Breast Development
(In Male-to-Female transsexuals)

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 had numerous accounts by transwomen (particularly on the GeoCities hosting site) describing their excellent breast development. I took these reports with what I thought was large pinch of salt, but this page was initially far too positive and I began making changes to reduce expectations, The article is now very dated, however I 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. Calpernia Addams

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.

Transwoman Melanie Annie communing with her breasts.

The Breast
A breast (also known as a mammary gland) is a complex structure consisting of a mass of fatty tissue and nerves served by a good blood supply. Fully developed, each breast when lactating is capable of supplying a pint (600ml) a day of notorious milk to a nursing infant - essentially enough for a mother to breast feed twin babies in their early months. Visible in the centre of the breast is the protruding nipple, which is surrounded by a pigmented circular area called the areola. Small glands in and around the nipple provide lubrication and protection against infection, which is particularly important for breast-feeding mothers. Produced by the lobules (consisting of alveoli) in the interior of the breast, milk is carried to the nipple by a collection of tubes known as ducts.

Above, the male breast, and below the female breast

Arguably the most famous breasts in the world are still those of Marilyn Monroe. But her 34B /32C bra size now seems very modest.

Breast Development in the Genetic Woman
At birth the rudiments of the functional mammary gland are in place for both boys and girls - the nipple and areola are formed along with a rudimentary system of mammary ducts extending into a small fat pad on the chest wall. The mammary gland remains a rudimentary system of small ducts until puberty when in genetic woman the advent of oestrogen secretion by the ovaries brings about the first stage of the four stages of mammary development: mammogenesis. Only the breasts of childbearing women go through the next two stages - lactogenesis and lactation. Finally, the breasts of post-menopausal women go through involution.

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:

Tanner Stage	Average Age (Girls)	Description
0	N/A	Men and prepubescent girls
I	10 - 12 years	Increased nipple size
II	+ 6 months	Increased areola size. A breast bud develops - a small tender lump behind the nipple
III	+ 18 months	The breasts visibly start to develop and the size of the nipple–areola complex increases.
IV	+ 24 months	The breasts fill out but the areola is still a prominent mound
V	+ 42 months	The areola becomes confluent with the fully developed breast, leaving only the nipple proud

Actress Lisa Allison appeared in a few modest 16+ movies, her textbook Tanner V breasts gaining far more attention than her acting skills.

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 common for a woman's breast size to temporarily increase by up to a full cup size.

A pre-SRS transwoman with exceptional Tanner V breast development from hormones. No obvious implants or tattoos to enlarge the areola.

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 ceases the breast undergoes partial involution, losing most of its milk producing cells and structures. Most woman who have had their first child ultimately end up with slightly smaller breasts than before they became pregnant because they now have less fatty tissue, also once their breasts are no longer swollen with milk they can sag in an increasingly unsightly manner - particularly after multiple children.

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 entering their menopause, the renewed influx of estrogen can stimulate breast tissue redevelopment and an increase in bra size.

Breast Development in the Transsexual Woman
Transwomen on female hormone therapy experience a development of their breast tissue that is anatomically and histologically identical to a cis women. Every person whether genetically male or female is born with milk ducts — a network of canals that transport milk through the breasts. In the male-to-female transsexual woman the mammary glands stay quiet until the commencement of hormone treatment releases a flood of oestrogen's, causing them to grow and swell in what is effectively a female puberty, initiating the first phase of mammogenesis.

Sarah after 10, 17 and 26 months on hormones - age 23 and 24.

The transwoman's breasts then slowly evolve and gradually increase in size, often with periods of growth and periods of apparent standstill. Her breasts follow exactly the same early stages of development as are seen in a natal female puberty. As already mentioned, the breast growth and development is medically defined by "Tanner's Five Stages":

Tanner Stage	Description (as applies to transsexual woman)	Example
Stage I (Pre-hormone treatment)	The undeveloped "pre-adolescent" pre-hormone type breast consists of a small elevated nipple (papilla) only, with no significant underlying breast tissue.
Stage II (Hormone treatment started)	After 6-8 weeks of hormone treatment subareolar nodules can be (painfully) felt and the nipple becomes very sensitive. After about three months breast buds will visibly start to form. There is an elevation of the nipple and surrounding breast area as a small but increasingly obvious mound, and the areola diameter may begin to enlarge (particularly in young women). Milk ducts inside the breast begin to grow. Elderly transwomen may not get beyond this stage. There is a lack of material for satisfactory breast implants - any implant will be very obvious.
Stage III	This stage is reached by most transwomen after between six months and a year of continuous hormone treatment. There is further enlargement and elevation of the breast and areola (with no separation of their contours). The areola may begin to darken in colour. The milk ducts give rise to milk glands that also begin to grow.
Stage IV	If achieved, it will take one to two years on hormones to reach this stage. There is a projection of the areola and papilla to form a secondary "mound on a mound" above level of breast. Many twenty-something transsexual women display this characteristic after pro-longed hormone use.
Stage V	Only a very few transsexual women (most under age 20) reach this "mature" stage after two to four year of continuous hormone treatment. The breast has now fully filled out and only the nipple still projects, the areola has recessed and become part of the general breast contour i.e. the secondary mound has disappeared. Good quality breast augmentation surgery with suitable breast implants can result in an excellent Tanner V-like appearance.

