countries (5). Many of these women suffer from both ongoing nutritional deficiencies and the long-term cumulative consequences of undernutrition during childhood. Pregnancy-related health and nutritional problems affect a woman's quality of life, that of her newborn infant well beyond delivery, and that of her family and community.
The effect of women's prenatal health and nutritional status on child growth, health, survival, and development occurs both through reproductive performance and survival and through fetal growth and development. McGuire and Popkin's (6) review of studies on the nutritional status of pregnant and lactating women showed that women in developing countries consumed only about two-thirds of the recommended daily intake of energy and that their average weight for height was, in most cases, well below the 50th percentile for small-framed women in developed countries. Moreover, the energy and nutrient intakes of pregnant and lactating women tended to be only slightly higher than those of nonpregnant women, although the nutritional requirements of pregnant and lactating women were significantly greater. Other studies, for example the study by Black et al (7), showed that micronutrient deficiencies, particularly deficiencies of iron and vitamin B-12, were frequent in pregnant women in Mexico. Poor health and nutrition are associated with repeated, closely spaced pregnancies that progressively reduce women's nutritional reserves to the point of nutritional depletion, known as the maternal depletion syndrome (8–10).
The definitive negative outcome of poor prenatal health and nutrition, as well as inadequate care during pregnancy and delivery, is reflected in the high prevalence of maternal mortality in developing countries; nearly 600000 women die each year from pregnancy-related causes (11). As shown in Table 1, the global maternal mortality rate is 460/100000 live births; the rate for developing countries is 500/100000 live births, and the rate for developed countries is 10/100000 live births. Within the developing world, however, there are huge regional variations—from 140/100000 live births in Central America to 1080/100000 live births in eastern Africa (12). Adolescent girls have a 2–5 times greater risk of mortality than do other women of reproductive age (1). Indeed, of all the human-development indicators, the greatest disparity between developed and developing countries is in the risk of maternal mortality (11). Although poor prenatal nutrition contributes directly and indirectly to this large mortality rate, the extent of its contribution has not been measured because the main reported causes of maternal mortality (hemorrhage, obstructed delivery, eclampsia, sepsis, and unsafe abortion) greatly overshadow the role of nutrition itself. It is well established, however, that stunted women are at higher risk of obstructed labor as a result of cephalopelvic disproportion (13). Nationally representative data collected in the Demographic and Health Surveys show that significant proportions of nonpregnant women were at risk of adverse pregnancy outcomes by virtue of their short stature (<145 cm), low body weight (<45 kg), or both (Table 2) (S Rutstein, personal communication, 1998). Between 1% and 20% of these women were chronically energy deficient (14), although there is no consensus about the value of body mass index as an indicator (15).
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TABLE 1.. Selected maternal health and nutritional indicators, 19981
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TABLE 2.. Maternal nutritional status1
Maternal mortality, however, is not the only adverse or most frequent outcome of pregnancy. More than 40% of pregnancies in developing countries result in complications, illness, or permanent disability for the mother or child (1). Because of a woman's childbearing and nurturing roles, her pre- and postnatal health and nutritional status is an important determinant of the survival and development of her fetus and newborn child. More than 7 million newborn deaths are associated with maternal health- and nutrition-related problems resulting from poorly managed pregnancies and deliveries or inadequate care of the neonate soon after birth (5).
An intergenerational cycle of ill health and growth failure in which undernutrition in childhood leads to small body size in adulthood has been described (16, 17). Malnourished women (ie, women who are short, are underweight, do not gain sufficient weight during pregnancy, or are anemic) are more likely to have miscarriages or stillbirths or to deliver babies with intrauterine growth retardation (IUGR) or low birth weight (LBW; 18–20), which are linked, in turn, to increased risk of perinatal and infant mortality (21–23). Globally, 15.3% of all babies are born with LBW, >2.5 times more so in developing (16.4%) than in developed (6.2%) countries (24). Severe anemia in pregnancy is believed to increase the risk of maternal mortality in childbirth (23) and about half of the infants whose mothers have died do not survive to celebrate their fifth birthday (25). There is also evidence to suggest that severe maternal iron deficiency causes reduced iron storage in the fetus and the newborn infant, which predisposes the infant to iron deficiency anemia (18). In addition, malnourished women do not have adequate capacity to sustain prolonged lactation (19, 20).
