Fertility Control

Methods of contraception

Extent of contraceptive practice

Effectiveness

Sterilization

Abortion

Methods of the future

BIBLIOGRAPHY

“Fertility control,” as the term is used in this article, refers to patterns of human behavior that have as their primary objective the prevention of unwanted pregnancies and births. Individuals and couples adopt these patterns in accordance with their cultural values, reinforced by formal or informal social pressures.

The methods of fertility control are traditionally grouped into four categories: abstinence, contraception, sterilization, and induced abortion. The boundaries between these categories, however, are not clearly delineated and will become even less so in the future. The rhythm method, for example, is a method of contraception, but it also requires abstinence during a portion of the menstrual cycle. Oral contraception interferes with reproduction for periods of time and is sometimes referred to as temporary sterilization, while surgical sterilization has been called permanent contraception.

The term “birth control,” coined by Margaret Sanger in 1914 (Lader 1955), is generally used as a synonym for contraception. From the beginning, the term was intended to exclude abortion, and, in general, sterilization and abstinence have also been excluded. A number of terms substituted for birth control, such as family limitation, child spacing, family planning, and planned parenthood, appear, for the most part, to be intended to promote social acceptance rather than to improve communication.

History . Under some circumstances pregnancy and/or childbearing have been considered undesirable or have actually been proscribed in human societies since the dawn of history. Anthropologists have noted the practice of abortion among many preliterate peoples throughout the world. It is also probable that abstinence and coitus interruptus became known as methods of fertility control at the same time as the connection of coitus with pregnancy. It would appear, however, that fertility control was practiced only sporadically throughout most of man’s long history. Since levels of mortality were generally high in premodern societies, only those societies survived where the level of natality was also high.

The practice of fertility control on a scale sufficient to influence the trend of the birth rate began in France toward the end of the eighteenth century (France … 1960) and in other countries during the nineteenth century (Himes 1936). Generally, it spread from the well-to-do and educated classes to the underprivileged, and from the cities to the countryside. In some countries, however, farm owners were among the first to restrict the size of their families in order to avoid property division.

At present, fertility control is practiced in one form or another and with varying degrees of success by most couples in the industrialized countries of the world and by social minorities, mainly urban, in nonindustrialized countries. However, even in societies where fertility control is not widely practiced, many recent surveys have shown that the majority of couples approve the idea of family limitation (see, for example, Berelson 1966). The preferred size of family, as indicated by the respondents, tends to be substantially smaller than the average number of children per family in the community.

Methods of contraception

Contraception, according to the usage of most writers on the subject, includes all nonpermanent measures to prevent coitus from resulting in conception. In older demographic literature, it has been customary to distinguish between “appliance methods,” that is, mechanical devices and spermicides, and “nonappliance methods,” such as withdrawal or the rhythm method. More recently, the major distinction is between the “traditional methods” and the “modern methods,” the latter referring to oral and intrauterine contraceptives. Still another classification is made by the Roman Catholic church, which distinguishes between “natural birth control,” that is, the rhythm method (see below), and “artificial birth control,” comprising all other methods.

Folk methods . The principal folk methods of contraception are coitus interruptus and the douche. Coitus interruptus or withdrawal of the male prior to ejaculation is the oldest contraceptive procedure known to man. It appears in the Old Testament (Genesis 38) and has been noted by anthropologists in many parts of the world. In western and northern Europe, where relatively late marriage has long coexisted with close and frequent social contacts between unmarried adults and with a strong condemnation of pregnancy out of wedlock, withdrawal appears to have been the method by which premarital pregnancies were averted. At a later time, the practice was transferred into married life. There can be no doubt that coitus interruptus was the principal method by which the historical decline of the birth rate in the West was achieved. Statistical studies suggest a level of effectiveness similar to that of vaginal methods (see Table 3).

