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Committee to Study the Prevention of Low Birthweight; Division of Health Promotion and Disease Prevention; Institute of Medicine. Preventing Low Birthweight. Washington (DC): National Academies Press (US); 1985 Jan 1.

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Preventing Low Birthweight.

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Low birthweight is a major determinant of infant mortality in the United States. Most infant deaths occur in the first 4 weeks of life, the neonatal period, and most are a consequence of inadequate fetal growth, as indicated by low birthweight (2,500 grams—about 5.5 pounds—or less). Inadequate fetal growth may result from prematurity (duration of pregnancy less than 37 weeks from the last menstrual period), poor fetal weight gain for a given duration of pregnancy (intrauterine growth retardation), or both. The risk of mortality increases as birthweight decreases; very low birthweight infants (1,500 grams or less) are at greatest risk.

The proportion of low-weight births not only is a major determinant of the overall neonatal mortality rate for a population, but also is an important factor in the differences in neonatal mortality rates among various groups in the population. Thus, the higher neonatal mortality rates seen for nonwhite mothers, teenage mothers, and mothers of low educational attainment are explained largely by higher proportions of low birthweight infants among these groups.

In addition to increasing the risk of mortality, low birthweight also increases the risk of illness. Although low birthweight is not a major determinant of the total burden of morbidity among infants and children, the relative risk of morbidity among low birthweight infants is high. The association of neurodevelopmental handicaps and congenital anomalies with low birthweight has been well established; low birth-weight infants also may be susceptible to a wide range of other conditions, such as lower respiratory tract infections, learning disorders, behavior problems, and complications of neonatal intensive care interventions. Moreover, a low-weight birth and the infant's subsequent problems may place substantial emotional and financial stress on a young family.

Although the neonatal mortality rate in the United States has dropped greatly over the past 15 years, there has not been a comparable decrease in the incidence of low-weight births. Instead, the mortality decline has been accomplished primarily by improving the survival of low birthweight infants, largely through neonatal intensive care. The proportion of infants born at low birthweight has changed only modestly since the late 1960s, and little change, if any, has been seen in the proportion of infants born at very low birthweight. The current statistics suggest that further reductions in neonatal mortality and decreases in the differentials between high-and low-mortality subgroups will require a reduction in the rate of low birthweight.


Despite steady advances in the science of obstetrics, our understanding of the basic causes of preterm labor and intrauterine growth retardation is limited. In the absence of adequate information about etiology, a large body of information has developed about factors associated with low birthweight, often termed “risk factors” because their presence in an individual woman indicates an increased chance, or risk, of bearing a low birthweight infant. These factors include demographic characteristics, such as low socioeconomic status, low level of education, nonwhite race (particularly black), childbearing at extremes of the reproductive age span, and being unmarried; medical risks that can be identified before pregnancy, such as a poor obstetric history, certain diseases and conditions, and poor nutritional status; problems that are detected during pregnancy, such as poor weight gain, bacteriuria, toxemia/preeclampsia, short interpregnancy interval, and multiple pregnancy; behavioral and environmental risks, such as smoking, alcohol and other substance abuse, and exposure to various toxic substances; and the health care risks of absent or inadequate prenatal care and iatrogenic prematurity. Newer hypotheses suggest that another group of factors also may place a woman at risk of low birthweight, particularly preterm labor: stress, uterine irritability, certain cervical changes detected before the onset of labor, some infections, inadequate plasma volume expansion, and progesterone deficiency.

By grouping the factors as summarized above, the committee observed that many risks for low birthweight can be identified before pregnancy occurs; detection and possible intervention need not always wait until the prenatal period. Smoking is perhaps the best example of this perspective. The grouping also helps to highlight the importance of behavioral and environmental risks and the need for interventions that go beyond medical care. The demographic measures can help to define target populations. The cluster of health care risks highlights the fact that not all risks for low birthweight derive from characteristics of women themselves. And finally, the category of evolving concepts of risk suggests some important research areas. These themes appear throughout the report.

The committee concluded that a variety of factors are clearly and consistently linked to low birthweight. These factors should be used to help define high-risk groups and to develop and target interventions. It is also apparent, however, that the importance of each factor for an individual or a group cannot be calculated easily; that the risks for low birthweight are widely distributed throughout the population; and that a substantial incidence of low birthweight deliveries will continue to occur outside of groups currently defined as high risk. These circumstances highlight the need for greater understanding of risk and causation, but should not be used to minimize the value of using existing risk information for targeting interventions.

