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Article 1: How Biological, Cultural, Historical, Mental and Political Factors Influence Women’s Health
cultural groups. Hahn and Muecke call the birth culture of a particular society, “an inherited belief system which informs members of a society about the nature of conception, the proper conditions of procreation and childbearing, the workings of pregnancy and labor, and the rules and rationales of pre- and post-natal behavior.” (10) A key aspect of any birth culture is its belief about the functioning of the body, and the nature of conception and pregnancy, especially when the woman is most likely to conceive. In all human societies, pregnancy and childbirth are more than just biological or medical events. They are also part of an important transition of the woman from the social status of woman, to that of mother. As with all social transition, during the journey from one status to another, the individual must be protected from harm by the observance of certain ritual beliefs and behavior. Many rituals of obstetrics are just ways of transmitting culture within a society. This type of cultural message can be transmitted to the new mother through her birth experience. (10) In modern industrial society, women’s roles are changing, and women are often placed in role conflict situations. They are expected to be both productive, and reproductive; to have both careers and families. At the same time they are criticized by society when they specifically choose either of these options, or if they try to do both at the same time. In this way, society solidifies the established stereotypes of women as being delicate and fragile, incapable of assuming male roles in public domain. (10) The gender roles prescribed by a particular gender, i.e., being allocated at birth to the social category of either male, or female may, under some circumstances, have a negative effect on an individual’s health. Those conditions where the beliefs, expectations and behaviors inherent in a particular gender culture can be said to contribute towards ill health may be termed diseases of social gender. In modern industrial societies, many women are increasingly the focus of contradictory influences from their gender culture. These role conflicts have greatly increased the stresses in the lives of modern women. (10) There are few societies worldwide, in which women give birth alone and unaided. “The social nature and significance of birth ensures that this biological, and intensely personal process carries a heavy cultural overlay.” (2) According to Van Gennep in 1908: “Birth is a rite of passage that embodies a culture’s deepest beliefs, which are transmitted and reaffirmed during this critical, transitional time. According to Sheila Kitzinger, 1978: “Birth practices point to the core values of the culture, and tell the observer a great deal about the way a culture views the world, and women’s place in it.” She states that where women have a high status, there is a rich set of nurturing traditions that develop around birth. Where women’s status is low, the opposite occurs. According to Martin, 1987; Robbie Davis-Floyd, 1992; there is an extreme emphasis on technology in the United States. This is mirrored within its birth practices, in which laboring women are placed in a hospital, and presented with technological interventions. This approach is presented as prestigious, and high technology. The western medical system believes that the more technology available, the fewer complications possible in birthing, However, statistics show that quite the opposite is true. In the 1960’s, as a result of scientific research and advancing technology, as well as the economification of birth, midwifery in the U.S. nearly disappeared. This is a pattern that has repeated itself in countries without a traditional midwifery model of care. These countries have imported the western model of birthing. However, maternal mortality statistics show that in the countries that have the lowest maternal mortality rate of Japan, Holland, Sweden, and Denmark, over 70% within cultural birth practices, most births are attended by midwives (Wagner 1994; Fiedler 1996). (2) In the 1980’s, evidence mounted against typical obstetric management, and obstetricians came under fire. During this time malpractice lawsuits soared. Some time in the 1990’s, these doctors changed their tactics, and went on the offense. The American College of Obstetricians and Gynecologists (AGOG) decided that it would begin a public relations campaign. They would sell to the public the idea that OB’s are heroes, doing their best to safeguard the health and well being of women and babies. Anyone who criticized this became an enemy. They have waged a disinformation campaign to present a hospital as an unquestionable necessity in childbirth. Most OB’s are taught in medical school (inculturation) that birth is a dangerous, damaging business that they need to intervene into, and that all that stands between a laboring woman and disaster is the doctor. They believe that they can convince the public of anything, if it is said by someone the people trust, and say it loud enough, and often enough. Currently, the overwhelming dominance in western medicine of obstetric practices in childbirth further ensures silencing of any dissent. (3) The academic examination of childbirth as a social phenomenon did not begin until the 1960s. Before then, childbirth beliefs were based on writing by medical historians who stressed