Postcoital douches with plain water, vinegar, and various products advertised under the name of “feminine hygiene,” long used for purposes of family limitation, have lost popularity in recent decades. Since sperm has been found in the mucus of the cervical canal within 90 seconds after ejaculation, medical opinion considers the contraceptive effectiveness of douching as quite unsatisfactory.

Vaginal methods . Vaginal contraceptive methods are designed to prevent the entry of sperm into the uterus by a mechanical barrier and/or to kill the sperm by chemical action. The condom or sheath, a cover for the penis during intercourse, made its first appearance in England in the eighteenth century. Since the latter part of the nineteenth century, the early “skin” condoms, made from the intestines of sheep and other animals, have gradually been replaced by the cheaper and more convenient rubber sheaths. A large proportion of the condoms sold in the United States prior to 1938 were inferior in quality. Since supervision over condoms has been assumed by the Food and Drug Administration, their quality has improved greatly.

The condom offers protection not only against unwanted pregnancy but also against venereal disease. It can be used without special instruction and elaborate preparation in any situation where coitus is possible.

The diaphragm, known in the United Kingdom as the Dutch Cap, was invented by a German physician, Wilhelm P. J. Mensinga, prior to 1882. Before the advent of oral contraceptives, it was the contraceptive device most often recommended by physicians in private practice and in birth control clinics throughout the United States and Europe. The diaphragm, inserted into the vagina and covering the cervical os, prevents the entry of sperm into the uterus. To fit a diaphragm, a pelvic examination by a physician or other trained health worker is necessary. Because of this requirement, the method is not suitable for general use in countries where medical personnel and medical facilities are scarce.

The contraceptive effectiveness of the condom and diaphragm is high and appears to be approximately equal for the two methods. Occasional failures occur, for example, if a condom tears or a diaphragm is displaced during coitus. A rate of 2 to 3 pregnancies per 100 women per year would seem to be a high estimate for consistent users. If motivation is weak, much higher pregnancy rates must be expected.

Chemical contraceptives consist of a spermicidal compound and a vehicle for its introduction and distribution within the vagina. Various creams and jellies and, more recently, foams with a highly spermicidal action, have been developed by the pharmaceutical industry. Insertion into the vagina is accomplished, prior to intercourse, by means of an applicator. The effectiveness of these methods seems to be lower than that of the diaphragm or the condom. Because vaginal tablets can be manufactured easily and cheaply and because no pelvic examination, fitting, or apparatus is needed, they have been considered eminently suitable for programs of population control in the economically underdeveloped regions of the world. However, the results of clinical and field trials have not been encouraging, and it does not appear likely that this method will prove sufficiently acceptable and effective to be of value in reducing the rate of population growth.

Rhythm method . The rhythm or safe period method of contraception, also known as periodic continence, is based on the fact, recognized independently in the early 1920s by Ogino in Japan and Knaus in Austria, that conception is possible during only a small fraction of each menstrual cycle. The fertile days can be determined either by the application of a simple formula to the menstrual history of the woman or by the observation of changes in basal body temperature during the menstrual cycle, or by a combination of both.

Rhythm is at present (that is, in 1966) the only method of fertility control, other than complete abstinence, sanctioned by the Roman Catholic church. Its contraceptive effectiveness has been the subject of much controversy. The theoretical effectiveness of the method, correctly taught and understood, and consistently practiced according to the Ogino formula, is roughly comparable to that of vaginal methods. The use-effectiveness, on the other hand, which may be modified by errors of instruction or comprehension and by the couple’s willingness to take chances, has been consistently less than that of vaginal methods in comparable situations.

Oral methods . The contraceptive “pill,” long thought of as an attractive solution to the problem of fertility control, became a reality in the late 1950s. Since 1956 several oral contraceptives have been extensively tested in many countries. No permanent or serious side effects were noted in any of the clinical trials, but laboratory studies of various organ systems have in some instances revealed deviations from normal values. The significance of these changes cannot yet be evaluated. Women who discontinue the medication conceive promptly. Oral contraceptives have established themselves not only as virtually 100 per cent effective, if taken according to prescription, but also as highly acceptable to most users, including many women in the lower socioeconomic strata who had been unsuccessful with other contraceptive methods.