Newborns with IUGR and babies with LBW have the greatest risk of infection because of reduced immune competence. Poor nutrition in early childhood not only increases the risk of perinatal, infant, and child morbidity and mortality but also affects long-term physical growth (26, 27), cognitive development and future learning capacity (28), school performance (28, 29) and educational outcomes, and work performance (30). Girls often experience discriminatory child-care, feeding, and health care compared with boys that can result in protein-energy malnutrition (PEM) and micronutrient deficiencies. The increased nutritional demands for adolescent growth, coupled with chronic PEM and micronutrient deficiencies and often early childbearing, preclude many teenage girls from fully realizing their growth potential (31, 32). Moreover, Bruner et al (33) found that treating anemic US adolescent girls improved the girls' cognitive abilities, which may have important implications for the many adolescent mothers in developing countries. During their reproductive years, particularly during pregnancy and lactation, many women continue to experience PEM and micronutrient deficiencies, although some are affected by the consequences of overnutrition. In the postreproductive years, undernutrition, anemia, osteoporosis, and other nutrition-related problems are observed frequently in women (4). There is also growing concern that poor fetal and infant health and nutrition determine health risks, such as coronary heart disease, in adulthood (34, 35). Clearly, the lack of attention to women's nutrition has enormous implications for social, economic, and national development.
It is difficult to estimate the extent of women's malnutrition, even in pregnant women, in developing countries because few nationally representative studies have been done. This is compounded by the lack of consensus on the appropriate indicators and reference standards for women. In 1985, Leslie (2) conservatively estimated that of the 1130 million women aged >15 y living in developing countries, almost 500 million were stunted as a result of PEM, 250 million were at risk of iodine deficiency disorders, and almost 2 million were blind because of vitamin A deficiency. Vitamin A deficiency is more frequent in Asia and Africa than in other countries (36), and in endemic areas night blindness has been observed to be 5–25 times more frequent in pregnant women than in preschool children (37, 38), indicating women's increased vulnerability to vitamin A deficiency during times of increased vitamin A requirements. On the basis of data collected in 1998 and on the assumption that 59% of pregnant women and 47% of all women (39) are anemic, >745 million of the >1514 million women of childbearing age (15–49 y) are anemic. Prevalence rates of anemia in pregnant and nonpregnant women are greater in Asia (60% and 55%, respectively) and in Africa (51% and 42%, respectively) (40) than in Latin America (35% and 20%, respectively) (41). PEM, iodine deficiency disorders, and iron deficiency are known to disproportionately affect females throughout infancy and childhood as well as before and during pregnancy.
The magnitude of female undernutrition and the enormous social, economic, health, and developmental implications of poor prenatal nutrition of women and children provide a compelling rationale for systematic stronger action. Because of the reproductive consequences and the long-term effects of childhood malnutrition on adult physical and intellectual productivity, as well as of the widespread effect of women's health and nutrition on child survival, women's productivity, family welfare, and poverty reduction in the community as a whole, securing adequate nutrition of women, particularly before and during pregnancy, is a socially and economically important goal for developing countries.
CONCEPTUAL FRAMEWORK
Throughout women's entire life cycle, their health and nutrition is affected by complex social, cultural, psychologic, biological, and health service–related factors that are highly interrelated. A conceptual framework, adapted from Tinker et al (4), that identifies the critical points for action is outlined in Figure 1. Social, economic, and cultural factors include social status, female discrimination, fertility patterns (eg, pregnancy intervals, teenage pregnancy, and unplanned pregnancies), and disease exposure. Individual behavior and psychologic factors include dietary practices, reproductive patterns, health-seeking behavior, and use of health and nutritional services. Biological factors include age of menarche, menstruation, pregnancy, and increased risk of infections.
