|Note: I wrote the first version of this page in 1999. At that time I had read no medical studies describing breast development in male-to-female transsexuals, but the burgeoning World Wide Web included numerous accounts by transwomen (particularly on the GeoCities hosting site) reporting excellent breast development. I took these reports with what I thought was large pinch of salt, but this page was initially far too positive. I have since made edits and some additions to reduce expectations, but overall the article is now very dated. However I haven't found anything much better that I can recommend, and believe that it remains a useful read if treated with caution.|
For all women, breasts are a very important and very visible aspect of their "womanhood". The display or even the indication of breasts is instinctively viewed by observers as a strong evidence that someone is female. Breasts are regarded by both men and women as a key aspect of feminine beauty - in our modern society and historically.
The development of breasts gives the male-to-female transgender woman a tremendous confidence boost, and powerfully identifies her as a female to others. It is also impossible to ignore that the fact that breasts are immensely strong sexual symbols, and secondary sexual organs whose presence can be enjoyed by both the owner and their partner. Unlike a vagina, breasts can be easily and acceptably be publicly displayed in either part (cleavage) or full (e.g. topless sun bathing), or prominently implied underneath a skimpy top. Bra's and [usually] breast forms/padding are essential early purchases for every transsexual woman.
While ultimately most transsexual women have breast implants, the first step is always female hormone treatment to enable the growth of breasts to their maximum natural size. The resulting breast development after a few years can range from minimal to very respectable - and even in worst case, modern bra's, "push-ups" and breast enhancers can still do wonders appearance wise.
Above, the male breast, and below the female breast
Development in the Genetic Woman
Mammogenesis commences at puberty with the onset of oestrogen secretion by the ovaries - usually between the ages of 10 and 12 in a genetic girl. Oestrogen (often spelt 'Estrogen' in American English) stimulates breast growth by acting causing enlargement of the mammary fat pad, one of the most oestrogen-sensitive tissues in the human body, as well as lengthening and branching of the mammary ducts. The development occurs according to well-defined milestones called the Tanner stages:
The levels of oestrogen required to cause breast development are surprisingly low - until stage IV, the growth of the breast in a girl takes place with oestrogen levels similar to an adult male. That is why about 40% of male children also initiate "Tanner I" type mammary development during their early part of their puberty - their developing testis secrete significant quantities of oestrogens. However, as testosterone secretion also increases the breast development ceases and very few boys reach the Tanner II stage.
It takes just two to three years for a girl to achieve the majority of her breast growth. Stage V is aligned with the onset of the menstrual cycle - which results in the production of progesterone for the first time. The presence of progesterone stimulates the partial development of mammary alveoli, so that by the age of 20 the mammary gland in a woman who has not been pregnant consists of a fat pad through which pass 10 to 15 long branching ducts, terminating in grape-like bunches of mammary alveoli. In the absence of pregnancy, the gland maintains this structure until menopause. These ducts are very small and contribute little to breast size - this is a key reason why many doctors consider the prescription of progesterone to be unnecessary for transwomen.
Mammogenesis is completed during pregnancy, with the gland becoming able to secrete milk sometime after mid-pregnancy. Pregnancy is often considered to be the period of most extensive mammary growth. Indeed, extensive lobular and alveolar development occurs only during pregnancy. During pregnancy, it is not unusual for a woman's breast size to temporarily increase by a full cup size.
Lactogenesis (referred to as the time when the milk "comes in") starts about 40 hours after birth of a baby and is largely complete within five days. When nursing ceased the breast undergoes partial involution, losing most of its milk producing cells and structures. Many women have slightly smaller breasts after pregnancy and nursing because they have less fatty tissue and once the breast is no longer swollen with milk it can sag in an unsightly manner.
Innovolution completes after menopause, when most women move to a smaller bra size. However since the 1990's hormone replacement therapy has become a very common treatment for women starting their menopause, this can actually stimulate breast development and it is not unusual for bra size to actually increase.
Development in the Transsexual Woman
In the initial phase of hormone therapy subareolar nodules - which can be painful - are common. Both oestrogen and progesterone (despite the reservations of some professionals) should be taken - oestrogen stimulates cell mitosis and growth of the ductal system, whilst the growth, development and differentiation of the glandular tissue (lobules or alveoli) seems to be dependent on progesterone, and breast fat accretion seems to require both. A transwomen with well-developed breasts is thus quite able to nurse - given the right stimuli.