the progressive history of the scientific advance of obstetrics. These accounts told very little about women’s childbirth experience and their interpretations. Today, there is much more exploration into the details of a woman’s childbirth experiences. More research is being done on the medical, demographic, cultural, social, economic, professional, and symbolic aspects of pregnancy. (4) In the Western Culture, childbirth is generally associated with the medical environment of a hospital, doctors, nurses, and technology. Earlier in the U.S., medical professionals were only associated with childbirth only when a woman’s life was threatened. Childbirth was considered to be part of a woman’s domestic responsibility. Traditionally, only women attended other women. The experts on birthing then were women. (4) During the mid-18th Century, the expertise of women in birthing began to be questioned. Women in France began delivering babies in the hospital, attended by midwives and physicians. Hospitalization practice enabled doctors to study and understand the normal childbirth process. During the same time period, the English medical profession began to advance more surgical techniques. The creation of “forceps” was used to assist in extracting a fetus from a woman. The knowledge was transported to America. (4) In America, physicians then began attending the births of middle and upper class women. At first they attended along side traditional midwives, but soon they replaced midwives completely. Medical schools began to certify men as birth attendants, and this lead to a decline in traditional midwifery. (4) By the end of the 18th Century, physicians had inserted themselves into birthing roles through urban areas, including the poor. A large array of interventions became common when childbirth became medicalized, and included drugs, anesthesia, and many different birth aid instruments. These advances in technology created new problems, including tears and infections. Physicians forgot the history of birth, and their attitude symbolically changed from a partner in birth, to a controller of birth. Women only remained partly in control of their birth experience. They only alternative women had for full control of their experience during labor and birth was to remain at home, and have a midwife attend. (4) The medicalization of birth grew quickly in the northeastern urban areas of the United States. Some southern regions, as well as religious communities, maintained the traditional aspects of childbirth during the 19th and early 20th centuries. Immigrant groups were also likely to continue with traditional practices. In 1900, 90% of all births occurred at home. Some were unattended; others were attended by midwives or doctors who were often poorly trained. In 1900 only 10% of the nation’s physicians attended college. Most went directly to special medical training institutions. In 1910 a report on medical education found that the vast majority of these institutions offered substandard training. The maternal mortality rate was 6-9 deaths per 1,000 live births, whereas in 1950, 90% of all births occurred in the hospital. Many of these deaths could have been prevented, but crowded housing, poor hygiene, and waste control, and contaminated food and water supplies were major contributors to the spread of infectious diseases and deaths from infections. (11) In the first decade of the century, the federal government and public health departments began to include preventive health education programs, visiting nurses, improvements in sanitation and hygiene, better housing conditions, water chlorination, organized solid waste disposal, safer food and milk handling practices, improved animal and pest control, the expansion of disease control programs, immunization programs, and the creation of a public health care infrastructure that increased access to health care services. Following these additions, a steep decline occurred in maternal and infant mortality, from 600-900 deaths per 100,000 live births in 1900, to 11 per 100,000 live births among white women, and 30 per 100,000 live births among non-white women in 1940. The infant mortality rate dropped from 146 per 1,000 live births in 1900 to 34 per 1,000 live births by white women, and 49 per 1,000 live births by non-white women in 1940. These improvements further accelerated during the 1940’s and 1950s with the development of antibiotics, improved medical practices, the establishment of national vaccination/immunization programs, and the creation of qualification guidelines for physicians. The 20th Century brought more medicalization and hospitalization to the childbirth experience. Traditional midwives remained in the inaccessible parts of the country. With the increase of technology, women experienced greater mystification of childbirth, and lost even more control over their childbirth experiences. During this time though, women were choosing to take control over their own fertility, and they began to have smaller families. The significance and importance of having a positive birth experience increased because of this. At the same time, women understood less about the childbirth process itself, and still had little control of birth, even less than their grandmothers did. (4) This trend continued until the late 1950s and 1960s, when women began to express dissatisfaction with their medicalized birth experience. Europe began presenting a more natural birth approach, focusing on relaxation techniques, and encouraging woman to