Int

J Gynaecol Obstet

16 : 449- 455 , 1979

Perspectives on Fertility Control Malcolm Potts International Fertility Research Program, Resea rch Triangle Park, North Carolina, USA

ABSTRACT Potts M (International Fertility Research Program, Research Triangle Park, NC, USA). Perspectives on fertility control. lntj Gynaecol Obstet /6: 449- 455, 1979 The biologic, administrative and individual perspectives on fertility control are presented and discussed. The need to unite perspectives is demonstrated and the importance of adjusting human f ertility to new physiologies and social demands is stressed.

INTRODUCTION The control of human fertility presents somewhat different problems when seen from the perspective of the epidemiologist, the biologist, the administrator and the individual man or woman who makes choices about methods. The facts and the insights each uses are different and each is affected by different personal and political pressures. The th eme which unites the perspectives of different groups is th e ever present need to adjust human fertility to new physiologic and social demands.

EPIDEMIOLOGIC PERSPECTIVE Predictably, the analysis of the side effects of family planning methods revolves around those side effects which are easy to measure and which appear rapidly rather than those which develop over the course of years. Therefore, death and serious morbidity tend to be measured sooner than beneficial effects. Unfortunately, the elements which appear first in epidemiologic studies are not necessarily those which are going to prove most important in the long term; neither are they always elements of immediate concern to the man or woman making individual "decisions about fertility control. But, it is the epidemiologic data which have dominated the This work was supported in part by the International Fertility Research Program and the Office of Population, United States Agency f or International Development (A ID/pha-C- 1172).

scientific journals and overflowed into the public media. Family planning methods Our knowledge of contraceptive side effects is continually evolving. Over the last decade, early abortion by mechanical means has proved safer than was expected, while oral contraceptives have developed more problems than were foreseen . For example, the risk of death from menstrual regulation and legal early abortion is now so low that, were it bi?logically possible, a woman over 40 years of age mtght have a menstrual regulation once every month for a year and still not run the risk associated ~ith some of the reversible methods of contraceptiOn. The broad conclusions of epidemiologic studies a re simple to state (9- ll, 18) : I. The risks for contraception for nearly all women are less than those of an unwanted pregnancy, with the exception of older women who are using the pill and who are at additional risk because of factors such as smoking. 2. The combination of a mechanical method of contraception which is backed up with early abortion induced with modern methods by a trained person is an order of magnitude safer than the use of the intrauterine device (IUD) or oral contraceptives. 3. Male sterilization involves less risk than female sterilization although the risks of each are minimal when the dangers of either are amortized over many years of protection offered . There are numerous ways to set up the equation which balances the risks and benefits of fertility regul a tion. It is possible to look at the risks associated with short-term choices or to look at risks evidenced over a fertile lifetime. The benefits of avoiding unwanted pregnancy can be balanced against the possible adverse effects of the method used. Commonly, analyses concentrate on death rates and involve small risks spread over a large population . Sometimes it is difficult to translate such results into useful information for the individual who must make choices about fertility regulation.

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Pregnancy and medical supervision The risks associated with methods of fertility regulation and with pregnancy differ in different socioeconomic environments. The risks of pregnancy vary greatly among various countries. For example, the recorded maternal mortality rate per 100 000 live births is 202 in Thailand, 123 in Mexico and 12 in England and Wales. Maternal mortality is least accurately recorded where it is highest. In a careful study of over 20 villages (total population 231 000) in Bangladesh between 1967 and 1970 (3), 41 maternity-related deaths were recorded from among 5802 pregnancies, or a mortality of 7.1 per 1000 pregnancies (7. 7 per 1000 live births). Maternity-related deaths made up 30% of all deaths to women aged 10- 49. In the 1524 age group, women had twice the death rate of men the same age. The excess mortality was entirely due to childbearing. Bangladesh is ,n ot alone in her problems. In the villages in India, 93% of deliveries take place at home, half of these are attended by dias, one in ten by trained midwives and the rest by neighbors and relatives without even the familial transmission of knowledge associated with the traditional birth attendant. Even in the Philippines, half of the births are attended by hilots. The traditional midwife may handle a normal delivery well, but is helpless in front of a number of possible complications, especially hemorrhage and toxemia. The risks associated with a method also vary between countries. A comparative study between Oxford and Bangkok suggested that deep-vein thrombosis (as detected by fibrinogen labeled with radioiodine) occurred in 1. 7%-3.8% of the postoperative hysterectomy and cancer surgery patients in Thailand against 12%-35% of the cases in England (4). Vegetarians in India are anemic and the bleeding associated with IUDs is more serious than in the West . Sickle-cell anemia, which is prevalent in West Africa, can interact with systemic contraceptives. The range of skills available to supervise methods or to treat possible complications differs among countries. This factor is easy to overemphasize in the case of the pill . Certainly, highly sophisticated Western medicine is not a guarantee of safety, and some studies suggest that people admitted to intensive care units after coronary thrombosis have as bad or a worse outlook than those treated at home (6). In the case of IUDs with the possible complications of infection, differences in the quality of care could be more important. The availability or nonavailability of safe, e-arly, legal abortion services is of great importance and influences choices about other methods. For examlnt J Gynaecol Obstet 16