FIGURE 1. . Determinants of women's health and nutritional status.
To have an effect on women's health and nutritional status, programs that are socially, economically, culturally, and biologically appropriate are needed throughout the female life cycle, beginning as early as possible. In other words, women's health and nutrition have to be considered as part of an intergenerational continuum under the rubric of reproductive and child health (ie, pre- and postnatal care, including family planning, child survival, child development, school health, and adolescent health). This framework highlights the important role for public and private health services and 2 practical conclusions need to be emphasized. First, the consequences of women's undernutrition on child survival and development are at least as important as is the direct biological effect of undernutrition on the fetus during pregnancy and the infant during lactation. Second, a focus on prenatal nutrition ignores the more fundamental problem of a woman's nutrition throughout her entire life, of which prenatal nutrition is only a small, albeit important, contributory factor. This is significant because nutritional status, unlike disease, is cumulative over time and not an isolated incident (16).
STRATEGIES
Strategies to improve prenatal nutrition need to go beyond the conventional approach of providing services to pregnant women through the traditional maternal and child health care programs. Instead, a more comprehensive life cycle approach is needed that addresses the risk factors present well before pregnancy, ideally beginning in early childhood or, at the very least, before pregnancy or before girls reach reproductive age.
The promotion of optimal nutrition in girls during childhood is a sound strategy for affecting female nutrition because it can result in a build up of the nutritional reserves needed during periods of increased nutritional demand, including the adolescent growth spurt, pregnancy, and lactation. Such action should be complemented by specific programs during critical periods, eg, adolescence, childbearing age, pregnancy, and lactation. Research in Guatemala, for instance, showed that improved nutrition during early childhood had longer-term payoffs than was previously thought in terms of greater stature and fat-free mass, especially in females; improved work capacity in males; and enhanced intellectual performance in both sexes (17).
Although primary health care nutritional programs are often targeted at women, particularly pregnant women, in practice most are designed primarily to reduce malnutrition in children. Leslie (2) made an important distinction between being the target and being the beneficiary of a program. Women have been the targets of health and nutritional programs aimed at improving fetal growth (birth weight) or children's growth but paying little attention to the health and nutritional needs of the women themselves. There is currently a move toward getting consensus that health and nutritional programs implemented well before women become pregnant, and within a life cycle perspective, will have a long-term effect on both the mother and the child, although data to support this are still lacking. It is also probable that women are more likely to be motivated to participate in program activities that have a clear benefit for themselves as well as for their children.
POLICY AND PROGRAM OPTIONS
In an ideal world, policy and program options are based on a generally accepted, research-proven, conceptual framework that has been tested in an appropriate environment. Unfortunately, this has rarely been the case for prenatal nutrition in developing countries. There is an urgent need to identify the conditions and circumstances under which prenatal undernutrition (eg, PEM or specific micronutrient deficiencies) can be prevented throughout a woman's reproductive cycle or improved during pregnancy, after which the appropriate strategy can be carefully shaped to the particular situation in each country or setting.
On the basis of the documents reviewed and of personal experiences, the text that follows identifies some general and specific policy (4) and program options that have either been shown to be effective or are likely to be effective, although there may be no data to support the latter. More data are needed to show the effectiveness of programs under the specific conditions that are present in most developing countries.
Policy options
Broaden policy support for enhanced investments in female education
Given the strong evidence associating higher levels of maternal education with improved child survival and nutritional status (42) and very likely with better nutritional status of women themselves, investment in the education of females is expected to have enormous payoffs in health, nutrition, and development (43, 44). These effects are likely to be mediated through more- efficient purchasing and intrahousehold distribution of food (45), a greater propensity and more- efficient use of health services (42), fewer pregnancies, and increased employment opportunities for women (46). It is therefore an important component of any policy to enhance the status of women.