anticipate their birth with joy, empowered with knowledge, not fear and ignorance. They believed, as their great-grandmothers had, that childbirth should and could be accomplished with less pain, less medication, and less medical and surgical intervention. Thus began the movement of “Prepared Childbirth”. (4) Preparation for childbirth is a concept that has been popular in the United States for the last 40 years. It involves attending organized classes to prepare a woman, and her partner for labor and delivery. Some couples desire to have a “natural childbirth” experience, without the use of medication for pain relief, and with minimal mechanical monitoring. Others wish to learn more about birthing events. Organized classes provide an opportunity to learn about local birthing options and a chance to discuss personal issues and concerns. They provide the ability to gain knowledge about pregnancy and childbirth, and to develop pain management skills, breathing techniques, muscle strengthening exercises, and different body positions to facilitate labor, which promotes an uncomplicated birth. The greatest advantage of childbirth education is the opportunity to prepare for a more satisfying birth experience. (4) Modern Western medical practices stress the physiological, rather than the psychosocial aspects of pregnancy and birth. As a result, there is a tendency to medicalize this normal female biomedical event. Birth has been transformed into a medical “problem”. Thus, the western cultural view of birth is not just a natural physiological process, but a “problem that needs treating”. In this view the perceptual message that is conveyed sends a message to everyone about our culture’s deepest values and beliefs. Following this pattern of cultural thinking, in western society, technology is supreme, as are the institutions and individuals who control and dispense it. This impression is strengthened by the frequent use of medical interventions commonly used in western births, including the administration of drugs, episiotomy, and the high rate of surgical births, which transforms even the most natural birth into a medical procedure. The western medical view of labor and birthing encourages the separation of the actual birth from the rest of the woman’ s life experience, and treats it as an isolated medical event. (10) The profession of nurse-midwife was established in the United States in the early 1920s by Mary Breckinridge, a pioneering nurse who founded the Frontier Nursing Service (FNS). The FNS provided family health services to isolated areas in the Appalacia mountains by sending public health nurses to their patients by horseback. (11) There is a distinction between professional midwives, and traditional birth attendants. Professional midwives are trained health professionals that have formalized training, and meet professional standards determined by their country. Sometimes they do attend home births, but most often they practice in hospitals and birthing centers, under the guidance of a doctor. They have greater access to medications, and technology in the hospital, and are trained in lifesaving skills. (8) Professional midwives play an important role in application of patient safety within the care they provide. The Institute of Medicine (IOM), and the Joint Commission for the Accreditation of Health care Organizations (JCAHO) have noted common errors in health care that place patients at risk for adverse events at the hands of health care workers. Adverse outcomes in perinatal health care result in significant emotional and financial costs to all. The WHO (World Health Organization) recognizes that professional midwives can safely manage most pregnancies, and have the skills to refer complex complications to a doctor. But well-trained professional midwives can continue to handle the majority of births. (8) A study of 3,257 out-of-hospital births attended by Arizona licensed direct-entry midwives between 1978 and 1985 shows a perinatal mortality rate of 2.2 per 1,000, and a neonatal mortality rate of 1.1 per 1,000 (Sullivan and Weitz, Yale University Press, 1988). A study of Washington State licensed Midwives compared licensed midwife-attended birth outcomes to low-risk births attended by physicians in the hospital, certified nurse-midwife attended hospital births, and certified nurse-midwife attended home births. Overall, births attended by licensed midwives out of hospital had a significantly lower risk for low birth weight, than those attended in hospital by certified nurse-midwives, but no significant differences were found between licensed midwives and any of the comparison groups on any other outcomes measured. (Birth, 1994). A study of 1,001 direct-entry midwife-attended home births in Toronto revealed a 3.5% cesarean section rate and a neonatal death rate of 2 in 1,000. One of the two babies who died was born at the hospital nine hours after care was transferred to a physician. This study noted that “The rates of transfer for emergencies for mother and baby were notably low. Maternal morbidity and neonatal morbidity were also low.” (Birth, 1991). A study of granny lay midwives practicing in North Carolina’s rural areas of socio-economic deprivation, found that they were achieving an infant mortality rate of 1/3 that of hospital births, and 1/7 that of physicians doing births in private clinics (Journal of the American Medical Association, 1980, Vol. 244). Data from the Utah Department of Health Planned for home birth show neonatal mortality rates of 