pie, greater risks are likely to be taken in older women using the pill in countries such as Brazil, where abortion is not available, than in the United States, where abortion is legal. Certain methods of fertility regulation have beneficial as well as adverse side effects. Condoms reduce the possibility of venereal disease and perhaps of cervical cancer. Systemic contraceptives have a complex series of effects, many of which are beneficial, whether in short-term changes such as the reduction of anemia or in possible long-term effects such as altering the incidence of certain malignancies. In summary, the epidemiologic perspective of the risks and benefits of fertility control is valuable but incomplete.

BIOLOGIC PERSPECTIVE The biologist sees man as a mammal subjected to the special stresses of civilized living and to some extent this specialist encompasses narrower disciplines, such as pathology and clinical medicine. Civilized living has placed a number of new strains on the biology of human reproduction. Not only has the situation arisen where the species can replace itself by having fewer than ten children in a lifetime, but the age of the menarche has declined. The expectation of a woman living to the menopause has greatly increased and long intervals for lactation are becoming increasingly rare. These are all factors which tend to raise fertility at the very time when the social and economic pressures are to lower it (15). Man is unusual among mammals in that we copulate frequently and at all seasons, as well as during pregnancy and lactational amenorrhea and after the menopause. We have a long gestation period and deliver a helpless infant with a very large skull who is to be breast-fed for up to two or more years. The age of the menarche, the duration of anovulation due to breast-feeding and the onset of the menopause are the three factors which originally limited the number of deliveries which a woman had in a lifetime. Evidence from the few human communities which appear to have no volitional restraint on fertility suggests that a woman can, on the average, bear ten live children in a fertile lifetime. Some of the highest reproductive rates in the world were recorded in rural Quebec only a generation ago. The Hutterites on both sides of the United States/Canadian border are other often quoted examples of unrestrained fertility. A biologic perspective of human reproduction assists in providing the judgment and advice which modern methods of contraception demand. Among

Fertility control persjJectives

many lay people, as well as some members of the medical profession, the perception has grown that the use of hormonal contraceptives is "unnatural." It is perhaps more realistic to appreciate that modern living makes a great many unnatural demands on the reproductive system of women, certain of which have serious and demonstrably harmful effects. It is reasonable to assume that the female reproductive system is tailored by evolution to conceive frequent pregnancies within relatively few cycles of ovulation followed by long intervals of lactation. In the present world, women frequently delay childbearing to their twenties, have few children and rarely breast-feed for more than a few months. Thus, they spend the greater part of their lives exposed to the hormonal changes of the menstrual cycle rather than to the more extended, relatively constant and different hormonal states of pregnancy and lactational amenorrhea. This change carries with it a series of pathologies. Endometriosis and fibromyomata are partially linked to delayed and infrequent childbearing, but the most important changes relate to carcinoma of the breast. There is a definite correlation between the age a woman bears her first child and the probability of developing breast cancer (7). Epidemiologic studies of populations of Japanese who have migrated to the United States and then had children demonstrate that the incidence of cancer of the breast changes in these two generations from the low level found in Japan to the high level found in the United States. Breast cancer, like lung cancer, appears to be partially induced by environmental change. Short (14, 15) has suggested the interesting and simple hypothesis that the total number of menstrual cycles to which the breast is exposed prior to the protective effect of pregnancy could account for differcn t patterns of breast cancer; the menarche is later and the first delivery earlier in Japanese than in North American women. Alternative explanations relate to nutrition, which in turn interacts with body structure and the age of the first menstruation, and to the profile of circulatory estrogens in young women. It is interesting that use of oral contraceptives appears to reduce the incidence of breast disease (1, 17, 19) and that there has been no change in age-specific mortality trends for fertile age women in recent years (13) . It is possible that women will always be using some form 'o f hormonal contraception, perhaps not the present pill, but a medication designed not only to prevent conception but also to prevent the development of those diseases associated with voluntary infertility. Whatever the ultimate pattern of prevention, modern living is associated with an epidemic