More research is needed on risk factors, not only those somewhat speculative but also those firmly linked to low birthweight. For some factors, such as race, research is needed to understand how the factor exerts its effect. For others, such as alcohol, the magnitude of risk at various levels of consumption should be better defined. And for both definite and less certain risk factors, efforts should be made to distinguish risks for very low birthweight (1,500 grams or less) from risks for moderately low birthweight (1,501 to 2,500 grams) at various gestational ages, because the sequelae and incidence trends of these two classes of low birthweight differ.

The committee's review of risk assessment instruments indicates that they are helpful in distinguishing between high-and low-risk pregnancies. The not infrequent occurrence of low birthweight deliveries in low-risk women, however, suggests that additional research is needed to improve the predictive capability of these systems. It also indicates that clinicians must be alert to the possibility of low birthweight even in pregnant women judged to be at low risk of such an outcome.


The committee investigated trends in the rate of low birthweight and the composition of low-weight births in the United States as a whole and in five selected states (California, Massachusetts, Michigan, North Carolina, and Oregon) during the past 10 to 15 years. For the nation, the proportion of low-weight births declined from 7.6 percent of live births in 1971 to 6.8 percent of live births in 1981.

The decline in rates was confined to the moderately low birthweight group. No decline, or perhaps a slight increase, was observed in the very low birthweight group. Although birth certificate data on gestational age are incomplete and of uncertain quality, the observed decline in low birthweight was apparently concentrated mostly in the full-term low birthweight group.

Both white and black low birthweight rates have declined, but blacks remain at increased risk of low birthweight compared with whites. The data show no closing of the gap, although quantifying the white-black differential in low birthweight rates depends on the index used to measure the gap. White and black low birthweight rates vary appreciably among the states studied.

Teenage mothers and those 35 years of age or older have higher rates of low birthweight than mothers in their twenties or early thirties. Teenage mothers have the highest relative risk of low birthweight, especially among whites. Childbearing by teenagers is more prevalent among blacks, however. The risks of low birthweight among teenagers probably derive more from other factors associated with teenage childbearing (such as low socioeconomic status and poor utilization of prenatal care) than from young age itself.

For both races, the risk of low birthweight declines sharply among mothers with at least 12 years of education. The relationship between education and low birthweight is independent of maternal age and race. The gap in low birthweight rates among mothers with disparate educational attainment is not closing, and may be widening. Because educational attainment of mothers generally has increased during the past 10 to 15 years, the finding of a widening gap in low birthweight rates among mothers with disparate education suggests that the poorly educated may constitute an increasingly high-risk group.

Unmarried mothers have consistently higher rates of low birthweight. The elevated risk is not attributable to differences in age or race. The proportion of unmarried mothers appears to be increasing; among blacks, 56 percent of mothers were unmarried in 1981.

No clear change has occurred in the relationship between parity and the risk of low birthweight. High-parity births continue to have a slightly greater risk of low birthweight, and termination of the last pregnancy in a fetal death increases the risk of low birthweight in the subsequent pregnancy. Among mothers with a previous live birth, an interpregnancy interval of less than 6 months enhances the subsequent risk of low birthweight.

The risk of low birthweight is reduced among mothers who initiate prenatal care during the first 3 months of pregnancy. The proportion of mothers with early prenatal care has increased during the past 10 to 15 years. This has been accompanied by a decline in low birthweight rates among mothers in the early care group.

The committee performed a multivariate tabulation of single live births in the United States during 1981 according to educational attainment, marital status, age/birth order category, and the timing and quantity of prenatal care. With all other factors controlled, a change in timing of initiation of prenatal care was associated with a minor reduction in the risk of low birthweight. The estimated contribution of prenatal care to a reduction in the low birthweight rate was more marked, however, when care was gauged by an index of “adequacy” that reflected both the start of care in the first trimester and number of visits. The tabulation suggests that the analyzed risk factors might account together for as much as 30 percent of the risk of low birthweight in both races. Moreover, the sensitivity of the estimated contribution of prenatal care to the method of measuring such care suggests that the pattern of care may have an important influence on the risk of low birthweight.


The committee concluded that, although there are many unanswered questions about the causes of and risks for low birthweight, policymakers and health professionals know enough at present to intervene more vigorously to reduce the incidence of low birthweight in infants. Methods already available have demonstrated their value in reducing low birthweight. These and a few new measures merit additional support. No single approach will solve the low birthweight problem. Instead, several types of programs should be undertaken simultaneously. These range from specific medical procedures to broad-scale public health and educational efforts.