Strengthen legislative and other support for women's nutrition
Improvements in legislative and other support for women's nutrition would help provide universal food fortification; provide consumer price subsidies and targeted food distribution; provide labor-saving devices for women; improve women's access to agricultural extension services and credit for small-scale business; reduce discrimination against women in employment practices; encourage women's control over family resources; remove credit restrictions against women; enact fair marriage legislation; abolish practices harmful to women's health (eg, violence against women); remove legal impediments to the effective delivery of health services for females (eg, impediments to contraception and barriers to service based on age, sex, or marital status); support appropriate training and delegation of responsibility, particularly for nonphysician health care in rural areas; and encourage private sector participation in the delivery of health services for women.
Improve equity and efficiency in financing health and nutritional services for women
Improved equity and efficiency in financing health and nutritional services for women could be achieved by selecting a package of highly cost-effective nutritional programs to be publicly financed; establishing cost-recovery schemes that target public expenditures at the poor; and protecting poor women and removing legal impediments to the effective delivery of health services.
Increase women's access to health and nutrition services
Women's access to health and nutritional services could be improved by designing delivery strategies to meet women's needs; strengthening the health care delivery infrastructure; improving the quality of services for women; increasing the number of health care providers for women; and delegating responsibilities to nonphysicians.
Other policy initiatives
Other policy initiatives include integrating women into healthcare and nutrition planning via local health committees and women's groups; strengthening collaboration with the private sector through nongovernment organizations and for-profit providers; intensifying public education to promote the use of health services and healthy behaviors; advocating both policy changes and behavior modification; meeting informational needs on indicators of health status; designing programs based on culture-specific health needs, formative research, and program-based operations research; and monitoring and evaluating programs.
Program options
Women's nutrition is expected to be equally or more strongly influenced by policies and actions intended to improve nutrition in the entire household (eg, increased crop yields, higher income, food price subsidies, better nutrition knowledge, and food fortification) than by those targeted solely at women. The components that need to be considered in designing effective community- and household-level programs that the health care system can target toward women, with the emphasis on prenatal nutrition, are presented below.
A comprehensive health and nutritional program
The provision of regular health and nutritional services for women requires a comprehensive program rather than single, isolated programs. Although framed in the context of a life cycle approach, such a program focuses on specific female life periods: prepregnancy, pregnancy, delivery and lactation, early childhood, adolescence, and childbearing age. An important aspect is that appropriate information, education, and communication (IEC) aimed at key behavioral modifications for that life period is given. The essential health and nutritional care program includes the components that follow.
One important component is the prevention and management of unwanted pregnancies and management of abortion services by improving access to birth-spacing information and services, including counseling, education, and family planning. Significant efforts are being made and substantial progress has been achieved in several developing countries to reduce fertility and increase birth spacing (47). Family planning services still need to be fully integrated with other health and nutritional services for women of childbearing age. IEC family planning strategies need to incorporate women's health and nutritional concerns. Existing service-delivery channels for contraceptive products can be used effectively for the provision of iron supplements and other nutritional services for women.
Another important component is expanded health and nutritional services for nonpregnant women, including adolescents. This has been a highly neglected area. Both the availability of and the access to health services by women are often restricted to prenatal and delivery services, often involving limited contact with health personnel, usually a few times during pregnancy and a few hours during delivery. Women's visits to health services, for either curative or preventive child health care, are excellent opportunities for health workers to tap and provide health and nutritional preventive services (education, counseling, and micronutrient supplements) to women. The delivery of micronutrient and possibly even food supplements to female adolescents through the school system can also be considered.
A third essential component of a health and nutritional care program is enhanced maternity care that is effective, affordable, accessible, and acceptable and that includes prenatal health and nutritional services, safe delivery, and postpartum care. The well-documented increase in the coverage of prenatal services, currently >50% in most developing countries (5), offers a unique opportunity to reach women during pregnancy with a package of health and nutritional services, including education and counseling and micronutrient supplements. About a third of women in these countries, however, still do not have access to good-quality health services during pregnancy (Table 1) and childbirth, especially poor and uneducated women who live in rural areas.