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of breast malignancy. One in 20 women in Britain will die of breast cancer, as will one in 18 in the United States. Certain methods of fertility regulation involve the risk of teratologic damage. An IUD or hormonal contraceptive could affect the embryo if pregnancy supervenes. It has been suggested that the pattern of coitus associated with the use of periodic abstinence may be a cause of embryonic defects and abnormal sites of implantation, such as placenta previa (4). Species, dose and timing of the dose in relation to development are all relevant variables making study difficult. Pincus and Rock are said to have chosen to work on the female reproductive system partly because the eggs have been packaged and set aside before birth and are not subject to risks associated with pharmacologic agents active against spermatogenesis. While teratology has its special problems, species differences are a recurrent issue. If, for example, penicillin had been tested on guinea pigs, it would have been found to be a highly toxic preparation. Species differences are more marked in relation to the reproductive tract , particularly that of the female. Implantation in the insectivorous bat is much like that in the human female, but the handling of sperm in the female tract is profoundly different. Many aspects of pregnancy in the apes are similar to those in Homo sapiens, but the breasts on the gorilla develop during the first pregnancy whereas, in the human female, they develop at the menarche. In most countries, animal tests are required before a physiologically active contraceptive is licensed. The example of the development of breast nodules in beagle dogs given prolonged doses of medroxyprogesterone acetate (Depo-Provera, The Upjohn Co, Kalamazoo, MI, USA) demonstrates the problem of interpreting effects between species. Such findings must be taken seriously, but they can do no more than raise the index of suspicion; they cannot provide a definite answer to safety or danger in the human species. Species differences are compounded by the time scale concerned in the development of cancer and by the variety of biologic outcomes. The use of a hormonal contraceptive could raise, lower or leave unchanged the incidence of cancer. It could act in different directions on different types and locations of cancer, and it could have a paradoxical effect at different stages in the development of a particular malignancy. For example, pregnancy in a young woman reduces the chance of cancer of the breast, but it accelerates an established cancer in an older woman . Each combination of artificial steroids might have a different effect on the course of malignant disease; an injectable contraceptive without an Int.} Gynaecol Obstet 16

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estrogen component given for long intervals would have a different effect from a combined pill given discontinuously. What can be asserted at the present moment is that the basic questions about hormonal contraceptives and human malignancy remain largely unanswered for oral contraceptives and for medroxyprogesterone acetate. The difference between medroxyprogesterone acetate and the pill is not so much in the biologic issues related to their use, but in the political and administrative pressures applied when they have come up for approval in the United States Food and Drug Administration.

