Nowhere is the issue of the pathogenic effect of the boom versus the bust better illustrated, and nowhere is the question of the use of the lag as a statistical device more central, than when we look at infant mortality. The early studies of the business cycle, as we have seen, found infant deaths to increase in the boom. Predictably, however, when Brenner studied this relationship he found increases in infant mortality to be a response to economic downturn after a lag of varying numbers of years. The death rate of infants aged one month to one year (post- neonatal mortality), for example, is said to be related to increases in unemployment with a lag of 3–5 years.69 Figure 2.1, which is taken from
Brenner’s article on the topic, illustrates this point. In the figure, percentage changes in post-neonatal mortality occurring over five-year intervals are plotted annually for half a century. Brenner has advanced the infant-mortality graph by four years, to match the lag that his statistical analysis reveals, and to show a mirror-image relationship between the lagged graph of infant mortality and an inverted graph of unemployment (i.e., unemployment and lagged infant mortality rise and fall together).
There are problems with this analysis, however. In the first place, if we do away with Brenner’s lag and put the graph of post-neonatal mortality back where it started, four years later—as in Figure 2.2—we see that there is a respectable fit between the mortality graph and the inverted unemployment rate. In other words, it seems that post-neonatal mortality rises when unemployment falls. This picture suggests that we should at least look to see if such an inverse correlation is statistically significant—but Brenner does not do so.
In the second place, there is no logical explanation for a four-year lag in post- neonatal mortality. Deaths in this age group—one month to one year -are typically related to the immediate environment and are due to such causes as intestinal and respiratory disease, infections and accidents. One would predict a lag of no more than a month behind an economic change in most cases. Even if one hypothesized that the infant was at increased risk of death due to economic influences working throughout the mother’s pregnancy and delivery, then the maximum lag period in those instances would be less than two years. A four-year lag makes no rational sense.
Finally, there exist excellent a priori grounds for assuming a direct link between high infant mortality and the boom. Victorian observers were well aware that infant mortality in Britain decreased during crises in trade.70 Figure 2.3
demonstrates that the contemporary commentators were correct: infant mortality rose and fell with the industrial growth rate through the latter half of the nineteenth century.
The reason for this effect, maintained the philanthropists and physicians of the time, was the employment of mothers. In the industrial areas of Victorian England a very large proportion of young married women were employed in the factories from dawn to dusk—or longer. Female factory hands returned to work within two weeks of the birth of a child, frequently leaving the infant in the care of elderly child-minders or girls as young as seven years of age. Fatal accidents to infants in the care of incompetent minders were not uncommon. Laudanum and other widely available preparations of morphia were freely used to quiet fractious babies. Early weaning was essential and infants were routinely fed with watered- down and often contaminated milk. Deaths from intestinal infection were prevalent.71
Physicians pointed out that infant mortality was highest where more women were employed in the factories. Around the Lancashire cotton mills the death rate was particularly high, and the Medical Office of Health for Staffordshire offered the following figures for 1880.72
There is another reason—one that is particularly relevant to the topic of this book—why infant mortality may increase during the boom. Women who are raised in poverty have poor nutrition in childhood and are consequently small in stature and likely to have small pelvic cavities and birth canals that are malformed by rickets (vitamin D deficiency). During the boom, their nutrition is likely to
Figure 2.1 Five-year changes in the US unemployment index (inverted) and the neonatal mortality rate per 1,000 live births. Neonatal mortality is moved forward four years to show the relationship with a four-year lag
Source: Reproduced from Brenner, M.H., “Fetal, infant and maternal mortality during periods of economic instability,” International Journal ofHealth Services, 3:145–59, 1973, by permission of the publisher.
improve and, when pregnant, the developing fetus will be larger than usual. As a result, labor will be more difficult and rates of brain damage and infant mortality due to
Figure 2.3 General mortality and infant mortality for England and Wales, and industrial growth for the UK 1810–1920; 920; expressed as five-year averages
Source: Mitchell, B.R., European Historical Statistics 1750–1970, abridged edn., New York: Columbia University Press, 1978.
Figure 2.2 Five-year changes in the US employment index and the neonatal mortality rate per 1,000 live births. Neonatal mortality is not lagged
obstetric complications will increase. We will return to this issue in Chapter 9. At that point it will be argued that the risk of obstetric complications and infant brain damage—and thus the risk of later development of schizophrenia—increases in different classes at different phases during the advance of industrialization. The result is a curious changing pattern of occurrence of schizophrenia.