Intrauterine methods . Intrauterine contraceptive devices (IUDs) are small, variously shaped objects (rings, spirals, loops, etc.) which are inserted into the uterus by a physician. The procedure takes only a few minutes and requires no anesthesia. The devices are made of chemically inert materials, such as polyethylene or stainless steel, and may remain in the uterus for an indefinite period. The mechanism of action of the IUDs is not fully understood. The best available evidence suggests that the presence of a foreign body in the uterus reduces the time required for the movement of the ovum through the Fallopian tube from three to four days to one day or less and that the fertilized ovum, therefore, reaches the uterus at a time when neither it nor the endometrium is ready for implantation. There is some evidence, however, that the ovum may not be fertilized at all.

Since 1960 several types of IUDs have been carefully studied in the United States and elsewhere (Tietze 1966; International Conference … 1964). In some cases the uterus expels the device, usually during a menstrual period and occasionally without the woman being aware of it, or the device must be removed because of side effects such as bleeding and/or pain. No evidence has been produced that the IUDs are carcinogenic, nor does their use interfere with fertility after they have been removed. During use, 2 to 3 accidental pregnancies per 100 women per year must be expected even with the more successful types of IUDs. These failures may occur after an unnoticed expulsion or, more frequently, with the device in situ. No case of fetal malformation attributable to an IUD has been reported.

The sociological importance of the IUDs lies in the fact that they offer the only fully reversible method of birth control now available which requires a single decision rather than sustained motivation on the part of the users. The insidious dissipation of user interest, which has played so frustrating a role in all other methods of contraception, is of little importance with the IUD. Regardless of apathy, fatigue, or sexual excitement, the contraceptive device is in place and no further action is required of either the man or the woman.

Extent of contraceptive practice

The first nationwide investigation of the extent of contraceptive practice in the United States was the Growth of American Families (GAF) Study, conducted in 1955 (Freedman et al. 1959). A second survey along similar lines was carried out in 1960 (Whelpton et al. 1965). According to these surveys, the proportions of white couples with wives 18-39 years of age who had taken up the practice of birth control prior to the interview were

Table 1 — Per cent of white couples ever using contraception: United States, 1955 and 1960 1955

70 per cent in 1955 and 81 per cent in 1960. Among couples who had never tried to prevent conception, many were found to be sterile or sub-fecund. The extent and type of contraception varied with religious affiliation and with such indications of socioeconomic status as wife’s education and husband’s income (see Table 1).

Among nonwhite couples, included for the first time in the 1960 GAF Study, only 59 per cent reported use of contraception, a substantially lower proportion than among the lowest educational and income groups of white couples.

The great majority of couples using birth control relied on one or more of five methods (see Table 2). It should be noted that the 1960 survey was completed before oral contraceptives came into general use.

Close correlations were found in the GAF surveys between choice of contraceptive method and level of education, as well as other indicators of socioeconomic status. Use of the rhythm method by Catholics was strongly associated with advanced education. A similar association was found for the diaphragm among Protestants and among those Catholics who had experience with “artificial birth control.” Conversely, use of the douche and especially of withdrawal were inversely associated with educational level, while the condom was a popular method at all socioeconomic levels. The findings of the GAF Study have been confirmed, to a large extent, by the Family Growth in Metropolitan America (FGMA) Study (Westoff et al. 1961). According to a nationwide survey taken in late 1965 (Ryder & Westoff 1966), about

6.4 million married women under 45 years of age (26 per cent) had used oral contraception, while 3.8 million were relying on the “pill” at the time of the interview. Use was found inversely associated with age and directly with education (see Table 3).