It's important to realise that the results of female hormone treatment eventually become obvious to everyone, whether called breasts or "man boobs". For the pre-transition woman on hormones - it becomes increasingly difficult and embarrassing to go topless - local swimming pool, the beach, or in the bedroom with a partner.
It takes about two years of hormone therapy for a transwoman to achieve maximum breast growth. Unfortunately, even if this is quite generous, the overall appearance of the breasts is often hampered by the transgirl having a larger chest cage than the average average cis-woman. Even when their bra-cup size is actually the same, a transwoman will often consider her bust development unsatisfactory compared to that of a similarly developed cis-female. As a result, a majority of transwomen have augmentation mammoplasty.
In older transwomen, their small breasts are also likely to be spaced widely, and one breast is often noticeably larger than the other. These problems make it difficult to monitor the degree of breast development in mature transsexual women using the Tanner scale.
The suggested average breast size of adult genetic women (post-puberty, pre-menopause) in Europe and the USA varies widely from study to study. The census seems to be that slightly ,more than half of all women are naturally a B or C bra cup, but relatively few (<25%) are a D cup or greater. Triumph's European Bra Size Survey from 2007 famously found that 57% of UK women were a D cup or more (18% C, 19% B, 6% A), and the average size increased to DD in the 2015 survey! But these highly improbable findings were undoubtedly biased by the absence of any checking of the submitted responses, and the survey has little credibility.
All transsexual women like to 'round up' the breast development they achieve from hormones and other more uncertain methods. But multiple studies paint a rather depressing picture.
Breast size can be quantified by measuring the maximum hemi-circumference over the nipple with a flexible tape. The following table shows the results from one study of breast development, measured in the sitting position, of 500 transsexual women:
It clearly shows that the breasts of male-to-female transsexual women are considerably smaller than genetic XX women. To make matters worse, the width of the average transsexual woman's thorax is greater than that of the average female thorax, and so the breast development is proportional to the chest size even less than the figures indicate.
A second study published in 2017 of the breast development of 229 European transwoman age 18 to 68 (the median average being a surprising young 28) after a year on hormone therapy (estrogen and anti-androgen) showed similar disappointing results. The study used the approach of measuring the circumference of the chest underneath the breasts and at the largest part of the breasts. The difference between these two measurements was then used to determine breast growth and bra size. The study found:
To compound the disappointment, the study showed that almost all of the breast growth happened during the first six months of cross hormone therapy (CHT), and that it had tapered to almost no growth by the final three months. I.e. it seems that a transwoman has not achieved substantial breast growth after six months on hormones, she is unlikely to be much better off several years later.
The final amount of breast development obtained by a transsexual woman on hormone treatment is undoubtedly very variable and depends on a numbers of factors:
Firstly, and one thing no Mng about, is the fact that their body has since the foetus stage been exposed to larger amounts of testosterone hormones than a girl. The cumulative effect on the body is very significant - the most obvious early differentiation is a penis rather than a vagina, but there does seem to be a significant impact on potential breast growth as well. Women suffering from AIS (i.e. genetically XY male, but unaffected by androgens) are as well endowed bust wise as their female relatives, so the constant drizzle of testosterone in the womb and onwards seems to have an irreversible effect on the potential breast development of "boys".
Secondly, genetics also play a very significant role - some people are genetically predisposed to have copious amounts of fat cells in therefore large breasts, others practically none. Thus amply endowed sisters are a promising sign that development will be good, while flat chest'ed sisters are a serious worry!
Thirdly, breast growth seems to be very age dependent - the younger a person and the more recent puberty the better the development will be. But even 20-something is likely to disappointed.
Finally, other smaller factors come into play in determining the size of a woman's breasts, including nutrition, exercise, health, and weight. For example, if a woman's body weight falls below its optimum then her breasts can shrink dramatically as the fat cells in them are burnt up (or in the case of a skinny transwoman are perhaps never deposited), while if her weight is above optimum then the apparent or relative size of her breasts may diminish as they are swallowed by the surrounding "padding".
