3. Genesis of Hellin's law

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

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

County (Län) Period Reference Stockholm city 1749–1858 ST, 1860–62:43–47 Stockholm county 1749–1773, 1795–1858 ST, 1860–62:134–141 Uppsala 1749–1773, 1795–1859 ST, 1860–62:280–288 Södermanland 1749–1773, 1795–1859 ST, 1860–62:317–324 Östergötland 1749–1773, 1795–1860 ST, 1863–65:164–171 Jönköping 1749–1773, 1795–1862 ST, 1863–65:266–273 Kronoberg 1749–1773, 1795–1862 ST, 1863–65:274–281 Kalmar 1749–1773, 1795–1868 ST, 1870:211–220 Gotland 1759–1869 ST, 1870:27:221–231 Blekinge 1749–1773, 1795–1869 ST, 1870:232–240 Kristianstad 1749–1773, 1795–1871 ST, 1873:133–142 Malmöhus 1749–1773, 1795–1871 ST, 1873:143–152 Halland 1749–1773, 1795–1871 ST, 1873:153–162 Göteborg and Bohus 1749–1773, 1795–1859 ST, 1860–62:388–400 Älvsborg 1749–1773, 1795–1874 ST, 1875:127–136 Skaraborg 1749–1773, 1795–1876 ST, 1877:156–168 Värmland 1795–1865 ST, 1877:170–176 Örebro (Närke) 1749–1773 ST, 1877:166–169 Västmanland 1749–1773, 1795–1887 ST, 1888:159–170 Kopparberg 1749–1773, 1795–1887 ST, 1888:171–182 Gävleborg 1749–1773, 1795–1887 ST, 1888:161–172 Västernorrland 1792–1888 ST, 1888:173–184 Jämtland 1792–1888 ST, 1888:185–196 Västerbotten 1802–1860 ST, 1863–65:50–57 Norrbotten 1802–1860 ST, 1863–65:44–49

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].

worldwide. Our group has used these data in different studies [1, 15].

been of great value in our studies [1, 12–14].

6 Multiple Pregnancy - New Challenges

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,


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

1. The rates of twin and higher multiple maternities.

3. The regional and seasonal variations in TWRs. 4. The rates of live and stillbirths among twins.

seasonality of the birth.

5. The sex composition of sets of multiple maternities. 6. The sex ratio among single and multiple maternities.

2. The crude birth rates among single and multiple maternities.

7. The effect on the number of multiple maternities of the age of the parents, the marital status and confession of faith of mothers, the residence in urban and rural regions, and the

Historical Studies of Hellin's Law

9

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

In addition, he considered weight and prematurity among multiples and mortality among multiples and mothers. This list indicates clearly that Neefe introduced a thorough research programme for twinning studies. It is noteworthy that Neefe did not comment on the relation between the rates of multiple maternities, and consequently, he did not explicitly foretell Hellin's law [1].

Strassmann [20] noted the findings in [16, 17] and concluded, using Veit's total data set, that there is one twin maternity per 891 and one triplet maternity per 892 total maternities. Strassmann related the number of multiple maternities to the number of all maternities, in contrast to Hellin [21], who related the number of multiple maternities to the number of single maternities. However, both used the same relation, 1:89 [1]. While in the literature authors generally refer to Hellin, they formulate the law according to Strassmann's version. While in the literature authors generally refer to Hellin, the law was already formulated by Strassmann in 1889. Hellin's law has

Drejer [22] was apparently unaware of Hellin but referred to Strassmann, stating that he had noted the relation between the rates of twin and triplet maternities. Drejer was dubious about the regularity between the rates. He stressed that under such circumstances the rule had to hold also for higher multiple maternities, but he could not find any clear indication of this being the case [1]. Particularly important scientific observations are often associated with a person, but historians of science have, however, noted that often the person associated with a particular finding was not its original discoverer. Scientific observations and results are frequently associated with people who have high visibility and social status, and the results are named long after the discovery. Based on his studies on the history of statistics, Stigler [23] proposed his own Stigler's law of eponymy. In brief, the law says: "No scientific discovery is named after its original discoverer". Stigler himself attributes the discovery of Stigler's law to Merton [24], which makes the law self-

Hellin's law has played a central role in the history of research on multiple maternities. The interest in Hellin's law is mainly the result of its being mathematically simple and approximately

played a central role in the history of research on multiple maternities [3].

referencing. Consequently, in this study, one must bear in mind Stigler's law [1].

4. Investigations of Hellin's law

Figure 1. Temporal trends in TWR and transformed TRR and QUR per 103 for the Prussian data presented in [16]. Note the excess among QUR.

Hellin's law. He also presented the sex compositions within the twin, triplet and quadruplet sets and noted a lower sex ratio (males to females) among multiple births than among singleton births [1].

