Cessation of childbearing in the absence of contraception in Sri Lanka

In data from the Sri Lanka Fertility Survey, 1975, the cessation of childbearing is examined among women who have never used contraception. The sample consisted of 6810 currently or previously married women, 57% of whom reported that they had never used contraception. Cessation of childbearing is studied according to age and marriage duration. The variables analyzed are age at last birth, proportions infertile during the last 5 or 7 years, and the infertile open interval. The duration of breastfeeding is taken into account where necessary, and the contraceptive users and nonusers are compared where appropriate. Non-users tend to cease childbearing early, and therefore are infertile for longer periods during their marriages. It is probably age of the 1st child that influences decisions on future fertility. Among women aged 45-49 who married before age 20 and continued in their 1st marriage, mean age at last live birth in non-users, was 34.5 years, about 2 years earlier than in those who had used contraception. Non-users who married at any age below 30 years cease childbearing well below age 40. The proportion not currently pregnant and infertile over the past 5 years increases with marriage duration among the fertile non-users in each age group. When age at last birth and the duration of breastfeeding in the open interval are taken into account and the reference period is increased to 7 years, the period of infertility increases with marriage duration among nonpregnant non-users below age 45. The proportion of women who were currently not pregnant and had remained infertile over the past 7 years is higher among the older non-users whose 1st child was born more than 10 years ago.     

Duration between marriage and first birth and marital instability

This paper considers whether marital instability varies by the duration between marriage and 1st birth among ever-married white and black American women. Analysis of data from the June 1985 Current Population Survey suggests that the duration between marriage and 1st birth has a generally monotonic relationship with the probability of white women separating or divorcing from their 1st marriage; the relationship has remained relatively constant over time. For blacks, no consistent association is found between marital dissolution and the duration between marriage and 1st birth. Black women having a premarital conception and postmarital birth and those having their 1st birth during their 2nd year of marriage have a similarly high risk of dissolution. Conversely, blacks having their 1st birth 8-12 or 25-42 months after marrying have a low probability of dissolution. Childless women and those with premarital births generally has the greatest probability of marital disruption for whites. Racial differences may occur because blacks view the 1st birth and marriage differently than whites. That is, because blacks are much more likely to have premarital births and to have a shorter duration between marriage and 1st birth, blacks and whites in the same 1st birth interval category may be dissimilar and have different values resulting in a differential effect of the timing of the 1st birth on marital instability by race. Caution is needed when interpreting the pattern of association between delayed childbearing (and to a lesser extent, births occuring a few years after marriage) and marital instability. Results for whites were similar at each marriage duration and it is assumed delayed childbearing was not a result of marital instability. Marital instability was expected to have its strongest effect on the timing of the 1st birth during the 1st years of marriage. Marital instability may be partially responsible for the delaying of childbearing among blacks. However, blacks who delay but are married at 1st birth have a relatively low risk of separating or divorcing.     

Stable aggregate fertility in a time of family change: a decomposition of trends in American fertility, 1970-1999

Population-level birth rates in the United States were largely stable between 1970 and 1999. This stability contrasts with rapid change in marriage rates and fertility timing during the same period. In this article, I use decomposition techniques to analyze this seeming paradox. I decompose the general fertility rate into four components: age distribution, marital status, age-specific nonmarital fertility, and age-specific marital fertility. Absent other changes, declining time spent married would have led to substantial decline in fertility. Several factors combined to counterbalance these changes in marital behavior. Among white women in the 1970s and 1980s, marital fertility rates increased at older ages, consistent with a scenario in which women postponed both marriage and childbearing; increased nonmarital birth rates during this period were not a driving factor in overall fertility trends. Increased nonmarital fertility was more important in compensating for declining time spent married among African American women and among white women in the 1990s.     