Good but not generous final breast development is typical for many women starting hormones in their early 20's.

Small, pert and strangely pre-teen like breasts are common for those starting hormones in their early 30's. Many transwomen are dissatisfied with this and eventually have breast augmentation.

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.

Loira, mid-20's - after two years hormones. The breasts are similar to many girls in their early teens, but unfortunately on a larger rib cage.

A transwoman in her 30's. The hormone regime is not known, but but the development is consistent with 4 or 5 months of full dose hormones.

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.

A 30-something transwoman flashing a breast for the camera. She's been taking female hormones for over ten years, no surgery.

How Big?

Unusual looking long-term un-augmented breast development by a transsexual woman who started hormones at age 23 - the picture is taken 11 years later. She wears a 42C bra.

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:

Description	Average	Min.	Max.
After 12 months Treatment	10 cm	4 cm	22 cm
Maximum Development (After 18-24 months Treatment)	18 cm	4 cm	28 cm
Normal Cis-Female Development	22cm	12 cm	36 cm

Andrea began hormones in her 20's. The upper picture is a 'before' and the lower picture shows the results after 30 months - an A cup bordering on B, and Tanner III bordering on IV.

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:

Just 21 (9%) of the women had a bra size of an A cup or larger (12+ cm difference)
14% had an AA cup (10-12 cm difference)
26% had an AAA cup (8-10 cm difference)

50% had little or no hormone induced breast development

A transwoman who began hormones in her 40's. If her claim of no surgical augmentation is correct, her breast development is far above average.

To compound the disappointment, the study showed that almost all 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.

Tanner III breast development (full A to small B cup) is typical for transgirls who start taking oestrogen hormones in their late teens or early twenties.

The final amount of breast development obtained by a transsexual woman on hormone treatment is undoubtedly very variable and depends on a number of factors:

Firstly, 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 chested 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.

A mature post-SRS MTF transsexual - however there's a suspicion of augmentation

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 125 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. Although all patients were judged to have reached at least Tanner III after 24 months on hormones, breast development had almost stopped at by this time, and just 8% were Tanner V.

Eva Robin's began taking estrogen hormones when age 13, in the form of contraceptive pills supplied by a sympathetic neighbour. Within a few years she was wearing a B-cup bra but her breast growth then stopped. Shown age 19, 33 and 52.

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.

Photos showing the effect of two years of oestrogen treatment on two teenage transgirls.
Left, age 19, unnamed (Tanner III). Right, age 15, 'Simon' (Tanner IV). The order is correct.

Julia and Bia show a breast shape common in 20-something transsexual women who start hormones after puberty (even by just a few years) but have not had breast augmentation.

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.

Alexandra started taking hormones in her early 20's (left) and is shown several years later (right). Further breast development is unlikely.

Empirical evidence strongly indicates that for the best possible breast development, oestrogen hormone treatment (rather than just puberty blockers) should begin well before the on-set of male puberty. There is certainly no disputing the fact that genetically XY women suffering from AIS usually have excellent breast development during the normal puberty years despite having estogen blood levels far below that of most pubertal girls. Based largely on the controversial treatment of treatment of intersex children with XY genes, only beginning oestrogen hormones around age 11/12 is likely to achieve breast growth similar to pubescent CIS girls. In terms of breast volume, the final result is then likely to be only slightly less than the girl's mother and sisters.

There seems to be no medical studies of the effects of hormone therapy on very young teenage 'XY' girls, possibly because (in Europe at least) this often involves medically unsupervised self-medication and the results are unverified. The Standards of Care Version 7 - published in 2012 - prevents (for many good reasons) the hormone treatment of adolescents under age 16 and as result in the early years of this century almost no reputable medical professional in Europe would prescribe female hormones to a transgirl under 18. However, doctors are ceasing to be dogmatic about following the standards rigidly because of the self evident success of early intervention, e.g. in 2016 the UK's NHS abandoned its minimum age 16 policy for the prescription of hormones for transgender children. Transgirls under 16 now have a significant chance of being prescribed estrogens, rather than just puberty blockers.

