Part 53

From these figures it appears that the maximum fertility of married women is attained, in Denmark at the age of 31, in Norway at the age of 31.7, and in Sweden at the age of 32 years. In the case of unmarried women, the maximum fertility is at the ages of 24 to 26 years. In the Austrian Empire, the maximum fertility of women is attained at about the age of 30 years; in England it is attained between the ages of 20 and 25 years.

Divergent results as regards the fertility of married women at different ages were obtained by Goehlert from the examination of 5,290 cases from the reigning families of Europe. In the favourable position as regards means of subsistence occupied by the members of these families, marriage naturally occurs, in most cases, much earlier in life, the mean age at marriage being between 19 and 22 years—the youngest mother (in the Capet dynasty) was only 13 years of age—and for this reason the figures relating to the younger age-classes are larger than in the previous tables. But as a result of this, the reproductive capacity also undergoes an earlier extinction, so that of these women, not one gave birth to a child when she was over 50 years of age. Goehlert gives the following table, compiled from these 5,290 instances:

Under 20 years 8.8% From 20 to 25 years 25.4% From 25 to 30 years 29.4% From 30 to 35 years 21.6% From 35 to 40 years 11.5% Over 40 years 3.3%

In these cases the maximum fertility was obtained at the age of 27.

The physiological fertility of women is much more clearly manifested when we compare the fertility of women who have been married a few years only, with the fertility of women in the later years of married life. In the earlier period, the effective fertility more nearly approaches the physiological fertility, because at this time the various influences by means of which fertility is later so greatly diminished have not yet come into operation. In this connection the following data, published by Körösi, regarding the percentage fertility of recently married women, and that of married women in general, will be found of interest:

═══════════════════════╤═══════════════════════╤═══════════════════════ │Recently-married women.│ All married women. ───────────────────────┼───────────────────────┼─────────────────────── At ages 20 to 35 years.│ 32.9%│ 20.6% At ages 35 to 40 years.│ 32.7%│ 14.7% At ages 40 to 45 years.│ 21.4%│ 5.9% ═══════════════════════╧═══════════════════════╧═══════════════════════

Inasmuch as we learn from this table that in the case of women aged 40 and upward, the newly married exhibit a fertility of four times as great as that of married women in general, in whom pregnancy has already become rare, we can infer the influence upon fertility of abstinence and of artificial measures for the prevention of conception.

On the average, the maximum fertility of woman, that is, the maximum of effective fertility, is attained at the age of 18 to 20 years. Extreme youthfulness, and also the opposite condition, too advanced an age, when marriage is entered on, impair a woman’s fertility; whereas the conditions most favourable to fertility are that, at the time of marriage, the uterus should have attained its fullest development, and the ovaries also should be completely mature; this is not usually the case at puberty, but rather at the age of 20, 21, or 22 years. In Austria-Hungary, of 100 marriages in which the wife’s age at marriage was less than 18 years, the average offspring in the course of a single year were 36 to 38 children; in the case of 100 marriages in which the wife’s age at marriage was 18 to 20 years, the average offspring in a year were 40; this being the maximum fertility, the number of offspring in a year per hundred marriages (i. e., the percentage fertility), now undergoes a regular decline as the wife’s age at marriage increases; at an age of 25, the percentage fertility is 32; at the age of 30 years, the fertility is 24%; at the age of 35, 17%; at the age of 40 years barely 10%; at the age of 45, 7%; at ages 45 to 50, 0.1%. Thus, from the last figure, we see that of a thousand women marrying at the age of 50 years, one only gives birth to a child. Men obtain their maximum fertility (i. e., procreative capacity) at the age of 25 or 26 years; at this age their fertility amounts to 35% (that is, of 100 marriages at this age, 35 children will on the average be born within a single year); at the age of 35 years, the percentage fertility of men falls to 23; at the age of 45 years, it is 9½%; at 55, 2.2%; at 65, ½% (Körösi-Blaschko).