Birth spacing in Pakistan

Life table analysis was applied to data from the 1975 Pakistan Fertility Survey to identify child spacing differentials between population subgroups. Women in urban areas had shorter birth intervals than their rural counterparts from parities 1-6; only after parity 7 was this differential reversed. Similarly, women with some education had shorter birth intervals at the earlier parities than uneducated women. While overall family size is relatively homogeneous in Pakistan, women of more modern backgrounds seem to space their children more closely than traditional women. Age at marriage appears to play an important role not only in determining the length of the 1st interval, but also that of subsequent intervals. An unexpected finding was that ever users of contraception had distinctly more rapid spacing of their births than never users. The median interval to 1st birth was shortest in North West Frontier Province, but similar in Punjab and Sind. Multiple classification analysis revealed that some differentials in child spacing by education, residence, and province persisted even after other variables were controlled. Cohort of mother had an independent effect, with younger cohorts having shorter birth intervals. However, the variable that had the strongest effect on length of interval (aside from the 1st interval) was breastfeeding duration. It is likely that increasing urbanization and improved levels of education among women will lead to high levels of marital fertility associated with shorter birth intervals. Even though these trends tend to increase the age at marriage, they are associated with shorter durations of breastfeeding. In the longer term, greater use of contraception among women in the modern sector may partially counteract the fertility increasing effect of reduced birth intervals.     

Differentials of fertility between polygynous and monogamous marriages in rural Bangladesh

This paper discusses polygynous marriages in rural Bangladesh, using marital status and birth registration data from the Demographic Surveillance System (DSS) of the International Center for Diarrheal Disease Research, for the period 1975-79. Of all the marriages recorded during this period about 5% were polygynous. To identify the women polygynously married, 1974 census data of the DSS area were used. The difference in age at marriage between the polygynous groom and his subsequent wife was 15 years on average. The socioeconomic indicators studied were education, occupation and area of dwelling space. In general, these indicators between women in monogamous marriages were significantly higher than between the women in polygynous unions. During the period 1976-79, 863 polygynous marriages were recorded (4.9% of all marriages in the study area). Polygynous marriages were found to be less frequent among men with 2ndary and higher levels of education. The highest proportion of polygynous marriages occurred among husbands with no schooling or Koranic education. The general fertility rate of women in monogamous marriages was significantly higher than for women in polygynous marriages, overall and in all age groups except 20-24. During the period 1975-79, the mean number of liveborn children for monogamous women was higher than that of polygynous women.     

Fertility at low and high altitude in Central Nepal

Since the 1930s, a number of different studies have tended to show that fertility is lower at high altitude. The present investigation attempts to provide some answers to this question by examining completed fertility rate (CFR) in Highland and Lowland villages in Central Nepal and relating rate differences to age at menarche, age at 1st childbirth, age at 1st marriage, incidence of venereal disease, birth control (vasectomy or hysterectomy), length of postpartum amenorrhea, and breastfeeding. Data was obtained by direct questioning, and under-reporting of births thus cannot be excluded. Fertility histories were taken from post-menopausal women over the age of 45 years. Results indicate no significant difference in reported menarcheal ages between highlanders and lowlanders. Age at 1st marriage and 1st childbirth were both significantly later in highlanders. CFR was significantly lower in highlanders. It would appear that the reduced fertility rate at high altitude can be partly attributable to later age at marriage and later 1st childbirth. Other factors, e.g., husband absenteeism and remarriage have also been suggested as possible contributors to the observed difference. This paper presents the results of a multiple regression analysis using 9 dependent variables: ages of marriage, 1st childbirth and menarch, the average gap between pregnancies, the average amount of time the husband was away, the number of marriages, presence or absence of venereal disease at some time, whether birth control was practiced and altitude status. Average pregnancy gap, age at 1st childbirth and presence or absence of venereal disease were the only variables that independently made a significcant contribution to CFR variance. The increase in pregnancy gap may be related to longer periods of breastfeeding in high altitude women and there would be a concomitant delay in recommencement of menstruation. In testing the hypothesis, no difference is found in reported duration of breastfeeding or in postpartum amenorrhea. The age at marriage and age at 1st childbirth accounted for over 16% of the explained variance in CFR. Some of the observed difference in CFR can be explained by the difference in marital age but not by the interval between marriage and 1st childbirth, as it was very similar in both groups. The lower CFR among the high altitude population could be due to lowering of biological fecundity at high altitude, or simply a matter of choice. The difference might reflect human reproductive hormone differences between high and low altitude populations. Further research will be needed to determine whether or not differences in CFR can be explained by variation in these factors.     