The top photo is of a 27 year-old transwoman after 18 months on hormones. The lower picture is of a 56 year-old transwoman (also shown left, age 53) after 10 years on hormones. Comparison shows many similarities, although the younger women has greater development in far less time.

This 53 year-old trans-woman has been on hormones (0.675 mg Premarin, 10 mg Progesterone, 2 mg Estrofem) for 7 years. However, there's a suspicion of augmentation

Nevertheless, it increasingly appears that beginning hormone treatment when age 16 is already beyond the optimal age for good breast development. Whilst most girls who start hormone treatment at in their mid/late teens will eventually develop "B cup" Tanner IV or V type breasts, this is by no means certain. For example, the model Caroline Cossey started hormones at age 17 but owes most of her famous 36C chest to breast implants two years later, and Caroline is far from unique. Many young transsexuals are dissatisfied with their breast growth as they compare themselves with other girls, and begin to compete for boyfriends.

Self-Deception
Most transgender women starting hormones when already adult claimed to achieve significant breast growth, often within a few months. I initially took these claims at face value, but seeking more information I conducted between 2001 and 2003 an unscientific on-line survey of transwomen to identify their hormones regimes, and the effects obtained.

The breasts of a transwoman in her 20's and then 40's. Between the two pictures breast implants have been added and removed, resulting in breast droop oddly similar to a mature woman who has breast fed several children.

Unfortunately I didn't trust the results as there was a very odd finding. All seven respondents who had begun taking hormones by age 19 or less were satisfied with their breast development (albeit all only claiming an A or B cup) and none had had breast augmentation. By comparison, a majority of the 39 respondents who started hormones age 20 or later claimed to have achieved very good breast development (C or D cup) from hormones, however 27 had since had breast augmentation surgery. Sadly, I just didn't believe the survey results for the over 20's.

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.

My final conclusion was that many adult transwomen will achieve only Tanner III "A cup" breasts from hormones use, although a few will get adequate - even generous (a very few!) - breast development.

Breast Growth in Young Transwomen

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 - probably from age 10 - and was still flat-chested when she turned age 15. However, she then began taking estrogens and her breast development thereafter was remarkable. She was initially reluctant to wear a bra, but by age 17 had reached a 34D/E cup! Her large breasts forced her to wear a bra for comfort - "I have boobs [and] need to wear bras". A year later. age 18, she launched her own Jazz bra.

From the left, Jazz age 15 years 5 months, 17 years 2 months, 17 years 9 months and 18 years 3 months. She is also
shown right, age 18 year 3 months promoting her 'Jazz bra' - after a huge 14 kg weight loss compared to a year earlier.

Even among teenage cis-girls, Jazz's breast development is well above average, as she acknowledged herself in a YouTube video soon after turning 17:

"I did not get any surgery on my breasts, and surprisingly they have grown to be the large size that they are today. Anyway, the reason why my boobs have grown so large is because my mom has really big boobs and I feel like her genetics is what caused me to ... blossom like this. I got lucky ... I've been very fortunate to have my breasts grow the size that they are today and it's something unexpected. [My] endocrinologist ... said she has never really seen anyone develop the way I have in terms of my boobs."

Transgender actress Trace Lysette claims that her breast development is solely due to the hormones she started taking after High School (age 19?), and that she hasn't had breast augmentation. She has no tell-tale signs of BA, and isn't afraid to go topless when script calls for it. Agencies give her bra size as 34C.

... and the More Likely

The early prescription of oestrogen 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 genetically XY transwoman's best possible breast development from hormones was a bra-cup size less than her XX mother. I soon discarded this theory in the face of supposed "evidence" that this was a very pessimistic view, but 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 B-cup.

Paulinha d'Bouar started taking hormones age 18, shown age 22.

Fast forward to the 2010's and there is a long list of young transgender models (e.g. Teddy Quinlivan, Ines Rau, Valentina Sampaio, Geena Rocera ...) who started taking antiandrogens (i.e. testosterone blockers) and female hormones whilst in their teens. Their breast development is generally unimpressive, and several have needed small breast implants to gain the perky nubile breasts that are essential for a top female model. Even young transgender Youtube stars (e.g. Blaire White, Maya Henry, Samantha Lux, Elena Genevinne, Princess Joules, Emma Ellingsen ...) all seem to have had breast augmentation.