Whereas hitherto we have considered only the monogenous fertility of married women, we must remember that the figures relating to their biogenous fertility are also of interest—that is to say, the changes which a woman’s fertility experiences in married life in respect of the peculiarities of her husband; and of these peculiarities, the easiest to make the object of statistical investigation is the husband’s age. The age of the husband exercises an important influence upon the fertility of the wife, as is proved by the following figures published by Körösi:

════════════════════════════╤════════════════════════════════════════════ AGE OF THE FATHER. │ AGE OF THE MOTHER. ────────────────────────────┼──────────────┬──────────────┬────────────── „ │ 25 years. │ 30 years. │ 35 years. ────────────────────────────┼──────────────┼──────────────┼────────────── 25 to 30 years │ 35.6%│ 25.0%│ 21.2% 30 to 35 years │ 31.2%│ 23.6%│ 19.9% 35 to 40 years │ 27.5%│ 21.8%│ 19.4% 40 to 45 years │ │ 16.7%│ 14.0% 45 to 50 years │ │ 14.4%│ 10.9% 50 to 55 years │ │ │ 10.9% ════════════════════════════╧══════════════╧══════════════╧══════════════

Also:

══════════════╤═══════════════════════════════════════════════════════════ AGE OF THE │ AGE OF THE FATHER. MOTHER. │ ──────────────┼──────────────┬──────────────┬──────────────┬────────────── „ │ 25 years. │ 35 years. │ 45 years. │ 55 years. ──────────────┼──────────────┼──────────────┼──────────────┼────────────── Under 20 years│ 49.1%│ │ │ 20 to 25 years│ 43.0%│ 31.3%│ 16.0%│ 25 to 30 years│ 30.8%│ 27.3%│ 18.5%│ 30 to 35 years│ 33.5%│ 23.7%│ 14.4%│ 8.1% 35 to 40 years│ │ 18.9%│ 11.8%│ 6.7% 40 to 45 years│ │ 6.6%│ 6.1%│ 3.0% ══════════════╧══════════════╧══════════════╧══════════════╧══════════════

We learn from these figures that the maximum fertility is exhibited by a woman 18 years of age, when married to a man 25 years of age; less fertile is a woman 25 to 30 years of age married to a man 28 years of age; still less fertile is a woman 35 years of age married to a man 29 years of age. Neither the age of the mother alone, nor that of the father alone, is determinative of the fertility of the marriage, for the fertility of young wives married to elderly husbands is quite different from that of young wives married to young husbands. Very various age-combinations are possible, and each exhibits an average fertility peculiar to itself.

We can also regard the question from the standpoint of the difference between the ages of husband and wife respectively. In this connection, Körösi is led by his tables to the conclusion that wives between the ages of 18 and 20 years attain their maximum fertility when married to men 7 years older than themselves; women of 25 years when married to men 3 years older than themselves; women of 29 years when married to men of the same age; women of 30 years and upward attain their maximum fertility only when married to men younger than themselves. Men, on the contrary, always attain their maximum fertility when married to women younger than themselves. The age of maximum fertility differs in the two sexes, and those marriages will be most fruitful in which husband and wife are each of the age most favorable to fertility. This will be the case when the age of the wife is 18 to 20 years, and that of the husband 24 to 26 or perhaps 29 years.

In connection with the question of fertility, we have also to take into consideration the vitality of the children born, that is, what proportion of those born survive. According to Körösi’s interesting papers regarding the fertility of the inhabitants of Buda-Pesth, we learn that for every 100 marriages which have persisted for thirty years and upward, there were born, on the average, 539 children, of whom during this period 241 died, so that the percentage of survivals was 55.28. Parents who have lost one only of several children must, therefore, regard themselves as exceptionally favoured by fortune.

Social position, occupation, and religion, have, according to the last-quoted author, a notable influence on fertility. His investigations showed that the Roman Catholics and the Jews exhibited the greatest fertility; among the Catholics there were 541 children, and among the Jews 557 children, per 100 marriages. Amongst 100 Protestant families, on the other hand, only 479 children had been born. It will be seen that the theory of the comparatively enormous fertility of the Jewish race is not supported by these statistics. The Jews do, however, exhibit a greater power of rearing children, for among them the marriages of more than 30 years’ duration had 61⅔ % of the children still living; among the Protestants 57¾% survived; and among the Catholics only 52–⅗%. It thus appears that the surviving offspring per 100 marriages of 30 years’ duration were, among the Catholics 278, among the Protestants 252, and among the Jews 349.