The following chart shows the result of a study that tracked the breast development of nearly a hundred transgender women (varying in age from 17 to 64) after they began female hormone treatment:
The study found dramatic changes in the first 12 months of hormone treatment, with over 90% of patients reaching at least Tanner III. But there was only modest improvement thereafter, with barely 8% of patients achieving Tanner V after 24 months, by which time breast development had almost stopped in all patients.
After a prolonged pause breast tissue growth may restart - although there is usually a trigger such as a change in the hormone regime, an orchiectomy, or SRS.
Age Matters - A Lot ...
Towards the end of puberty (age 15 to 17) a genetic "switch" in the human body seems to flick and the likely amount of breast development rapidly falls away to a much lower level. Since about 2001 it has become quite common for young transgirls to be prescribed anti-androgen 'puberty blockers'. These have very important effects such as preventing facial hair and the voice deepening, but they don't seem to stop the clock on potential breast development.
The now large volume of evidence is that a 12 or 13 -year old boy-to-girl who begins taking female hormones (sadly, probably obtained on the black market) is likely to develop breasts not much smaller than his sisters and mother; the same person starting hormone therapy as a 18 year-old may be lucky and still have satisfactory results; but as a 30 year-old she will be lucky to reach even an A cup, and as a forty+ year-old can only expect modest breast budding.
Empirical evidence strongly indicates that for the best possible breast development, oestrogen hormone treatment (rather than just puberty blockers) should begin before the on-set of male puberty. Based largely on the controversial treatment of treatment of intersex children with XY genes, beginning oestrogen hormones around age 12/13 is likely to achieve breast growth very similar to pubescent CIS girls. There is certainly no disputing the fact that genetically XY women suffering from AIS usually have excellent breast development during the normal puberty years. However there seems to no medical studies of the effects of hormone therapy on young teenage 'XY' girls, undoubtedly because (in Europe at least) this often involves medically unsupervised self-medication. In the early years of this century almost no medical professional in Europe would prescribe female hormones to a transgirl under 18, and it's only since about 2015 that transgirls under 16 have had any significant chance of being prescribed estrogens, rather than puberty blockers.
In terms of breast volume, the final result is then likely to be only slightly less than the girls mother and sisters. However such hormone treatment is unsupervised and the results are unverified as the Standards of Care still prevents (for many good reasons) the hormone treatment of adolescents under age 16. However doctors are ceasing to be dogmatic about following the standards rigidly, e.g. in 2016 the UK's NHS abandoned its minimum age policy for the prescription of hormones for transgender children.
It appears that 18 is already beyond the optimal age for good breast development. Whilst most girls who start hormone treatment in their teens will eventually develop "B cup" Tanner IV or V type breasts, even this is still by no means certain. For example the model Caroline Cossey started hormones at age 17 but owes most of her famous 36C chest to implants two years later, and Caroline is far from unique.
Certainly many young transsexuals are dissatisfied with their breast growth as they compare themselves with other girls, and begin to compete for boyfriends.
Conversely, while most transgender women starting hormones when already adult will achieve only Tanner III "AA cup" breasts, a few (a very few!) will get adequate, even ample, breast development.
There is undoubtedly a degree of wishful thinking and 'rounding up' in the breast measurements and bra sizes claimed by transsexual women. In particular, the claims often made by middle aged transwomen to have developed large breasts after a year or two on hormone therapy are improbable and should be treated very sceptically.
The Exceptional ...
Television star Jazz Jennings is a "pin-up girl" for the benefits of early female hormone treatment. She was on [male] puberty blockers for many years - possible from age 10 - and was still flat-chest'ed when she turned age 15 (e.g. photo right). However she must have started started taking estrogen around her 15th birthday as her breast development thereafter was remarkable, By age 17 she had very obviously reached a D/E cup Tanner V. She stopped wearing a bra when she no longer needed to pad, but her increasing breast development soon forced her to again wear a bra for comfort - "[As a girl] I have boobs too, and I need to wear bras as well" - and soon after she launched her own Jazz bra !
But even among teenage transgirls, Jazz's breast development is well above average, as she acknowledged herself in a YouTube video (photo right) soon after turning 17:
... and the More Likely
The early prescription of estrogen hormones has many benefits for transgirls, but guaranteed good breast development is not one of them. In 2001 I developed a 'rule of thumb' that a transwoman's best possible breast development from hormones was bra-cup size less than her mother, I discarded this theory in the face of supposed "evidence that similar or even greater development was apparently common. I have now reverted to my original supposition!
