Population planning in Asia in the 1970s

Analysis of data from various phases of a study of post-partum amenorrhoea in Bangladesh illustrated good aggregate consistency of response on menstrual status, but less individual consistency on duration of post-partum amenorrhoea. Using life table techniques, the median duration of amenorrhoea was calculated as 19.9 months for women with births between February and September 1974. There were substantial seasonal variations in duration, with the median decreasing from 21.5 months for women with February births to 16.9 months for those with September births. By contrast, the median duration of post-partum amenorrhoea varies by only two months for women in the lowest and highest quartiles of weight and weight for height. The seasonal pattern was similar for all weight groups.     

Prospective study of birth interval dynamics in rural Bangladesh

Abstract A group of 209 married, fecund women in rural Bangladesh were studied prospectively for 24 months from 1969 to 1971 to define some of the biological and sociological factors relating to fertility performance. These women were selected from a larger study population of 112,000 that had been followed with a daily house-to-house vital registration programme since 1966. The selected women were interviewed bi-weekly and were asked questions about menstruation, pregnancy, lactation, husband's occupational absences, and monthly urine tests for pregnancy were taken. The results for 193 non-contracepting women revealed that the seasonal pattern of births previously observed in this population could be associated with a corresponding seasonal pattern of conceptions and that this was due to a seasonal trend in fecundability. The highest conception rates were in the coolest months of the year. Post-partum lactational amenorrhoea was very prolonged, averaging 17 months for women with a surviving child. The appearance of the first post-partum menstrual flow (onset of ovulation) also had a seasonal trend which could not be adequately explained. The median waiting time to conception, once menstruation had resumed was eight months. This interval was influenced by seasonal fluctuations, as well as by the age of women and by husbands' absences. The foetal wastage rate was 15·0 per 100 conceptions, with 62 per cent of the foetal losses occurring during the second month of gestation. Overall, the average birth interval was 33 months, with the prolonged lactational amenorrhoea accounting for almost 45 per cent of this interval. From the Department of Population Dynamics, Johns Hopkins University, School of Hygiene and Public Health, Baltimore, Maryland 21205.     

Prospective study of birth interval dynamics in rural Bangladesh

A group of 209 married, fecund women in rural Bangladesh were studied prospectively for 24 months from 1969 to 1971 to define some of the biological and sociological factors relating to fertility performance. These women were selected from a larger study population of 112,000 that had been followed with a daily house-to-house vital registration programme since 1966. The selected women were interviewed bi-weekly and were asked questions about menstruation, pregnancy, lactation, husband's occupational absences, and monthly urine tests for pregnancy were taken. The results for 193 non-contracepting women revealed that the seasonal pattern of births previously observed in this population could be associated with a corresponding seasonal pattern of conceptions and that this was due to a seasonal trend in fecundability. The highest conception rates were in the coolest months of the year. Post-partum lactational amenorrhoea was very prolonged, averaging 17 months for women with a surviving child. The appearance of the first post-partum menstrual flow (onset of ovulation) also had a seasonal trend which could not be adequately explained. The median waiting time to conception, once menstruation had resumed was eight months. This interval was influenced by seasonal fluctuations, as well as by the age of women and by husbands' absences. The foetal wastage rate was 15·0 per 100 conceptions, with 62 per cent of the foetal losses occurring during the second month of gestation. Overall, the average birth interval was 33 months, with the prolonged lactational amenorrhoea accounting for almost 45 per cent of this interval.      

Nutrition and Fertility in Bangladesh: Breastfeeding and Post Partum Amenorrhoea

From 1975 to 1980 a prospective study a nearly 2,500 married, fertile women was conducted in Matlab, Bangladesh at the International Centre for Diarrhoeal Disease Research. Women were interviewed at monthly intervals to collect information on nutritional and reproductive status, in order to study the factors associated with natural fertility. The median duration of amenorrhoea for women with no child deaths was 15.5 months, with older women and those of higher parities recording longer durations than younger women or those of lower parities. Median duration of amenorrhoea for women with six or more years of education was 8.4 months compared to 16.4 months among women with no education. When classified by weight at pregnancy termination, average duration of amenorrhoea of women weighing less than 38 kg was 17.6 months compared to 13.6 months among women weighing more than 44 kg. Proportional hazards analyses show that mother's education, parity, month of birth, supplementation practices and nutritional status were significantly associated with the probability of resuming menstruation.     

