Accepted for/Published in: JMIR Formative Research
Date Submitted: Jun 4, 2025
Date Accepted: Sep 26, 2025
Patterns of Prior Induced Abortions and the Likelihood of Subsequent Natural Pregnancy Loss: An Exploratory Application of Pregnancy Outcome Sequencing
ABSTRACT
Background:
Research concerning the long-term health consequences of induced abortion is constrained by both the limitations in the availability of data necessary to construct complete reproductive histories, as well as the limitations in the analytical methods necessary to interpret them.
Objective:
We sought to determine the association of induced abortion and the likelihood of a subsequent natural loss by investigating a woman’s pregnancy outcome sequence (POS), a research construct that defines the number and order of all pregnancy outcomes (birth, induced abortion, natural loss) in each woman’s reproductive history.
Methods:
Utilizing the Medicaid Analytic eXtract (MAX) files from the Centers for Medicare and Medicaid Services (CMS) Chronic Conditions Warehouse (CCW), we identified a study population of 508 unique POSs, representing 5,455 women, each of whom had one to 16 pregnancy outcomes, for a total of 14,198 pregnancies. We applied an iterative analytical approach which included aggregate POS correlation analysis, logistic multiple regression and simultaneous confidence intervals (Agresti and Tukey-Kramer methods). We also established counting methods to populate the data tables for each analytical phase.
Results:
Overall, we found evidence to conclude that both prior abortions and natural losses are significantly associated with the risk of subsequent natural losses. For abortion, there is evidence of a dose-response relationship from zero to three abortions and the likelihood of subsequent natural loss. For natural loss, the risk of a subsequent natural loss is significant after two natural losses and between the first and second. There is no association of prior birth(s), or any combination of birth/abortion or birth/natural loss with the risk of subsequent natural loss.
Conclusions:
The POS, applied for the first time in this analysis, demonstrates that the order and combinations of pregnancy outcomes may result in varying conclusions which were previously undetectable.
Citation
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