The question whether, and to what extent, the age of the parents has an influence on the vitality of the children, is answered by Körösi’s mortality statistics in the sense that mothers below 20 years of age give birth to a larger proportion of children deficient in vital power. Where the mothers had married at the age of 16, the mortality of their offspring was, among Catholics 43%, among Jews 33%; married at 17, Catholic mortality 44%, Jewish 30%; married at 18, Catholic mortality 42%, Jewish 32%; married at 19, Catholic mortality 41%, Jewish 29%; married at 20, Catholic mortality 40%, Jewish 26%. Of the children whose fathers had married at the age of 24, 32% had died; of those whose fathers had married at 23, 37% had died; of those whose fathers had married at 20, 42% had died; and of those whose fathers had married before 20, actually 44% had died. It thus appears that the children alike of very young mothers and of very young fathers have a lessened chance of survival.

Inasmuch as the fertility of the wife is a product of two factors, her own peculiar fertility, and that of the procreating male, the question of the fertility of women cannot be accurately treated independently of this second consideration; hereby, however, is introduced a multiplicity of obscure combinations, by which the value of all the statistical data of fertility in women is seriously impaired.

These data give as the measure of fertility, the number of children per marriage actually brought up, embracing fruitful marriages, sterile marriages, and those not yet fruitful. In Berlin, in Copenhagen, and in Buda-Pesth, the average thus attained was slightly less than three births to each family, whilst the number of children actually living averaged two per family. A more accurate representation of fertility is obtained by ascertaining the number of children born, and the number of children living in relation to the duration of marriages reckoned in years, that is beginning with marriages of one year’s duration, and proceeding year by year to the highest recorded duration of marriage. In this way interesting statistics have been obtained; for example, one who has completed thirty years of married life may count on the average that five or six children will have been born to him, but may also reckon on having buried two or three at least of these. (Körösi.)

Fertility is, as many facts indicate, also dependent on nutrition. A distinct proof, says Spencer, writing on the “Coincidence between high Nutrition and Genesis,” that abundant nutriment increases the number of births, and vice versa, is found among the mammalia; compare, for instance, the litter of the dog with that of the wolf and the fox. Whilst the dog’s litter numbers 6 to 14, that of the wolf numbers 5 to 7, that of the fox 4 to 6. The wild cat gives birth to 4 or 5 kittens once a year, the domesticated cat to 5 or 6, twice or thrice annually. The most remarkable contrast, in this respect, exists between the wild and the domesticated breeds of swine. The wild sow gives birth once a year to a litter of 4, 8, or 10 pigs (the number increasing in successive litters); the domesticated sow has often as many as 17 in a single litter, whilst in two years five litters, each numbering 10 pigs, are commonly born.

Darwin also draws attention to the fact that animals under domestication, being fed more abundantly and regularly than their wild allies, procreate at shorter intervals and are markedly more fertile than the latter. He states that the wild rabbit has four litters annually, each numbering 4 to 8 young; whereas the tame rabbit reproduces its kind six to seven times annually, and gives birth to litters numbering 4 to 11. Among birds, analogous phenomena are observed. The wild duck, for instance, lays 5 to 10 eggs in the course of the year, whereas the tame duck lays from 80 to 100; the wild grey goose lays 5 to 8 eggs, the domesticated goose 13 to 18.

It must be added that this exceptional fertility is manifested in animals that are quite inactive in comparison with their wild allies; not only are they richly fed, but they get their food without working for it. Moreover, it is easy to observe that among the domesticated mammals the well-fed are more fertile than the ill-fed.

