Socioeconomic position and the risk of spontaneous abortion: a study within the Danish National Birth Cohort.
OBJECTIVE
To investigate the relationship between different indicators of socioeconomic position and the risk of spontaneous abortion.


METHODS
Cohort study.


METHODS
1996-2002, Denmark.


METHODS
All first time participants, a total of 89 829 pregnant women, enrolled in the Danish National Birth Cohort were included in the present study. Overall, 4062 pregnancies ended in spontaneous abortion. Information on education, income and labour market attachment in the year before pregnancy was drawn from national registers.


METHODS
Spontaneous abortion, that is, fetal death within the first 22 weeks of pregnancy, was the outcome of interest. The authors estimated HRs of spontaneous abortion using Cox regression analysis with gestational age as the underlying time scale.


RESULTS
Women with <10 years of education had an elevated risk of spontaneous abortion when compared with women with >12 years of education (HR 1.19 (95% CI 1.05 to 1.34)). The HR estimates for the four lowest income quintiles were all increased (HRs between 1.09 and 1.15) as compared with the upper quintile but did not differ considerably from each other. In general, no statistically significant association was found between labour market attachment and the risk of spontaneous abortion; however, the group of women on disability pension had an increased HR of spontaneous abortion when compared with women who were employed (HR 1.32 (95% CI 0.82 to 2.13)).


CONCLUSIONS
Educational level and income were inversely associated with the risk of spontaneous abortion. As these factors most likely are non-causally related to spontaneous abortion, the findings indicate that factors related to social position, probably of the environmental and behavioural type, may affect spontaneous abortion risk. The study highlights the need for studies addressing such exposures in order to prevent spontaneous abortions.
Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
Filippa Nyboe
FN
Norsker
Laura
L
Espenhain
Sofie
S
A Rogvi
Camilla Schmidt
CS
Morgen
Per Kragh
PK
Andersen
Anne-Marie
AM
Nybo Andersen