A study of MZ and DZ twins suggests that cultural differences are less important than individual environmental experiences in determining the age of first sexual intercourse. Certain personality factors are found to be correlated with this trait and there is also evidence that genetical differences may predispose individuals to cross this threshold at an earlier or a later age.

This paper reports the social and medical characteristics of women resident in Aberdeen city who were sterilized in 1951–52, 1961–62 and 1971–72, 211, 399 and 1125 women respectively. In 1951–52 women were offered sterilization, the majority being lower social class mothers with five or more children who were sterilized concurrently with abortion; the small number of upper social class women had one or two children and were sterilized for medical or obstetric reasons. By 1961–62, sterilization as a mean of family limitation was becoming acceptable to women in all social groups, families were of four or five children and the women were much younger when they were sterilized post-partum. Later in the 1960s, oral contraception, IUDs and laparoscopy and vasectomy were introduced. In 1971–72, women themselves requested sterilization, the two–three child family was the norm, the proportion of upper social class women continued to increase, and interval sterilization was gaining ground.

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.

One of the major goals of health programmes in the developing world is to improve maternal and child health. Two important steps towards achieving this goal are the promotion of birth spacing and the promotion of breast-feeding. Since birth spacing requires some type of fertility control measures, modern contraceptive programmes are becoming an integral part of maternal and child health programmes. The next logical question would then appear to be, ‘What are the appropriate contraceptives, particularly among the modern methods, for use during lactation ?’

Although steroid contraceptives have been in widespread use for many years, there still appears to be considerable uncertainty in the minds of many clinicians and family planning programme decision-makers regarding their prescription to nursing mothers. This uncertainty appears to be reflected in replies to a questionnaire sent by the Human Reproduction unit of WHO to scientists in its network of Collaborating Centres for Clinical Research in Human Reproduction regarding the current status of the use of steroid contraceptives by nursing mothers in different national settings. Although the information was, of necessity, in some cases imprecise, the following impressions were gained about eighteen countries: (Australia, Canada, Chile, Egypt, Holland, Hungary, India, Mexico, Nigeria, Philippines, Singapore, Sri Lanka, Sweden, Thailand, Turkey, United Kingdom, USA, Zambia).

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.

Of 50 women who were having their third or subsequent legal abortion, 23 were pregnant because their contraceptive method had failed, 24 because of erratic contraceptive use, and three had changed their mind about an initially welcome pregnancy. There was a significant relationship between erratic use and a history of medical consultation for psychiatric reasons, and a suggestion that unsettled relationships and low educational status are also related to erratic use.

Inappropriate contraceptive advice was an important factor in several cases. Since the perfect contraceptive does not exist, and since some people are more unlucky than others, repeated abortion cannot be eliminated, but it may be reduced by giving especially careful contraceptive advice to those who are clearly at risk.

There is no evidence that abortion is being deliberately used as a method of birth control.

One hundred and thirty six lactating women were studied, 42 controls and 94 taking oral contraceptives. Combination pills of oestrogen and progestogen (Primovlar and Minovlar) and a low dose progestogen pill (Norgestrel) were used. The selection of a particular formulation was based on the endocrine profile of an individual; this reduced drop-outs due to side effects.

The change in the quantity of milk was assessed by test-feeding followed by manual expression. Milk was also analysed quantitatively. Significant reduction in the milk yield was found with the Primovlar and Minovlar groups but no change was observed with Norgestrel. No change in the quality of milk was found for any of the three groups.

The proposed method of bleeding pattern analysis avoids the problem of defining the menstrual cycle. The difficulty of maintaining a cyclical approach becomes acute when methods of fertility regulation are used which are known to disrupt seriously previously experienced bleeding patterns.

By using eight simple measures relating to the pattern of bleeding over a fixed period of time, it is possible to present sensitive indicators previously available but not used. These indicators will permit a more meaningful comparison of data obtained from different groups of women or for the same woman over time. The eight measures relate to the number, average duration and variability of bleeding episodes taking place within a defined period of time; the variability of the bleeding-free interval; the average duration and variability of the bleeding episode and its succeeding bleeding-free interval; and the number of days on which bleeding has occurred.

Agreement was reached by the Workshop participants regarding the terms to be used, the definition of these terms, the statistical approach to be adopted and the analytical procedures to be followed in the analysis of bleeding patterns. It is hoped that this alternative approach to bleeding pattern analysis will assist researchers, clinicians and other investigators in the collection, analysis and interpretation of menstrual bleeding patterns.

An example of this approach is given in the following paper by D. Mayes. This example is based on data in the form of diary cards made available to the Family Planning Research Unit, Exeter University, by John Guillebaud of the Churchill Hospital, Oxford.

The purpose of this paper is two-fold; first, it seeks to examine the differences in menstrual bleeding patterns between users of three IUD models and second, it presents the advantages and disadvantages of the methods of analysis recommended by the Exeter Workshop on Bleeding Pattern Analysis reported by Snowden (1977, see p. 107 of this issue). The principal feature of this means of comparison is that the pattern of menstrual bleeding is assumed to be complex and multivariate. Previous analysis has tended to concentrate on the length of menstrual cycles, where such cycles are denned as the interval between the onset of one period of menstrual bleeding and the next. In addition to this type of information, the present study also incorporates information on the length and variability of periods of bleeding and intervals between bleeding. This information is readily available and easily collected.

The contraceptive method used during lactation should be chosen on the basis of (a) effectiveness in preventing pregnancy and (b) its effect on lactation. Combined hormonal contraceptives affect lactation adversely due to the oestrogen component. Progestogen-only contraceptives may increase the quantity and quality of milk yield during lactation. In the present study the effects of four progestational drugs used immediately after delivery were investigated. No adverse effect on initiation of lactation was found. The side effects of the drugs are reported. No pregnancies were reported during the period of the study.