In the United Kingdom the first major investigation of the contraceptive habits of the population was conducted in 1946-1947 on behalf of the Royal Commission on Population. In 1959-1960 new data were obtained from the Population Investigation Committee’s marriage survey (Rowntree & Pierce 1961). In terms of religious affiliation and socioeconomic status, the patterns of contraceptive practice were found to be similar to those reported in the United States. In regard to methods, there are important differences. While the condom is the most widely used method in both countries, British couples tend to rely far more often on coitus interruptus and far less often on the diaphragm than American couples. Catholic couples in the United Kingdom showed less preference for the rhythm method than Catholic couples in the United States.

In Japan ten surveys on birth control were conducted between 1950 and 1965 (Muramatsu 1966). During this period the proportion of couples who reported current use of contraception increased from 19 per cent to 52 per cent. The proportion of couples practicing contraception was higher in the six major cities of Japan than in the other urban areas and was lowest in the rural districts. The familiar socioeconomic gradient was also present. The condom, the most widely used method of contraception in Japan, was reported by a majority of users in each survey since 1952. Next in popularity was the rhythm method, an example of a prophet (Ogino) honored in his own country.

The extent of contraceptive practice and the methods used have also been studied in a number of other countries throughout the world. Generally speaking, the practice of contraception is inversely correlated with the level of the birth rate and rarely reaches 10 per cent of all couples in the rural areas of the developing countries. The proportion tends to be higher in towns and among the better educated. It has been suggested that the more widespread practice of contraception in industrialized societies is connected with the decline, in these societies, of the extended family and the correspondingly greater opportunities afforded to young, unmarried adults for training in contraceptive practices (Ryder 1959).

Effectiveness

Study of the effectiveness of contraception requires a distinction between “theoretical effectiveness” and “use-effectiveness.” Theoretical effectiveness is the effectiveness of a method under ideal conditions, that is, used consistently and according to instructions, without any omissions or errors of technique. Use-effectiveness refers to the contraceptive practice of a particular population and reflects such variables as the socioeconomic and cultural characteristics and the degree of motivation of the couples concerned.

Theoretical effectiveness is not accessible to measurement and can only be inferred from the performance of the most successful group of users. Use-effectiveness is measured in terms of failure rates per 100 woman-years of use, according to the formula first proposed by Raymond Pearl (1932), or preferably by means of cumulative failure rates, according to the life table procedure described by R.G. Potter (1963).

Comprehensive information on the effectiveness of contraception, as practiced by young urban couples in the United States during the 1950s, was obtained during the course of the FGMA Study (Westoff et al. 1961, pp. 83-101). During the 28,607 months of exposure to the use of contraception reported by the couples included in the survey, 534 accidental pregnancies occurred, corresponding to a failure rate of 22.4 per 100 years of exposure. Failure rates for individual methods ranged from about 14 per 100 years of exposure for the condom and the diaphragm to about 40 for the rhythm method and the postcoital douche (ibid., Table B-2). These rates reflect use-effectiveness—not theoretical effectiveness. Some of the couples admitted that they were “taking chances” in their contraceptive practice. Without such omissions, both admitted and unadmitted, it must be presumed that the failure rate for each method would have been much lower.

This conclusion is strongly supported by the results of reinterviews with the same couples about three years later. It was found that the couples who had used contraceptive measures since marriage and already had the number of children they desired experienced a failure rate of only 3.7 per 100 years of exposure for all contraceptive methods combined and a rate of 2.6 if they used the condom, the diaphragm, or withdrawal (Westoff et al. 1963, pp. 38-44). Couples who intended to have additional children and who, therefore, wanted to postpone pregnancy rather than prevent it altogether had much higher failure rates, similar to those experienced prior to the first interview.

Sterilization

Surgical sterilization was originally used to protect women whose life or health was threatened by pregnancy. Dr. James Blundell of London is credited with having first proposed the procedure in 1823. Effective techniques were developed in the latter part of the nineteenth century when aseptic surgery and anesthesia became available. At about the same time, sterilizing operations began to be widely used on males, mainly in connection with operations on the prostate. Growing confidence in the efficacy and safety of surgical sterilization led to its use for eugenic purposes, that is, to prevent persons suffering from hereditary disabilities, especially mental deficiency, various psychoses, and idiopathic epilepsy, from having offspring.

