2. Prerequisites for twinning research

In the nineteenth century, a series of statistical congresses, most notable in Brussels in 1853 and in St. Petersburg in 1872, was important for the start of demographic research and especially twinning research [3]. Levi [4] gave a detailed presentation of the suggestions accepted at the congress in Brussels.

[T]here ought to be an annual registry of population, exhibiting the births by sex, by age of both parents, legitimate and illegitimate, number of twins, stillborn, marriages and divorces, by months. The deaths, by sex, by age, and by months, distinguishing among dead children, till three years of age, the legitimate from the illegitimate. The deaths by month, with the causes of death, and the profession of the deceased; marriages, with the age of the parties, their condition, profession, and number of children, distinguishing the legitimate and those acknowledged as such. Considering the extreme importance of a uniform nomenclature of diseases equally applicable to all countries, the attention of learned men is to be called to the question for further consideration at some future congress.

According to Brown [5], the principal discussion at the St. Petersburg congress centred around facts relating to the movement of the population and the mode in which they should be registered. Among the facts to be registered were in multiple maternities the sex and number of the children, stillborn or born alive, whether legitimate or not and the age and parity of the mother on the birth date.

Westergaard [6] has devoted a whole chapter in his history of statistics to the presentations of the statistical congresses in the middle of the nineteenth century and their importance [1]. The first congress was held in Brussels in 1853. Brussels was chosen as the first meeting place because the Belgian Central Commission undertook the great preparatory work. The congress was held under the presidency of Adolphe Quetelet. The aim of the congress being chiefly a practical one, there was no room for lectures on special scientific problems. During congresses after Brussels, discordance increased among the European countries, and thus, the International Statistical Congress came to an end.

Recently, Droesbeke [7] gave a short but detailed presentation of the planning and findings of the Brussels congress and subsequent international statistical congresses. His text agrees the ideas of Westergaard [6]. A commission was created in March 1841 as a first step towards the realization of the congress. The president of the Central Commission of Statistics, Adolphe Quetelet, played a central role in the planning process. Quetelet was held in high esteem in London since 1833, when he had taken part in the congress of the British Association for the Advancement of Science, at the end of which he had contributed to the creation of a section devoted to statistics. The idea to organize a congress, the main objective of which was to lay down a common foundation for statistical data to enable international comparisons, was presented by Quetelet 1851. He offered to

Regression analyses of twinning and triplet rates yield rather good fits with respect to Hellin's law, but deficiencies in the triplet rates are commonly present. According to Hellin's law, historical data show deficiencies in triplet rates, but recent data reveal excesses, especially among older mothers. The excesses obtained are in good agreement with other studies of recent data. Here, we pay special attention to the use of Hellin's law in investigations of

In the nineteenth century, a series of statistical congresses, most notable in Brussels in 1853 and in St. Petersburg in 1872, was important for the start of demographic research and especially twinning research [3]. Levi [4] gave a detailed presentation of the suggestions accepted at the

[T]here ought to be an annual registry of population, exhibiting the births by sex, by age of both parents, legitimate and illegitimate, number of twins, stillborn, marriages and divorces, by months. The deaths, by sex, by age, and by months, distinguishing among dead children, till three years of age, the legitimate from the illegitimate. The deaths by month, with the causes of death, and the profession of the deceased; marriages, with the age of the parties, their condition, profession, and number of children, distinguishing the legitimate and those acknowledged as such. Considering the extreme importance of a uniform nomenclature of diseases equally applicable to all countries, the attention of learned men is to be called to the

According to Brown [5], the principal discussion at the St. Petersburg congress centred around facts relating to the movement of the population and the mode in which they should be registered. Among the facts to be registered were in multiple maternities the sex and number of the children, stillborn or born alive, whether legitimate or not and the age and parity of the

Westergaard [6] has devoted a whole chapter in his history of statistics to the presentations of the statistical congresses in the middle of the nineteenth century and their importance [1]. The first congress was held in Brussels in 1853. Brussels was chosen as the first meeting place because the Belgian Central Commission undertook the great preparatory work. The congress was held under the presidency of Adolphe Quetelet. The aim of the congress being chiefly a practical one, there was no room for lectures on special scientific problems. During congresses after Brussels, discordance increased among the European countries, and thus, the Interna-

Recently, Droesbeke [7] gave a short but detailed presentation of the planning and findings of the Brussels congress and subsequent international statistical congresses. His text agrees the ideas of Westergaard [6]. A commission was created in March 1841 as a first step towards the realization of the congress. The president of the Central Commission of Statistics, Adolphe Quetelet, played a central role in the planning process. Quetelet was held in high esteem in London since 1833, when he had taken part in the congress of the British Association for the

multiple maternities.

