Although an interest in illegitimacy as a societal phenomenon is often limited by the scarcity of data, we may utilize recognized procedures of standardization in estimating illegitimacy ratios and rates where none are reported.

When we know only the age-specific marital status of women in the childbearing years (15 to 44) we may utilize age-specific legitimate and illegitimate fertility rates of the high and low illegitimacy countries, Jamaica and Japan, to estimate the range within which a national ratio would fall. In all there are sixty-eight major countries of the world for which we have that minimum data on age and marital status of females.

Some of those countries also report the number and percentage of illegitimate births but offer no information on age-specific rates. In those cases we may compare the ratios produced by the four model sets of rates (run against actual age and marital status for the sixty-eight nations) with the ratio actually reported by individual countries. Where the ratio produced by a model matches the reported ratio, with similar crude birth rates, we may assume similar age-specific legitimate and illegitimate fertility rates. Even where there is no perfect match we still learn something of the general pattern of rates.

Finally, the output of the standardization procedure also allows a comparison of the relative importance of marital status versus differential illegitimate fertility rates in determining the percentage of births out of wedlock.

While we must recognize the problems inherent in international comparisons of illegitimacy, the subject is of such significance that we cannot and we need not wait for more, or more perfect, data to be available. Rather, an increased interest in maximizing whatever comparative data we do find, may, in itself, aid in the improvement of methods and reliability of collection and publication of relevant information.

Data showing the relative ages of husbands and wives at marriage in one post-war year are available for many countries, and show that the age distribution of wives for men of a given age varies appreciably from country to country. So also does the age distribution of husbands for a given age of bride. The range of the average ages of marriage partners, from country to country within Europe, is about 2 years for either sex.

The first part of the paper investigates how far these variations are associated with the corresponding international differences in the supply of men and women available for marriage. There is some correlation—mostly positive at the younger and older marriage ages and negative at the central marriage ages. The results show an affinity with those of a similar study based on time trends in one country alone: England and Wales.

In so far as age distributions at marriage are not directly associated with the supply of people available as partners, international variations may be regarded as the expression of differences in social custom, in economic history or in taste. In the second part of the paper such differences are exhibited and discussed. For a given age of one spouse, partners in most countries are older than in Britain but younger wives are found in some Communist countries and also in the Commonwealth.

In the final section, the development of the marriage age experience in two countries—France, and England and Wales—is compared over the period 1911–61, and some interesting differences are revealed, especially in relation to the effects of world wars, of economic depressions and the history of contraceptives. In 1911, appreciably older husbands and younger wives were found in France than in Britain, but today the differences between the two countries are much smaller.

The basal body temperature was recorded by 1353 healthy fertile women aged 18 to 49 years inclusive through 12,247 cycles. The post-ovulatory (hyperthermic) phase of the cycle was significantly longer by 1·31 days in cycles with a slow or staircase rise of temperature than in cycles with an acute rise. The hyperthermic phase increased in length in a rectilinear fashion from 10 to 13 days as the total cycle length rose from 22 to 29 days; over total cycle lengths from 29 to 33 days the length of the hyperthermic phase remained around 13 days.

A semi-longitudinal study of growth in children up to 5 years of age in a rural Jamaican community is described. One of its aims was to investigate the relationship between growth and factors in the social environment such as family structure, parental characteristics, housing and income. A strong relationship between growth and socio-economic variables was found. This apparently masked whatever effects the quality of care or separation from parents may have had upon child growth.