Because of a lack of data, the committee was not able to calculate the precise impact of the recommended interventions on the incidence of low birthweight. Based on the information that is available, however, the committee believes that if the recommended interventions were implemented, the nation would be able to meet the goal set by the U.S. Surgeon General for 1990—that low birthweight babies should constitute no more than 5 percent of all live births, and that no county or racial/ethnic subpopulation should have a rate of low birthweight that exceeds 9 percent of all live births.

The committee was not able to calculate the cost or cost-effectiveness of most of the recommended interventions because of problems in the quality and uniformity of available cost data, difficulties in delineating the services received, and uncertainties about target populations. The committee found, however, that it could perform a straightforward analysis of some of the financial implications involved in the provision of prenatal services to pregnant women. A description of this analysis is presented at the end of this summary.

Moving ahead in the directions advocated by the committee will require that the problem of low birthweight become more widely understood and recognized as an important national issue. Low birthweight and its consequences merit the attention of Congress, state governments, professional groups, business and labor organizations, church and women's groups, schools, and the information media. The federal government, particularly the executive branch, is uniquely positioned to play a leadership role in stimulating necessary discussion and action. The committee recommends that the Department of Health and Human Services define and pursue a variety of activities designed to focus attention on low birthweight—its importance, its causes and associated risks, and pathways for its prevention. Such leadership must include an increased commitment of resources to the problem of low birthweight through approaches such as those outlined in this report.

Throughout the report, and in relation to each of the interventions advocated, the committee emphasizes the need for research on a wide variety of issues. It also highlights the importance of more adequate data systems and better techniques to monitor the impact of various programs on low birthweight and on pregnancy outcome generally.


Numerous opportunities exist before pregnancy to reduce the incidence of low birthweight, yet these are often overlooked in favor of interventions during pregnancy. In a fundamental sense, healthy pregnancies begin before conception. The committee emphasizes, therefore, the importance of prepregnancy risk identification, counseling, and reduction; health education related to pregnancy outcome generally, and low birthweight in particular; and the full availability of family planning services, especially for low-income women and adolescents.

Among the risk factors that can be recognized and dealt with before pregnancy are certain maternal chronic illnesses, smoking, moderate to heavy alcohol use and substance abuse, inadequate weight for height, poor nutritional status, susceptibility to rubella and other infectious agents, age (under 17 and over 34), the possibility of a very short interval between pregnancies, and high parity. For some of these factors, reducing the risk before conception may offer more protection than doing so once pregnancy has been established.

Prepregnancy counseling is especially important for women who already have had a low birthweight delivery because the risk of repeating a poor outcome is high. Health care professionals should pay special attention to risk factor identification and reduction in these women.

Realizing the benefits of prepregnancy risk identification will require:

  • further discussion by the relevant professional groups of the content and timing of counseling, with particular attention to data on the risks associated with low birthweight (and other poor pregnancy outcomes) that can be modified before conception;
  • incorporation of such consultations into a wide variety of settings to reach as many women as possible;
  • development of appropriate written materials for women and the professionals who counsel them;
  • health services research to monitor the costs and results of prepregnancy consultations;
  • willingness of third-party payers to reimburse such services, once defined and evaluated;
  • education of health care providers and other professionals in touch with women of reproductive age about these concepts;
  • determination of the adequacy of health services resources in a given setting to manage problems that are identified through prepregnancy assessment; and
  • additional research on how best to influence the health-related behavior of individuals, particularly teenagers.
  • A second strategy for the period before pregnancy involves health education related to reproduction. Education about reproduction, contraception, pregnancy, and associated topics already is provided in a variety of ways: by public information campaigns; in school-based classes, group sessions, lectures, and related printed materials; and in various health care settings. To increase the impact of these education programs on the problem of low birthweight, they should be expanded to include the following six topics:
  • the major factors that place a woman at risk of poor pregnancy outcome, including low birthweight;
  • the general concept of reducing specific risks before conception and the advisability of preconception counseling to identify and reduce risks associated with low birthweight;
  • the importance of early pregnancy diagnosis and of early, regular prenatal care (including how to obtain such services);
  • the importance of immunizing against rubella and of identifying other infection-related risks to the fetus;
  • the value of altering behavior to reduce a range of risks associated with low birthweight, including smoking, poor nutrition, and moderate to heavy alcohol consumption; and
  • the heightened vulnerability of the fetus to environmental and behavioral dangers in the early weeks of pregnancy, often before pregnancy is suspected or diagnosed, and therefore the need to avoid x-rays, alcohol and drug use, selected toxic substances, and similar threats in the first trimester.

