The fitness of human zygotes depends on both biological and demographic parameters. Some of the demographic parameters are changing at present in this country and accurate estimates of them are not available but this imprecision has no great bearing on the estimate of fitness offered below.

Of 100 human zygotes, now, in this country, it is estimated that embryonic and early fetal loss (before the end of the 3rd month) accounts for 44; induced abortion, 7; late fetal loss (after the 3rd month), 4; and mortality between birth and maturity, 1½. Of the remaining 43½ who reach maturity, it is estimated that 8 fail to reproduce, leaving 35½ who do reproduce.

The standard error of this estimate must be large because of the large standard error of the estimate of the incidence of natural reproductive wastage from which it was derived.

This is a retrospective study of 1754 patients seen at the Brook Pregnancy Advice Service (Avon) in the 3½ years January 1971 to June 1974; 1653 patients were referred for termination of pregnancy. The ages of the patients ranged from 13 to 44 years; the age peak was 19 years. Most patients attended between the 7th and 10th weeks of pregnancy; the peak was at 8 weeks. The majority of patients from outside the clinical area were referred for abortion privately. Patients from within the clinical area were referred to the NHS slightly more often than privately. There is a delay of 2–4 weeks for an NHS gynaecological appointment and a further 1–4 weeks before termination. Private patients are seen within 7 days and their abortions are performed within a few days. Patients from within the clinical area are more likely to return to the clinic for follow-up. There is a considerable fall-off in the continuation of follow-up for all patients returning to the clinic.

Birth records in Birmingham were examined for evidence of reproductive compensation following a fetal or infant death. Mothers with a stillbirth, a neonatal death, or a post-neonatal death in 1964 were identified, controls were selected, and subsequent reproductive patterns up to 1969 were compared. There was substantial reproductive compensation following the post-neonatal deaths and a lesser degree after neonatal deaths. Stillbirths were followed by compensation in the first year but this was not maintained and there was a net reduction of effective fertility over the whole 5-year period. Within this pattern, the extent of compensation varied according to the number of older surviving children. Both fetal and neonatal deaths tended to recur. There is evidence that reproductive compensation is partly attributable to pre-existing fertility differentials, but also to eventdetermined modifications of reproductive behaviour. With respect to haemolytic disease of the newborn the data provide some evidence in support of the theory that gene frequency stability depends upon reproductive compensation, but the interpretation of the data in this respect is not completely reliable.

This small study has looked at only one aspect of the reliability of survey data–their repeatability at an interval of 2–6 months with a different interviewer. Even for basic factual data such as date of birth, household composition and number of children there were some errors. Some were coding errors, some punching, some appeared to be reporting errors, but the numbers were small and no discernible patterns emerged.

For other factual data, such as ability to have more children or the use of different methods of contraception, the repeatability seemed to vary with the hardness of the categories. Sterilization was reported consistently, but more loosely defined characteristics, such as difficulty in conceiving or carrying a pregnancy to term, proved relatively unreliable; birth control methods which involved use of an appliance were more consistently reported than withdrawal and the safe period.

If ‘hard’ facts were reported more consistently than ‘soft’ ones it might be thought that attitudes would be reported less consistently than facts. But the dimension of hard versus soft cuts across both factual and opinion data. Fortunately for us, the question about whether they wanted more children appeared relatively hard; only 2% appeared to have changed their minds radically about this. Their memory of their intentions about becoming pregnant on the last occasion was more consistent than their reports about use of contraception around the time of conception.

Using the ISCC and the Burnham-Clark-Munsell tests, the colour aptitude and colour memory of a group of art students have been compared with a control group, matched for sex and age. The results of the colour aptitude test show that, for the men, but not for the women, the art students performed significantly better than the control group. With the colour memory test, there was no significant difference between the art students and the controls but, overall, the women had better results than the men.

The data of Pakrasi & Halder (1971) have been further analysed. No evidence was found to refute the hypothesis that there is no correlation between the sex of consecutive births except in families of four or more.