The post-partum non-susceptible period: Development and application of model schedules

Summary The duration of the post-partum non-susceptible period is a major determinant of birth intervals in populations with relatively low levels of contraception. Since it depends largely on the length of breast-feeding, it may change rapidly with socio-economic development. Its study is, however, seriously hampered by the limited and defective nature of most data that can be obtained. In the absence of intensive, large-scale prospective studies, sizeable reporting errors and/or sampling fluctuations are almost inevitable. A system of model schedules that summarise the underlying regularities found in empirical schedules is proposed. With a logit transformation, observed schedules of breast-feeding can be related to a standard breast-feeding schedule by just two parameters. Similarly, observed schedules of post-partum amenorrhoea can be related to a standard amenorrhoea schedule. The two systems provide a means of obtaining relatively robust estimates of the duration of lactation or amenorrhoea from partial and flawed data. Several applications of the models for estimation problems, for simulation purposes and for the analysis of the relationships between breast-feeding, amenorrhoea and post-partum abstinence are discussed.     

The demographic effects of a contraceptive programme

Abstract The calculation of the number of births prevented for each item of contraceptive service provided entails the integration of a variety of factors relating to the potential fertility of users and the duration and effectiveness of use. This article differs from previous essays of this kind in that estimates of future potential fertility are based not on fertility rates but on age-specific means of inter-live birth intervals, modified by periods of use overlapping post-partum sterility, and by the probabilities attached to the development of permanent sterility and to the successful adoption of extra-programme birth control. In the first three years after acceptance of intra-uterine contraception by some 9,000 postpartum women of several ethnic origins in Singapore, it is calculated that about 4,800 births were prevented.     

Dynamics of contraceptive use and breastfeeding during the post-partum period in Peru and Indonesia

This paper examines the interaction between contraceptive use and breastfeeding in relation to resumption of intercourse and duration of amenorrhea post-partum. We used data from the month-by-month calendar of reproductive events from Demographic and Health Surveys (DHS) in Peru and Indonesia. The analyses show that breastfeeding women were less likely than non-breastfeeding women to have resumed sexual intercourse in the early months post-partum in both countries. In Peru, but not in Indonesia, breastfeeding women had a significantly lower odds than non-breastfeeding women of adopting contraception. Although the likelihood of contraceptive adoption was highest in the month women resumed menstruation in both countries, about ten per cent of subsequent pregnancies occurred to women before they resumed menses. These results emphasize the importance of integrating breastfeeding counselling and family planning services in programmes serving post-partum women, as a means of enabling those who wish to space their next birth to avoid exposure to the risk of a pregnancy that may precede the return of menses.     

Premarital pregnancies and out-of-wedlock births in denmark, 1950–65

Although comprehensive investigation of child spacing patterns requires consideration of those births that were conceived before marriage, detailed data on such births often are not available, especially in the United States. Danish statistics on first births by duration of marriage and on out-of-wedlock births permit evaluation of trends in premarital pregnancies. For the period 1950-65, they point to (1) a rise in the percentage of all brides who are pregnant at marriage; (2) an increase in the proportion of first births occurring within both six and nine months of marriage; and (3) a rise in out-of-wedlock births.The trend for the country as a whole also characterizes Copenhagen, but at a higher level, and this reflects the capital's more urban character, greater permissiveness, and attraction to young migrants. Age differentials indicate that as high as 90 percent of all first births among married women aged under 20 years and over 50 percent of those to women aged 20-24 years are premaritally conceived. The rise in the number of first births among young women largely accounts for the overall rise in the level of premarital conceptions. Compared to its suburbs, Copenhagen in 1965 had higher levels of premarital conceptions. The overall residential differential stems both from higher proportions of such births in all age groups in Copenhagen (but especially those aged 20 years and over) and from the fact that Copenhagen has proportionally more first births occurrinq to women aged under 20 years, the age group in which the rates of premarital conceptions are especially high.     