The committee believes that health education should be an important component of low birthweight prevention. It should be provided in a variety of settings, particularly in family planning clinics and schools, and should be strengthened in the private sector as well. This education should focus on the role of men as well as women in choices about reproduction; family planning should be a shared responsibility, and education about pregnancy should not be confined to women.

Family planning services also should be an integral part of overall strategies to reduce the incidence of low birthweight. Several studies suggest that family planning has contributed to reducing the rate of low birthweight in the United States over the past 20 years, probably by reducing the rate of childbearing among high-risk women, by increasing interpregnancy intervals, and by other means.

The large number of unintended pregnancies in the United States, the percentage of women at risk of unintended pregnancy who do not use contraception, and the number of abortions indicate that existing family planning strategies do not meet the need for services. The reasons for this problem range from service inadequacies to the knowledge, attitudes, and practices of women themselves.

The unmet need appears to be largest among two groups at high risk of low birthweight, the poor and the young. For this reason, the committee emphasizes the importance of Title X of the Public Health Service Act. Title X authorizes project grants to public and private nonprofit organizations for the provision of family planning services to all who need and want them, including sexually active teenagers, but with priority given to low-income persons. The committee urges that federal funds be made generously available to meet documented needs for family planning. The Title X program and family planning services should be regarded as important parts of the public effort to prevent low birthweight.


Efforts to reduce the nation's incidence of low birthweight must include a commitment to enrolling all pregnant women in prenatal care. Many of the women who now receive inadequate prenatal care are those at greater than average risk of a low birthweight delivery. Moreover, participation in a system of prenatal care is a prerequisite for many individual interventions that help reduce the risk of low birthweight.

In reaching this conclusion, the committee reviewed carefully the data documenting the effectiveness of prenatal care and concluded that, although a few studies have not been able to demonstrate a positive effect of prenatal care, the overwhelming weight of the evidence indicates that prenatal care reduces low birthweight and that the effect is greatest among high-risk women. This finding is strong enough to support a broad national commitment to ensuring that all pregnant women, especially those at socioeconomic or medical risk, receive high-quality prenatal care.

National, state, and local data indicate that the proportion of mothers beginning prenatal care in the first trimester increased steadily from 1969 until 1980, but that this trend has leveled off or possibly reversed since 1981. The committee views with deep concern the possibility that the nation's progress in extending prenatal benefits to all women has been disrupted.

In developing the major recommendation that all pregnant women should receive early and regular prenatal care, the report describes the population of women who receive little or no prenatal care; the reasons why such women receive insufficient care; and several ways to remove important barriers. Principal barriers discussed in the report include:


Financial constraints: These may result from absent or inadequate private insurance to cover prenatal care, lack of public funds for prenatal care, or lack of support for public agencies that provide maternity services. In its recommendations, the committee chose to focus on Medicaid because it is the largest public program financing prenatal care. Support of the Medicaid program, which helps finance care for many high-risk women, should be part of a comprehensive effort to reduce the nation's incidence of low birthweight. Changes in the program, a topic of considerable controversy both in federal and state governments, should be dedicated to enrolling more eligible women and to providing them with early and regular, high-quality prenatal care.

The Health care Financing Administration (HCFA), in collaboration with the Division of Maternal and Child Health (DMCH), should establish a set of generous eligibility standards that maximize the possibility that poor women will qualify for Medicaid coverage, and thus be able to obtain prenatal care. All Medicaid programs should be required to use such standards.

Medicaid policies and reimbursement rates also should reflect the high-risk nature of the Medicaid-eligible population. Program policies should not set a limit on the number of prenatal visits, because pregnant women enrolled in the Medicaid program may require more frequent visits and more specialized care than more affluent, low-risk women. DMCH should develop a model of prenatal care for use in publicly financed facilities, and the guidelines incorporated into this model should be adopted by all Medicaid programs. HCFA and appropriate state agencies should monitor adherence to this standard of care.


