R. G. Potter

Birth intervals: Structure and change

Abstract The average birth interval may be analysed into several additive components: gestation, post-partum amenorrhoea, anovulatory cycles, time required for conception after ovulation is established, and time added by pregnancy wastage. Dissecting the birth interval in this fashion helps to clarify several points regarding fertility in the absence or near absence of family limitation. In addition the ratio of time required for conception after ovulation is established, relative to the total birth interval, termed the ‘ovulatory ratio’, has considerable bearing on the effects registered by contraception and induced abortion. The higher this ratio, the more nearly equivalent an induced abortion is to averting a live birth since the spans of childbearing time absorbed by the two events become more nearly equal. Ovulatory ratios are greatly increased by effective contraception. For that reason, induced abortion has much greater impact when used as a supplement to contraception than when relied upon alone. ...

Applications of field studies to research on the physiology of human reproduction; lactation and its effects upon birth intervals in eleven Punjab villages, India.

A field study on lactation and its effects upon birth intervals was undertaken in 11 Punjab villages India. From a variety of sources genalogies parish records and special field studies it has been found that in societies practicing little or no birth control average birth intervals range from barely more than 2 years to nearly 3 years. Within populations older mothers tend to have longer birth intervals than younger mothers. The relevance of lactation to birth spacing has long been suspected. Several studies the first in 1942 have shown that when the infant survives the average birth interval is as much as a year longer than when the child is born dead or dies neonatally. This Khanna study provides a broad scope of prospective as well as retrospective data for approximately 1500 couples of childbearing potential over a 3-5 year period. It is evident that in the Punjab villages of the Khanna study lactation substantially prolonged postpartum amenorrhea. When an infant survived 1 month or more lactation usually lasted well over a year and the median length of postpartum amenorrhea was 11 months; whereas if the child was stillborn or died in the first month of life the mother did not lactate and the median length of postpartum amenorrhea was in the vicinity of 2 months.

A case study of birth interval dynamics

Abstract A birth interval free from pregnancy wastage may be viewed as the sum of three sub-intervals: (1) the period ofpost-partum amenorrhoea following a birth; (2) the menstruating interval extending from end of post-partum amenorrhoea to next conception; and (3) the months of pregnancy losses, then in addition to the above three components there is a fourth component, which may be termed ‘time added by pregnancy wastage’. A basic understanding of birth intervals requires the ability to relate the central tendencies and variability of birth intervals to the means and variances of these four components. The present analysis draws upon uniquely detailed materials from the India-HarvardLudhiana Population Study that took place in eleven villages of the Punjab, India, during the years 1953–59. Means and variances of post-partum amenorrhoea, menstruating intervals, and time added by pregnancy wastage are estimated for two broad age classes and the results related to corresponding statistics for total birth ...

Contraceptive effectiveness as a function of desired family size.

An attempt to account for varying contraceptive failure rates in terms of the number of children couples desire in conjunction with their actual fertility is reported. Method acceptability has been used to explain the variation in willingness to use contraception regularity of contraception use and contraceptive effectiveness. These reasons along with the assumption that variation in method acceptability is related to differential motivations to limit numbers and control spacing were tested in the following hypotheses: 1) as the number of children individual couples desire is approached or achieved the proportion attempting fertility control increases; and 2) the success of fertility control improves as fertility approaches the number of children desired. The data indicate that the hypotheses were strongly supported. Several implications of these relationships are noted.

Some selected findings of the princeton fertility study: 1963

ResumenDeepués de tres años se hizo una reencuesta de una muestra probabilística de respondientes que al principio vivían en siete de las áreas metropolitanas más grandes de los Estados Unidos y que habían tenido el segundo hijo seis meses antis de la primera entrevista. Se encontró en la encuesta anterior que la efectividad de la contraconcepcíon fue comparativamente baja entre el casamiento y el nacimiento del primer hijo, y no mejoró grandemente entre el primero y segundo hijo. La reencuesta reveló, sin embargo, que deepués del nacimiento del segundo hijo la eficiencia de la contraconcepcíon mejoró fuertemente. Los autores llegan a la conclusión de que el control de nacimientos se practica primordialmente para espaciarlos en los primeros años dematrimonio y con una eficiencia comparetivamente baja. A medida que las parejas alcanzanel tamaño deseado de familia la efectividad de su práctica anticoncepcional aumenta fuertemente. La encuesta ezploró una vez más una amplia serie de hypotesis relativas a factores sociales y psicológicos vinculados a la fecundidad. Se encontró quela religión es un factor importante. Los Católicos quehan asistido a escuelas de la iglesia especialmente collegios tendían a mostrar una fecundidad mayor que los otros. Se encontró que la variable categoría socio-económica tenía una correlación baja con la fecundidad, y que la correlación era positiva para los Católicos y negativa para los Protestantes. La movilidad social no fue relacionada con la fecundidad. Los resultados completos del estudio se presentan en un monografíaEl Tercer Hijo publicada porla PrincetonPress. Los autores están preparando una tercera entrevista para la muestra referida.