Pregnancy outcome and the time required for next conception

Abstract Variations in the time required for next conception by outcome ofthe preceding pregnancy, and the age of woman, are studied for Taiwanese women. Pregnancy interval, defined as the period between the end of one pregnancy and the beginning of the next, is taken as a measure of the time required for the next conception. The averages and variances of pregnancy intervals are estimated from reports of pregnancies occurring in a probability sample of 2,443 married women, aged 20-39, living in Taichung (Taiwan) in 1962. The effects of 'truncation bias' and 'memory bias' on the two moments of pregnancy intervals are estimated indirectly by cross-classifying women according to their ages at interview and their ages at the beginning (or end) of each pregnancy interval. The moments of post-partum amenorrhoea are, then, estimated indirectly from the moments of pregnancy intervals. The effects of truncation bias and memory bias are compensatory in this sample. In the absence of contraception, women, on an average, took longer to conceive following a live birth than following a foetal death. The time taken for next conception increases as women become older irrespective of the outcome of the preceding pregnancy.     

Birth outcomes for Arabic-named women in California before and after September 11

Persons who were perceived to be Arabs experienced a period of increased harassment, violence, and workplace discrimination in the United States in the weeks immediately following September 11, 2001. Drawing on prior studies that have hypothesized that experiences of discrimination increase the risk of preterm birth and low birth weight, this study explores whether there was an effect on birth outcomes for pregnant women of Arab descent. California birth certificate data are used to determine the relative risk of poor birth outcomes by race, ethnicity, and nativity for women who gave birth in the six months following September 2001, compared with the same six calendar months one year earlier. The relative risk of poor birth outcomes was significantly elevated for Arabic-named women and not for any of the other groups.     

The negligible influence of premarital cohabitation on marital fertility in current danish cohorts, 1975

This paper studies the influence of premarital cohabitation on marital fertility by applying life table methods to data for cohorts of Danish women born in 1926–1955, collected in retrospective interviews made in 1975. For each five-year cohort, the data have been analyzed by duration of marriage or by duration since previous birth, for women who had no reported births before marriage. Our main empirical results are: (a) that women who married at age 15–19 had higher rates of marital first and second births than those married at ages 20–24, and (b) that premarital cohabitation had very little influence on births of these two first orders in our data.     

Seasonal Patterns of Reproduction in Matlab,Bangladesh

In Bangladesh twice as many births occur in December as in July. This paper examines the seasonal patterns of the risks of conception, fetal loss and return of menses post partum in a longitudinal study of 2,300 women in 14 villages of Matlab, Bangladesh. Life tables were estimated for each month of entry event and then ‘period’ life tables were constructed with the risks for a given calendar month. Confirming the results of earlier studies, risks of resumption of menses were higher in November and December, regardless of time elapsed since the last birth. Similarly, there are increased conception risks in the period from February to April for all fecundable women. The time of lowest fetal loss and stillbirth risks is in the cool season, though this variation makes only a minor contribution to the overall seasonality of births. The pattern of fecundability estimated from data on coital frequency did not match the pattern estimated from reported conceptions; these discrepancies imply possible seasonal changes in other parameters of fecundability besides intercourse.     

Trends and differentials in breast feeding: An update

Analysis of the 1973 National Survey of Family Growth shows a continued downward trend in breast feeding by successive cohorts of American mothers. The downward trend is evident in both measures of incidence (ever-breast feeding) and duration of breast feeding for first and higher-order births. For all cohorts higher-order births are less likely to be breast fed than first births. However, breast feeding of higher-order births is typically of a longer duration. Differentials in breast feeding reveal strong associations with indicators of social class; women who are college graduates, who work as professionals, and who are married to professional husbands are most likely to breast-feed their infants. Differentials in average duration of breast feeding are often reversed from differentials in ever-breast feeding.     

The effect of number of births on women's mortality: systematic review of the evidence for women who have completed their childbearing

Mortality in women who have completed their childbearing may increase with the number of births experienced because of maternal depletion or a trade-off between reproduction and mortality. We report a systematic review of the evidence on this association. We searched Medline, Embase, Popline, and the Science Citation Index for published and unpublished studies up to September 2003, and the book catalogues of relevant London libraries. Where necessary we also contacted authors for additional information. Mortality declined with increasing numbers of births in twelve historical cohorts, but in eight contemporary cohorts the highest mortality was seen in the nulliparous and in women with more than four births. All effects seen were small and there were few statistically significant results. Studies examining the relationship in other ways (such as by linear trends or by mean number of births by age at death) found inconsistent associations. We discuss methodological, social, and biological factors that may have affected these associations.     