Lack of maternity care providers: The number of private physicians providing prenatal care is inadequate in many parts of the country. Of particular concern is the evidence that the participation of obstetrician/ gynecologists in Medicaid is relatively low and may be decreasing, thereby limiting the number of private practitioners available to care for high-risk, low-income women. To overcome this problem, the committee recommends that HCFA develop a series of demonstration/evaluation projects aimed at increasing the participation of obstetrician/gynecologists in Medicaid. Approaches should include reducing delays in reimbursement, increasing reimbursement rates, and increasing the number of prenatal visits reimbursed by Medicaid. The results of these projects should be vigorously disseminated to policy leaders. To the extent that provider attitudes are found to impede Medicaid participation, local and national professional societies, including the American College of Obstetricians and Gynecologists, should undertake appropriate education to encourage members to increase their Medicaid patient loads.

The increased risk of a poor pregnancy outcome among high-risk women creates an additional disincentive to caring for these groups. Poor outcomes raise the possibility of a malpractice suit, and the threat of malpractice has emerged as a barrier to expanding obstetric care to women at risk of low birthweight and related problems. In response to increasing malpractice insurance premiums and other factors, obstetrician-gynecologists are decreasing their obstetric case loads and decreasing the number of high-risk patients in their practices. Because prevention of low birthweight requires fully available prenatal care and, more important, specialized care for high-risk women, these findings are of major concern.

A partial solution to the problem of access would be to place greater reliance on certified nurse-midwives and nurse practitioners, who have been shown to be particularly effective in managing the care of pregnant women at high risk of low birthweight because of social and economic factors. Maternity programs designed to serve high-risk mothers should increase their use of these providers; and state laws should be supportive of nurse-midwifery practice and of collaborations between physicians and nurse-midwives/nurse practitioners.


The possibility that there are insufficient prenatal care services in sites routinely used by high-risk populations, such as Community Health Centers, Maternity and Infant Care Projects, hospital outpatient departments, and health departments: The committee emphasizes the importance of these organized facilities, especially local health departments, in the effort to increase access to prenatal care. Health departments are highlighted in the report because almost every person in the United States lives in an area that is served by one, because they are known to be active providers of prenatal care, and because their comprehensive programs often are especially suitable for low-income women at high risk for pregnancy problems. National and state data indicate that reliance on health departments for maternity care has increased in the 1980s.

To address unmet needs for prenatal care, health departments should be given increased resources. Every community is different, however, and in some it may be more appropriate to provide additional support for Community Health Centers, Maternity and Infant Care Projects, hospital outpatient departments, or related settings.


Factors that make women disinclined to seek prenatal care: Access to prenatal care is affected by a pregnant woman's perceptions of whether care is useful, supportive, and pleasant; by her general knowledge about prenatal care; and by her cultural values and beliefs.

Two major strategies exist to overcome barriers related to these factors: i.e., general education about prenatal care and the development of a personal, caring environment in which such services are provided, especially for socioeconomically disadvantaged women. Among the attributes that should be built into this environment are accessibility, including easy access for telephone consultations; responsiveness to the concerns that are most salient to women in early pregnancy, such as relief of first trimester nausea and recognition of the need for emotional support and acceptance; and flexibility in the package of services offered so that providers are encouraged to help women obtain nonmedical benefits. Other attributes are described in the full report.


Inadequate transportation and child care services: Provision of child care and transportation should be viewed as an integral part of prenatal care services for socioeconomically disadvantaged populations. Distance and difficulty in arranging babysitting for other children can lead women to put off seeking care unless an emergency occurs.


Lack of systems to recruit hard-to-reach women into care: Sometimes health care programs must do more than provide an open door. They must take the initiative to find and educate women about the importance of care. Two methods are the use of outreach personnel and the establishment of referral relationships with other service systems, such as the Special Supplemental Food Program for Women, Infants and Children (WIC).

The committee believes that the use of outreach workers is an effective way to improve access to care for difficult-to-reach populations. More research is needed, however, on the comparative advantages of different case-finding approaches, the costs of different outreach systems and their effectiveness, and the types of personnel best suited to various program goals and target groups.

A System of Accountability

The committee believes that although many different factors contribute to the problem of inadequate access to prenatal care, an underlying cause is the nation's patchwork, nonsystematic approach to making prenatal services available. Numerous programs have been developed in the past to extend prenatal care to more women, but no institution bears responsibility for ensuring that such services are available to those who need them. Without a structure of accountability, gaps in care will remain, and efforts to expand prenatal services will continue to face major organizational and administrative difficulties.

