Medical and social characteristics of couples who obtained a vasectomy at a Leicester Family Planning Association (FPA) clinic were compared with those from earlier studies. There were several differences which would suggest that the operation is now more popular with the public than in the late 1960s.

The results are presented of a survey of male subjects attending the Kingston Contraceptive Clinic for vasectomy. The men living in the Kingston Area (KA) were compared with those living in the Out of Kingston Area (OKA) for economic and other differences.

For both groups, the average age of the subjects at the time of interview was 36 years and the average age of their partners was 33 years. The couples in both groups had an average of 2·4 living children. The OKA sample had been married on average 3 years longer than the KA sample.

Economic differences were minimal, both groups having an average weekly income £22 in excess of the estimated average national wage. Educationally the groups were broadly similar, the OKA sample having a higher proportion of graduate subjects. The social class distribution of both samples was significantly different from that of the South-East of England, and showed that usage of vasectomy was predominantly by Social Classes II, IIIN and IIIM. This is interpreted as indicating the gradual spread of acceptability of vasectomy as a means of birth control through the social classes, in a manner similar to that already documented for the pill.

There is currently both an absolute and relative reduction in births to older women. In a single hospital population the number of older women. In a single hospital population the number of older women having amniocentesis for pre-natal diagnosis is only a small, though increasing, proportion of those at risk. The main factors in failure of offering amniocentesis are late booking and communication difficulty.

An experiment was designed to test the effect of a synthetic hypothetical human female pheromone on sexual behaviour. Sixty-two married couples participated for 3 menstrual months. No effect was found.

The use of the diaphragm and other vaginal caps has declined in the last decade with the rise of oral contraceptives and intrauterine devices. This is particularly clearly shown in the group of women attending family planning clinics. These changes have been accompanied by a shift in predominance from male methods to those initiated and managed by women.

Various characteristics of diaphragm acceptors at the King's group of hospital clinics have been studied from January 1972 to May 1976 and compared with those of women accepting other methods such as the pill and intrauterine device. There are marked differences in age at first attendance, and at various stages of family building; there are also differences in marital status and whether working outside the home or not. In the group of housewives accepting the diaphragm, there is an increased proportion whose partners are in non-manual occupations.

These differences are discussed in relation to the acceptability of vaginal barriers, the duration of their use and their effectiveness in the long term. If immediate acceptability could be improved by a new design, they might play a more useful part as a women's method of fertility control.

A probabilistic model of the human reproductive process is used to assess the success of hypotheses designed to explain human sex ratio fluctuations. It is shown that theories based on different maturation rates or effective lifetimes of X- and Y-bearing spermatozoa cannot account for many of the major sex ratio fluctuations.

A specific physiological model is proposed, based on differential motility of the two types of spermatozoa in the female reproductive tract, which together with differential fetal mortality, accounts successfully for most of the ratio fluctuations. On this theory the principal factor determining sex ratio is the physiological state of the female reproductive tract which in turn is governed by complex physiological and psychological parameters.

The sex composition of 862 sets of Australian triplets was independent of decade and State of birth during the period 1920–69. The triplet rate increased by 40% during the 50 years in contrast with declining rates reported elsewhere. The increase was due to dizygotic and trizygotic types, together but not individually, and occurred despite an 8·6% decrease in the average national maternal age over the same period. Adjustment for age led to standardized individual zygosity rates, estimates of which were compared with reported values obtained elsewhere. The dependence of zygosity rates on maternal age was shown to rise progressively as the number of ova released in triplet formation increases.

Current fertility rates of Asian and West Indian immigrant women in Britain are estimated by an indirect procedure. The data on which the estimates are based are the published statistics of registered births, and the 1971 Census country of birth tabulations.

It is shown that between 1969 and 1974 the total fertility rate of both groups declined at a faster rate than that of the indigenous population. The estimated total fertility of Asian women is, however, higher than that of West Indian women; the differences can be attributed at least partly to differential timing of migration.

The estimates of fertility rates for Asian and West Indian women provide a basis for a more realistic appraisal of local birth data.

Pupils in schools in the Glasgow area show incidences of colour vision defect higher in the Roman Catholic schools than in the non-denominational. This may be due to the Celtic origins of Roman Catholics in the West of Scotland.

Of 40 women who had abortions between 20 and 24 weeks gestation and had felt fetal movements, eleven had a history of significant menstrual irregularity, six had changed their minds about an initially welcome pregnancy, five had been told that they were not pregnant, and five had either been refused by the NHS or were unable to get sympathetic advice at an earlier stage. In only fourteen cases was ‘wishful thinking’ or an unrealistic attitude to the possibility of pregnancy an important cause.

Twenty-five of the women were followed-up at a minimum of 3 months after their abortion. Five reported feeling depressed because of their abortion but none of them had required specialist advice, and only one had time off work or school for this reason.

The present study was designed to assess the preference for and the continuation rates achieved with two previously available contraceptives (the pill and the IUD), and one newly introduced method (depomedroxypro-gesterone acetate, or DMPA), in a rural area of Thailand. After the presentation of balanced educational material on the three contraceptives, women were offered a free choice of method. It was found that 73·8% of all women adopted DMPA as their method of choice, and that this preference was not influenced by the educational lecture. In contrast, 16·9% of women chose the pill and 9·3% chose the IUD. The injection was perceived as a convenient method when compared to the other routes of administration, but the dominant preference for DMPA appeared to be largely due to ill-defined personal factors and the influence of friends. The 1-year life-table continuation rates with DMPA (75·5 per 100 women) were significantly higher than the continuation rate achieved with the IUD in this rural population (66·5 per 100 women). The continuation rates with the pill were 72 per 100 women, but the excessively high loss to follow-up with this method made the interpretation of the results difficult. It is suggested that if women are offered a free choice of contraceptive methods under a quasi experimental situation, useful information can be obtained on the potential value of new methods for an on-going family planning programme.