ADMINISTRATIVE PERSPECTIVE Epidemiologists deal in probabilities; biologists can always ask more questions than they can provide answers; but administrators, like individuals deciding on contraceptive methods, must make "yes" or "no" decisions. They must not only react to real and perceived physical risks of fertility regulation methods, but also to political and logistic side effects. Ultimately, all administrative decisions which balance the risks and benefits of contraception involve human judgment. For the expert committee member, the World Health Organization or the US Congressman on the Hill, decisions about contraceptive risks and benefits are not a game of chess where every move can be predicted, but a game of poker where the element of bluff is a reflection of a person's own prejudices, aspirations and human experiences. Sir Alan Parkes (8) has posed the basic issue concerning the use of oral contraceptives: "It is always difficult to prove a negative and impossible to do so in advance. In fact, we face the dilemma that no woman should be kept on the pill for 20 years, until, in fact, a substantial number have been kept on the pill for 20 years." We may even have to expand this cautious statement to cover two generations-the user and her offspring. Even the most understood of methods may suddenly come under scrutiny. It has been suggested, for example, that the talc used in packaging condoms may reach the surface of the ovaries and could, in extreme circumstances, be carcinogenic. It is a speculation that will not and should not affect the use rates of condoms, but it underlines the fact that proof of safety is impossible. As one bumper sticker proclaims: "Living is hazardous to health!" If we understand the nature of the administrative decisions regarding the use of contraceptives, we can pose with greater precision the questions that "drug regulatory agencies must answer. A drug regulatory agency can never determine that an agent is safe to lnt J Gy naecol Obstt t 16

use in advance of widespread use, although this is the question many people (particularly in the US) believe to be at issue. In reality the basic question is, " On the evidence available from biology and epidemiology, is it reasonable to make this drug available?" Such a question recognizes that every use of fertility regulation is an experiment on our own species. There are no short cuts. One suspects, for example, that, if the strict criteria currently being applied to medroxyprogesterone acetate remain, no new pharmacologically active method of contraception will ever be introduced. There can be a logic behind such a puritan approach, providing the implications are understood. It is possible to control human fertility with the available methods backed up with safe and early abortion. An alternative is to press for a more phased introduction of a new drug or device with improved postmarketing surveillance, to move the focus of control from the provider to the user and to ensure that the user can make an informed choice. Fertility regulation methods are either self-administered or require the skills of a second party. Administrative decisions about who does what have great implications concerning availability or nonavailability of family planning choices. The differences between nations are marked in the extreme. For example, there are more Indian-trained physicians working in National Health Service in Britain than in all 600 000 villages in India. The restriction of oral contraceptives or other modern methods of contraception to a doctor's prescription can well deny the method to the bulk of the world's population. Unless IUDs can be inserted by auxiliary medical workers, they will have little impact. Fortunately, community-based distribution programs, based on the skills of villagers themselves (often, as in Thailand, with only one day's training), have demonstrated that doctors can safely and responsibly delegate the distribution of the pill to others. In 1973, the International Planned Parenthood Federation's central medical committee concluded that "the limitation of all contraceptive distribution to doctors' prescriptions makes the method geographically, economically, sometimes culturally inaccessible to many women." In 1976, a Joint Working Party on Oral Contraceptives set up by the Department of Health and Social Security in Britain stated (5), "We do not regard it as necessary to restrict authority to issue prescriptions for oral contraceptives to doctors." Community-based distribution programs now extend to millions of women in Latin America, Thailand, Indonesia, the People's Republic of China and certain groups in developed countries. The following questions focus on the factors relevant to medical prescription (16):

Fertility control perspectwes

1. Is the drug addictive? 2. Does the dose have to be adjusted for each individual? 3. Is overdose lethal? 4. Are there certain categories of people for whom the drug is especially dangerous? In relation to the pill, the answer to the first three questions is negative. Risk groups are mainly categorized on the patient's history and not on the results of physical examination. In the case of medroxyprogesterone acetate, the answer to all four questions is negative, a lthough unlike the pill the giving of an inj ection requires steri le equipment and an understanding of its use. Trained auxiliaries have been successfu ll y delegated the responsibility of performing vasectomy and minilaparotomy procedures. Medical aux iliaries and traditional practitioners are being trained to do first trimester abortion and menstrual regulation . Decisions about delegation must not be con fu sed with statements about the absence or presence of side effects. A community-based distribution program acknowledges that there are risks associated with oral contraceptive use. A case cou ld be argued for permitting distribution by less qualified people with the possibility of more side effects were this the only way of preventing pregnancy. Unwanted pregnancy, after a ll , is the sexually transmitted disease with the highest incidence of short- and long-term side effects, and risks are greatest in areas where ski lled personnel are in shortest supply. However, in nearly a ll cases, experience has shown that lay people, auxi liaries and junior doctors can be woven together with the avai lable specialist ski lls in such a way as to provide not on ly a broad service but a lso one with the optimum level of care. Objective analysis shows that medical practitioners are not a lways the most consistent supervisors of fertility regulation methods (2). Most methods are so simple that doctors find it difficult to maintain a high level of interest ; the nonspecialists may do a routine task better than the specia list; an auxi liary may perform as well as a doctor.

