By Trystan Reese
Last updated June 24, 2020
Even though I have given birth to a baby after over a decade of testosterone use, I still hear from medical providers who tell me that testosterone causes sterility. I’ve said over and over again that I am not a fluke— hundreds and maybe thousands of transgender men all over the world have successfully given birth or otherwise contributed their eggs to a pregnancy. But sometimes you need hard scientific evidence to back you up. And I’m pleased to say that we finally have it, courtesy of Boston IVF and their new study on trans fertility!
Boston IVF’s study looked at the medical charts of 26 transgender men who went through at least one egg harvesting cycle at one of their clinics. An egg harvesting cycle is a process where the patient goes through an estrogen-based hormone regimen to encourage their eggs to mature, and then completes the cycle by having those mature eggs gathered during an office visit. This process is used if someone would like to preserve their eggs as they get older or plan to transition, or if they plan to fertilize the egg through IVF and carry the embryo themselves or have a partner carry the pregnancy immediately or sometime in the future.
They matched the data from the trans cohort with cisgender women who had been through egg harvesting procedures, linking up trans patients with cisgender patients who shared similar demographics (age, weight, etc.) to look for differences between the two groups. And they found… nothing. Well, close to nothing. The two cohorts were almost exactly the same in terms of how many mature eggs were produced by each group, which is what the study was looking at.
In order to understand why this study is important, let’s talk about how testosterone impacts our reproductive systems and what this new study proves.
Testosterone and Ovulation
A trans health expert will tell you that testosterone is a “dose-dependent ovulation suppressant.” That’s a fancy way of saying “if you take your testosterone the way you’re supposed to, it will stop ovulation.” But let’s be clear— that “if” is doing a LOT of work in that sentence. It is extremely common for a trans person to miss a shot. You might get busy and forget. You might be afraid of needles and postpone it because you dread doing it. Your pharmacy might run out, or you go to pick it up and that guy who always harasses you is working so you have to come back another day. Your doctor might switch to being in-network with different insurance so you have to find a new provider. You might not have insurance at all. Etc. So if you miss a shot (or are too late or too early on a shot), you could ovulate and become fertile. Additionally, that “if” comes into play with regards to how well your provider is managing your hormone levels. They might not be checking your levels frequently enough (or at all). They might not be trained specifically in trans health and might not know what to look for. So all that is to say: testosterone SHOULD stop ovulation from occurring, but there are a lot of variables that might impact the success of that process. In the Boston IVF study, some of the participants waited until their menstrual cycles came back, and that took an average of four months. Other participants didn’t want to wait for their cycles, so the clinic measured their hormones to identify when their levels had returned to a point at which an egg harvesting cycle would likely be successful. For those who waited for their cycles, it took an average of four months for those cycles to return.
Testosterone and Egg Health
Okay, so let’s start with biology 101. Those of us who are born with eggs and a uterus are actually born with all the eggs we will ever have. It’s not possible to create more eggs once we are born, and once we are born, our body starts shedding/absorbing those eggs almost immediately. It starts slowly, so our millions of microscopic eggs start reducing a little bit right away, and the process accelerates around puberty. We continue to lose eggs until around age 36, which is when our egg reserve, as it’s called, is drastically diminished. Between roughly 36 until menopause (when we run out of eggs completely), our egg supply is pretty low and it can be harder to get pregnant and stay pregnant (or to harvest and use eggs for pregnancy in someone else). So however many eggs we have at any given time, that egg reserve is full of immature eggs— you can’t just go in and grab them and use them for anything. They’re like pupas that would be useless outside the body. In order to actually use one of those suckers, it has to mature (which is what ovulation actually does). The egg travels around in there, slowly getting to the point where it sits in the Fallopian tube, mature and waiting to be fertilized by sperm. So that’s a bit about how eggs work (in a very simplified version that my doctor friends will probably shake their heads at). The question then becomes— what happens to those eggs while we are on testosterone? Well, the answer might blow your mind. The answer is: nothing. I mean, the body continues to shed/absorb immature eggs as it would anyway, and as long as you’re not ovulating, your body isn’t sending one egg at a time down the maturation corridor to sit in your Fallopian tube once a month. But other than that, your egg reserve just chills in there, waiting to be completely depleted (menopause) or to be used through ovulation. It’s a little bit like the egg processing plant just shuts down temporarily. If you stop taking your testosterone, eventually (usually within six months) the processing plant opens its doors again and starts releasing one mature egg each month (or so). In fact, the Boston IVF study found that egg quality and quantity (in addition to other variables around pregnancy and egg harvesting) were the same between transgender men and cisgender women.
Testosterone and Pregnancy
In this same study, some of the transgender men who had their eggs harvested chose to get pregnant through IVF (the eggs were fertilized with sperm in a lab, and the resulting embryo was reimplanted in their body). Those men had the same pregnancy experiences and outcomes as the cisgender women in the study. Several other studies have looked at pregnancy outcomes of transgender men and non-binary folks who’ve given birth and have found the same thing— other than the social stuff of being not a woman while being pregnant, trans pregnancies are the same as other pregnancies. You see the same time to conception (time spent trying to get pregnant), same pregnancy experiences, same delivery outcomes. People who have been on testosterone prior to becoming pregnant sometimes make different choices than the average cisgender woman who has a baby (trans folks are more likely to opt for birth outside of a hospital setting, they are more likely to request a cesarean birth, and they are less likely to breastfeed/chestfeed) but medically speaking, pregnancy is a pregnancy, regardless of the gender identity or past hormone use of the pregnant person.
A warning: if you become pregnant while on testosterone and you plan to carry the pregnancy to term, it is critical that you stop taking your hormones throughout the entire pregnancy. Testosterone could cause serious harm to the developing fetus.
We hope this was helpful in educating you on the results of this new study! We recommend you also head to our partnership project with Fertility IQ and check out the video series on trans fertility. We also have lots of other resources in our trans family-building library.
Leung, Angela, et al. “Assisted Reproductive Technology Outcomes in Female-to-Male Transgender Patients Compared with Cisgender Patients: a New Frontier in Reproductive Medicine.” Fertility & Sterility, American Society for Reproductive Medicine, Nov. 2019, www.fertstert.org/article/S0015-0282(19)30619-3/abstract.