The federal government, which has long supported prenatal care and urged that all women secure such care early in pregnancy, is uniquely positioned to play a leadership role in the effort to ensure access to prenatal services. The committee recommends that the federal government, through the Department of Health and Human Services, increase its commitment to these goals by:

  • providing sufficient funds to state and local agencies to remove financial barriers to prenatal care (through channels such as the Maternal and Child Health Services Block Grants, Medicaid, health departments, Community Health Centers, and related systems);
  • providing prompt, high-quality technical consultation to the states on clinical, administrative, and organizational problems that can impede the extension of prenatal care;
  • defining a model of prenatal services for use in public facilities providing maternity care; and
  • funding demonstration and evaluation programs and supporting training and research in these areas. States should take a complementary role in extending prenatal services. This could be accomplished by designating one organization—probably the state health department—as responsible for ensuring that prenatal services are available and accessible in every community. Through such an organization, each state should:
  • assess unmet needs for prenatal care;
  • serve as a broker to contract with private providers to fill gaps in services; and
  • if necessary, provide prenatal services directly through facilities such as Community Health Centers and health department clinics.

In addition, each state should designate a local organization in each community—probably the local health department—to be the “residual guarantor” of services and to arrange care for pregnant women who still remain outside of the prenatal care system.

To begin the development of a functioning system of responsibility and accountability, the committee recommends that the Secretary of the Department of Health and Human Services convene a task force charged with defining a system for making prenatal services available to all pregnant women. Such a group should include representatives from Congress, the Public Health Service, HCFA, state governments and health authorities, maternity care providers, and consumers.

This task force should focus on at least four specific issues: (1) how to bring together the knowledge and goals of maternal and child health programs with the “financial power” of the Medicaid program; (2) how to build on the strength of existing experience with the regionalization of perinatal services to combat the problem of low birthweight; (3) how to improve the capacity of state and national data systems to assess unmet need for prenatal services; and (4) how to ensure that prenatal care is financed adequately in times of cost containment, when preventive services often lose the competition for dollars.


Participation in conventional prenatal care programs is associated with a reduced incidence of low birthweight. The committee believes, however, that enhancing the content of prenatal care could increase its contribution to the development of healthy infants.

The committee has identified seven components of prenatal care that merit increased emphasis in the effort to prevent low birthweight.


Establishing explicit goals: Explicit goals can help focus the attention of the patient on the purposes of prenatal visits and help the provider structure appropriate interventions. Examples of goals include reducing the risks of preterm delivery and intrauterine growth retardation, prevention of fetal anomalies and perinatal mortality, and preparation for labor and delivery. Defining the prevention of low birthweight as a major goal of prenatal care will require a variety of adjustments in clinical practice. For example, current prenatal care seems particularly oriented toward the prevention, detection, and treatment of problems that are manifested in the third trimester. By contrast, may of the risks associated with low birthweight, including smoking and poor nutritional status, require attention early in pregnancy. These issues suggest a different schedule of visits from that currently followed, putting additional emphasis on care and education in the first and second trimesters of pregnancy.


Using formal risk assessment systems: Prenatal care should include formal assessments of risk, initiated at the first visit and repeated throughout pregnancy to identify developing problems.


Increasing the accuracy of pregnancy dating: Accurate dating of pregnancy is a cornerstone of good prenatal care. Without it, the clinician is less able to detect intrauterine growth retardation, to determine if labor is premature and the extent of the prematurity, or to avoid iatrogenic prematurity caused by labor induction or an elective cesarean section.


Expanding the appropriate use of ultrasound imaging: A federal consensus development conference in 1984, sponsored jointly by the National Institutes of Health and the Food and Drug Administration, concluded that available data do not support routine ultrasound examination of all pregnancies, but identified almost 30 specific situations in which ultrasound is warranted. Among these are many indications relevant to the prevention of low birthweight.


Increasing the detection and management of behavioral risks: Prenatal care should include explicit attention to detecting behavioral risks associated with low birthweight, especially smoking, nutritional inadequacies, moderate to heavy alcohol use, and substance abuse.


Expanding prenatal education: Health education for women who are pregnant or contemplating pregnancy should be expanded to include greater emphasis on behavioral risks in pregnancy; early signs and symptoms of pregnancy complications such as preterm labor; and the role that prenatal care plays in improving the outcome of pregnancy. Childbirth education classes could play an expanded role in the prevention of low-weight births. To do so, these classes should begin earlier, place greater emphasis on the prenatal period and the risk factors described above, and make a greater effort to enroll women from lower socioeconomic groups.


