Objectives This study aims to estimate the association between pregnancy-associated maternal cancers, diagnosed both prenatally and postnatally, and birth outcomes.
Design Population-based register study.
Setting National registers of Denmark and Sweden.
Participants A total of 5 523 365 children born in Denmark (1977–2008) and Sweden (1973–2006).
Primary and secondary outcome measures: gestational age, birth weight, size for gestational age, Apgar score, caesarean section and sex were the outcomes of interest. ORs and relative risk ratios (RRR) with 95% CIs were estimated using logistic regression and multinomial logistic regression, respectively.
Results In this study, 2% of children were born to mothers with a diagnosis of cancer. Children whose mothers received a prenatal cancer diagnosis had higher risk of being born preterm (RRR: 1.77, 95% CI 1.64 to 1.90); low birth weight (RRR 1.84, 95% CI 1.69 to 2.01); low Apgar score (OR 1.36, 95% CI 1.20 to 1.56); and by caesarean section (OR: 1.69, 95% CI 1.59 to 1.80). Associations moved towards the null for analyses using postnatal diagnoses, but preterm birth (RRR: 1.13, 95% CI 1.09 to 1.17) and low birth weight (RRR: 1.14, 95% CI 1.09 to 1.18) remained statistically significant, while risk of caesarean section became so (OR: 0.95, 95% CI 0.91 to 0.98). Additionally, statistical significance was reached for large for gestational age (RRR: 1.06, 95% CI 1.01 to 1.11), high birth weight (RRR: 1.04, 95% CI 1.01 to 1.06) and caesarean section (OR: 0.95, 95% CI 0.91 to 0.98).
Conclusions Results suggest an association between pregnancy-associated cancers and adverse birth outcomes in the offspring. While this is strongest for prenatally diagnosed cancers, some smaller associations exist for postnatally diagnosed cancers, indicating that cancer itself could affect fetal development, or that cancer and adverse birth outcomes share risk factors. Future studies on maternal cancer during pregnancy should consider including some postnatal years in their exposure window.
- birth outcomes
- cancer epidemiology
- register-based epidemiology
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Contributors The study was conceived by LHA, AE and CHRH. It was planned by LHA, AE, CHRH, NCM, JO and JL. The data analysis was performed by NCM. The manuscript was written by NCM, with revisions and final approval from LHA, AE, CHRH, NCM, JO, MG and JL.
Funding This work was supported by grants from Novo NordiskFoundation (12535), Nordic Cancer Union (176673, 186200), European ResearchCouncil (ERC-2010-StG-260242-PROGEURO), the Danish Council for IndependentResearch (DFF -6110-00019), Karen Elise Jensens Fond (2016) and Program for Clinical Research Infrastructure(PROCRIN) established by the Lundbeck Foundation and the Novo NordiskFoundation.
Competing interests None declared.
Patient consent Not required.
Ethics approval Danish Data Protection Agency (j nr 2008-41-2680), Scientific Ethics Committee of Central Jutland Region (VEK, sagnr M-20100252) and the Research Ethics Committee (EPN) at the Karolinska Institute (reference number 2008/4:6).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
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