Finally, a health and nutritional care program must include extended nutritional assistance to vulnerable female groups to improve overall nutritional status, including supplementary feeding, micronutrient supplements, and food fortification. Nutritional assistance has usually been restricted to limited supplementary feeding and the distribution of iron supplements to pregnant women rather than to all women because of resource constraints. Providing a program of nutritional services to all women of childbearing age may be a more effective way to improve prenatal nutrition than are limited prenatal programs, which are unlikely to begin early enough in pregnancy to have a significant biological effect. For example, providing long-term preventive weekly iron or multivitamin and mineral supplements to nonpregnant women, ideally beginning during adolescence, or implementing a widespread iron-fortification program may improve the iron reserves of these women to the extent that the need for preventive daily supplementation during pregnancy could be reduced significantly.
Behavioral change programs
Behavioral change programs include expanded promotion of positive health and nutritional practices for females, including behavioral changes to improve maternal, infant, and early childhood feeding and to eliminate self-inflicted female discrimination. Most health and nutrition educational activities currently targeted toward women focus almost exclusively on child feeding, particularly breast-feeding. There is a need to redirect some of the IEC efforts toward women themselves. Concrete efforts are needed to improve women's eating practices, which is important for the health of the women themselves and for that of their children, particularly in rural areas where women endure the dual burden of moderate-to-high levels of physical work and frequent pregnancies without noticeable increases in energy and nutrient intakes. Studies showed that female discrimination in developing countries may to a large extent be self-inflicted (48) as a result of a "self-sacrificing" role through which they meet their own needs last. For example, increased female wages were associated with improved nutrient intakes of most household members except the women themselves (49). IEC activities targeted toward women could be specifically designed to reduce and ultimately remove these attitudes.
It is also important to delay childbearing among adolescents. First births can be delayed by postponing the age of marriage and the onset of sexual activity and by using effective methods of family planning. This requires culturally sensitive IEC programs for changing individual and societal motivations for early childbearing and enhanced opportunities for formal education of girls.
Another crucial behavioral change is the removal of sex discrimination. Enhancing the social status of women will require specific policies and intensive IEC efforts addressed at the population as a whole and at women in the community, at schools, and in the workplace.
The implementation of a comprehensive health and nutritional program may not be feasible because of financial and resource limitations. Although a comprehensive approach would be expected to lead to significant and sustainable improvements in women's nutrition, and hence prenatal nutrition, a minimal program can be tailored to the local situation in accordance with the resources available. It should be emphasized, however, that nutritional programs that are restricted to the limited provision of health and nutritional services during pregnancy may not make a significant difference to the health and nutritional status of the mother and the child.
A minimum health and nutritional program
Given that financial and resource constraints frequently limit the number and scope of programs, the "minimum package" of key nutritional programs identified by Baker et al (50) was modified and expanded to specify the programs required to improve the nutrition of adolescent girls and pregnant and lactating women. The purposes of this minimum package are to delay first pregnancy, improve knowledge and practices related to reproductive health and nutrition, and improve access to quality prenatal and postpartum services.
For adolescent girls, the following minimal programs are recommended:
For pregnant and postpartum women, the recommended minimal programs can be categorized as service-delivery and health-promotion programs. The service-delivery programs 1) provide iron and folate supplements during pregnancy; 2) monitor pregnancy weight gain; 3) provide antimalarials, antihelminths, and other micronutrient supplements, when appropriate, including postpartum vitamin A in vitamin A–deficient areas; 4) provide prompt diagnosis and treatment of illness; and 5) provide and target supplementary food to at-risk and undernourished women by using appropriate indicators for screening, beginning as early as possible during pregnancy.