That in the human species also, fertility is influenced to a notable degree by nutritive conditions, is shown by statistical investigation. After years distinguished by an exceptionally good harvest the number of children born is considerably greater than in normal conditions; whereas after a famine the opposite is observed. Malthus’s law of population states, inter alia, that the population increases when the amount of available nutriment increases, that is, that favourable nutritive conditions cause an increase, that unfavourable nutritive conditions cause a decrease, of population. Hardships and exhausting occupations diminish the fertility of women. The remarkable fertility of the Kaffirs is referred to the fact that this people, possessing large herds of cattle, lead a life comparatively free from care; it is no less true that the Boer women, who lead a life of well-fed leisure, have very large families; whereas the Hottentot women, poor, ill-nourished, and hard working, seldom bear more than three children.

Generally speaking, it may be said that fertility of the soil, in connection with an easily gained livelihood, favours also human fertility, notwithstanding the fact that certain statistical data seem to conflict with this proposition. Sadler, for instance, concludes that an increase in the price of the necessaries of life does not per se check fertility, but, indeed, rather increases it; he considers that the apparent decline in fertility is due to the fact that the number of marriages diminishes, owing to the rise in prices. We must, however, point out, that an increase in price of the necessaries of life is often associated with a rise in wages, and is therefore not necessarily identified with deficient nutrition; when, however, such a rise in prices leads to actual want, a limitation of fertility will certainly result; this has been proved by Legoyt and Villermé with regard to failure of the crops. Famine and disease lower the number of births; a less severe deficiency of nutriment often lowers only the quality of those born. Malthus was of opinion that the population of a country at any time was related to the quantity of nutriment produced or imported therein, on the one hand, and, on the other, to the liberality with which this nutriment was distributed to the individual. In countries where corn forms the principal crop, we find a thicker population than in pasture lands; and where rice is the principal crop, the population is even more abundant than it is in corn growing countries.

Passing to the consideration of the individual nutritive elements, we find that these also influence fertility. Above all, it has been proved that alcohol notably diminishes the fertility of women. Lippich states that of 100 women in Kärnten and Krain suffering from chronic alcoholism, 28.3 were barren. In England, where the abuse of alcoholic beverages is also very frequently observed in women, the same phenomenon has been noted. Matthews Duncan held that alcohol exercised a specific deleterious influence on fertility. Moreover, in addition to the constitutional disturbances produced by the abuse of alcohol, this beverage also exercises a well-known pathogenetic influence upon the female reproductive organs; with especial frequency, chronic oöphoritis may be shown to depend on this exciting cause.

A diet consisting mainly of fish is known to increase the sexual impulse, and is said also to increase fertility. Further, a diet consisting mainly of potatoes or rice is said to favour reproduction; compare, for instance, the fertility of the Hindoos, who abstain entirely from animal food, and of the Chinese, who live chiefly on rice. Davy maintained that the women of races living chiefly on fish were handsomer and more fertile than others: and Montesquieu suggested that there was an association between the abundant population of sea-ports and also of Japan and China, and the large quantity of fish consumed in those places. On the other hand, a diet consisting chiefly of meat is said to have an unfavourable influence in this direction; in support of this view it is pointed out that races living by the chase, and living therefore almost entirely on meat, have very small families. This generalization is invalidated by the fact that Englishwomen, who eat far more meat than the women of the Latin races, are nevertheless distinguished by their great fertility.

In his “History of Civilisation in England” Buckle writes: “The population of a country, although influenced by many other conditions, unquestionably rises and falls in proportion as the supply of nutriment is abundant or the reverse.” Herbert Spencer also states that “every increment in the supply of nutriment is followed by an increment in fertility.”

It must not be forgotten that, in addition to the more or less abundant supply of nutriment, there are always other influences affecting fertility; the general mode of life, race, climatic conditions, etc., may, in various ways, co-operate with or countervail the influence of nutritive conditions. If, with the best possible supply of nutriment, there is associated a luxurious and enervating mode of life, the abuse of alcohol, severe intellectual exertion, or sexual excesses, the general result will be a diminution in fertility. And it is easy to understand why Cros, although perhaps with little justification, goes so far as to regard easy circumstances as an active cause of depopulation. “It is the poor,” he writes, “and the less wealthy departments of France, in which we find the most children.” In estimating fertility, however, we must never fail to take into consideration the more extensive employment of means for the prevention of pregnancy among the upper classes of society.