Iris de Nie

47 IMPAIRED SEMEN QUALITY IN TRANS WOMEN 3 cohort had discontinued their medication for at least 3 months, and no negative effect on the semen parameters was observed. Lifestyle factors, such as tucking and wearing tight-fitting underwear, might increase scrotal temperatures which is associated with an impaired semen quality. 92 In 1985 a study was performed to evaluate the influence of tucking on semen quality in order to provide a contraceptive method in cis men.They found an inhibition of spermatogenesis after 3 months of daily tucking and semen parameters were lowest after 6 months. 89 Unfortunately, we were not able to reproduce this negative influence of tucking since it was not recorded in the medical files. Taking all these factors into account, we were not able to provide a clear explanation for the impaired semen quality in our cohort. The major strengths of our study are the large cohort size, which is much bigger than previous studies on this topic, since approximately 95% of all transgender people in the Netherlands are treated in our center, and the evaluation of potential influencing factors on semen quality obtained through access to the medical files. However, owing to the retrospective design of the study, information on transgender specific life style factors was only available for a few individuals and, for example, did not include the frequency and the duration of tucking or when tucking was last performed. As a result, we were unable to demonstrate that these habits might explain the observed reduced semen quality. Also, the retrospective design may lead to an underestimation of the prevalence of anxiety and depression in our cohort. Another limitation of the study is the absence of data on semen morphology as this was not recorded during the process of semen cryopreservation. Furthermore, although abstinence time was advised to be 2-5 days, exact abstinence time was not recorded and we were therefore unable the correct for this factor. For future studies itwouldbeworthwhile toprospectivelyobtaindata on endocrine laboratory results and detailed information about lifestyle factors at time of fertility preservation in order to adequately determine the etiology of the impaired semen quality in trans women. Furthermore, more knowledge of the influence of gender-affirming hormone treatment on spermatogenesis and its restoration after discontinuation might help to establish the optimal strategy for trans women with a desire for genetically related offspring. Conclusion Fertility preservation has now become widely available in the Netherlands for most trans women and enables them to parent genetically related children after medical transition. Our findings show a high frequency of impaired semen parameters compared to the general population. Since low pre-freeze semen quality results in an even lower post-thaw semen quality, the majority of trans women and their female partner or surrogate may need an invasive and burdensome treatment to establish a pregnancy.