Correlates of IUD Termination in a Mass Family Planning Program: The First Taiwan IUD Follow-up Survey

In the mass family planning programs found in an increasing number of developing countries more and more attention is being given to the problems of maintaining high levels of continuing use of contraception, once it is adopted. Previously, interest was concentrated on influencing large numbers of couples to begin contraception. Many of these programs have relied on the new intrauterine contraceptive device (IUD) as the principal method offered. The assumption usually made initially was that continuation rates would not be a great problem since the new devices theoretically could remain in place for years and required no recurrent decision for use. Only discontinuation required a decision. It soon became apparent in Taiwan and elsewhere that, despite its many advantages, the IUD was not a perfect contraceptive and that many couples were terminating use. Only a very small proportion of terminations were due to pregnancies; a larger share resulted from involuntary expulsions, and the greatest proportion everywhere was the result of voluntary removals. Although some women discontinued use of the IUD to have a child, most voluntary removals were made at the request of the patients who complained of minor side effects such as excess bleeding, headaches and back-

A FERTILITY DIFFERENTIAL IN ELEVEN PUNJAB VILLAGES.

India, a country that is still largely rural, is devoting sizable funds to promote family planning. Accordingly it is of practical interest to learn as much as possible about the extent of family limitation being practiced in her rural areas. Examples of studies already published are those by Chandrasekaran and George,1 Dandekar,2 Das Gupta et al.,3 Driver,4 and Rele.5 In this paper, the fertility of a village population of roughly 12,000 from the Punjab is examined for evidence of birth control. Data come from the India-Harvard-Ludhiana Population Study, also known as the Khanna Study after the town in which the study headquarters were situated. The main objective of this field project was to reduce fertility through an intensive program to encourage the practice of contraception. On the basis of a pilot and an exxad ploratory study, foam tablets were chosen as the most promising agent and in the main study these tablets were actively promoted for a three to five year period ending in December 1959 in seven test villages with a total population of 8,000. In four additional villages serving as controls nothing was said about contraception,

Knowledge of the Ovulatory Cycle and Coital Frequency as Factors Affecting Conception and Contraception

O NLY during a relatively short period, approximately in the middle of the menstrual cycle, does a woman have an appreciable chance of conceiving. The average duration of this fertile period is not known precisely but almost certainly averages under 48 hours.3 Since the time period is so brief, coital frequency has a bearing on conception ease. This relevance is the more assured because of evidence, furnished primarily by the studies of MacLeod and Gold,4 indicating that coital frequency can be increased without jeopardizing virility, except possibly in cases where the increase is to very high levels or the male is oligospermatic. Any relationship of coital frequency to contraceptive effectiveness is more speculative. Strong libido, reflected in high levels of sexual activity, may contribute to less effective contraception by generating more occasions for chance-taking and, in the case of rhythm, by making continence more difficult to maintain during the unsafe period. Having a less direct but potentially important bearing on conception ease and contraceptive effectiveness is knowledge of the fertile period with reference to its timing within the

The Third Child: A Study in the Prediction of Fertility.

Any social scientist with an interest in dem ographic research would profit by reading this book, whether the particular topics covered are in his field or not. Apart from the intrinsic value of the results, he will meet everywhere— in the design, description, specification o f hypotheses, discussion and comments— the exhaustive search for significant pattern and detail, assessed with balanced judgm ent, which marks the good social survey. A t first sight the findings of the study may appear disappointing since many o f the broad, sweepxad ing theories about the social and psychological influences on the fertility of American couples disappear in the careful analysis of interxad acting factors. This w ould be a mistaken attitude since crude and essentially useless generalizations about large, heterogeneous groups are replaced by specific evidence about the behavior o f limited and more homogeneous subpopulations. The book reports on the second phase o f the study of current fertility in the United States. The results o f the earlier survey work were given in Family Growth in Metropolitan America, by the same authors with Elliot G . Mishler, published in 1961, and reviewed in the Milbank Memorial Fund Quarterly (V ol. X L , p. 241, April, 1962). Briefly, the population studied is o f white, native Americans, living in the largest m etropolitan areas and having two children, o f whom the second was bom in September 1956. A probability sample

Some comments on the evidence pertaining to family limitation in the United States

Abstract Three types of data are reviewed for the contemporary United States. These are: (1) reports of respondents about their own family limitation; (2.) incidences of contraception, induced abortion and sterilization, especially in the terminal third of the reproductive period; and (3) the average pregnancy rate during contraception and its trend with increasing marriage duration. It is found that these data do not support each other and several hypotheses are proposed toward explaining the inconsistency.