Season of birth, stillbirths, and neonatal mortality in Sweden: the Sami and non-Sami population, 1800–1899

Abstract

Seasonal patterns of neonatal mortality and stillbirths have been found around the world. However, little is known about the association between season of birth and infant mortality of pre-industrial societies in a subarctic environment. In this study, we compared how season of birth affected the neonatal and stillbirth risk among the Sami and non-Sami in Swedish Sápmi during the nineteenth century. Using digitised parish records from the Demographic Data Base at Umeå University, we applied logistic regression models for estimating the association of season of birth with stillbirths and neonatal mortality, respectively. Higher neonatal mortality was found among the winter-and autumn-born Sami, compared to summer-born infants. Stillbirth risk was higher during autumn compared to summer among the Sami, whereas we found no seasonal differences in mortality among the non-Sami population. We relate the higher neonatal mortality risk among winter-born Sami to differences in seasonality of living conditions associated with reindeer herding.

Neonatal Mortality and Temperature in Two Northern Swedish Rural Parishes, 1860–1899—The Significance of Ethnicity and Gender

“…Previous studies of infant mortality between Sami and non-Sami populations have found generally higher mortality rates among the Sami population compared to the non-Sami population, as well as significant differences in neonatal deaths between parishes in the Sápmi area [4,12]. In the nineteenth century, the Sami experienced the highest neonatal mortality rate during the winter (December-February) [7]. The non-Sami population showed no clear seasonal pattern in neonatal mortality, yet a higher mortality was found among infants born in January and November [7].…”

“…In the nineteenth century, the Sami experienced the highest neonatal mortality rate during the winter (December-February) [7]. The non-Sami population showed no clear seasonal pattern in neonatal mortality, yet a higher mortality was found among infants born in January and November [7]. Furthermore, our previous research showed an association between extreme winter temperatures and neonatal mortality between 1800 and 1900, during which time neonatal mortality increased during the cold winter months (monthly mean temperatures below −15 • C) compared to the milder winter months, particularly among the Sami population [6].…”

“…Compared to other age groups, there is a risk that neonatal deaths have been underreported [2]. However, previous studies of neonatal mortality in Sápmi between 1800 and 1900 found that around 92% of the population had registered birth and death dates [7]. The starting year used in this study (1860) corresponds to the year when the state authority, Statistics Sweden, was formed, which resulted in even more accurate reporting of demographic data [38].…”

“…Based on information about family name, parish, occupation and family relations, an ethnical indicator that distinguished between the Sami population and the non-Sami population has been developed [39]. This ethnical indictor has been used in a variety of studies regarding marriage, fertility and mortality patterns in Swedish Sápmi [4,[6][7][8]13,23,39,40]. The available information about ethnicity does not allow a differentiation between nomadic and settled Sami.…”

“…Mortality rates in northern Sweden in particular, including in the Sápmi area (traditional land of the indigenous Sami), were sometimes as high as 250/1000 live births [5]. One of the factors associated with the high infant mortality rate in the Sápmi area is the harsh climate with long and cold winters [6,7].…”