In the United States, 32 states adopted legislation between 1907 and 1937 regulating the practice of eugenic sterilization. Some of these laws have been declared unconstitutional, but the majority are still in force. However, few states have used their authority extensively, and the total number of persons sterilized under these eugenic laws from their inception up to the end of 1965 was 65,000. During the early 1960s the number of eugenic sterilizations averaged about 500 per year.

Outside the United States sterilization for eugenic reasons is legally regulated in a few countries, notably in Scandinavia and in Japan. In Germany eugenic sterilization, involving a minimum of 200,000 persons, was practiced under the Eugenic Law of July 14, 1933, until 1945. This estimate does not include inmates of concentration camps who were sterilized without legal authorization.

In recent years discussion has centered on the legality and/or propriety of voluntary sterilization as a method of family limitation and on the use of sterilization in countries where high birth rates and rapid population growth threaten to produce serious economic and social difficulties (Blacker 1962).

Permanent sterilization in women is ordinarily accomplished by salpingectomy, that is, by the cutting, ligation (tying), and partial removal of the Fallopian tubes. In the male, the sterilizing operation (vasectomy) consists of the cutting, ligation, and removal of a portion of the spermatic duct. Since sterilization does not involve removal of the sex glands, it does not produce loss or impairment of sexual desire or of capacity for sexual response. Restoration of fertility by a second operation is possible but not certain. This fact restricts sterilization to persons permanently ineligible for parenthood and to mature couples who have all the children they want or are likely to want in the future. According to a number of studies, the great majority of sterilized patients are satisfied with the result, feel relieved from the nagging fear of pregnancy, and have no complaints. Regrets and more serious psychological side effects have, however, been occasionally noted in sterilized persons of both sexes, who were poorly chosen and/or not suitably prepared for the operation. Such undesirable side effects are most likely to occur if the marriage is unhappy or on the brink of breaking up, or when the operation is accepted reluctantly, under pressure from a spouse or other persons.

The number of voluntary sterilizations in the United States during the late 1950s is estimated at 110,000 annually, including 65,000 operations on women and 45,000 vasectomies. Later estimates are not available. Sterilization of women has been popular in Puerto Rico since the 1940s and has also gained wide acceptance in Japan (Koya 1961). In India the government encourages voluntary sterilization as a method of population control. By mid-1965 about 900,000 operations had been reported, two-thirds on men and one-third on women. South Korea, too, has included vasectomy in its national family planning program, and 49,000 vasectomies were performed from 1962 to 1964.

Abortion

Induced abortion, that is, termination of unwanted pregnancy by destruction of the fetus, has been performed throughout man’s history. Some cultures prescribe abortion under specific circumstances, others tolerate it, still others condemn it. In the United States most state laws stipulate prevention of the death of the pregnant woman as the sole ground on which pregnancy may be interrupted. In practice, many (but by no means all) reputable hospitals permit therapeutic abortion in cases where a serious threat to health is to be averted and for certain eugenic reasons, as when a pregnant woman catches a disease that is likely to cause malformations in the fetus. In New York City the number of therapeutic abortions equaled about one-fifth of one per cent of the number of live births in 1960-1962 (Gold et al. 1965). In a few countries, such as Denmark and Sweden, the interpretation of medical necessity for abortion is far more liberal, since it takes into account less serious threats to the woman’s physical or mental health, as well as her economic situation. In 1963 legal abortions amounted to about 5 per cent of the number of live births in Denmark, and to about 3 per cent in Sweden (Tietze 1966).