3.8 per 1,000 from 1989 to 1990, 0 per 1,000 from 1991 to 1992, 1 per 1,000 in 1993 and 2.2 per 1,000 in 1994 (Technical Report No. 201, Utah Department of Health Office of Public Health Data, 1998). Clinical practices and models of care for professional midwives may vary according to patient needs and values. Even though professional midwives may have memorized many facts, they may need more hands-on training in order to learn how to apply their knowledge in a clinical situation. (8) Transcultural training is a necessity, but is often lacking in the academic training, and is not directly experienced until clinical practice begins. Professional midwives are expected to keep on top of developments in the field of quality improvement research, and policy, throughout their practice, in order to continuously evaluate and improve the quality of care they provide. (9) Health care can be safely and effectively delivered through a variety of practice models. (9) Traditional midwives learn by an apprenticeship model of teaching, and don’t have institutionalized education. They have learned what they know about birth from other midwives, or through training programs instituted by their country, friends, neighbors and relatives, through hands-on experience. They mainly attend home births, and use very little technology in their practice. (8) Many cultures have a tradition of using midwives. These midwives feel that they are “called” to their profession, often because of their own birth experiences, or through someone else they had a relationship with, such as a family member. Usually, traditional midwives come from a similar cultural group as the women who they are caring for. They speak the same language, understand the culture, and live close enough to be available at any time. They can provide emotional and physical support to all pregnant women. Most of these women attend low-risk pregnancies, and refer complicated pregnancies to someone who has institutional health care training. (8) Traditional midwifery follows a holistic approach, and views childbirth as a normal physiological process that encompasses powerful, emotional, physical, cultural and spiritual dimensions; the understanding and value of connection, and the partnerships of the body and the mind, the mother and the infant, the midwife and woman, and the woman and her social context. A traditional midwife has the unique gift of a profound trust and belief in the sacredness of birth, and a woman’s power to birth on her own. At the same time, midwives are aware of what they can’t do, and know when to ask for biomedical interventions. (1) Midwives work to preserve the sacredness of birth and its social context within a culture, in order to reverse the global trend of devaluing the traditional systems. This trend encourages the natural process of birth, instead of encouraging the view that birth is a medical event which calls for technical intervention. If we encourage the exploration into alternative childbirth methods worldwide, statistics show that maternal outcomes will improve. (1) Much of the world does not have quality access to trained or professional birth attendants. The country of Cambodia is an example of this, as they have literacy rates very low in their population, especially among women. Very few of these women have the opportunity to receive a formal education, or even to go further as a health professional such as a doctor, or professional midwife. For those who are able to receive training, there a number of cultural factors that make it difficult for them to live in, or relocate to the rural areas where traditional birth attendants do the majority of births. Some developed countries have completely eliminated traditional birth attendants as a result of the raised basic status and education level of women. (8) In Antigua, Guatemala, there is a huge difference between maternal mortality rates there, and in developed countries. According to the World Health Organization, one in 3,700 women will perish in childbirth in the United States, but in comparison, in Latin America the risk of death is 1 in 130 during birth. The main reason for this statistical difference is the common lack of access to medical care. Only a small percentage of the wealthy women in these countries choose to birth in a hospital with doctors present. In these indigenous hospitals, the cesarean section rate is 35 to 50%, which is a number that far out paces WHO’s recommended c-section rate of 15%. (1) In Latin American countries, education and activism in childbirth is sadly lacking among educated women. Here, traditional midwives provide the majority of maternity care, and have responsibility to attend 60 to 75% of all of the births in Guatemala. Care providers serve a population that live in very poor conditions, have limited training and resources, as a result suffer from many chronic health problems. In spite of these odds, and their geographic isolation, they do very well with the resources that they do have. (1) More developing countries have attempted to develop the traditional midwifery model of care through training programs that introduce the biomedical model of birth. There is widespread understanding that there is a need to take culturally based traditional midwifery knowledge and practices into account when conducting training for midwives, but most programs internationally in the past have failed to do this. (1) Problems occur when programs have failed to create respectful working relationships with current