Grow Your Own : Breast Development Update

| Jan 28, 2019
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I have been asked to update my previous post about breast development. A few more pieces of the basic biology are now available. There have been some big changes about getting hormone therapy (HT) for breast development from providers. I now have the benefit of more research and first-hand experience with breast augmentation.


We know how hormone therapy (HT) grows breasts in trans women. To begin with, on the cells of the breast there are receptors for sex hormones, estrogen and testosterone. These sex hormone receptors are in opposition to one another. In order to get breast growth, one has to stimulate the estrogen receptors and not stimulate the testosterone receptors. The way this is usually done is through HT. Estradiol stimulates the estrogen receptors in the breasts directly but it also has an effect on the brain. Taking estradiol sends a message to the hypothalamus that all is well with sex hormone levels in the body and that it need not stimulate testosterone production and release. For natal males, this mechanism works by creating a substance called gonadotropin releasing factor that trickles down into the pituitary beneath it and triggers the release of a couple of hormones that stimulate the testes to manufacture and release testosterone. In HT for trans women, this mechanism is turned off by estradiol.


The theory behind trans woman HT is to maintain blood levels of estrogen in the range of the average female and reduce the levels of testosterone. You cannot do that yourself and it is dangerous to try. All bodies are different, they start out with different blood levels of hormones and achieve different levels from HT. You want just the right drugs and dosages to get the right levels. You can get into big trouble without a physician monitoring your blood levels and adjusting the drugs and the dosages for your body. Taking more estrogen than needed does not do anything to grow breasts but it will make you more vulnerable to blood clots which can kill you. Unfortunately, the percentage of do-it-yourselfers in some quarters is at least 22%. That is the result of a study in which some people in the UK were delayed in getting HT because their government healthcare system is overwhelmed by new patients. They took matters into their own hands. On the street, the do-it-yourself is estimated at about 50%.



So, in trans women HT we are stimulating breast tissue directly with estradiol and shutting down the main route for secretion of testosterone. The adrenal glands that sit atop the kidneys, still manufacture a little testosterone and releases it in times of stress. In HT, we mop up the testosterone with spironolactone. We prevent testosterone from becoming the more powerful dihydrotestosterone (DHT) using finasteride. Another way we lower effective testosterone levels in HT is that estradiol forms a molecular complex which binds to testosterone to render it inert.


So much for the estrogen/testosterone battle over breast development but there is a bigger war out there. There are also receptor sites on the breasts for progesterone, the forgotten sex hormone. We are just now learning about all of its qualities. For example, the folks over at Emory University (across town from me) have found that it helps with recovery from certain types of brain injury.

While estrogen stimulates the growth of stromal tissue which is the ductwork in the breast that moves milk around, progesterone stimulates the growth of the lobular tissue which produces the milk (see Figure 1) . In nature, progesterone achieves its highest levels during parts of the menstrual cycle and during pregnancy. During pregnancy, the body of the mother is preparing for nursing, so breasts get bigger.


Progesterone also blocks the same brain mechanism that estrogen does to cease triggering gonadal production of testosterone. Turns out that the feedback mechanism in the hypothalamus is pretty dumb. It responds to progesterone, estradiol, testosterone. (Oh yes, and anabolic steroids too. That is why the weight lifters get small testes and large breasts. But don’t follow that path, it leads to some really bad side effects and personality changes.) So, taking progesterone can insure that the hypothalamus is fooled and the brain stops calling for testosterone in trans women. This means that one should be able to take a lower dose of estradiol and get good HT results. Some physicians add progesterone to the drug “cocktail” specifically for this reason.


Well it looks like one ought to take estrogen and spironolactone and finasteride. Those are the basics. But what about progesterone? Depends on you and your physician. Some physicians like to keep the dose of estrogen as low as possible and add progesterone to lock up the hypothalamus. There is concern that estrogen can cause blood clotting in the deep veins of the legs or in the lungs. That was particularly true for the old ethinyl estradiol but less true for the estrogen we use now, estradiol valerate. Ethinyl estradiol is still around in birth control pills and other medications, so avoid it.

In the case of spironolactone, one has to look out for dehydration and too much potassium in the blood (hyperkaliemia) and sometimes too much calcium (hypercalcemia). This is because spiro is a potassium-sparing diuretic, meaning that it causes one to make urine and retain potassium. It is actually also prescribed in non-trans women as a diuretic to lower blood pressure. I had a few bouts of dehydration with it until my physician lowered my spiro dosage. He says that he has had several older trans women on HT who went through the same thing. That is not enough to form a scientific result, but HT has to be managed. Another reason of why you should not be doing it alone.


Some physicians maintain that adequate breast growth can occur without progesterone, so they do not prescribe it. Some shy away from giving medroxyprogesterone and say that they get better results with Prometrium, the micronized (“ground down” into smaller particles) version of progesterone. Some prefer to cycle Prometrium like the normal menstrual cycle. The bottom line is that we do not have enough scientific evidence to know what works and it may be different for each of us. Your doctor may have to try out different drug regimes. Scientific studies with control groups are out because it is unethical to deny a proven treatment. Researchers might try the strategy of delaying some people from getting HT as a control group, but you can see what will happen to your control group results with 22% or more following the do-it-yourself HT approach.