A review of randomized, controlled trials on the effectiveness of nutritional programs in pregnancy to reduce IUGR found that only balanced protein-energy supplementation was effective (3). The authors raised concern about the dearth of data to support recommended nutritional programs during pregnancy, some of which are used widely, even in women with no evidence of nutritional deficiencies. Although this review was limited to the effects of programs on IUGR, it highlights the need for better monitoring and evaluation of prenatal programs and for further operations research on how to improve the nutrition of women in general.
Health-promotion programs for pregnant and postpartum women 1) provide nutritional, breast-feeding, family planning, and HIV counseling and disease prevention education, and 2) involve men and other family members in behavior-modification activities so that they increase the demand for health services for girls and women.
Ten actions are critical to effectively implement a package of health and nutritional programs for women:
PROSPECTS AND CHALLENGES
The prospects for improving maternal nutrition are contingent on there being political commitment and national capacity to develop and implement sound policies and programs. Policy decisions and program implementation will be affected by the context of nutritionally relevant global trends that are characterized, on the positive side, by increased women's education, delayed age of marriage, declining fertility rates, smaller families, longer life expectancy, greater health-system coverage, and increased women's participation in the labor force. On the negative side, these global trends are characterized by severe resource constraints, slow economic growth, poor use of available health and nutritional services by females, and slow progress in improving the social status of women in many countries.
From a program perspective, possibly the most important factor favoring the implementation of enhanced health and nutritional services for women is the ongoing trend toward increased coverage of maternal services. A recent analysis of demographic and health surveys conducted in 12 countries between 1986 and 1996 showed that, overall, the countries experienced a steady increase in prenatal and delivery care coverage ranging from 2% to 34% for prenatal care, 2% to 39% for tetanus immunization, and 3% to 79% for delivery care (59). However, prenatal care coverage fell in 1 country and delivery care coverage declined in 3 countries. Quality of care was not assessed, which is important because it may not have improved significantly.
The challenges ahead are not insignificant. There is little documentation on program experiences to improve prenatal nutrition, women's food intake, and weight gain during pregnancy in developing countries. It is disappointing to note that, despite the research-based evidence that iron supplementation is efficacious, this relatively simple program was not effective in reducing the prevalence of anemia in women and children (58, 60). Most iron and folate supplementation programs for pregnant women and young children have serious operational constraints related to supply and distribution systems, access to health care services, motivation and behavior of health care providers, and compliance by the target population. Unresolved problems that affect the acceptability of and compliance with supplements continue to persist and include the lack of good-quality, low-cost generic supplements; suitable compounds and dispensing mechanisms (tablets, pills, syrups, liquid forms, and powder); appropriate regimens (daily or intermittent) for different environments (areas of endemic malaria and helminth infection); and potential adverse effects (real or overestimated).
Although there is little evidence that an iron-supplementation program works, it remains one of the few options available for improving the iron status of the population and appears to be the only program likely to meet the high iron requirements during pregnancy and early childhood (23). Operations research is moving toward testing systematic, intermittent supplementation of adolescent girls in schools and of nonpregnant women in the workplace to reduce the need for aggressive high-dose supplementation, with its associated potential adverse effects and low compliance, during pregnancy. This approach, however, assumes that the most at-risk adolescent girls attend school and that women work in organized work settings, which is not yet the case in most developing countries.
Regrettably, conceptual and implementational constraints have minimized the effect of efforts to improve women's nutrition, largely because the focus has been almost exclusively on the prenatal period (50). Many programs were conducted as small-scale research activities or vertical interventions or relied heavily on manipulating only the biological factors that influence women's nutrition. Such approaches are difficult to expand because of the lack of broad-based support and demand for the services. Although, as emphasized above, efforts to improve women's nutrition in a sustainable way must involve a life cycle perspective, the reality in most developing countries is that financial and resource constraints often reduce action to a few programs that tend to focus on pregnancy and, to a lesser extent, lactation. A stronger political commitment is needed to support women's health and nutritional programs and to create the demand for a minimum package of services.