Recognizing the importance of health care system factors: Prenatal care providers need to organize their programs to manage a wider variety of patient problems and risk factors. For example, nutritional counseling, psychosocial counseling, strategies to modify smoking and other health compromising behaviors, and related services should be provided directly or through a well-organized referral system.

Information on the causes of low birthweight and the risk factors associated with it has led to the development of several innovative programs designed to prevent preterm delivery. Preliminary data from these programs suggest several approaches that could be added to basic prenatal care to decrease the chance of a preterm delivery among high-risk women. These approaches stress repeated risk assessments, expanded patient education, and enriched provider education.

Efforts to arrest preterm labor hinge on its early detection and prompt management. Women at elevated risk of this problem should be taught to identify and lessen events in their daily lives that can trigger uterine contractions, which may in turn lead to preterm labor; the importance of early detection of the symptoms of preterm labor, such as bleeding and periodic contractions; how to differentiate normal contractions that occur throughout pregnancy from those signaling early labor; and what to do when the signs and symptoms of preterm labor Occur.

To complement patient education, provider education should include increased emphasis on the importance of being receptive to patients' complaints, some of which may indicate early signs of preterm labor; the need for prompt identification of preterm labor and the uses of hospitalization for observation and possible treatment of women with suspected preterm labor; and the various approaches available for arresting true preterm labor, such as tocolysis.

Many of the risk factors linked to preterm labor also are associated with intrauterine growth retardation (IUGR); thus, some of the prenatal care interventions designed to avoid one component of low birthweight also may help prevent the other. For example, careful risk assessment is as important for IUGR detection and treatment as it is for prevention of prematurity. The literature suggests that in caring for women at elevated risk of IUGR, prenatal care providers should place extra emphasis on reduction of behavioral risks such as smoking and alcohol use, nutritional surveillance and counseling, and early diagnosis and effective management of IUGR through accurate assessment of gestational age and fetal growth and maturity. Ultrasonography can help establish gestational age when uterine size/date discrepancies occur.

Programs Complementary to Prenatal Care

Because many of the risks associated with low birthweight have a behavioral basis, the committee examined selected interventions designed to reduce these risks, including smoking reduction strategies and nutritional intervention programs such as the Special Supplemental Food Program for Women, Infants and Children (WIC).

The committee urges that efforts to help women stop or reduce smoking in pregnancy become a major concern of obstetric care providers. Several attributes of successful programs drawn from the literature on smoking intervention programs are described in the report.

The committee also recommends that nutritional supplementation programs such as WIC be part of a comprehensive strategy to reduce the incidence of low birthweight among high-risk women and that such programs be closely linked to prenatal care.

The committee also evaluated stress and fatigue abatement approaches, although the evidence that these factors contribute to low birthweight is controversial. A variety of programs have been organized to reduce the levels of stress experienced by pregnant women. Some are concerned primarily with physical stress and fatigue, others more with psychosocial and emotional stress.

One potentially important stress-reducing intervention is maternity leave. The patchwork arrangement in this country of sick leave, disability leave, leave without pay, and other leave categories are not adequate to provide job security for pregnant women and new mothers who participate in the labor force. The committee recognizes that revision of maternity policies is a complicated issue, but suggests that more adequate maternity leave, particularly for certain high-risk women, could contribute to a reduction in low birthweight. At a minimum, labor unions, women's groups, and health professionals should explore this issue.

Encouraging Change in Prenatal Care

To encourage the provision of improved, more flexible prenatal care services, particularly for women at elevated risk of low birthweight, the committee recommends several specific strategies, two of which are that:

  • the professional societies representing the principal maternity care providers should carefully review the suggestions made by the committee regarding prenatal care to determine whether their general guidelines for clinical practice should be revised and enriched accordingly; and
  • the Division of Maternal and Child Health (DMCH), in collaboration with both consumer and professional groups, should define a model of prenatal services to be used in publicly financed facilities that provide care to pregnant women. This model should be updated and revised frequently to incorporate new knowledge and experience and should not be used in a way that discourages research on improved approaches to prenatal care.

Research Needs

Major progress in reducing low birthweight will require a far more sophisticated understanding of prenatal care content than now exists. Thus, research on the content of prenatal care should be a high funding priority for foundations, public agencies, and institutions concerned with improving maternal and child health. This research should focus on three major areas: (1) description and analysis of the current composition of prenatal care; (2) assessment of the efficacy and safety of numerous individual components of prenatal care; and (3) evaluation of certain well-defined combinations of prenatal care interventions designed to meet the widely varied needs and risks among pregnant women.

