In Canadian society the influence of first birth timing on the subsequent birth interval has been eroded over time, as shown by the Canadian Fertility Survey of 1984. The influence of first birth timing is significant for second births among women married during the baby boom period, but not for those married thereafter. Religiosity, marital status, and place of residence are significant factors in second birth timing in Canada.

Dynamic models of contraceptive use fill a theoretical gap. They bring behavioural content to the mathematically elegant Markov models of family building. They meet the criterion that Bulatao (1989) advances that method use, discontinuation and switching be considered not in isolation, but with reference to individual reproductive goals. Dynamic models help to link the literature on method choice with the literature on method effectiveness. These theoretical advantages are, at present, counter-balanced by empirical limitations. This article explores the theoretical and empirical underpinnings of dynamic contraceptive choice models.

Using Bongaarts' model, the relative importance of the proximate determinants of fertility is explored in five populations on the US–Mexico border. For the groups closest to natural fertility (the two Mexican groups), lactation, use of contraception, and marriage all were moderately important in terms of their direct effect on fertility. For the group with lowest fertility (Anglo-American), contraceptive use was an important factor inhibiting fertility; marriage was important but not nearly as important as contraceptive use. For the two US Mexican-American groups, contraceptive use was an important intermediate variable, not as important as for Anglo-Americans, but more important than it was for the two populations in Mexico. The proportion married was a moderately important factor for the Mexican-American groups. For these five populations the principal differences in fertility rates result from substantial differences in the use of effective contraception. Bongaarts' model proved very useful as an analytical framework in this study.

Family planning knowledge, attitude and practice surveys typically assess respondents' reproductive attitudes and intentions to use contraception. Longitudinal observation of individual respondents nevertheless shows that such questions are not strongly predictive of subsequent behaviour. This study examines 3 years' data which show that a set of such responses to questions are nevertheless substantially superior in predicting behaviour than any single indicator. Thus statistical techniques which bring into account the apparent multidimensionality of contraceptive motivation can greatly improve upon the estimation of future practice of family planning in a population.

Using individual birth history data from the Sudan Fertility Survey, 1979, parity-related differences in fertility are demonstrated, as well as differences between socioeconomic groups. Rural women, women with no education and those married to uneducated husbands show rapid parity progression and its cumulative effects on fertility which are consistent over all birth intervals. Urban women, women with some education and those married to educated husbands, however, go rapidly through their second and third birth intervals and then more slowly at higher parities. A limitation of the study was the inability to control fully for the effects of breast-feeding and contraception.

There is evidence for a reduction in high parity births,' starting in the 1970s.

Elective sterilization started to spread rather late in Flanders. Despite the sharp increase of this contraceptive method since the end of the 1970s, its frequency is still lower than in many neighbouring countries and much lower than in the US and Canada, mainly due to the lag in male sterilization. Further increase in contraceptive sterilization and a greater participation of men is expected in the near future.

Lifetime reproductive histories of a 1984–85 nationally representative sample of 870 women aged 25–59 years provided data to describe the evolution of fertility, contraception, breast-feeding, and natural fecundability in Costa Rica between 1960 and 1984. The contraceptive prevalence rate increased from 23% in 1965 to 58% in 1975 and 66% in 1984. Duration of breast-feeding was stable during the 1960s, decreased in the early 1970s, and increased after about 1976. Fecundability among women who did not practise contraception was lower than expected and declined between 1960 and 1975, probably because of selection effects. Despite a high consistency between estimations from the reproductive histories and other sources of data, some suggestion of omissions of short periods of contraceptive use in the distant past was detected. The survey may have reduced recall errors by using a calendar that summarizes major life events together. The analysis demonstrated the feasibility and usefulness of asking for lifetime reproductive histories in fertility surveys in developing countries.

In 1984–85 a representative sample of 286 Danish women and 336 men aged 16–20 years were interviewed about their sexual debut. Seventy-four females (25·9%) and 101 males (30·1%) had not yet experienced sexual intercourse. A maximum likelihood estimation method was used to establish the age distribution at sexual debut. This takes into account knowledge of age at interview among the non-experienced respondents and of the few who did not report age at sexual debut. The median age at first sexual intercourse was close to 16·8 years for both females and males. This appeared to be a consequence of age at debut declining among women and remaining unchanged among males during the preceding 20 years.

The determinants of contraceptive method choice in Sri Lanka are examined during a period in which contraceptive prevalence increased by over 60% and involved substantial use of sterilization and traditional methods. Data are from the 1975 World Fertility and 1982 Contraceptive Prevalence Surveys. Polytomous logistic regression is used to model four current contraceptive choices: non-use, use of a traditional method, use of a modern temporary method and use of sterilization. The analysis shows, in 1975 and 1982, strong socioeconomic as well as demographic effects on whether any method is used. However, in both years the type of method chosen is primarily a function of demographic considerations related to the couple's family-building stage rather than social status, implying that in Sri Lanka there are few socioeconomic barriers limiting access to different contraceptive methods. The family planning programme, however, has emphasized sterilization rather than birth spacing methods.

Shortly after the first reports on the acquired immunodeficiency syndrome (AIDS) in the United States, it became clear that the disease was also particularly frequent in Haitians living in North America (Pitchenik et at., 1983; Curran et al., 1985) and in Africans seen in Europe for medical care (Katlama et al., 1984; Clumeck et al., 1984). Subsequently, surveys in Haiti and in Central Africa confirmed the occurrence of epidemic foci of AIDS in these areas (Pape et al., 1983; Malebranche et al., 1983; Piot et al., 1984; Van de Perre et al., 1984).

