Objective To assess the association between perinatal losses and mother's long-term mortality and modification by surviving children and attained education.
Design A population-based cohort study.
Setting Norwegian national registries.
Participants We followed 652 320 mothers with a first delivery from 1967 and completed reproduction before 2003, until 2010 or death. We excluded mothers with plural pregnancies, without information on education (0.3%) and women born outside Norway.
Main outcome measures Main outcome measures were age-specific (40–69 years) cardiovascular and non-cardiovascular mortality. We calculated mortality in mothers with perinatal losses, compared with mothers without, and in mothers with one loss by number of surviving children in strata of mothers’ attained education (<11 years (low), ≥11 years (high)).
Results Mothers with perinatal losses had increased crude mortality compared with mothers without; total: HR 1.3 (95% CI 1.3 to 1.4), cardiovascular: HR 1.8 (1.5 to 2.1), non-cardiovascular: HR 1.3 (1.2 to 1.4). Childless mothers with one perinatal loss had increased mortality compared with mothers with one child and no loss; cardiovascular: low education HR 2.7 (1.7 to 4.3), high education HR 0.91 (0.13 to 6.5); non-cardiovascular: low education HR 1.6 (1.3 to 2.2), high education HR 1.8 (1.1 to 2.9). Mothers with one perinatal loss, surviving children and high education had no increased mortality, whereas corresponding mothers with low education had increased mortality; cardiovascular: two surviving children HR 1.7 (1.2 to 2.4), three or more surviving children HR 1.6 (1.1 to 2.4); non-cardiovascular: one surviving child HR 1.2 (1.0 to 1.5), two surviving children HR 1.2 (1.1 to 1.4).
Conclusions Irrespective of education, we find excess mortality in childless mothers with a perinatal loss. Increased mortality in mothers with one perinatal loss and surviving children was limited to mothers with low education.
- Perinatal loss
- Maternal mortality
- Loss of a child
- Cardiovascular mortality
- REPRODUCTIVE MEDICINE
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Contributors All researchers had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. FH, N-HM and RS designed and proposed the study. FH and RS analysed the data and prepared the graphs. FH drafted the manuscript. AW, KK, N-HM, LD and RS reviewed the preliminary analyses and the initial draft of the manuscript and provided critical comments. RS is guarantor for data quality.
Funding This study was supported by the Norwegian Research Council, through the University of Bergen, and in part by the Intramural Program of the National Institute of Environmental Health Sciences, National Institutes of Health.
Disclaimer The Norwegian Research Council, University of Bergen, and the US National Institute of Environmental Health Sciences had no role in the design and conduct of the study; in the collection, analysis, the interpretation of the data; or in the preparation, review or approval of the manuscript. The authors’ institutions had no role in the design and conduct of the study; the collection, management, analysis and interpretation of the data; or the preparation, review or approval of the manuscript.
Competing interests All authors have completed the Unified Competing Interest form at http://www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare no support from any organisation for the submitted work, no financial relationships with any organisations that might have an interest in the submitted work in the previous 3 years and no other relationships or activities that could appear to have influenced the submitted work.
Ethics approval The internal review board of the Medical Birth Registry of Norway and the regional ethics committee, REK Vest, Norway (2009/1868).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement The following sensitivity analyses are commented in the paper but not shown: To control for potential confounding, we excluded mothers who lost children aged 2 weeks to 7 years and repeated the main analyses. The results did not change. In the same way, we excluded mothers with pre-eclampsia and also here the results did not change. In the last sensitivity analysis, we wanted to evaluate whether gestational age of the perinatal loss influenced maternal long-term mortality. We did this by comparing mortality in mothers with a preterm loss with mothers with a term loss. There was no significant difference between the two groups. The data can be provided if needed by Frode Halland, firstname.lastname@example.org.