The Assistant Secretary for Health should take the lead in organizing activities to collect information on current prenatal care practices. Existing surveys conducted by the National Center for Health Statistics should include special emphasis on prenatal care content. Consumer experience with prenatal care should be analyzed, and the professional societies of the major maternity care providers should be consulted about ways to survey their members regarding various content issues. In some instances, direct studies of provider practices may be necessary.

Both public and private institutions should support studies to assess the effectiveness of well-defined combinations of prenatal interventions in reducing low birthweight and improving infant health generally. In particular, these studies should assess the merits of different prenatal care strategies for women at elevated risk of prematurity or IUGR.

Too often, research on prenatal care has been oriented toward the broad question of whether it improves pregnancy outcome. The appropriate goal now is to identify the components and combinations of prenatal services that are effective in preventing various poor pregnancy outcomes in well-defined groups of women.


The committee believes that a carefully designed public information program could contribute to the prevention of low birthweight. Such a program would help create a climate in which change and progress are possible and also convey specific types of information.

The committee sketched the broad outlines of a plan incorporating two major objectives. The first is to call the problem of low birthweight to the public's attention and to reinforce its importance with the nation's leaders. The second is to help reduce low birthweight by conveying a set of ideas to the public about avoidance of important risk factor s.

Public awareness of the low birthweight problem is fostered through discussions of the topic in reports by a variety of public and private organizations interested in maternal and child health. Thus, the committee recommends that the Office of the Assistant Secretary for Health develop and publicize a report every 3 years on the nation's progress in reducing low birthweight. Also, the statistical profile of the nation's health developed by the National Center for Health Statistics, Health: United States, periodically should include a special supplement or profile on low birthweight and its prevention.

Because many of the risk factors for low birthweight are widely distributed throughout the population, and because a substantial amount of low birthweight occurs among women judged to be at low risk, the committee concluded that a public information program on low birthweight should embrace a broad audience. Within this program, however, a special subset of messages should be developed to reach several high-risk target groups: pregnant smokers, young teenagers, and socioeconomically disadvantaged women. In the full report, several specific messages are suggested.

This public information program needs an organizational home and strong leadership. The committee recommends that the responsibility be assumed by the Healthy Mothers, Healthy Babies Coalition, a 4-year-old consortium of voluntary, professional, and governmental groups. The coalition should establish a formal executive secretariat to provide stability and permanence. Both public and Private funds should be provided to the coalition in amounts adequate to the task of leading a major public information campaign, which would include the production and distribution of high-quality, well-tested public information materials.


The fiscal implications of the strategies recommended by the committee for reducing low birthweight are difficult to evaluate. In general, estimates of the costs of measures that should be implemented in the period before pregnancy to reduce the risks associated with low birthweight are not available. Lack of information also prevented the committee from attempting to estimate the additional public expenditures that would be required to finance the recommended public information campaign and research efforts.

With regard to extending the availability of prenatal care, however, the committee found that a straightforward, common sense analysis could be performed regarding some of the financial implications involved in the provision of prenatal services to pregnant women. The committee defined a target population of high-risk women (women with less than a high school education and On welfare) who often do not begin prenatal care in the first trimester of pregnancy. The current low birthweight rate in this group is about 11.5 percent. The committee estimated the increased expenditures that would be required to provide routine prenatal care to all members of the target population from the first trimester to the time of delivery. These expenditures were compared with savings that could be anticipated through a decreased incidence of low birthweight resulting from the improved utilization of prenatal care by the target population. These savings were estimated for a single year and consisted of initial hospitalization costs, rehospitalization costs, and ambulatory care costs associated with general illness. The many assumptions that shaped these calculations are detailed in the report.

The analysis showed that if the expanded use of prenatal care reduced the low birthweight rate in the target group from 11.5 percent to only 10.76 percent, the increased expenditures for prenatal services would be approximately equal to a single year of cost savings in direct medical care expenditures for the low birthweight infants born to the target population. If the rate were reduced to 9 percent (the 1990 goal set by the Surgeon General for a maximum low birthweight rate among high-risk groups), every additional dollar spent for prenatal care within the target group would save $3.38 in the total cost of caring for low birthweight infants, because there would be fewer low birthweight infants requiring expensive medical care.

Copyright © National Academy of Sciences. All rights reserved.
Bookshelf ID: NBK214456


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