1970/80's celebrities such as Eva Robin's, Roberta Close and Amanda Lear who began hormones in their teens never reached more than a modest B-cup. The very long list of young transgender models (e.g. Teddy Quinlivan, Ines Rau, Valentina Sampaio, Geena Rocera ...) who undoubtedly started taking antiandrogens (i.e. testosterone blockers) and female hormones whilst in their teens is even less impressive as regards to breast growth.
Another television star, Valentijn de Hingh, is perhaps a good example to compare with Jazz as her life was closely followed by Dutch television from age 8 to 17. Although born physically male, her parents accepted her desire to be a girl and she transitioned when 9. The Standards of Care were then stretched to the limit - she started to take puberty blockers at 12, female hormones at 16 and had her sex reassignment surgery at 18. Since then has been working as a highly rated model, just outside a Top 100 "super-model" ranking.
Two steps forward, One step back
Fast forward to 2015, and I have become increasingly puzzled by the complaints of young (teenage) transgirls that after several years on hormones, they still have little or no breast development. This just doesn't seem to align with the experience of teenage girls in the 1990's and early 2000's, who commonly had good breast growth. After consideration of what may have changed, I think it could be the hormone regimen.
Teenage transgirls in the 1970's through to the 1990's often self medicated and took relatively high doses (by current standards) of estrogen hormones dubiously and dangerously purchased without a prescription, often from off-shore pharmacies. One of the most popular brands was 'Premarin' - a natural conjugated estrogen extracted from the urine of a pregnant mare. This is easily assimilated by the human body and strongly promotes in a teenager the development of female secondary sexual characteristics such as breasts, a feminine pattern of fat distribution, and even (anecdotally) a widening of the hips.
In the early 2000's there was a massive clamp down on off-shore pharmacies, whilst at the same time the medical professional (guided by the revised Standards of Care) became more willing to treat transgirls under the age of 18, albeit with significant provisos.
The prescriptions now being given to transgirls are usually for anti-androgen puberty blockers such as Lupron (Leuprolide Acetate) from age 14, with a relatively low dose of a synthetic estrogen steroid hormone such as estrodial only being added when they turn 18. The result is a very effective prevention of physical masculinisation such as facial hair, deepening voice and muscle build up. However the medications do little to promote feminisation and breast growth (indeed may hinder this), with the estrogen being added too late and of a type that breast tissue is not sensitive to.
The end result of the current approach often seems to be a 21-year old transwoman who despite (or rather, because of) years of medical treatment still looks like a young teenage boy physically, whilst in the same time her younger sister has transformed into a buxom woman.
I suspect that the medical profession needs to become far more aggressive in the prescription of female hormones rather than blockers for transgender children in the 14-17 age group (accepting the risk of the occasional mistake), and that pressure for this is building. Indeed the instances where transgirls of age 16 or less are prescribed estrogen by a doctor already seems to be moving from exceptional to quite common.
The Areola of Transwomen
One odd problem that transsexual women face is that their areola - the coloured skin surrounding the nipple - rarely expands in accordance with 'normal' female breast growth. The areolae of a man averages about 25 mm (1 inch) in diameter, but few woman are under 30 mm and 50 mm is common, and the areola of women who have large breasts or who are lactating may be over 100 mm (4 inch) in diameter. Unfortunately even well-endowed transsexual women tend to have male type arealoe - this seems to be a genetic limitation as AIS women (who are also genetically XY) face a similar problem despite otherwise above average breast development.
Another characteristic of the breasts of MTF transsexual women compared with genetic women is the smaller average diameter of their areola, even if the breasts themselves are actually quite generous in size. Only starting hormone treatment at a young age seems to avoid this tendency. Also, because the breasts of transsexual woman rarely reach full Tanner V size and maturity, their nipples often appear very prominent - although few object to this.
Low-cost anti-androgen's such as Spironolactone, Androcur or Finasteride are often included as part of a transwoman's hormone regimen. However there is an increasing suspicion (not backed by any formal medical studies) that high doses of these can cause incomplete breast development, and it is best to avoid these if possible. If an androgen blocker is really needed, Bicalutimide seems to be the best choice. The use of a "cocktail" of hormones that includes both oestrogen and progesterone may help reduce hypoplasticy, there is also anecdotal evidence that rubbing a progesterone cream in to the nipple area can help.