Among the Kipsigis, a population of south-western Kenya who do not use contraception, age at menarche and age at last live birth could be determined for a cohort of post-menopausal women, through reference to clitoridectomy ceremonies that can easily be dated. While a woman's age at last live birth was strongly associated with the length of her reproductive lifespan, completed family size was better predicted by age at menarche. The demographic implications of variation in menarcheal age are discussed.

Contraceptive use and method mix were analysed using Philippines national survey data of 1973, 1978, and 1983. The analyses suggest that the reported decline in contraceptive prevalence between 1978 and 1983 was due to under-reporting of use in 1973 and 1983. The shifts in contraceptive method mix were also partly from under-reporting of rhythm and other methods in 1973 and 1983. Nevertheless, the determinants of method choice were similar in all three sets of data. Filipino couples were making rational choices in terms of their contraceptive goals, access, evaluation, and competence. Modifications in the directions and magnitude of the relationships in determining method choice also occurred, partly reflecting the increased use of sterilization by older, higher parity women.

About two-thirds of the world's population live in areas where registration of vital statistics is unsatisfactory (Tietze, 1977), and in many countries such statistics from rural areas are unavailable or grossly underestimated (WHO, 1971). Most of the women who die in pregnancy and childbirth are poor and live in remote areas or city slums. Their deaths are accorded little importance and fail to enter registers.

Earlier studies on the seasonality of births indicate that a major peak occurs in August and September and a minor peak in January and February. This study uses the 1984 Canadian Fertility Survey data on reproductive history to examine birth and pregnancy seasonalities, and shows that the ‘worst’ months for births are January and February and the ‘best’ months are March, April and May. There is no systematic pattern in the seasonality of pregnancies, possibly because effective birth control allows couples to plan the timing of births.

Women in marital unions had more live births than those in consensual unions. The relationship between cumulative fertility and the number of fertile sexual unions is positive for the early childbearing years and negative for the later ones. There is no consistent pattern of relationship between fertility and the sociocultural independent variables for different subgroups according to nuptiality pattern. The relationship between fertility and nuptiality in the Dominican Republic is consistent with that for the Caribbean region.

Indirect techniques are applied to estimate the current level of fertility and mortality among Kuwaiti nationals in Kuwait during 1980–85. The various methods discussed provide estimates in the vicinity of 45 per thousand for birth rate and 8 per thousand for death rate. While child spacing by birth order in Kuwait is about 2 years, the proportion of childlessness is very low (1%). As a consequence of lower mortality and stable high fertility, the Kuwaiti population remains young.

The menarcheal age and frequency of menstrual disorders in mothers of dizygotic (DZ) and monozygotic (MZ) twins born in Denmark in 1984 or 1985 were compared with a control sample of mothers of singleton infants born in the same period. Compared to control mothers, mothers of DZ twins had a lower menarcheal age and a lower frequency of menstrual irregularities—menstrual cycles exceeding 5 weeks duration, varying length of menstrual cycles and episodes of menostasia. Mothers of MZ twins had a higher frequency of intermenstrual bleeding compared to mothers of singletons. All results were adjusted for maternal age and parity. The findings are relevant to the interpretation of aetiological factors leading to twin births and support the hypothesis of differences in sex hormone activity of the mothers of DZ twins in comparison with other women.

The association between breast-feeding patterns and resumption of menses post-partum was examined in a prospective study in Indonesia. In order to examine these relationships directly in a longitudinal study, it was first necessary to distinguish among women who experienced infant mortality before menses resumed, women who weaned before menses resumed, and women who had return to menses while breast-feeding.

Information on suckling patterns and menstrual status was collected by recall for 444 women at monthly visits for 2 years. Three main breast-feeding variables, minutes per episode, number of episodes per day, number of episodes per night, and other breast-feeding variables were derived for each woman, to give the average nursing pattern up to menses or the end of the study, whichever came first. While high levels of nursing for each of these three main variables were found to be significantly related to delay in return of menses post-partum, the interactions between more minutes per episode, and more frequent day- and night-time feeds, were found to be the most important factors in the delay in onset of post-partum menstruation in those women whose menses resumed while still nursing or who remained amenorrhoeic and nursing at the end of the study.

Contraceptive prevalence rates and estimates of continuation rates are derived from unique longitudinal data on post-partum behaviour collected in the Cebu region of the Philippines. Continuation rates vary by base-line and time-varying socioeconomic characteristics for certain contraceptive methods and for using no contraception. Calendar rhythm users have a much lower relative continuation rate than has been found in cross-sectional samples. For women who use a contraceptive method, breast-feeding does not appear to influence contraceptive continuation, but for those who use no methods, breast-feeding appears to substitute for other forms of contraception. Profiles by socioeconomic characteristics of those who continue to use each type of contraceptive method and who use no method could be used to direct family planning programmes towards population sub-groups. The results suggest that for women wishing to postpone a pregnancy, a family planning programme aimed at the young and less educated could effectively increase contraceptive use and continuation.

Measuring the mortality impact of health interventions is not straightforward; there is now ample evidence of this. So why bother? Clearly, the utility, sensibility and feasibility of measuring the mortality impact of health interventions depend on many factors, which makes it difficult to offer simple prescriptions. The failure of those demanding measurement to appreciate this has led, on the one hand, to the proliferation of largely unsubstantiated claims on the achievements of health interventions and, on the other hand, to disillusionment about the prospects of demonstrating any impact on mortality. It is not difficult to account for the complexity of this area nor the current state of uncertainty. Progress has largely reflected developments in its three components—mortality measurement, health research and programme evaluation. It is thus not surprising to find the almost exclusive emphasis on measuring impact on infant and child mortality; in developing countries, child health is given a high priority in the allocation of resources by governments and donor agencies, and the techniques for estimating child mortality are generally more advanced.