Major challenges
Translating current knowledge into practice
It will be a major challenge to translate current knowledge into practical application in the context of resource constraints in developing countries, ie, to move from theory to practice in a resource-limited setting. Baker et al (50) identified conceptual and implementational constraints to improvements in female nutrition that will need to be addressed if women's nutrition is to improve. The conceptual constraints include a consistent lack of political support for women's nutrition, nutritional programs narrowly focused on pregnant women, nutritional programs usually designed as pilot projects or small-scale research activities, lack of a consensus on the most appropriate and practical indicators of women's nutrition, and lack of information on the cost-effectiveness of programs. The implementational constraints, which are common to health programs, include limited service-delivery capacity and low use of existing services, poor program management, limited focuses on behavioral factors and behavioral change, and inadequate training of health personnel.
Determining definitions of prenatal nutrition and undernutrition in women
Another major challenge will be to develop acceptable, biologically meaningful and programmatically relevant definitions of prenatal nutrition and undernutrition in women by using anthropometric, dietary, and biochemical indicators. This is critical for problem definition, risk identification, program targeting, and monitoring and evaluation. Current indicators include anemia rates (based on hemoglobin concentration) and women's height, weight and weight gain, body mass index, and midupper arm circumference (61, 62). There is no general consensus, however, on the use and interpretation of anthropometric indicators in pregnant and nonpregnant women (15, 63, 64). Guidelines on the application of anthropometric indicators emphasize the use of these indicators as screening tools rather than for surveillance, and instruments designed for the latter purpose are pending satisfactory validation. A related question that needs to be addressed is the identification and interpretation of maternal undernutrition in poor communities in which a relatively large proportion of women are short but overweight (eg, in parts of Latin America), yet indicators of pregnancy outcomes also are not optimal.
Allaying women's concerns about weight gain and delivery complications
A review of research from 18 developing countries on changes in dietary practices during pregnancy found that food intake is consciously restricted during pregnancy because of the fear of delivery complications associated with having a large newborn (65). Although this concern is rational, there are no data to support it. Restricted food intake by pregnant women can compromise their nutritional status and needs to be addressed through behavioral change programs, when appropriate.
Understanding the physiologic and social adaptation mechanisms during pregnancy
Evidence from several studies suggests that pregnant women subsisting on limited energy intakes adapt to this situation through a physiologic reduction in their basal metabolic rate or a reduction in activity to conserve energy for fetal growth (66). These mechanisms affect the use and interpretation of nutritional indicators during pregnancy and the guidelines on energy intakes to sustain adequate weight gain. Irrespective of the physiologic adaptations of the body, Naeye (67) showed that a woman's nutritional store as she enters pregnancy is a more important determinant of perinatal mortality than is pregnancy weight gain per se.
Reducing persistent problems with health service development and access to quality prenatal care services
Prospects for steady increases in the availability of and access to quality health services for women in developing countries are uncertain given current financial constraints. However, great efforts have been made toward improving the efficiency of health care expenditures, enhancing coverage within existing resource constraints and, to a much lesser extent, improving access for poor, uneducated women, especially those in rural areas.
Problems with access to and quality of prenatal care services, however, are not exclusive to developing countries. In an attempt to understand the poor standing of the United States in the international rankings of infant mortality rates, a recent situation analysis identified the need for increasing access to prenatal care, redirecting the content of prenatal care, understanding the behaviors of pregnant and lactating women, and facilitating changes in the delivery of nutritional care (68). The new guidelines for the delivery of nutritional care issued by the US Institute of Medicine (69) address the predisposing factors that inhibit health professionals from including nutritional care in their practices, emphasize a more culturally sensitive approach to care, and recommend new tools for screening and targeting prenatal programs.
Women's nutrition remains a global issue with common problems and constraints that will be resolved only if women's health and nutrition are put in the context of the life cycle rather than into discrete compartments. This approach includes addressing the underlying social and cultural determinants of behaviors connected to women's nutrition at all stages of the life cycle.
ACKNOWLEDGMENTS
We thank Leslie Elder and Ritu Nalubola for their comments and suggestions on an earlier draft of the article.
REFERENCES