A Note on The Accuracy of Male Responses to Questions on Fertility

There seems to be little doubt that reliablefertility information can be obtained from Latin A merican women. The question remains, however, whether such information can be obtained from males. This paper presents evidence on the accuracy of reports of the number of live births collected in a survey of 1,640 male residents of the Monterrey, Mexico metropolitan area. The accuracy of the number of live births recorded in this survey is evaluated on the basis of (1) internal consistency, (2) the Mexican census, and (3) previous investigation. The present analysis indicates that the information collected is of good quality and potentially useful for several types of fertility analysis. No evidence was found of underreporting.     

Fertility exposure analysis: A new method for assessing the contribution of proximate determinants to fertility differentials

Summary Several recent papers have dealt with the problem of assessing the impact of the proximate determinants on fertility. All these approaches rely on combining a series of separately estimated aggregate level indicators. This paper proposes an approach which uses individual-level data and thus permits regression analyses as well as analyses for sub-groups. In the course of development it became clear that there are several deficiencies and inconsistencies in the measurement and formation of indices proposed elsewhere, which are overcome. We illustrate our approach with data from the Dominican Republic. The approach used involves attributing exposure to one or more of several states, including pregnancy, lactational and non-lactational components of post-partum amenorrhoea, absence of sexual relations and contraception. Key elements are efficacies of contraception and components of post-partum infecundity and the treatment of overlaps through an explicit hierarchy. We treat both unconditional (or additive) and conditional analyses. Intriguing findings on the age-specific pattern of fertility control emerge. Major advantages of regression analysis, such as simultaneous treatment of several variables and estimation of sampling variation are stressed.     

Reliability of reasons for early termination of breastfeeding: application of a bivariate probability model with sample selection to data from surveys in Malaysia in 1976-77 and 1988-89

Although extensively collected, data on people's reasons for their behaviour provided retrospectively have been met with some scepticism on the grounds that they may be subject to biases and errors that jeopardize their usefulness. This study investigates, for a sample of 1,327 births, the reliability with which women in Peninsular Malaysia recalled, at intervals 12 years apart, reasons for not initiating or for stopping breastfeeding less than 3 months after a birth. Overall, we find low to moderate reliability of recall. Levels of reliability are relatively high for some reasons (the child died and no or insufficient milk) but low for some others (child ill, breastfeeding inconvenient). Results from selection models show that reliability does not vary with the length of time since the child's birth but is inversely related to socio-economic status (proxied by education and employment). Social status, social norms, and health-related factors appear to be significant influences on women's consistency of reporting.     

Age at marriage and timing of the first birth

Summary An attempt has been made to measure the effect of age at marriage of brides on the timing of the first birth. In Australian vital statistics, first nuptial confinements have been tabulated by age of mothers and by single years of marriage duration in single months for the first two years and by single years for all other durations since 1916. A simple technique has been used to link such data with marriage cohorts. The study briefly reviews the prevailing patterns of the timing of first births by mothers' age at marriage and changes in this pattern since the marriages of the 1925/9 period. The analysis shows that after a period of relative stability of family formation patterns in the 1950s and early 1960s, women married in the late 1960s started postponing the first birth beyond the first two years of marriage. It is suggested that a fraction of the decline in total births recorded in Australia since 1972 can be attributed to the postponement of first nuptial confinements by women married in the late 1960s and early 1970s.     

Contraceptive overlap with post-partum anovularity

Abstract Contraceptive use in the early post-partum months is, for the majority of women, without any direct protective value because, whilst not ovulating, they are not exposed to the risk of pregnancy. This does not, of course, imply that contraception should be delayed until signs of the resumption of ovulation appear, as for many women the first sign of such resumption is pregnancy. There are, besides, logistic and psychological reasons which make early post-partum contraception advisable. It does, however, demand that any calculation of the demographic effects of contraceptive use should make due allowance for this null period of use.     

Contraceptive overlap with post-partum anovularity

Contraceptive use in the early post-partum months is, for the majority of women, without any direct protective value because, whilst not ovulating, they are not exposed to the risk of pregnancy. This does not, of course, imply that contraception should be delayed until signs of the resumption of ovulation appear, as for many women the first sign of such resumption is pregnancy. There are, besides, logistic and psychological reasons which make early post-partum contraception advisable. It does, however, demand that any calculation of the demographic effects of contraceptive use should make due allowance for this null period of use.