In still other countries, abortion is legally available either at the request of the pregnant woman or on broadly interpreted social indications. In the Soviet Union abortion was legalized after World War I. In 1936 this policy was reversed, and for the next two decades abortion was permitted on medical grounds only. In 1955 another reversal took place, and abortion on request was once more legalized. The adoption of similar legislation in most countries of eastern Europe has been followed by very rapid increase in legal abortions. In Hungary legal abortions have outnumbered live births since 1959 (Mehlan 1966). In Japan the Eugenic Protection Law of 1948 authorized interruption of pregnancy for economic as well as medical reasons. The subsequent interpretation of this law has been tantamount to making abortion available unconditionally.

In several countries where the practice of abortion is restricted by law, estimates of its incidence have been obtained by the survey method (see, for example, Armijo & Monreal 1965; Hong 1966). This approach has not yet been used successfully in the United States. In 1959 a committee appointed by the Conference on Abortion at Arden House, New York, concluded that a “plausible estimate of the frequency of induced abortion … could be as low as 200,000 and as high as 1,200,000 per year . . .” (Planned Parenthood … 1958, p. 180). No new data which would permit a more precise evalution are available.

Methods of the future

Continuing research in the field of human and animal reproduction promises new methods of fertility control, which may become available over the coming decade. Among the following procedures, some are now undergoing clinical evaluation, others are being studied in selected human volunteers, and still others are in various stages of development with laboratory animals: long-acting ovulation suppressants administered by injection; compounds suppressing spermatogenesis, for use as oral or injectable contraceptives in males; immunization of females against sperm; immunization of males against sperm, resulting in suppression of spermatogenesis; blocking of the spermatic duct by injections of plastic material which can be easily removed; compounds acting on the fertilized ovum prior to implantation; and compounds with destructive action on the young embryo.

CHRISTOPHER TIETZE

[See alsoFERTILITY; POPULATION, articles on POPULATION GROWTH and POPULATION POLICIES.]

BIBLIOGRAPHY

Publications in the field of fertility control, both medical and sociological, are extremely numerous, and the rate of publication will undoubtedly increase; accordingly, the works cited in this article constitute only a minute fraction of the available literature and may be rapidly superseded by new developments. A classified bibliography covering all aspects of the field (but with emphasis on the medical side) is Tietze 1965. Studies in Family Planning, an occasional publication of the Population Council, regularly summarizes much current research, especially that which deals with the social and demographic aspects of fertility control. The proceedings of the many international conferences on fertility control are published by the Excerpta Medica Foundation of Amsterdam.

ARMIJO, ROLANDO; and MONREAL, TEGUALDA 1965 Epidemiology of Provoked Abortion in Santiago, Chile. Journal of Sex Research1 : 143–159.

Berelson, Bernard 1966 KAP Studies on Fertility. Pages 655-668 in International Conference on Family Planning Programs, Geneva, 1965, Family Planning and Population Programs: A Review of World Developments. Univ. of Chicago Press.

BLACKER, C. P. 1962 Voluntary Sterilization: The Last Sixty Years. Eugenics Review54:9-23; 143–162.

Calderone, Mary S. (editor) 1964 Manual of Contraceptive Practice. Baltimore: Williams & Wilkins.

CONFERENCE ON RESEARCH IN FAMILY PLANNING, NEW YORK, 1960 1962 Research in Family Planning: Papers Presented at a Conference Sponsored Jointly by the Milbank Memorial Fund and the Population Council, Inc. Princeton Univ. Press.

France, Institut National D’ÉTUDES DÉMOGRAPHIQUES 1960 La prevention des naissances dans la famille: Ses origines dans les temps modernes, by H. Berques et al. Travaux et Documents, Cahier No. 35. Paris: Presses Universitaires de France.

FREEDMAN, RONALD; WHELPTON, P. K.; and CAMPBELL, A. A. 1959 Family Planning, Sterility, and Population Growth. New York: McGraw-Hill.

Gold, Edwin M. et al. 1965 Therapeutic Abortions in New York City: A Twenty-year Review. American Journal of Public Health55 : 964–972.