THE INDIVIDUAL PERSPECTIVE The man waiting for his vasectomy or the woman taking the pill may see decisions concerning fertility regulation ·very differently from the epidemiologist, the biologist or the administrator. Epidemiologists have not conducted a careful random trial comparing the relative risks of purchasing the pill without a prescription and of having an abortion with a bent coathanger, a lthough these

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are real choices for many millions of women . The biologist has not found a way of quantitating the cerebral emot ions associated with attempting to bring up five chi ldren with love and dignity on a dollar a day, compared with the possibility of developing antibodies to sperm ten years after a vasectomy. The committee of medical administrators, who sit in an a ir conditioned off:ce of a capital city deciding what tasks shou ld be delegated to medical auxi liaries, cannot know what it means to be in labor for four days, attended by a traditional midwife, to be delivered of a dead baby and left with a rectovaginal fistula. Individuals are making daily domestic decisions about their own families. Persons seeking contraceptive advice are usually healthy, unconcerned about the demographic problems of their country, but motivated by a desire to provide the best for their children and a wish to enjoy the pleasures and satisfaction of sexual intercourse with their partner. The individual perspective can easi ly come into con fli ct with that of the physician. A great many doctors attempt to cast decisions concerning fertility regulation in the traditional medical context. They feel couples should have a certain number of children before they wi ll offer steri li zation . In this way, fertility becomes a " disease" and steri li zat ion a "cure." Doctors will often perform abortions to save a woman's physical health, but not to preserve the economic health of the family. In reality, fertility regu lation differs philosophically from other branches of medicine. Persons make their own diagnosis: " I suspect I am fertile; I know I am having regular in tercourse; I have decided not to have a chi ld. " The physician is meeting people's choices, not diagnosing and treating their diseases. He or she is reduced to the role of a technician. Some doctors accept this element of service, but others find it a profound cha llenge. This conflict about roles is probably the major decisive factor in relation to abortion, rather than theologic assertions about the biologic facts of embryology. For the individual , the voluntary control of fertility enhances the quality of human reproduction by helping to confine pregnancy to those years in a woman's life when she is least at risk, by enabling her to provide maximum security for her offspring and by adding to the emotional aspects of sex for both partners . How shou ld the individual use the insights of the biologist and the epidem iologist to assign values to the risks and benefits of fertility control, and what shou ld he or she expect from medical advisors? The individual contemplating the use of contraceptives wi ll a lmost certain ly rate sexual activity as more important than most other domestic pleasure lnt j Cy naecol Obstel / 6

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pursuits such as, for example, organized sport. The statistics of the unusual are easy to pervert. Yet, illustrations of the level of certain risks demonstrate how the dangers of contraception, because of their sexual links, become more widely publicized than those of some other choices made by individuals (10). Among adolescents in the United States, the risks of death from drowning are 11.7 per 100 000, and for men aged 20- 24, it is 7.6 per 100 000. Such deaths are mainly sport-related . There is many times the likelihood of death in the family if the father buys an outboard motorboat than if the mother takes the pill; there is as much chance of death from one hour in a sailplane (4.4 deaths per 1000 hours) than from one year of pill using. In the USA, there is a greater danger from the accidental use of firearms (2.5 deaths per 100 000 of the population) than from the use of an IUD. For the black woman in the USA, the risk of murder is 14.7 per 100 000, for a black male 77.2 per 100 000 and for a young black male (25- 35 years) 150 per 100 000 per year. In other words, there is I 00 times a greater chance of a black man being murdered than of his wife or girlfr!end dying if she chooses to use the pill. It does seem paradoxical that the US government spends over 200 million dollars a year controlling the introduction of drugs, but is unable to legislate against guns. For every woman who dies as a result of oral contraceptives in Britain, many hundred men and women die because they smoke. The annual mortality for cigarette-induced lung cancer in Britain is 90 per 100 000 and for heavy smokers (who retain the cigarette in. their mouth between puffs) 410 per 100 000. Cigarettes present the foremost preventable cause of death in the United States. "For the American male (and probably likewise for the female) aged 40- 79 who smokes a pack or more cigarettes per day, smoking is an environmental hazard equal to all other hazards to life combined" (12). The individual may be alarmed by the newspaper headlines of young women who die on the pill and be unable to place them in epidemiologic perspective. But, in her own decision-making, other factors also come into play. The personal and economic consequences of one more child are usually significant to the individual woman, while the mortality associated with pregnancy may be discounted as a significant risk. If the balancing of risks does occur to the individual, it is in relation to the question "Am I going to be pregnant this month?" and not based on a cumulative lifetime hazard. The individual making a contraceptive choice is rarely looking at public health outcomes and will arrive at different conclusions than the epidemiologist. The individual lnt J Gynaecol Obstet 16