In this paper, non-marital pregnancies are defined as the sum of ex-nuptial confinements and the first nuptial confinements delivered within the first 8 months of marriage. Analysis is based on the annual statistics of live births, marriages and female non-married population as enumerated in the 1947–71 censuses. The incidence of non-marital pregnancies increased significantly in Australia between 1947 and 1971. This was found to be mainly due to rising ex-nuptial fertility rates, and, to a much lesser extent, to increased frequency of pre-marital pregnancies. A lesser proportion of pregnant non-married women were married before delivery in 1971 than in 1947. Some of the social implications are discussed.

Since the first rush of publications on IUDs following the start of Tietze's Cooperative Statistical Programme for the Evaluation of IUDs (Tietze & Lewit, 1970) there has rarely been a period in which a report relating to newer, ‘second-generation’ devices has not been published. There are degrees of sophistication in these reports varying from the odd anecdotal reference and highly subjective clinical impression to carefully constructed and evaluated large-scale clinical and field trials. This in itself creates problems, for the carefully constructed trials tend to be reported long after the clinical impressions have been publicized. In some cases the impressionistic information has so affected opinion that the presentation of data from large-scale trials providing greater validity and reliability becomes merely an academic exercise.

Clerical mortality rates in the United Presbyterian Church in the United States of America and the Lutheran Church-Missouri Synod have been studied in relation to selected social characteristics.

Overall mortality rates in the two study groups are more favourable than those for both the general US male population and for the total US white clergy. For most specific causes, the rates for the Lutherans but a high degree of similarity exists.

Possible explanations for these findings are discussed.

This paper attempts to assess, by assuming the sex of a live birth to be a binomial event, the contribution of desires for specific sex compositions to the level of birth rate. Data from India are utilized to quantify the contribution. It is found that the birth rate in India could be greatly reduced by an effective campaign of limiting family size to three, even if the campaign were accepted by only those couples who had achieved their desired family composition.

A retrospective study of 185 Thai males who had been vasectomized at Ramathibodi Hospital, Bangkok, between January 1970 and March 1973 was conducted during the period May–July 1973. At the time of the vasectomy the mean age of the men was 33·5 years and the mean age of their wives was 29·9 years; they had a mean of 3·7 living children. The motivation for seeking a permanent method of fertility control was a combination of adverse economic pressures, a degree of rationality in family building, and worry over additional pregnancies. Only a few of the men experienced any medical complications as a result of the operation, and the most significant factor associated with health was fatigue. Few changes in mental health, social relationships, or personal habits occurred as a result of the operation. Post-vasectomy changes in sexual relations were found to be minimal; if occurring at all, such changes were usually improvements. Taking into consideration the age of husband and wife, duration of marriage, and number of living children, the demographic impact of vasectomies in Thailand seems to be greater than that in other developing countries where comparisons can be made.

Eleven-year-old boys and their parents from southern Ontario, Canada, were used to examine relations among sibling constellation variables, social status indicators and a set of parent-sibling interaction variables which were highly predictive of mental ability performance. A two-term equation including father's occupation and either sibsize or the inverse of sibsize parsimoniously accounted for as much significant variance in the parent-sibling variables as complex many-termed equations. Within each socioeconomic group the amount of parent-sibling interaction decreased as the family size increased. It was also found that in high social status groups the amount of interaction in large families was greater than in small families from lower social status groups. By using refined environmental measures the study provides an increased understanding of the relations between social status, sibling constellation variables, family environment and cognitive performance.

The shape of the mandibular symphysis was studied in four groups of adult male Caucasians, aged 18–49. The composition of the groups and their numbers were as follows: (1) Down's syndrome (20), (2) familial idiopathic subnormality (20), (3) healthy individuals, IQ range 94−120 (22), and (4) healthy individuals, IQ 130+ (22). From lateral skull radiographs, the outline of the mandibular symphysis was digitized with a D-mac pencil follower. Selected distances and angles were computed and used as variables in a canonical analysis. Plots of the canonical variates discriminated appreciably between each group. Generalized distance measurements between group means were significant for all pairs of groups except 2/3 and 3/4. The results suggest a genetic link between intelligence and symphysis shape. This hypothesis will be tested by introducing a brain-damaged group, matched in intelligence, and for length of stay in hospital, with Group 2. The finding could influence developments in human genetics and psychology.