practicing midwives. It is absolutely necessary within a training program, to learn how the local midwives practice, and to involve them in incorporating effective evidence-based techniques into their practice, as well as training new incoming midwives by transferring their cultural knowledge. In this way, traditional practices are preserved, and current midwives within the culture are valued as health care providers, and mentors. Relationships are respectful between the experienced midwives, and students, which promotes an exchange of information needed to make intelligent, healthy decisions in the care of birthing women. This approach should be encouraged not only in developing countries, but also in industrialized countries, such as the United States. This approach could improve training for all midwives, and can encourage them globally to identify and articulate the essential and universal tenets of midwifery that are worthy of preservation and replication. (1) Sheila Cominsky’s ethnographic studies in Guatemala in 1977, offers insights into the ethnocentric attitudes of training programs, and the reasons why they have failed to change local practices, or improve maternal mortality outcomes. She suggests that biomedical training in developing countries has limited the roles of the local traditional midwives. Several other studies suggest that many biomedical obstetrical routines have cultural, rather than medical reasoning (Kitzinger 1979, Martin 1987, Rothman 1989, Goer 1995). An independent researcher hired by the World Health Organization to survey routine obstetrical practice concluded that only 10% of all routine obstetrical procedures were scientifically based (Fraser 1993). Evidence-based practice argues that routine use of obstetric interventions reflects cultural preferences, habit, and assumes that technology is superior to a natural approach to childbirth. The World Health Organization has valued evidence-based practice for over 15 years, and focuses this belief on developing scientific studies that assess a trend toward high-tech birth. Marsden Wagner, who is a former Officer for Maternal and Child Health for the WHO, has stated that several important documents were created to provide guidelines to normalize birth, and provide training for midwives, which would stop the unnecessary use of obstetrical procedures. (1) In Washington, D.C., on June 16, 2008; just in time for Father’s Day, at its annual meeting, the American Medical Association (AMA) adopted a resolution to introduce legislation outlawing home birth, and potentially make criminals of the mothers who choose home birth with the help of Certified Professional Midwives (CPMs, also known as “traditional midwives”) for their families. According to the website founded by a group called “The Big Push For Midwives”, Susan Jenkins, Legal Counsel, stated: “It is unclear what penalties AMA will seek to impose on women who choose to give birth at home, either for religious, cultural, or financial reasons – or just because they didn’t make it to the hospital in time. What we do know, however, is that any state that enacts such a law will immediately find itself in court, since a law dictating where a woman must give birth would be a clear violation of fundamental rights to privacy and other freedoms currently protected by the United States Constitution.” (7) Until the AMA proposed “Resolution 25 on Home Deliveries”, no state had considered legislation forcing women to deliver their babies in the hospital, or limiting the choice of birth setting. Instead, states have regulated the types of midwives that may legally provide care. Currently, 22 states already license and regulate CPMs, who specialize in out- of-hospital maternity care and have received extensive training to qualify as experts in the types of risk assessment and preventive care necessary for safe and high-quality care for women who choose to give birth at home. Certified Nurse Midwives (CNMs),who are trained primarily as hospital-based providers, are licensed in all 50 states and the District of Columbia. The resolution did not offer any science-based information for the AMA’s anti-midwife, or anti-home birth position. (7) According to Steff Hedenkamp, “Maternity care is a multi-billion dollar industry in the United States. So it’s no surprise to see the AMA join ACOG in its ongoing fight to corner the market and ensure that the only midwives able to practice legally are hospital-based midwives forced to practice under physician control. However, I am shocked to learn that they are taking this battle to the next level by setting the stage to outlaw home birth itself, which is a direct attack on those families who choose home birth, who could be subject to criminal prosecution if the AMA has its way.” (7) The AMA has also passed legislation in the form of “Resolution 814, which stemmed from the Scope of Practice Partnership (SOPP), to obstruct expansion and to restrict the licensed scope of practice of other health care professionals. These actions by organized medicine will limit access to providers who have the education, expertise and experience to offer safe, quality health care services to the public, particularly for rural, uninsured and other under served populations. The “Big Push for Midwives” Campaign objects to the misleading and divisive language used in the AMA SOPP Resolution, which pits medical doctors against other health care professionals at a time when the American public is faced with unprecedented health care shortages