The overall effect and appearance of their hormone-only induced breasts is judged unsatisfactory by some 50-60% of MTF transsexual women, and the vast majority of these seek augmentation mammaplasty (breast implants).Dissatisfied girls rushing to seek breast implants after just one or two years on hormones may then experience complications and misshaped breasts when another spurt of breast tissue growth sets in - as is quite common after SRS or an orchiectomy.
It should also be expected that the breasts will grow unevenly, e.g. the right may become much fuller that the left. In the long-term the differences will mostly even out, but even in mature genetic women there is often a quite visible difference in size and shape between the left and right breasts when a study is made of them. But if the difference is excessive (e.g. a cup size), to the extent that one breast has to be padded, then this can be largely eliminated by the use of different size breast implants.
The last decade has seen the emergence of an additional solution for transwomen who want to increase the size of their hormone induced breasts by a modest amount without surgery.
This essentially involves injecting fat cells into the breast tissue. Fat is taken through liposuction from the woman's belly or bottom. The fat cells are filtered out from the extract and then put into a cartridge for injection into her breasts maybe an hour later under local anaesthetic. Some practitioners refer to the 'fat cells' as 'stem cells' - technically this is correct although their ability (potency) to differentiate into different cell types is low.
After injection of the fat cells in to the breast, about 30% of the immediate gain is quickly lost, and the long-term loss is typically 50-70%. However it's a good option if a quick confidence boosting increase in breast size is needed, e.g. for a beach holiday, beauty contest or even a wedding!
For transwomen with reasonable but not quite sufficient hormone induced breast development, this technique can be a very good alternative to breast augmentation. It should round out their breasts and provide a modest boost in size. Importantly there are no signs of surgery and no implants to mare the feel of the breasts.
Although often only partially developed, the breast structure of a transsexual "XY" woman is basically the same as a genetically "XX" woman after the first phase of mammogenesis. Thus medical information and rules about female breasts (including the need for regular breast self-examination and mammogram's) apply just as much to transsexual women taking oestrogen as they do to genetic cis-women.
Assuming that hormones is the right route, patience is essential, it will take at least two years to achieve full breast growth and some imperceptible changes will continue for the rest of your life - as trying on a very old bra will reveal.
The earlier in life that oestrogen begins the better, but some girls who began treatment as young as 16 still have have only Tanner II/III type budding years later.
Realistically, most transsexual women starting hormone treatment over the age of 18 will be very lucky if they eventually genuinely fill a "B cup" bra from hormone use alone, and those over 30 an "A cup". However, if letters are important it should be remembered that despite a perception created by television and the press, the average cup size of a genetic cis-women is actually only "B". Many transwoman actually reach a breast circumference and volume of breast tissue close to the average for a natal cis-women, but because their larger skeletal frame it appears visually inadequate. One study of 60 transwomen incidentally mentions that 58 had had breast augmentation, with a high degree of satisfaction with the results.
In 2001 I suggested on the first version of this page that a transwoman's best possible breast development from hormones was one bra-cup size less than her mother. Medical studies have proven this to be far too simplistic, it may be still have some validity as a 'rule of thumb' for a teenage intersex and trans-girls, but doesn't apply for anyone over 19.
A Final Warning
Taking hormones hoping to somehow become a closet page 3 girl - but without anyone at work or even the wife noticing - is simply unrealistic. Breast growth is irreversible without reduction surgery, stop taking the hormones and the breast growth that has been stimulated will still be around ten years later, it does not melt away.
Further - breast tissue means the risk of breast cancer. In the UK this is the direct cause of death for 15% of women, whilst it's negligible for men. Transwomen are less susceptible than natal women to breast cancer - probably because of the late and limited nature of the average transwoman's breast development - but it's now a significant risk. Signs of breast cancer include a lump in the breast, a change in breast shape, dimpling of the skin, fluid coming from the nipple, a newly inverted nipple, or a red or scaly patch of skin. Transwomen over 50 who have been on hormones for ten years or more should seriously consider regular mammography screening.
Please contact me if you have any comments.
Below are pictures sent to me by transgender women of their hormone induced breast development (i.e. with no implants).
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Copyright (c) 2016, Annie Richards