Natal Factors Research Articles

On maternal and infant mortality, 1900-1960.

It has often been thought that maternal and infant mortality were closely linked and responded in a similar manner to the same social, economic, and medical determinants of mortality rates. If there were a close link it would be expected to be strongest between maternal and neonatal mortality, because the latter is usually ascribed to natal (or endogenous) factors. Conversely, the link between maternal mortality and post-neonatal mortality might be expected to be slight because post-neonatal deaths are usually due to environmental (or exogenous) factors. In this paper, which is based largely on the period 1900–60, it is shown that against expectation the links between maternal mortality and all components of infant mortality, including neonatal mortality, are very slight. The explanation can be found by examining the immediate causes of maternal and neonatal deaths. The advantage of placing these mortalities side by side and comparing their response to various determinants is that it brings to the fore features of maternal and infant mortality which are not obvious if they are examined in isolation.

Family occurrence of schistosomal hepatosplenomegaly and maternal effect

In this paper we present a study of members of 265 nuclear families, aged six or more. This study is based of family heredograms, and takes into account the clinical form of schistosomiasis observed before treatment with oxamniquine. The probability of occurrence of two or more cases of hepatosplenomegaly is low, notwithstanding the fact that it was observed in 38 families. Even less frequent is the occurrence of three or more cases observed in 17 families (P = 0.002). The concentration of the hepatosplenic form was higher among siblings than it was among mothers and children, or fathers and children. It was found to be not significant between husband (father) and wife (mother). These observations reinforce the evidence for the presence of a genetic component in susceptibility to the hepatosplenic form of the disease. In cases in which the mother was hepatosplenic there was a higher incidence of hepatosplenic children; the relative risk was a least five times higher than in those in which the father was the affected member (the maternal effect). In cases where both members were affected by the hepatointestinal form, the risk to the filial generation was similar to that of the population in general. Thus, in the process towards severe forms of schistosomiasis mansoni, pre and post natal factors might be involved.

Clinical, biochemical and pathological study of perinatal lambs in a commercial flock.

The birth and fate of 818 lambs born to 571 ewes on a low-ground farm in the Scottish Borders with a history of substantial perinatal mortality were monitored with a range of physiological, biochemical and pathological measurements. In lambs which survived, the rectal temperature, birthweight and plasma concentrations of fructose, insulin, thyroxine and the third component of complement at birth, and the weight at four months of age, decreased with litter size. One hundred and thirty-seven lambs were stillborn or died within four days and seven others died later. The mothers of 77 per cent of these lambs had low condition scores, but the lamb deaths did not correlate significantly with the condition scores. From data relating to birthweight, temperature, packed cell volume and plasma composition it was deduced that placental insufficiency was involved in 24 per cent of these deaths; acute hypoxaemia at birth accounted for 35 per cent, inadequate thermogenesis for 12 per cent and starvation for 13 per cent. The remaining 16 per cent of dead lambs could not be assigned to any of these categories. Using only clinicopathological criteria, 37 per cent of the lamb deaths were attributed to antenatal influences which included immaturity, developmental anomalies, and degenerative or inflammatory changes. Thirty-three per cent of the deaths were due to post natal factors which included, in declining order of frequency, starvation, enteritis, misadventure, pneumonia, navel infections and septicaemia. No conclusions could be drawn from the pathological examinations alone in the remaining 30 per cent, although almost half of these had low rectal temperatures after birth, death being attributed to hypothermia.(ABSTRACT TRUNCATED AT 250 WORDS)

Bibliography on Prenatal and Natal Influences in Twins

AbstractThe author agrees with earlier writers that most of the differences observed in monozygotic pairs are due to unusual or extreme environmental factors acting before or during the twins' birth. Although they are typical of development in twins, these environmental factors can hardly be considered typical of development in other individuals. This point, as a review of the literature shows, is often overlooked by those who study twins in the childhood or adult age ranges. As a result the inferences drawn from twin differences are frequently mistaken, or at least quite exaggerated so far as the significance of postnatal influences in non-twins is concerned. At the same tihe, if allowance is made for the environmental biases peculiar to twin studies, the findings may be said to establish more about the importance of heredity in the medical and behavior sciences than most investigators have thought. In the author's opinion the largest single source of bias is the mutual circulation that exists during prenatal development of the majority of monozygotic pairs. Data on that circulation's difference-producing effects are reviewed and related to studies of mature twins. Effects of lateral inversions (asymmetry reversals) and of “natal” factors (chiefly conditions of delivery) are also reviewed, and methods of judging the importance of all three of the biasing conditions are outlined. Need for obtaining systematic and complete information about the natal factors is stressed.

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