Going to see a shrink, or even an endocrinologist is no longer required for hormone therapy. Any kind of physician can start you on your way with HT if they tell you about the risks and you give informed consent. WPATH now lets them do this under its Standards of Care. Only catch is that they need to have knowledge about transgender HT. There are plenty of continuing education courses for providers to get the knowledge and there are other providers who know what to do and can be consulted. This means that your family doctor or any doctor with the knowledge, can now support you in HT. Like Dorothy on the Wizard of Oz, they could always have clicked their ruby slipper heels and written the prescriptions if they had had the knowledge.


Some Planned Parenthood and Free Clinic locations now prescribe and administer HT. The free clinics that will be glad to put you on HT as long as you take your estradiol and other drugs by injection and get tested regularly for sexually transmitted diseases (STI). Part of their mission is to deal with the public health problem from STIs and test for them so they can be treated. They administer HT drugs by injection rather than by pill, so that you will keep coming back to get the STI tests.


A trans woman on HT will achieve maximum breast growth in about 2 years. About half of trans women are happy with the growth they get but about half go in for breast augmentation surgery. I am slow to react, so I had 10 years of HT before getting implants. (I seem to have been busy, researching and writing three books on transgender science and I had some other things to do which seemed more important).

Dana Bevan after breast enhancement.


After 10 years of HT, I had AA breasts which do not look good on a 48 inch chest band body. All the clothing for females with a 48 inch band, starts with the assumption of D or DD cups size and only go up in cup size. I ended up using the breast forms, that I had been using before HT. (Size 18—the largest ones made, I think). You can forget all those tales that you will get breasts one cup size smaller that you mother. My mom was a C or D. I know because I inherited some of her old bras when she died. (Some of them approach bullet bra design, which was “the thing” at the time.) We know that breast growth is more satisfactory in younger trans women and that is probably because they still are growing, at least a little. Us older chicks stopped growing long ago. I did not start HT until I was in later life. ( I won’t tell you when because that would give my age away which ladies never do.)


WPATH guidelines say that you should get one gatekeeping letter from a shrink to get implants (you need 2 for Transgender Genital Plastic Surgery). I had one, but none of the surgeons I went to wanted to see it. As long as you appear mentally competent and can give informed consent, many surgeons will not ask for one. I went to three to get estimates and had a letter in my back pocket but they never asked. In theory, the letter is to rule out psychosis or mental disorder that might impact the success of the procedure.


They are safer than ever but your results may vary. Trans women have to go back to their surgeons if there are problems but they seem to be rare. Most surgeons will not charge you for their time for implant adjustment, but you will have to pay for the operating room. Most manufacturers say that you should have implants replaced after 10 years, to which I reply that I will be happy to be alive in 10 years. Unless there are problems of encapsulation or breakage, they should last longer than the ones I wrote about in my earlier blogpost. If you are on HT, you should do monthly breast exams and after age 50, get mammograms every 2 years. If you are under 50, you should start mammograms 10 years after starting HT, thence every 2 years. Implants complicate reading of the mammograms for radiologists, but they are used to that with natal females.


If you were a big male, you probably should have big implants, depending on how much growth you got out of HT. Since I am about as big as an NFL fullback, I got the largest silicone breast implants that they make—800cc. You can get bigger ones filled with saline but 800cc was fine for me. Took the nurse to convince the surgeon of that because he had seldom used that size. Nurse said, “I think she can carry them”. What you do not want to do is get implants that are too small, only to have to come back for larger ones later.


I was judged to be “uncooperative” by the staff because I refused to take more pain meds after the operation. I had a friend with me as my person on designated “Boob Watch” (instead of Bay Watch) who finally convinced me to take them. (One has to have to have a designated Boob Watcher for 24 hours until the anesthesia wears off). I needed the pain killers that first day but stubbornly never took the ones that I had gotten from the pharmacy before the operation. I still have them because pharmacies will not take them back and dumping them down the drain does not seem good for the ecosystem. I am not urging you to resist following your doctor’s orders but I have considerable respect about the downsides of pain killers because I used to do research on them.


Dana Bevan at the WPATH gala.

Most trans women I have talked to, are happy with their implants. I am now a 48C or a 46D which I learned are “sister sizes” in bra tech school. I did have trouble finding the right bra. Seems like above band size 36, there is no predicting the fit from band sizes and cup size letters. I bought about 22 of them by mail order, because there are no stores here that have bras my size. I returned all but 4. It was a bit of a panic because I wanted to wear a ball gown to the WPATH gala in Argentina about 2 months after the operation that had considerable front plunge. (See pictures and previous blog posts on the Argentina meeting). So, I am pretty happy for the way things turned out. I gave my old breast forms to my designated Boob Watcher and I should not need them again.

So, there is your breast development update.

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Category: Transgender Body & Soul


About the Author ()

Dana Jennett Bevan holds a Ph.D. from Princeton University and a Bachelors degree from Dartmouth College both in experimental psychology. She is the author of The Transsexual Scientist which combines biology with autobiography as she came to learn about transgenderism throughout her life. Her second book The Psychobiology of Transsexualism and Transgenderism is a comprehensive analysis of TSTG research and was published in 2014 by Praeger under the pen name Thomas E. Bevan. Her third book Being Transgender was released by Praeger in November 2016. She can be reached at [email protected]

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  1. WendyWinters WendyWinters says:

    Thank you for the article Dr. Bevan. It was very helpful.

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