GREAT BRITAIN, ROYAL COMMISSION ON POPULATION 1949 Papers. Volume 1: Family Limitation and Its Influence on Human Fertility During the Past Fifty Years, by E. Lewis-Faning. London: H.M. Stationery Office.

Himes, Norman E. (1936) 1963 Medical History of Contraception. New York: Gamut.

Hong, Sung Bong 1966 Induced Abortion in South Korea. Seoul: Dong-A.

INTERNATIONAL CONFERENCE ON FAMILY PLANNING PROGRAMS, GENEVA, 1965 1966 Family Planning and Population Programs: A Review of World Developments. Univ. of Chicago Press. → Edited by Bernard Berelson and others.

INTERNATIONAL CONFERENCE ON INTRA-UTEHINE CONCEPTION, SECOND, NEW YORK, 1964 1964 Proceedings. Excerpta Medica Foundation, International Congress Series, No. 86. Amsterdam: The Foundation.

Jaffe, Frederick S. 1964 Family Planning and Poverty. Journal of Marriage and the Family26 : 467–470.

Koya, Yoshio 1961 Sterilization in Japan. Eugenics Quarterly 8, no. 3 : 135–141.

Lader, Lawrence 1955 The Margaret Sanger Story and the Fight for Birth Control. New York: Doubleday.

MEHLAN, K.-H. 1966 The Socialist Countries of Europe. Pages 207-226 in International Conference on Family Planning Programs, Geneva, 1965, Family Planning and Population Programs: A Review of World Developments. Univ. of Chicago Press.

Muramatsu, Minoru 1966 Japan. Pages 7-19 in International Conference on Family Planning Programs, Geneva, 1965, Family Planning and Population Programs: A Review of World Developments. Univ. of Chicago Press.

Pearl, Raymond 1932 Contraception and Fertility in 2,000 Women. Human Biology4 : 363–407.

PLANNED PARENTHOOD FEDERATION OF AMERICA 1958 Abortion in the United States. New York: Hoeber.

POTTER, R. G. JR. 1963 Additional Measures of Use-effectiveness of Contraception. Milbank Memorial Fund Quarterly41 : 400–418.

ROWNTREE, GRISELDA; and PIERCE, RACHEL M. 1961 Birth Control in Britain. Part 1: Attitudes and Practices Among Persons Married Since the First World War. Part 2: Contraceptive Methods Used by Couples Married in the Last Thirty Years. Population Studies15:3-31, 121–160.

Ryder, Norman B. 1959 Fertility. Pages 400-436 in P. M. Hauser and O. D. Duncan (editors), The Study of Population. Univ. of Chicago Press.

Ryder, Norman B.; and WESTOFF, CHARLES F. 1966 Use of Oral Contraception in the United States, 1965. Science 153: 1199–1205.

Tietze, Christopher (editor) 1965 Bibliography of Fertility Control: 1950–1965. New York: National Committee on Maternal Health.

Tietze, Christopher 1966 Contraception With Intrauterine Devices: 1959–1966. American Journal of Obstetrics and Gynecology 96: 1043–1054.

TIETZE, CHRISTOPHER; and NEUMANN, LUSSIA (editors) 1962 Surgical Sterilization of Men and Women: A Selected Bibliography. New York: National Committee on Maternal Health.

Westoff, Charles F.; POTTER, ROBERT G.; and SAGI, PHILIP S. 1961 Family Growth in Metropolitan America. Princeton Univ. Press.

Westoff, Charles F.; POTTER, ROBERT G.; SAGI, PHILIP C.; and MISHLER, ELIOT G. 1963 The Third Child: A Study in the Prediction of Fertility. Princeton Univ. Press.

Whelpton, Pascal K.; CAMPBELL, ARTHUR A.; and PATTERSON, JOHN E. 1965 Fertility and Family Planning in the United States. Princeton Univ. Press.