and more than 45 million uninsured children and adults. The health care professionals that are targeted by the SOPP include nurse practitioners, physician assistants, podiatrists, optometrists, psychologists, chiropractors and midwives, who are the solution to the problem of a lack of health care availability, not the problem. (7) Sue Hedenkemp states: “The claim that SOPP can or should determine what is best for the patients of other health care professionals represents an outdated and patronizing line of thinking that can’t possibly serve the needs of today’s patients, particularly childbearing women and their babies.” (7) According to Maternal Mortality, 2000, more than 500,000 women died during pregnancy and childbirth in 1995, and many millions more suffered without treatment. Ninety-nine percent of maternal deaths occur in developing countries, most of them preventable. Infections and blood loss account for the majority of these deaths. To reduce maternal mortality, more investment into the health system is needed to improve the quality and coverage of delivery services, and provide prenatal and postnatal care for the poor. In regions where skilled attendants are not routinely available, the goal is to have skilled attendants at 90% of births by 2015. The way to reduce maternal mortality is to provide family planning, maternal care, skilled birth attendants, and neonatal care. Health workers with midwifery skills are the key to reducing maternal mortality. They improve women’s social status, and ensure gender equity in health care. These issues are important in reducing maternal mortality rates in underdeveloped countries. (5) According to the American Public Health Association, “Supporting Access to Midwifery Services in the United States (Position Paper)”, American Journal of Public Health, Vol. 91, No. 3, March 2001: “In terms of quality, satisfaction, and costs, the midwifery model of care for pregnancy and maternity care has been found to be beneficial to women and families, resulting in good outcomes and cost savings… With its focus on pregnancy as a normal life event, and health promotion for women of all ages, the midwifery model of care is an appropriate alternative or complement to the medical approach to childbirth.” According to Murry Enkin, et al, A Guide to Effective Care in Pregnancy and Childbirth. Oxford University Press, 2000: “It is inherently unwise, and perhaps unsafe, for women with normal pregnancies to be cared for by obstetric specialists… Midwives, on the other hand, are primarily oriented to the care of women with normal pregnancies, and are likely to have more detailed knowledge of individual women.” According to the Coalition for Improving Maternity Services, The Mother-Friendly Childbirth Initiative, 1996: “Midwives attend the vast majority of births in those industrialized countries with the best perinatal outcomes.” According to Dower CM, Miller JE, O’Neil EH and the Task force on Midwifery, Charting a Course for the 21st Century: The Future of Midwifery, San Francisco, CA: Pew Health Professions Commission and the UCSF Center for the Health Professions, April 1999: “It is the finding and vision of the Task force that the midwifery model of care is an essential element of comprehensive health care for women and their families that should be embraced by, and incorporated into the health care system, and made available to all women.” Bibliography (1) Article: Published in Childbirth Solutions, Inc.; “Weaving a Cultural Exchange: Midwives Working Together.” Published in Midwifery Today, January 2000. http://www.childbirthsolutions. com/articles/worldbirth/guatemala/index.php. (2) Article: Published in the Blackwell Dictionary of Anthropology, by Thomas Barfield, ed.; Oxford: Blackwell Publishers, 1996. Article titled: “On Childbirth”. (3) Article: Published in Midwifery Today, Inc. “The Assault on Normal Birth: The OB Disinformation Campaign,” by Henci Goer. Autumn 2002; Issue 63. (4) Alexander, Linda Lewis; LaRose, Judith H.; Bader, Susan Garfield. “New Dimensions in Women’s Health.” Pp. 193-196. (5) Article: 2000. A Better World For All. “Maternal Mortality”. http://www.paris21.org/betterworld/maternal.htm (6) Article: Published by Citizens for Midwifery. “Safety in Birth Begins With Midwifery Care,” Fact Sheet. www.cfmidwifery.org. (7) Article: Published by the Big Push for Midwives; “Father Knows Best Meets Big Brother is Watching: Physician Group Seeks to Outlaw Home Birth – Is Jail for Moms Next?” http://www.thebigpushformidwives.org/amastmt .aspx. (8) Article: “Midwifery Education: Professional Midwives and Traditional Birth Attendants: What is the difference?” http://haneydaw.myweb.uga.edu/twwh/midwifery.html. (9) Article: American College of Nurse Midwives Position Statement. “Creating a Culture of Safety in Midwifery Care”. ACNM Board of Directors, September 2006. (10) Helman, Cecil G. “Culture, Health and Illness”, 5th Ed. Pp. 193-196. (11) “A Century of Women’s Health 1900-2000”. Office on Women’s Health, U.S. Dept. of Health and Human Services, April 2002. For the statistics on the safety of home births attended by midwives, please reference the following articles: http://www.changesurfer.com/Hlth/homebirth.html; and BMJ.com, February 14, 2008; “Outcomes of Planned Home births with Certified Professional Midwives: A Large Prospective Study in North America”, by Kenneth C. Johnson and Betty-Anne Davis; BMJ, 2005; 330-1416-doi: 10. 1136 bmj. 330.7505. 1416. |
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