4 Multiple Pregnancy - New Challenges

congress in Brussels.

mother on the birth date.

tional Statistical Congress came to an end.

2. Prerequisites for twinning research

question for further consideration at some future congress.

bring together at a congress in Brussels the persons, who in various countries, are dealing specifically with statistics, in order to give their works a common impulse, and to adopt, for the computations, uniform grounds which will allow for comparison of observations and results. (Bulletin of the Commission, 1853, p. 106).

Furthermore, Droesbeke describes the congress programme and stressed the content of the congress according to Quetelet's words:

It is to be hoped that the works which belongs to this science will now be taken on, in every State, following the bases which have been laid down during the Congress of Brussels. It is not any more a theoretical wish, to see the states adopt uniform bases for scientific works in order to make the results comparable; the opportunity of implementation of the idea has been proclaimed; the framework has been chosen and the reading of the report […] will demonstrate what is allowed to expect from the wisdom, maturity, perfect intelligence and good harmony which presided over the deliberations of the Congress.

Finally, Droesbeke listed the Statistical Congresses during the nineteenth century that followed the first one in Brussels.

Recently, Randeraad [8] directed attention to and even criticism of the international statistical congresses in the second half of the nineteenth century. He stated that it would be overly simplistic to assume that they were an outright success. In fact, no more congresses were held after 1876. Furthermore, he stressed that:

More importantly, by then it was clear that the aspirations of the early congresses had been too high. International uniformity in statistics was evidently not a goal that could be reached overnight. Much of this failure to bring about rapid change can be explained by the difficulties in realizing effective knowledge transfers, in other words effective communication, in an age that was not fully prepared for truly international activities. It has been shown that the second half of the nineteenth century was a period of numerous experiments in internationalism, but at the same time rampant nationalism nipped many initiatives in the bud.

In most countries, the registers were deemed lacking in essential facts; those of Belgium and Sweden were perhaps the most detailed for scientific inquiries [3]. Arosenius [9] presented a detailed study of the emergence of the official statistics of Sweden. His presentation shows just how difficult the development of the process is until an official statistics of modern proficiency is born.

Already in the eighteenth century, Wargentin published demographic data for Sweden. However, he did not pay any attention to twinning and higher multiple maternities [10]. Berg [11] published a comprehensive study of multiple maternities. He analyzed the rates of multiple maternities in Sweden from 1776 to 1878. He also presented corresponding data for several European countries and analyzed the sex combinations of twin, triplet and quadruplet sets in Sweden from 1869 to 1878. His study was published in Swedish, and thus, few scientists were aware of this paper. Since Swedish is the native language of our group, Berg's results have been of great value in our studies [1, 12–14].

3. Genesis of Hellin's law

The Veit data set from Prussia (1826–1849), presented by Fellman and Eriksson [1] in Table 2, consists of 13,360,557 maternities, including 13,208,868 single, 149,964 twin, 1689 triplet and 36 quadruplet maternities [16]. Veit analyzed the temporal trend in the twinning rate (TWR) and noted very small variations, but during the first half of the period, the annual TWRs were almost constantly higher than during the last half of the period (except for the year 1849). The trend may be seen elsewhere ([1], Table 2 and Figure 1). For the total data set, Veit noted the following rates: for twin pairs 1:89, for triplet sets 1:7910 and for quadruplet sets 1:371126. He did not give the relations between TWR, triplet rate (TRR) and quadruplet rate (QUR), that is,

Year All Single Twin Triplet Quadruplet

Table 2. Data from Prussia, 1826–1849, according to Veit (1855) [16].

Maternities

Historical Studies of Hellin's Law

7

http://dx.doi.org/10.5772/intechopen.79583

During the second half of the nineteenth century, Statistics Sweden published in the journal Statistisk Tidskrift an extensive time series of demographic data. The data were given separately for different counties of Sweden and contained the size of the population, the number of births (live and stillborn) and twin, triplet and quadruplet sets. A list of these data was given in Table 1 in [1], indicating that Sweden has overall the oldest continuous population statistics worldwide. Our group has used these data in different studies [1, 15].


Table 1. The Division of Sweden into 25 counties for regional data concerning population size, births and multiple maternities, 1749–1888 (ST = Statistisk Tidskrift) [1].
