Unsolved mystery: Trans women have significantly lower semen quality than cis men – before starting HRT

Zinnia JonesSperm banking is the recommended method of fertility preservation for trans women prior to medical transition (Coleman et al., 2012), as cross-sex hormone therapy can impair fertility, and gonadectomy (removal of the testes during vaginoplasty or orchiectomy) results in permanent sterility. Semen cryopreservation before starting hormone therapy is a precautionary measure, as the impact of HRT on fertility can be highly variable between individuals – contrary to certain myths and misconceptions, taking hormones does not reliably produce permanent or even temporary sterility in trans women. In a literature review, Schneider et al. (2017) reported:

Whereas three publications described a marked reduction of the spermatogenic level in all patients examined, eight publications reported inconsistent results. Histological analyses showed highly variable outcomes from qualitatively normal spermatogenesis and undisturbed Leydig/Sertoli cell morphology to full testicular regression with severe cellular damage and hyalinization.

This wide variation in the effects of HRT on sperm production makes clear why trans women cannot rely on cross-sex hormones as a method of birth control; trans women engaging in sexual activity that could result in pregnancy should still use an appropriate contraceptive method.

However, in studies of semen cryopreservation by trans women, one puzzling result continues to appear: Trans women’s semen is of measurably lower quality than that of cisgender men on a number of key measures – before they’ve begun hormone therapy. It remains unclear why this would be the case.

Hamada et al. (2015) reported on the results of semen cryopreservation by 29 trans women at the Cleveland Clinic in Ohio and the Ghent University Center in Belgium, finding “very poor” semen quality and “poor sperm morphology” from the two patients of the Cleveland Clinic, as well as a “high frequency of impaired pre-freeze semen quality” among the patients from Ghent:

Of 27 patients, 7 (25.9%) had oligozoospermia, 9 (33%) had asthenozoospermia and 7 (25.9%) had teratozoospermia. The total motile sperm count per ml was low in 19 (70%) of the patients, and some of them chose to discard up to 6–7 semen samples.

The authors speculated on a number of possible causes for this finding, none of them conclusive:

The aetiology of these observations is unknown. Nevertheless, several possibilities can be hypothesised to explain these abnormalities such as psychological stress (Eskiocak et al., 2006), self-induced high scrotal positioning of the testes, wearing of tight underwear, undisclosed feminising hormone use, androgen receptor gene polymorphism (Hare et al., 2009) and unidentified genetic disorders.

Crucially, they observed that these differences in semen quality can come to bear on the accessibility of various assisted reproduction options using banked sperm:

Exploring the aetiology of poor semen quality of TW is of paramount importance in order to take the necessary action to improve semen parameters before referral to sperm banking. Better post-thaw semen parameters not only improve fertilisation rates using ART but also allow patients to select relatively inexpensive methods of ART such as IUI rather than the more costly IVF and ICSI.

Li et al. (2018) likewise examined the quality of trans women’s cryopreserved sperm from a cryobank in Massachusetts, while also comparing this to the quality of banked sperm from cisgender men at the same location. Again, a statistically significant difference was found on most measures:

Following exclusion of cisgender sperm bankers with health issues that might impact semen quality and transgender sperm bankers with known prior hormonal therapy, we compared the semen parameters of 141 healthy cisgender sperm bankers and 78 healthy transgender sperm bankers. The transgender sperm bankers demonstrated lower sperm concentration, total motile sperm count, and post-thaw sperm parameters. The transgender sperm bankers also demonstrated a higher incidence of oligozoospermia.

Once again, there was no obvious explanation for this disparity:

Based on our current understanding of transwomen, there is no inherent explanation as to why these patients should have decreased sperm concentration, TMSC, and post-thaw motility. The transwomen sperm bankers were significantly younger than the cismen sperm bankers, but the majority were adults, so we expected normal semen parameters (Centola et al., 2016). This may point to unreported hormonal therapy or some inherent physiologic issues with spermatogenesis in transwomen which has yet to be elucidated.

Both Hamada et al. and Li et al. raise the possibility that the trans women studied may have been taking cross-sex hormones without disclosing this, and that this may account for the observed differences in semen quality. However, a recent study (Marsh et al., 2019) shows that this is unlikely to be the case. In this study, specimens from 22 trans women were compared to samples from 17 cis men who had fathered a child within the past two years, and all subjects were given blood tests for levels of FSH, total testosterone, and estradiol. Notably, the authors found that these hormone levels “were not different between the groups” – yet trans women’s semen quality was still significantly lower on several measures compared to cis men:

Several semen parameters were significantly lower in transgender women compared with the fertile cisgender men control group including sperm concentration, total sperm per ejaculate, total motile sperm, and morphology.

This study also queried subjects on practices such as tucking, wearing tight underwear, and frequency of ejaculation, all of which can have an effect on semen quality. However, these were likely not the cause of the observed differences:

The use of tight undergarments and the practice of tucking was significantly greater in the transgender group (Table 2); however, there was no correlation between the use of tight undergarments or tucking and either sperm concentration or total motile sperm (Fig. 4). In addition, the frequency of ejaculation was not different between transgender women and cisgender men (Table 2).

The authors also note that men confirmed to be fertile tend to have a greater sperm concentration than men in the overall population, but that even when accounting for this, sperm concentration in the general population of men “is still higher than the median found in the group of transgender women in the current study”, and “it appears sperm numbers in the group of transgender women in the current study are lower than those reported in several studies representing the general population”.

However, the authors raise another possibility: that higher rates of depression, anxiety, and stress among trans women have an adverse effect on their semen quality. They note that these conditions have been associated with poor semen quality in numerous studies of cis men, and on an inventory of these symptoms, trans women in the present study “exhibited higher levels of stress, anxiety, and depression compared with the cisgender men group”. Still, for trans women participants, these correlations were only significant between sperm concentration and stress and anxiety symptoms, and not for depression and sperm concentration, or any of the three symptoms and total motile sperm. Additionally, among cis men in the study, no significant correlations were observed between any of these symptoms and sperm concentration or total motile sperm:

Finally, the authors offer that “Enhanced education related to personal behaviors or treatment to reduce effects of stressors prior to cryopreservation may improve future fertility potential”, but conclude:

The etiology of the differences in semen parameters is not known. Future research should be directed toward elucidating what factors are responsible for differences in semen quality in transgender women.

The bottom line is that there are significant, consistent differences where there appears to be no reason to expect that such differences would be present, and it remains uncertain how we can account for these. At a minimum, figuring out what’s going on here has the potential to improve results from fertility preservation for trans women. Depending on the causes behind this, we just might learn something new about trans women’s health disparities as well.

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About Zinnia Jones

My work focuses on insights to be found across transgender sociology, public health, psychiatry, history of medicine, cognitive science, the social processes of science, transgender feminism, and human rights, taking an analytic approach that intersects these many perspectives and is guided by the lived experiences of transgender people. I live in Orlando with my family, and work mainly in technical writing.
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