Covariates of age at first birth in Guyana: a hazards model analysis

Analysis of data from the Guyana Fertility Survey on the trends and covariates of age at 1st birth among various birth cohorts of women ever in union indicates that an early entry into union is associated with young age at 1st birth and higher number of children born. Multivariate analysis showed that women with higher education, urban residence, and entry into 1st birth compared to others, and that young women are delaying their 1st birth for longer durations than older women. Work status of women before 1st birth and the starting age of union seem to be the 2 major contributory factors for age at 1st birth. Noticeably, the role of education has changed and is now more significant among younger cohorts than among older ones for 1st birth timing.     

Intergenerational transmission of reproductive behaviour in Botswana

The purpose of this study was to investigate intergenerational transmission of reproductive behaviour in Botswana. The major source of data was the 2001 Botswana AIDS Impact Survey where a nationally representative random sample of men and women aged 10-64 years was selected using a stratified two-stage probability sample design. Covariates in the analysis include age, education, marital status, religion, age at first birth, residence, duration at residence and contraceptive use. The main analytical technique is linear regression. The results indicate that the reproductive behaviour of older generations has a significantly positive influence on the reproductive behaviour of the subsequent generation, but does not affect the subsequent generation homogeneously. The effect appeared much stronger for women who initiated childbearing at an older age, for women who had never been to school, and for the cohort aged 50-59 years. These findings suggest that number of siblings, as a reproductive behaviour determinant, may very well have confounded previous reproductive behaviour analyses in Botswana. The study draws attention to the importance of the effect of origin family size in determining reproductive behaviour outcomes in Botswana.     

Probabilities of marriage in two outer Hebridean islands, 1861-1990.

A study has been made of the probabilities of marriage of females and males aged 15-49 (either as a whole or in 5-year age groups) in two Outer Hebridean islands, Harris and Barra. The results were compared with ages of marriage and with the frequencies of permanent celibacy. The marriages took place between 1861 and 1990. Median ages of marriage rose to maxima in the 1930s and 1940s, then fell steeply, levelling out latterly. Permanent celibacy was consistently high among females, but rose from much lower levels in males to maxima in the 1970s and 1980s. It is concluded that in these populations age at marriage and the extent of permanent celibacy are largely independent of one another. In both islands the overall probabilities of females marrying fell until the 1920s, and then rose. The last decades showed stability (Barra) and a fall (Harris). Males showed only slight falls to about 1910; data were absent for between 1911 and 1960, but subsequently there was little rise in probability. These overall changes seemed to be associated with reciprocal variations in probabilities in the younger and older age groups. Declining overall probabilities were associated with declines in younger and increases in older age-group probabilities, and vice versa. Non-parametric correlations between median ages of marriage and probability of marriage were negative and generally significant for the 15-19 age group. Among the older age groups coefficients were generally positive. There was some evidence of an association between probability of marriage and sex ratio in any group of potential mates. The effect appeared more marked among 15- to 19-year-old females. Local factors which might explain at least part of the decline in nuptiality for the greater part of the period under study include the decline in the fishing industry and the 'land hunger' which existed until the late 1920s. This decline is interpreted as a 'Malthusian' response to economic and social conditions, but it coexisted with a 'neo-Malthusian' strategy, in the shape of declining marital fertility. The 'Malthusian' strategy seems to have been largely abandoned around the 1950s, but it may have reappeared during the 1980s.     

