Keywords
Chornobyl accident
cohort,
long-term follow-up
thyroid disease
radioiodine
How to Cite
Abstract
The in utero period represents one of the most radiosensitive
stages of human development; however, epidemiological evidence
regarding the long-term effects of such exposure remains limited.
Therefore, the establishment of in utero–exposed cohorts and
their prospective long-term follow-up is of particular importance.
Objective. To describe the formation, characteristics, and long-term
follow-up of a cohort of individuals exposed in utero as a result of the
Chornobyl accident, and to assess the stability of its structure across
different stages of observation. Material and methods. The cohort
of the Ukrainian-American Project «Study of the Consequences of In
Utero Radiation Exposure Following the Chornobyl Accident» was
established within the framework of the Ukrainian-American Project
«Scientific Project to Study Cancer and Other Thyroid Diseases in
Ukraine as a Result of the Chornobyl Nuclear Power Plant Accident».
It includes mother–child pairs in which the mother was pregnant
during the period of active radioiodine contamination following the
Chornobyl accident and resided in radiation-contaminated areas
of Kyiv, Zhytomyr, and Chernihiv regions. A comparison group was
formed from areas with low levels of radioactive contamination. The
analysis was based on data from two cycles of clinical screening and
subsequent follow-up conducted through remote questionnaires as
of the end of 2025. Results. A total of 5,042 mother–child pairs were
initially identified, of which 2,582 participants constituted In Utero
cohort after the first screening cycle. Participation in the second
screening cycle reached 70.6% (n=1,822), and 96.4% (n=2,490) of participants
were successfully contacted during follow-up. The cohort
demonstrated overall stability in key demographic, geographic, and
exposure characteristics across study stages. The distribution of thyroid
radiation doses remained unchanged. The prevalence of thyroid
pathology in the In Utero cohort was lower than in the UkrAm cohort
but exceeded population-based estimates in most cases. Conclusions.
The cohort of individuals exposed in utero as a result of the
Chornobyl accident has maintained its structural integrity over longterm
follow-up and can be considered suitable for further analytical
epidemiological studies. These findings support continued follow-up
to better understand the long-term health effects of in utero radiation
exposure.
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