The Wappäus data set was collected from different European countries and comprised 19,698,322 maternities, including 226,807 twin and 2623 triplet maternities [1]. Wappäus [17] presented the rates of multiple maternities, but did not discuss the relation between the number of twin, triplet and quadruplet maternities [1].

Bertillon [18] foresaw Hellin's law. He considered multiple maternity data from different countries in central Europe. In his study, he presented the number of triplet maternities per year and per one million total maternities. He also presented the number of total maternities per one triplet maternity and the number of twin maternities per one triplet maternity, i.e., he considered the relation between twin and triplet rates. However, he did not relate the number of total maternities to one twin maternity. Fellman and Eriksson [1] presented a translated version of his table ([18], page 285) and included in columns calculations of the number of total maternities in relation to one twin maternity and the annual mean number of maternities. They believed that had Bertillon included the first of their columns in his table, he would have discovered Hellin's law [1].

Shortly after the congresses in Brussels and St. Petersburg, Neefe [19] published his classical work. He emphasized how important the abovementioned statistical congresses were for the standardization of the demographic registers in different countries, and he used the new possibilities that the improved birth registers offered. Although other contemporaneous studies were published, Fellman and Eriksson [1] stressed that the history of twinning research starts with this publication. Neefe analyzed a long series of problems connected to twinning; these problems have been shown to be central in later studies. He considered inter alia:


Hellin's law. He also presented the sex compositions within the twin, triplet and quadruplet sets and noted a lower sex ratio (males to females) among multiple births than among single-

Figure 1. Temporal trends in TWR and transformed TRR and QUR per 103 for the Prussian data presented in [16]. Note

The Wappäus data set was collected from different European countries and comprised 19,698,322 maternities, including 226,807 twin and 2623 triplet maternities [1]. Wappäus [17] presented the rates of multiple maternities, but did not discuss the relation between the

Bertillon [18] foresaw Hellin's law. He considered multiple maternity data from different countries in central Europe. In his study, he presented the number of triplet maternities per year and per one million total maternities. He also presented the number of total maternities per one triplet maternity and the number of twin maternities per one triplet maternity, i.e., he considered the relation between twin and triplet rates. However, he did not relate the number of total maternities to one twin maternity. Fellman and Eriksson [1] presented a translated version of his table ([18], page 285) and included in columns calculations of the number of total maternities in relation to one twin maternity and the annual mean number of maternities. They believed that had Bertillon included the first of their columns in his table, he would have

Shortly after the congresses in Brussels and St. Petersburg, Neefe [19] published his classical work. He emphasized how important the abovementioned statistical congresses were for the standardization of the demographic registers in different countries, and he used the new possibilities that the improved birth registers offered. Although other contemporaneous studies were published, Fellman and Eriksson [1] stressed that the history of twinning research starts with this publication. Neefe analyzed a long series of problems connected to twinning; these problems have been shown to be central in later studies. He considered inter alia:

number of twin, triplet and quadruplet maternities [1].

ton births [1].

the excess among QUR.

8 Multiple Pregnancy - New Challenges

discovered Hellin's law [1].


In addition, he considered weight and prematurity among multiples and mortality among multiples and mothers. This list indicates clearly that Neefe introduced a thorough research programme for twinning studies. It is noteworthy that Neefe did not comment on the relation between the rates of multiple maternities, and consequently, he did not explicitly foretell Hellin's law [1].

Strassmann [20] noted the findings in [16, 17] and concluded, using Veit's total data set, that there is one twin maternity per 891 and one triplet maternity per 892 total maternities. Strassmann related the number of multiple maternities to the number of all maternities, in contrast to Hellin [21], who related the number of multiple maternities to the number of single maternities. However, both used the same relation, 1:89 [1]. While in the literature authors generally refer to Hellin, they formulate the law according to Strassmann's version. While in the literature authors generally refer to Hellin, the law was already formulated by Strassmann in 1889. Hellin's law has played a central role in the history of research on multiple maternities [3].

Drejer [22] was apparently unaware of Hellin but referred to Strassmann, stating that he had noted the relation between the rates of twin and triplet maternities. Drejer was dubious about the regularity between the rates. He stressed that under such circumstances the rule had to hold also for higher multiple maternities, but he could not find any clear indication of this being the case [1].

Particularly important scientific observations are often associated with a person, but historians of science have, however, noted that often the person associated with a particular finding was not its original discoverer. Scientific observations and results are frequently associated with people who have high visibility and social status, and the results are named long after the discovery. Based on his studies on the history of statistics, Stigler [23] proposed his own Stigler's law of eponymy. In brief, the law says: "No scientific discovery is named after its original discoverer". Stigler himself attributes the discovery of Stigler's law to Merton [24], which makes the law selfreferencing. Consequently, in this study, one must bear in mind Stigler's law [1].