Marriage structure and contraception in Niger

Analysis of the 1992 Niger Demographic and Health Survey showed that although roughly two-thirds of both polygamous and monogamous women approve of birth control, polygamous wives are less likely than monogamous wives to discuss family size or birth control with their husband or to plan on using birth control. The study suggests that characteristics of polygamous couples have caused polygamous women to be more resistant to birth control use than monogamous women. The polygamous women tended to be married to older men who had not gone to primary school and who desired more children than monogamous husbands. The influence of marital structure is not significantly associated with intention to use birth control when the husband's age and the wife's ideal number of children were controlled for in the multivariate logistic regression model suggesting that background social factors may be more influential. In fact, educational level and age at first marriage were significantly associated with attitudes towards birth control and also with marital structure.     

Duration of marriages and remarriages in Chiomonte (Turin) in the XVII–XVIII century

This is a preliminary study of the duration of marriages and remarriages by widowed people in Chiomonte (Turin) from 1670 to 1729, a period that saw long periods of war alternating with brief intervals of peace. We analysed 748 marriage acts and evaluated the age at first marriage, the duration of marriage, the frequency of remarriage by widowed people and the number of widowed people who remarried. The data were analysed in five-year intervals. The results show that the population of Chiomonte was essentially permanent, since the end of the marriage could be established in 77,6% of cases. The mean duration of marriages increased from the end of the XVII century and around 51% of all marriages lasted more than 20 years. Historical events had different effects on the matrimonial behaviour. After the mortality crisis in 1690–91, marriages and remarriages increased in 1691–94, a typical response of populations decimated by an epidemic. However, the matrimonial behaviour in the decade 1704–14 was different, in that there was a strong increase in exogamous marriages (56.52% of all marriages). Remarriages, especially of widowed persons, also increased in that period. Although these data are preliminary and from a brief time period, they reveal particular aspects of the marriage and remarriage behaviour, thus helping to clarify the biodemographic evolution of the Chiomonte population.     

Age at menarche, at first intercourse, and at first pregnancy

Data from an urban sample of American women of reproductive ages demonstrate that age at menarche is correlated with age at first intercourse, that age at first intercourse is correlated with age at first pregnancy, and that menarche is therefore correlated with age at first pregnancy. This applied to both blacks and whites when examined for the early years of the reproductive cycle. Girls with early menarche, compared to those with late menarche, are more than twice as likely to have had intercourse by age 16, and almost twice as likely to have given birth or had a pregnancy terminated by age 18. It is therefore useful to think of the timing of menarche as an indicator of the probability of early intercourse and early childbearing.     

Continuing fertility transitions in a plural society: ethnic trends and differentials in Peninsular Malaysia

Fertility in Peninsular Malaysia has declined continuously from the late 1950s, reaching a total fertility rate of 3735 in 1983. All ethnic groups in Malaysia have contributed to this modern demographic transition but the rate of change has been most rapid for Chinese and Indians, Malay fertility having reached a plateau in the early 1980s. The effect of age structure, marital patterns and marital fertility (by parity) on the fertility declines for each ethnic community are analyzed. There has been a tendency, in each ethnic group, for the age distribution within the group of reproductive-age women to grow younger, reflecting the entry into the younger reproductive ages of the large birth cohorts of the 1950s and early 1960s. The effect of this on crude birth rates is hard to determine, because rising age at marriage and increasing use of contraception meant that fertility was increasingly concentrated in the more central reproductive ages. By the 1990s, the earlier declines in fertility will bring about a decline in the proportion of the total population made up of females in the main reproductive ages. After that point, further declines in fertility will be reflected in a sharper decline in the crude birth rate and hence the rate of population increase. Between 1947 and 1980, the age at marriage changed dramatically for females of all ethnic groups. The transition to higher age at marriage for Chinese was completed earlier, and since 1970 has risen by only a year. For Malays and Indians, the rise began later, proceeded faster and continued right up to 1980 when the medium ages at 1st marriage were Malays 22, Indians 23, Chinese 24 years. In 1980, Malay women on average were marrying 5 years later, and Indian women 6 years later than had their mothers' generation in 1947. The proportion never-married among Malay and Indian women aged 20-24 rose from 1/10 to 1/2 over this period; relatively greater changes are evident at ages 25-29. Other factors are the almost complete shift from parent-arranged to self-arranged marriages. Family size desired has decreased for all groups and the decline in breastfeeding has been offset by the sharp increase in the practice of contraception. Continuation of these trends would lead to replacement-level fertility for Malaysian Chinese and Indians by the year 2000. Malay fertility is likely to continue to decline but at a more moderate pace.     