Data published annually by the Registrar General for England and Wales indicate that over the past 10 years the numbers of births—and, since 1968, of legal therapeutic abortions—to teenagers have increased substantially. During much of the same period the fertility of older women declined. This paper examines the recent demographic trends in teenage pregnancy, and compares the fertility of these teenagers with that of older women.

The personality dimension ‘introversion-extraversion’ as a factor in the socialization of approved school delinquents has been examined. Contrary to expectations of certain theorists, the allegedly more easily socialized introvert is usually not under-represented in delinquent populations. The possibility was investigated, therefore, that the level and type of attention an individual receives during the socialization process is a function of personality factors thought to reflect socialization capacity. The findings supported this hypothesis from which it would follow that a significant correlation between delinquent behaviour and such personality characteristics is improbable.

Studies of school age children who were severely malnourished in infancy have focused primarily on somatic growth and intelligence, but information about behaviour is almost completely lacking. In this study the social behaviour of 71 Jamaican school boys who were severely malnourished in infancy (index subjects) is compared with that of classmates of the same age and sex (comparisons) and also with the nearest sibling of the same sex where available. The child's behaviour in his home setting was assessed through an interview with the child's parent or parent substitute. It was found that the index children differed significantly from their comparisons in several ways. They were less liked by siblings and more unhappy at school. They more often behaved immaturely, were more clumsy and were either more highly active or lethargic. They were also more often withdrawn, solitary or unsociable. Differences between index boys and their siblings were not statistically significant on individual questions but were in the same direction as the index-comparision differences. No relationship was found between the age when admitted to hospital for malnutrition and later behaviour. Examination of the aetiological role of malnutrition and other biological and social factors is the next step in the present study.

Data from New South Wales are analysed to show how the interval between confinements depends on the parity of the mother. When an average interval is calculated it is a weighted average for mothers of varying parity. The weights depend in part on the parity progression ratios and as changes in the parity progression ratios alter the composition of the population by parity, this affects the weightings used and thus affects the average interval obtained.

For any interval, age of mother can be calculated at the birth of either child. When age of mother is calculated at the birth of the second child, it is found that the interval is shorter for younger mothers than older mothers. However, when age of mother is calculated at the birth of the first child, there is no significant variation in the interval with age of mother.

The problem of involuntary childlessness and its effect on marital happiness has been studied in an investigation involving interviews with 75 childless couples and a matched control of 75 couples with children. Marital happiness in various phases of the couple's relationship is plotted; in childless women this is seen to fall to its lowest ebb during the phase immediately before the problem is brought to the attention of the doctor, whilst in men it occurs whilst waiting for the medical diagnosis to be made. It seems that whilst childless marriages in themselves are not necessarily less happy than those with children (though all the childless couples interviewed had sought to change their situation by seeking medical help) such marriages are based on a different equilibrium from that of couples with children. In childless marriages there is often closer communication between the partners and a greater degree of communis opinio. People with children are sometimes over-careful in their approach to those without children. Attitudes and behaviour with regard to fidelity are seen to differ; the childless couples interviewed were less permissive in this respect than those with children. Alternatives in the form of artificial insemination, adoption, careers and pets are briefly considered.

Long-term evaluation of continuous microdosage of norgestrel suggests reappraisal of this form of oral contraception.

The influence of the country of origin of the father on mean birth weight of offspring of Jewish immigrants to Israel has been examined in an analysis of 98% of records of live births for the period 1968–70. The mean birth weight of infants born to parents from the same country (in-group marriages) was 3309 ± 570 g and that of infants whose parents came from different countries (out-group marriages) was 3289 ± 565 g: these differences are not significant.

Infants born to immigrants from North African countries are heavier, and those born to immigrants from Asian countries lighter, than the Israeli mean. Apart from Algeria (whose immigrants have babies heavier than those from other North African countries) and India and Yemen (whose immigrants have babies lighter than those from other countries of Asia) there were no significant differences in adjusted mean birth weight by country of origin, within each continental group.

Mean birth weight is determined by a combination of maternal and environmental factors, paternal factors having little effect.

Analysis of birth weights of second and subsequent generations of Israeli-born, by origin of their grandparents, shows a fall in mean birth weight of those of North African descent and a rise in those of Asian descent, i.e. a tendency to approach an Israeli mean.

(Summary in Hebrew, p. 164.)