The condition of the endometrium after a 5-day "dry" immersion

One of the reasons for the female factor of infertility is a decrease in ovarian reserve and
hormonal dysfunction, caused both by natural physiological aging and by the impact of a number
of adverse environmental factors. Therefore, even under Earth conditions, late reproductive age
is a risk factor for childbearing. Given the data on the average age of the first space flight in
women (about 38 years), long-term space flight, including beyond the Earth's magnetosphere,
may be an additional factor in the potential risk of impossibility of reproductive function. At the
same time, deep space exploration in the future will require the development of methods for
protecting the reproductive system, especially in women.
According to the literature data, women more often postpone the implementation of the
reproductive function until they have made several space flights [1]. Considering that the
average age in the first space flight is 38 years for women [2], it is not surprising that the use of
assisted reproductive technologies is common in this category of women due to the mature age
of the mother [3]. In addition, women often suppress their menstrual cycles during spaceflight,
especially during long-duration flights, by extensive use of combined oral contraceptives
containing estrogen and progestin [3,4], which may make a modulating contribution to the
interpretation of the results. research and statistical analysis.
Given the above, the study of the influence of space flight factors on the reproductive
function of women is relevant, first of all, for the development of individual recommendations
for the implementation of a life strategy in the post-flight period.
In this work, we studied the state of the structure of uterine tissues in 11 healthy female
volunteers aged 22 to 40 years before and after a 5-day "dry" immersion (2022, State Scientific
Center of the Russian Federation — IBMP RAS), which was used as a model of weightlessness. A
transvaginal ultrasound transducer was used, which was performed on the 4th and 9th days of the
menstrual cycle before immersion and on the same days of the cycle following the dry
immersion. The beginning of stay under the conditions of experimental exposure was
synchronized with the menstrual cycle of the subjects.
All subjects were warned about the conditions of the experiment and gave written
informed consent to participate in it in accordance with the Declaration of Helsinki and the
norms of Russian and international law. The “dry” immersion technique and all medical
procedures were approved by the Commission on Biomedical Ethics of the State Scientific
Center of the Russian Federation, Institute of Biomedical Problems of the Russian Academy of
Sciences (Minutes No. 615 dated 06/06/2022).
The results obtained indicate that there were no significant differences before and after
immersion in the structure of the endometrium and the size of the uterus, which may indicate, on
the one hand, the absence of such a short-term effect on this part of the female reproductive
system, and, on the other hand, indirectly prove the absence of congestive changes in this pelvic
organ and exclude such an artifact from consideration when analyzing the results of studies of
other organs of the reproductive system.

This work was supported by the program of fundamental research of the SSC RF – IBMP
RAS 65.4. and UNU “Transgenbank”.