Mortality and age differences in marriage.

Data from the 1971 census population were used to evaluate the effects of age differences of married partners on mortality rates. Different age groups were isolated to highlight the association between mortality and age of spouse for specific ages of married men and women. Men married to much younger or to older women exhibited a higher mortality rate than men married to women who were only a few years younger than themselves. A similar trend was observed among women married to much younger or much older men compared with those whose spouses were a few years older or of similar ages as themselves. Trends for other age groups (women aged 60-69 years, men below 40, and women below 30) did not exhibit a clear pattern. Although statistical biases within age groups may in part account for the differences in the findings, the trend which emerged from the analysis suggests that lower morbidity is associated with the most common age combinations (husbands same age or slightly older than wives). Other factors could also account for the differences (e.g., selection of healthy partners in 1st marriages, differences in lifestyles between married and single).     

Testosterone levels and their associations with lifetime number of opposite sex partners and remarriage in a large sample of American elderly men and women

Testosterone (T) has been argued to modulate mating and parenting behavior in many species, including humans. The role of T for these behaviors has been framed as the challenge hypothesis. Following this hypothesis, T should be positively associated with the number of opposite sex partners a male has. Indeed research in humans has shown that T is positively related to the number of opposite sex partners a young man has had. Here we test, in both men and women, whether this relationship extends to the lifetime number of sex partners. We also explored whether or not T was associated with current marital status, partnership status and whether or not the participant remarried. Using a large sample of elderly men and women (each sample n > 700), we show that T is positively and sizably associated with the number of opposite sex partners in men. When controlling for potential confounding variables such as educational attainment, age, BMI, ethnicity, specific use of a medication and time of sampling this effect remained. For women, the relationship between T and number of opposite sex partners was positive but did not prove to be robust. In both men and women there was no evidence for an association between T and current marital status and partnership status (being in a relationship or not). However, remarriage was positively associated with T, but only in males. Results are discussed with reference to the literature on T and sex partners, remarriage and more broadly the challenge hypothesis.     

Demographic and endocrinological aspects of low natural fertility in Highland New Guinea

The Gainj of highland Papua New Guinea do not use contraception but have a total fertility rate of only 4.3 live births/woman, 1 of the lowest ever recorded in a natural fertility setting. Reproductive and marital histories were obtained from 305 females and 206 males aged 10+. Each subject was asked about: number of live born offspring ever produced; number of stillbirths ever produced; number and names of offspring currently being nursed; number of current and past spouses; and the cause of dissolution of all past marriages. Blood samples were drawn from 172 volunteer female subjects aged 10-60 years and ovarian function was classified by concentration of progesterone. From an analysis of these cross-sectional demographic and endocrinological data, the causes of low reproductive output have been identified in women of this population as: late menarche and marriage, a long interval between marriage and 1st birth, a high probability of widowhood at later reproductive ages, low effective fecundability and prolonged lactational amenorrhea. These are combined with near-universal marriage, and a low prevalence of primary sterility similar to that found in other populations. Of all the factors limiting fertility, by far the most important are those involved in birth spacing, especially lactational amenorrhea. The effects of widowhood on Gainj fertility are negligible. Factors acting to lower fertility fall into 2 categories: those that determine the age of onset of reproduction and those that act to space births. Given the observed pattern of birth spacing, however, the delay in commencement of reproduction represents on average no more than 1 or 2 live births averted/woman. In contrast, were age at 1st reproduction held constant while reducing birth intervals to a mean of 2.0-2.5 years, total fertility would increase to about 7 or 8. Future research on natural fertility should focus on specific behavioral and physiological mechanisms governing the reproductive process.     

