TOPLINE:

Previous studies on early pregnancy loss and breast cancer risk were often small and relied on self-reported data. This large Finnish registry study found no significant association between induced abortion or miscarriage and breast cancer risk, regardless of timing or frequency of pregnancy loss.

METHODOLOGY:

• A case-control study of population-based registry data included 31,687 women diagnosed with breast cancer between 1972 and 2021 and 158,433 female population controls matched by birth year and parity.
• Data collection included information on induced abortions, miscarriages, deliveries, postmenopausal hormone therapy use, socioeconomic status, and occupation from Finnish national registries.
• Multivariate conditional logistic regression analysis was performed to evaluate associations.

TAKEAWAY:

• Among premenopausal women (age < 50 years), the odds ratio (OR) for breast cancer after pregnancy loss was 1.00 (95% CI, 0.92-1.09), while for postmenopausal women (≥ 50 years), it was 0.95 (95% CI, 0.86-1.06).
• The OR for breast cancer after miscarriage was 1.02 (95% CI, 0.89-1.16) in premenopausal women and 0.92 (95% CI, 0.79-1.08) in postmenopausal women.
• The risk did not vary significantly by the number of induced abortions or miscarriages or by age at first induced abortion or miscarriage.

IN PRACTICE:

“Induced abortion or miscarriage was not associated with subsequent risk of either pre- or postmenopausal breast cancer in this nationwide Finnish registry-based study,” wrote the authors of the study.

SOURCE:

The study was led by Sushmita Katuwal, PhD, Unit of Health Sciences, Faculty of Social Medicine, Tampere University, Tampere, Finland. It was published online in Acta Obstetricia et Gynecologica Scandinavica.

LIMITATIONS:

According to the authors, many previous studies on this topic relied on self-reported pregnancy history data or did not adequately control for key confounding factors such as parity or hormonal therapy use, which are established determinants of breast cancer risk.

DISCLOSURES:

The study received support from the Cancer Foundation Finland and research funds from Helsinki University Hospital. The funding organizations had no role in the study design, data collection, analysis, interpretation, or manuscript preparation.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.