is facing a tree with branching choices, not an equation with balancing statistics.

CONCLUSIONS The decisions which determine access to the means to control fertility are made by administrators and politicians who draw on epidemiologic and biologic insights. Conflict often arises because the decisions are not always congruent with the needs of the individual. Up until very recently in the developed world, social elites often made decisions which withheld the means of fertility control from the less privileged. The developing world, on the whole, is learning more rapidly than the West did at a comparable state in the demographic transition. However, tension still remains, particularly in relation to availability and supervision of methods. Society must regulate drugs, register medical practitioners and define their activities. But the decisions society makes are not necessarily the best for the individual. They often reflect historical prejudices: abortion is legal in Japan, but the pill is not permitted as a contraceptive and IUDs were illegal until a few years ago. Abortion is legal in Eastern Europe and the reversible methods of contraception are promoted, but sterilization is unthinkable. Sterilization is popular in the Philippines and the reversible methods are promoted, but abortion is unthinkable. In the 1960s, British women (who could afford it) had to fly to Sweden if they wanted an abortion, while a few years ago Swedish men (who could afford it) had to fly to London if they wanted a vasectomy. An objective historical analysis of the introduction of the reversible methods of contraception, such as the pill and injectable contraceptives, suggests that the widespread use of these methods is as much a response to demand by individuals who have made private choices (often with an incomplete understanding of the evidence), as it is an end point of a reasoned series of decisions by medical scientists. An element in the poker game which decides the availability of drugs is the right of individuals to take risks with their lives. On the whole, we apply more stringent rules to the risks that other people take than we do to ourselves. The decisions society must make can differ qualitatively from those of the individual. A pluralistic society which separates church and state does not have to decide whether abortion is murder. That decision depends upon a different philosophic interpretation of the same body of biologic facts about which there are manifest disagreements. As with other aspects of religious freedom, the state must

Fertility conlroljJersjJect ives

define the range of freedom and not decide theologic issues. It should be no more surprising to find an abortion clinic in a city where a sign ificant number of people are sincerely opposed to abortion than it is to find a church, a chapel, a synagogue and a mosque in the same town . Ferti lit y regulation is what Sir Dougald Baird once called the Fifth Freedom and is what the United Nations has labeled a basic human right. But if this freedom of choice is to be enjoyed, then those who provide and those who receive services may need to change their att itudes. Perhaps the main role which the medical profession and to some extent drug regu latory agencies fulfill is to provide the most up-to-date factual evidence in as object ive a way as possible, being carefu l to point out those things that are sti ll matters of specu lation and attempting to use a terminology that is intelligible to the ordinary person. Beyond this, indi viduals have to decide what they are going to do, just as they make a free choice about flying in airp lanes, smoking cigarettes or diving into swimming pools. Those who offer sterilization shou ld not regard it as a treatment fo r a disease, namely overfertility , but as extending human freedom of choice. The obli gation of the provider is not to decide who shou ld have a sterilization , but to ensure that a free, unpressurized , informed choice is made and that the man or woman concerned understands the other options of fertility regulation that they might adopt. Individuals, for their part, should neither ask statutory bodies to provide a proof of safety which logicall y cannot be provided, nor to redress the injustice of random misfortune by suing the medica l practitioner who happened to have prescribed the pill the year they suffered their stroke. Changes wi ll occur if consumers and providers have access to information and if they discuss the ri sks and benefits of fertility regulation . This, in turn , may help the hundreds of millions of couples who still li ve beyond the frontier of choice. The evidence emerging from the World Fertility Survey is that the drive for small families outruns avai lable services. In the end, it is not so much technology or motivation that restrains the spread of family planning, but administrat ive decisions and medical practices.

