In a study carried out in an African population in Western Nigeria and a Caucasian population in Aberdeen, Scotland, it was found that DZ twinning rates varied with maternal age and parity, the MZ twinning rate remaining fairly constant. However, women aged 30–34 were found to have the highest rate in Western Nigeria whereas the peak in Aberdeen population occurred in the older age group, 35–39 years. Other factors that influenced DZ twinning rates were maternal height, social class and ethnicity (in the Nigerian population), and illegitimacy (in the Aberdeen population). No significant association was found between twinning and maternal blood groups or season of the year in either of the two populations. An important factor that also influenced twinning in the two populations was the maternal serum FSH level. The levels were much higher in the Nigerian population than in the Aberdeen population. Furthermore, in the Aberdeen population, twin-prone and non-twin-prone women had similar serum FSH levels, whereas the levels were much higher in twin-prone women in the Nigerian population. This finding is consistent with the fact that the Nigerian population has a much higher twinning incidence (approximately 50 per 1,000 maternities) than Aberdeen population (approximately 12 per 1,000 maternities).

This article describes a study designed to test a method for assessing the cost to the health services of illegally induced abortion and the feasibility of estimating the incidence of induced abortion by a field interviewing approach. The participating centers included three hospitals in Ankara, Turkey; three hospitals in Ibadan, Nigeria; one hospital in Caracas and one in Valencia, Venezuela; and two hospitals in Kuala Lumpur, Malaysia. Hospitalized abortion cases were classified as induced or spontaneous or as "probably induced," "possibly induced," or "unknown" according to a classification scheme comprising certain medical criteria. The sociodemographic characteristics of induced and spontaneous abortion cases were subjected to discriminant function analysis and the discriminating variables best characterizing the induced versus the spontaneous abortion groups were identified for each center. On the basis of this analysis, the "probably" and "possibly" induced and "unknown" categories were further classified as induced or spontaneous abortion, with stated probabilities. Thus an overall estimate is made of the proportion of all hospitalized abortions that can be considered illegally induced outside the hospital. Selected results on costs of induced and spontaneous abortion are shown. The method further tested the feasibility of obtaining valid survey data on abortion from the communities studied by re-interviewing the women hospitalized for induced and spontaneous abortion six months later in their homes. This exercise showed a degree of under-reporting of abortion that varied widely among centers, even among women who had admitted illegal induction at the time of hospitalization. The feasibility of estimating the incidence of illegal abortion by field studies is discussed in the light of these findings.

The dizygotic twinning rate in Western Nigeria is the highest on record (45—50 per mil maternities). It is suggested that, rather than to peculiarities in the population structure or to genetic factors, such a high incidence might be due to the presence in the diet of estrogen-like substances.

No abstract

Summary Serum levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured daily for 10 days from the 7th day of the menstrual cycle in 15 healthy Yoruba women, six of whom had singleton infants, seven of whom had had one set of twins, and two of whom had had two sets of twins. Mean FSH levels were higher at the peak and for four days before and after the peak in women who had had twins, compared to those who had had singletons, and higher still in the women who had had two sets of twins. Mean LH levels and the height of the LH peak were less clearly related to the twinning history.