Application of a multivariate analytical technique to the World Fertility Survey data for Java and Bali indicates that demographic variables, particularly the length of the preceding birth interval, are more important in explaining infant and child mortality differentials than are such social variables as education of parents or urban–rural residence. These findings are weakened to some extent by the lack of satisfactory data on household economic status which might have provided a better base for indirectly discerning the effects of nutrition and sanitation on mortality at young ages.

Recent data do not demonstrate any trend away from consanguineous marriages in the urban Middle East. The continued observance of this preferential custom may correspond to the persistence of an archaic trait among urban dwellers; if this holds true, then one would expect consanguineous couples to conform more to the traditional family pattern than others. In order to test this hypothesis, 100 women married to a relative and 100 matched controls, selected from a hospital setting in Beirut, were interviewed with respect to their household type (nuclear/extended), residential pattern (proximity of parents and parents-in-law's residence to theirs), contacts with family and sex definitions. A substantial proportion of the respondents comply with the traditional norms prevalent in the Middle East (25–55%, according to the criterion), but no difference is detectable between cases and controls in this respect.

Estimates of preferred family sizes are derived from those achieved at various durations of marriage, using a Monte Carlo simulation model of reproductive histories, slightly modified in its representation of breast-feeding. The method of estimation consists in inverting the relationship between these two distributions (wanted and achieved births) which form respectively an input to and an output of the model. The increasing preference for families of two children is shown in cohorts married in England and Wales in 1951, 1956, 1961, 1966 and 1971 for women's ages at marriage 20–24 and 25–29. Sensitivity to assumptions regarding contraceptive effectiveness is tested, and ranges established for estimates. The evolution and stability of family size preferences are discussed.

In all European countries for which data exist, there was a maternal-age-specific decline in dizygotic twinning rates during the 1960s. For most of these countries, this decline continued through the 1970s, but in a few it apparently ceased. The causes of the declines and of their abatement are unknown. However, there were declines in sperm quality during the 1960s and 1970s in some parts of the world, including parts of Europe, and it is speculated here that this decline in sperm quality may be related to the decline in dizygotic twinning.