REFERENCES I. Arthes FG, Sartwell PE, Lewison EF: The pi ll , estrogen

a nd the breast. Cancer 28:1 39 1, 197 1.

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2. Cartwright A: Parents and Fami ly Pl a nning Services. Rutledge & K egan Paul, London , England, 1970. 3. Chen LC, Gesche MC, Ahmed S, Chowdhury AI, Mosley WM : M atern a l mortality in rural Bangladesh. Unpublished paper from Dacca, Bangladesh, Ford Foundation, 1974. 4. Chumnijarakij T , Poshyac hinda V: Postopera tive thrombosis in Tha i women. Lancet 1: 135, 1975. 5. Department of H ea lth a nd Social Security: Report of the Joint Working Group in Oral Contracept ives. Her Majesty's Stationary Office, London , England, 1976. 6. Gordis L, Nagga n L, Tonascia J: Pitfalls in eva lu atin g the impact of coron a ry care unit s on mortality from myocard ia l infarctions. Johns Hopkins Med J / 4 /:28 7, 1977. 7. MacMa hon B, Cole P, Brauns T: Etiology of human breast cancer: a review. J Natl Cancer Inst 50:2 1, 1973. 8. Peel J, Pou s M: Textbook of Contraceptive Prac tice. Cambridge University Press, Cambridge, England, 1969. 9. Polls M, Di ggory P, Peel J : Abortion. Cambridge Universit y Press, Cambridge, England, 1977. 10. Pous M , Speidel JJ , Kessel E: Rel ative risks of various means of fertilit y con trol used in less developed countri es. In Risks, Benefits, and Controversies in Ferti lit y Control (ed J Sciarra, GI Zatuchni, JJ Speidel), p 28. Harper & Row, H agerstown, MD, 1978. 11. Potts OM, Swyer GIM : Effectiveness and risks of birthcontrol met hods. Br Med Bull 26:26, 1970. 12. Ravenholt RT: Cigarette smokin g: magnitude of the hazard. Paper presented at the Annual Meeting of the Epidemic Int elligence Service, Center for Disease Control, Atlanta, GA, 1978. 13. R avenholt RT, Rineha rt W : Age-specific mortalit y trends in the United States relat ive to use of oral contraceptives. In Risks, Benefits a nd Controversies in Ferti lit y Control. (ed J Sciarra, GI Zatuchni, JJ Speidel) , p 17. Harper & Row, Hagerstown, MD, 1978. 14. Short RV : The evolution of human reprod uction . Proc R Soc Lond (Bioi) 195:3, 1976. . 15. Short RV : Man the changing animal. In Physiology and Genetics of R eprodu ction , part A. (ed EM Coutinho, F Fuchs) . Plenum Publishing Co, New York , 1976. 16. Smith M , Kane P : The Pi ll Off Prescript ion . Birth Control Trust, London, 1975. 17. Taber BZ: Breast cancer a nd oral contracep tion . J Reprod M ed 15:97, 1975 . 18. Tietze C, Lewit S: Mort a lity a nd ferti lity con trol. Int J Gynaecol Obstet 15:100, 1977. 19. Vessey MP, Doll R , Sutton PM: In ves ti gat ion of the relationship between oral contraceptives and benign a nd mali gnan t disease. Cancer 28:1395, 1971.

Address for reprints : Malcolm Potts, Execu tive Director International Fertility Research Program Research Triangle Park, NC 27709 USA

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Perspectives on fertility control.

Int J Gynaecol Obstet 16 : 449- 455 , 1979 Perspectives on Fertility Control Malcolm Potts International Fertility Research Program, Resea rch Tria...
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