The characteristics of the first 200 cases of vasectomy reversal have been analysed. The mean time from vasectomy to reversal was 4.8 years. It varied according to the reason for requesting reversal, and was particularly short when the operation had been performed at the time of the partner's pregnancy. Thirty percent of the men were with the same partner and 70% a new partner. Vasectomy reversal cases tended to be younger than vasectomy patients as a whole but did not differ significantly in social class. In this series of reversals, spermatozoa were present in the ejaculate throughout the 20-week follow-up time in 80% of the men; the pregnancy rate was 44%.

The subsequent contraceptive behaviour following reported side effects in users of oral contraceptives in the southern region of Brazil is examined in relation to discontinuation of pill use, changing to other methods, termination of contraceptive use, the role of the physician in influencing a woman's decision to discontinue pill use, and discontinuation according to the type of problem experienced.

In 2904 currently married women, aged 15–44, almost 75% reported that they had used the pill at some time, and of these 45.6% were still doing so. Women who reported problems with the pill were less likely to be current users (25%) than the women who did not (65%). However, overall contraceptive prevalence was about the same in both groups. Women who stop using oral contraceptives are more likely to be using traditional methods than women in the general population, especially if they want more children. Termination of pill use varies little according to the type of problem reported. Women with problems who sought medical attention were more likely to stop using the pill and so were women advised to stop by their physician, but the major factor affecting discontinuation was the reported experience of a problem.

Examination of the effect of various socioeconomic, cultural and demographic characteristics of married women in Ilorin, Nigeria, who are in their prime childbearing ages, on their contraceptive knowledge and on their attitudes towards modern contraception shows that only the woman's education, age and area of residence within the city have significant independent effects on contraceptive knowledge. More than 90% of the women interviewed thought that women should be free to practise family planning. Also, more than 95% of all the women believed that too frequent births could endanger the health of the mother and her children. However, only the women with previous contraceptive knowledge overwhelmingly (more than 80%) thought that the best way to prevent too frequent births is by family planning. On the contrary, 66.5% of those without previous contraceptive knowledge before this study suggested that traditional abstinence should be used and only 28.9% suggested family planning. Adequate awareness of the availability and usefulness of family planning methods can influence attitudes of women towards contraception and may also enhance contraceptive use.

A study of families affected by thalassaemia major demonstrated that before antenatal diagnosis became an option, premature curtailment of reproduction was the most common parental response to their understanding of the genetic implications of the diagnosis. Subsequently parents of younger patients used antenatal diagnosis to meet or almost meet their birth expectations. There was no evidence that antenatal diagnosis contributed to any process of ‘compensating’ for existing affected offspring.

The relation between infant mortality and fertility is studied using data from the 1975 fertility surveys in Pakistan and Sri Lanka. It is found that the unadjusted data support child replacement, but that this is much less the case once controls are introduced for demographic and socioeconomic factors. Replacement is slightly more pronounced when there are fewer surviving male children.

The campaign for one-child families in the People's Republic of China has created world-wide interest. This study compares the general rates of single-child families in China and in 60 other countries and shows that China's current rate (12.5) is relatively low in comparison with some developed countries, e.g. Hungary (25.0). The mean age-specific single-child rate for 54 less developed countries shows a different pattern from that for seven developed countries; this is likely to be due to the later age of marriage and longer birth intervals of women in the developed countries.

This paper considers how changes in women's socio-cultural characteristics have influenced recent patterns of differential fertility in the United States and whether the convergence of fertility differentials observed up to 1970 has continued. Analysis of data from the June 1980 United States Current Population Survey, suggests that there has been no change in differential fertility in recent years. Age at first birth, length of first birth interval, income and education were all negatively associated with fertility, among both older and younger women. When fertility expectations were examined, however, the association of the independent variables with expected completed fertility was weaker among younger women, indicating that there has been some convergence in expected completed fertility. Further narrowing of differentials in actual fertility depends on how successful the younger women are in preventing future unplanned births.

The fertility of the Sudanese population (North) is close to natural. The high observed fertility rate in Sudan is found to be a function of the high proportion married and ineffective family planning procedures. The main inhibitor is prolonged lactational amenorrhoea. The high level of fertility exists in spite of a low level of fecundability. The duration of separation between spouses, due to temporary or seasonal migration of husbands, and the pathological causes of high primary sterility, which contribute to the low fecundability, need further investigation.

Birth records of Hutterite colonies were examined for the presence of seasonal variation in conception rate. Month of conception was inferred by counting back 9 months from date of birth. Over 4300 births, occurring between 1758 and 1964 and spanning the years that the colonies inhabited the Ukraine and then migrated to the United States and Canada, were included in the analysis. When combined, the European and North American births showed a seasonal pattern with a general rise in conceptions from December to June followed by a decline in conceptions from July to November. The major peaks in conceptions were in April and June, with a minor peak in December. Separate examination of the European and American records revealed a secular change. The seasonality of North American conceptions was dramatically reduced when compared to the very distinct European seasonal pattern. It is assumed that both biological and cultural factors are responsible for the seasonal variation observed. The influences of light cycle, date of marriage, and work and holiday schedules on conception rates are discussed.

Data from the 1974 Korean National Fertility Survey indicate levels, trends, and socioeconomic differentials in adult mortality in the Republic of Korea. The indirect techniques of parental survival and the time location of mortality are used to estimate mortality levels and to discern time trends in adult mortality. Socioeconomic variables are considered for their relationship with levels of adult mortality. The index of household wealth (based on the ownership of modern goods, size and space of household) and education stand out as the most important differentials in adult mortality. The trend in mortality decline is most pronounced for the subgroups representing higher levels of educational attainment and greater ownership of modern goods even after adjusting for the interrelationship between these two variables.

Estimates of preferred family sizes are derived from those achieved at various durations of marriage, using a Monte Carlo simulation model of reproductive histories, slightly modified in its representation of breast-feeding. The method of estimation consists in inverting the relationship between these two distributions (wanted and achieved births) which form respectively an input to and an output of the model. The increasing preference for families of two children is shown in cohorts married in England and Wales in 1951, 1956, 1961, 1966 and 1971 for women's ages at marriage 20–24 and 25–29. Sensitivity to assumptions regarding contraceptive effectiveness is tested, and ranges established for estimates. The evolution and stability of family size preferences are discussed.