This paper examines the antifertility effects of an IUD (Lippes Loop) subsequent to the discontinuation of its use. The experiences of 4449 urban Taiwanese women who discontinued the use of the Lippes Loop initially inserted during the period July 1962 to May 1965 are analysed. These women were followed annually for 6 to 9 years through clinic visits and home interviews. The effect of duration of IUD use on average fecundability and sterility is examined after controlling for women's age at discontinuation of use of the IUD. The results indicate that, among Taiwanese women, the level of sterility increases and the average fecundability decreases with the increase in the duration of IUD use. These differentials are quite substantial and are mainly observed among those women who were at least 30 years of age at the discontinuation of IUD use. Various implications of this finding are discussed. The results refer only to the Lippes Loop and cannot be generalized for other types of IUD.

At a hospital contraceptive clinic with between 1200 and 2400 new clients each year, regular recording is made of the social and personal characteristics of the clinic users together with their contraceptive and reproductive histories. An analysis has been made of the differences found between those accepting the pill and those the intrauterine device (IUD) at their first attendance. Age and parity show marked differences and these are related to employment and ethnic origin. Previous contraceptive use showed distinct differences; IUD acceptors were more likely to have had induced abortions. These findings are discussed in relation to the prevalent use of these two methods and it is suggested that IUD fitting should be more widely available.

An investigation of the incidence and pattern of non-marital pregnancies in New Zealand, and their outcome as nuptial or ex-nuptial births, has revealed four major features. The post-war period has been marked by a steady increase in the incidence of non-marital pregnancies, especially since the early 1960s (following the inclusion of Maori vital events). Pre-marital or bridal pregnancies increased during the 1950s, but have steadily declined at all ages between 16 and 23 years during the 1960s and early 1970s. Nuptial fertility rates for women aged 35 years and over have declined continuously since 1945, and since the early 1960s the decline has commenced for women at younger ages as well. Ex-nuptial fertility rates have been increasing throughout the post-war period and particularly since the early 1960s.

A study of the differentials in fertility of Iraq's Mohafadhas, and the association of fertility with various socio-cultural factors, is handicapped for want of the reliable vital statistics from which measures of fertility can be satisfactorily derived. The alternative method, using a simple measure of fertility, the child–woman ratio, which requires only a knowledge of the population in age groups is therefore used. Since this measure is computed from census statistics, it is affected by differences in enumeration errors and in mortality and migration. An attempt has been made in this paper to keep these factors constant by using a modified child–woman ratio for comparing fertility levels.

The analysis showed that fertility rates vary from region to region, between Mohafadhas within a region and between rural and urban areas. One important broad geographic variation was that the Northern region was the area of high fertility. For the Mohafadhas, significant differences were noted in only six of the sixteen Mohafadhas of Iraq. Rural–urban difference was minimal, with few exceptions, and it was not always in the same direction. The intra-rural variations in the fertility ratio were far more important than intra-urban differences.

Correlation analysis showed that the average age at marriage, the proportion never married and the sex ratio in the reproductive ages were the important factors in explaining fertility differences between Mohafad has. There was virtually no correlation between fertility and urbanization or literacy.

Guerrero (1975) has cited a wealth of direct data supporting the hypothesis that timing of insemination is related to the sex of the resulting zygote. It is argued here that if this hypothesis were correct, then parental coital rate would be associated with the sex of the resulting children. It is suggested here that empirical data support this inference and hence support the hypothesis.

It is estimated that if Pmale (the probability that a zygote will be male) declines linearly across the fertile period, that decline is from about 0·57 to 0·45.

Analysis of stillbirth data from the State of Wisconsin demonstrates that the association of stillbirth rate with mother's age is basically an artifact of analysis rather than a reflection of genuine effects of age on risk. When births to mothers of a single parity are subdivided according to the amount of education completed by the mother, the association between stillbirth rate and maternal age in each educational group differs substantially from the others. The association observed for all births of a single parity is inapplicable to any educational subdivision of the data.

It is argued that the associations which are observed are the consequence of social forces which distribute women of varying intrinsic risk of stillbirth unevenly among age–parity categories.

The first part of the paper traces changes in the length of the childbearing period and ages of women at the time of their first and last births among women in Australia married between 1905–09 and 1965–69. The source of information was survey data concerning the respondents themselves (once married, currently married women aged under 60 years at 1971) and information that they gave concerning their mothers' childbearing experience. The main observations are that the trend towards smaller families was more marked among the mothers and that the change in the size distribution of families was the major factor in reducing the length of the childbearing period for marriages occurring up to the Second World War, while closer spacing of children was the major factor since then. The second part of the paper examines more detailed supplementary information about the respondents, including changes in the dispersion of the timing of births, the rapid rate of childbearing among the 1955–59 marriage cohort, reasons for delaying the first birth, and differences in behaviour according to education and religion. The discussion raises the question of the rationality of the trend towards closer spacing of children, with special reference to the interaction between a woman's work role and family role.

The decline in the number of legitimate live births in England and Wales from the peak in 1964 has been partitioned into components due to changes in fertility rates, components due to changes in the composition of the population exposed to risk, and an interaction component. Fertility rates specific for age of mother at birth of child, duration of marriage, parity and age of mother at marriage were considered but in all cases it was found that the decline was not as great as the change in fertility rates implied. This was due to increases in the number of births due to changes in the composition of the population exposed to risk.

The decline in the number of births due to changes in fertility rates specific for age of mother/duration of marriage/parity/age at marriage has been expressed as a percentage of the number of births to each specific group and it was found that generally the percentage decline became greater as age of mother/duration of marriage/parity/age at marriage increased. However this did not apply for the youngest age groups, the shortest durations of marriage, the youngest ages at marriage and the lowest parity. This result needs further investigation. Is this evidence of a deferment of births by young mothers (with short durations, low parities and young ages at marriage)? Alternatively, is this evidence of the beginning of a really significant and widespread change of attitude to family size?

The combination of results from the 1971 Population Census and data specific to Birmingham make it possible to revise past estimates of the numbers of coloured persons in Great Britain. Such information also permits projections of the relative age structures of the coloured and total populations of Birmingham under differing fertility assumptions and Thomas's (1970) conclusions may therefore be revised.

In a medical practice in which artificial insemination has been carried out for over 40 years, 40% of women inseminated with donor semen (AID), and 21% inseminated with homologous semen (AIH) gave birth to children. Up to December 1975, 399 pregnancies were achieved using fresh donor semen and nineteen with deep-frozen semen. There was no apparent increase in the incidence of birth anomalies in children conceived with frozen semen, nor was there a significant increase in the incidence of still-births, ectopic pregnancy or miscarriage when compared to the rate in the normal population. Eight conceptions were achieved using deep-frozen semen stored for 6 months or longer, and one pregnancy was achieved with a specimen frozen for 3 years. Good cryosurvial was observed in semen frozen for up to 6·7 years. The development of many of the children was followed, and it was concluded that the great majority of marriages into which AID children were born, were undoubtedly enriched and psychological and sociological problems were few. The whole field still awaits the implementation of recommendations concerning the legal status of children born as a result of AID.