Voluntary sterilisation among Canadian women

Using data from the 1984 Canadian Fertility Survey, proportional hazards modelling was employed to determine factors associated with the likelihood of voluntary sterilisation among 5315 women of childbearing age, and the trends in timing and differences in the likelihood associated with different age cohorts. Multivariate analysis suggests that educational attainment, parity and duration since last birth at the time of sterilisation, religious commitment, province of residence and marital status at the time of sterilisation, are all important predictors. Education and parity attainment emerged as the best predictors of the timing of voluntary sterilisation in all age cohorts, but the contribution of other covariates varies between cohorts.     

The practice of consanguineous marriage in oman: prevalence, trends and determinants

The practice of consanguineous marriage has been the culturally preferred form of marriage in most Arab and the Middle Eastern countries, including Oman, but due to a paucity of population-based data in the past there is a dearth of information about its form and dynamics in Oman. Recent national-level surveys allow this gap to be filled. This paper examines the prevalence, trends and determinants of consanguineous marriages in Oman using data from the 2000 Oman National Health Survey. The results indicate a very high prevalence of consanguineous marriage in Oman, as more than half (52%) of marriages are consanguineous. First cousin unions are the most common type of consanguineous unions, constituting 39% of all marriages and 75% of all consanguineous marriages. The study observed various patterns of consanguinity, some of them common with other Arab nations, and some unique in nature. Women's age at marriage, employment, place of childhood residence and geographical region appear to be significant determinants of consanguineous marriages. Consanguineous marriage shows a strong association with marital stability, early age at marriage and early-age childbearing. There has been no appreciable change in the prevalence of consanguineous unions in Oman over the last four decades despite massive socioeconomic development and modernization. However, recent marriage cohorts show slight declining trends. The results suggest that consanguinity is likely to remain stable in the future or decline at a slow rate. Specific health education and genetic counselling should be followed in line with WHO recommendations to minimize the negative health consequences of consanguinity for child health.     

Parental age difference, educationally assortative mating and offspring count: evidence from a contemporary population in Taiwan

Using contemporary population data from Taiwan, we examine the relationships between parental age difference, educationally assortative mating, income and offspring count. Controlling for women's reproductive value (measured by age at first birth), we find that an older husband is associated with fewer offspring, whereas a husband with similar or higher education is associated with more offspring. Concerning resources, we find that women's income is negatively associated with fertility and husband's income is positively associated with fertility among highly educated women. These results are consistent with the view that women compensate for trade-offs between education, income generation and childbearing by seeking mates with a higher status.     

Reproductive life of some Gujar women of Punjab

Data was collected on current age, age at menarche, marriage age, maternal age at 1st birth, age at the birth of last child, age at menopause, total number of conceptions, live births, stillbirths, abortions, dead children and living children for a sample of 150 Gunjar women of Punjab, India, during September and October 1977 to study their reproductive life. The women ranged in age from 45-55 years. The mean age at menarche was 14.90 years for the sample. The median age at menopause was 46.20 years. The mean age at marriage of the present sample was 12.56+-2.50 years; the mean age of the mother at the birth of her 1st child was 16.85 years; and the mean age at the birth of the last child was 38.68 years. The average number of conceptions was 7.2; the average number of live births of these 150 women was 6.90. The fertility of this population was natural as they were not using any family planning method.