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.

Valentijn de Hingh was born in 1990 and is shown age 21 after five years taking estrogen.
Her modest A cup size breasts are rather lost on her 6ft 1in tall skeleton - a common problem for transwomen

Two steps forward, One step back

Ashley Martin posted these photo's on social media whilst transitioning in her late teens. The effect of 18 months on oestrogen hormones is prominent!

During the 2010's I have become increasingly puzzled as to why so many young (teenage) transgirls seem to have so little breast development after several years on hormones. It just doesn't align with the experience of teenage trangirls in the 1990's and early 2000's, most soon had obviously budding breasts, with breast growth quickly reaching at least a B cup. After consideration of what may have changed, I think it must 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) skeletal characteristics such as a widening of the hips if started young enough.

Teddy Quinlivan began taking hormones in 2011, age 17. She's shown (left) age 21, still just an AA cup. She had a modest breast augmentation a few years later - taking her to an A cup (right).

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.

A photo published by transwoman Cosima Elliott. She unwisely had small implants whilst her breast tissue was still developing from hormonal stimulation.

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 areolae of transsexual women are usually small compared to genetic XY women.

The Areola of Transwomen

A 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. 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 women 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.

T

Two Tgirls in their late twenties. Genetics and the lottery of life have resulted in different development, but both girls have the small areola common for transwomen.

his seems to be a genetic (XY) limitation. Not only do young tranwomen who start hormone treatment in their teens often suffer from this problem, but it is also common with AIS women (who are genetically XY) whose average breast development exceeds cis-women.

One positive is that because the breasts of transsexual woman rarely reach full Tanner V size and maturity, the nipples often remain very prominent - and there are few complaints about this!

A hypoplastic tubular breast.

Hypoplastic Breasts
Many transsexual women, particularly those starting hormones over about the age of 25, suffer from under-developed or hypoplastic breasts. Such breasts are very small or narrow, lack normal fullness, and may seem bulbous or swollen at the tip due to an over-prominent nipple-aereolar complex - their narrow elongated appearance leads them to be termed "tubular breasts", and nicknamed "snoopy breasts". This condition is occasionally found in genetic XX woman, but is far more prevalent in transwomen. The shape is usually caused by a failure to sufficiently develop the glands and lobules which help fill out the breast. As a tubular breast consists primarily of just fatty tissue, milk production and breast feeding can be problematic - although of course this is rarely relevant for transsexual women.

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 into the nipple area can help.

Many transsexual women suffer from small or under-developed breasts. This can be helped by breast augmentation as shown.

Breast Augmentation

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.

Fat Transfer

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 and the claimed six months of breast growth in the diagram below is very dubiouis.

Sadly, whilst the immediate increase in breast volume after the injection of the fat cells into the breast might be substantial, in the real world about 30% of the gain is lost within a few weeks, and the long-term loss is typically 50-70%. Nevertheless, it's a good option if a quick and confidence boosting increase in breast size is needed, e.g. for a beach holiday, a beauty contest or even a wedding!

Madis - a transsexual woman with exceptionally good Tanner V type breast development, large areola and appropriate veins. There are no indications of breast augmentation. Maybe 1% of MTF women reach this level of development.

For transwomen with reasonable but not quite sufficient hormone induced breast development, this technique can be a 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. Whilst the temporary stretching of the skin can result in some subsequent breast drooping - this is often desirable for middle-age transwoman seeking a natural appearance equivalent to cis-woman of similar age.

Breast Cancer

Breast tissue means the risk of breast cancer. Breast cancer is the primary cause of death of about 6% of cis-women in the UK, whilst it's negligible for cis-men.

When this article was first written in 1999, breast cancer was simply not considered relevant for transwomen as so few cases had been observed. That was despite the fact that transgender women who take high levels of estrogen develop breast tissue similar to that of cisgender women, comprising breast ducts, lobules, and acini. It's now clear that the lack of cancer cases was due to the small number of transwomen, and the fact that the vast majority of these only started taking hormones to develop their breast tissue in their 30's or later.

A mammogram of a 60 year old transwoman (taking estrodial) showing a retroareolar mass in her right breast. Thankfully a biopsy classified it as benign, rather than cancer.

Sadly, twenty years later the situation has completely changed. There are now large numbers of transwomen who have been taking high-level doses of oestrogen for decades, and many started in their teens or twenties. Because hormonally-driven breast tissue development in transgender women is similar to that in cis-women, similar benign breast problems have become commonplace, e.g. breast lumps (fibroadenomas), cysts, and lesions (pseudoangiomatous stromal hyperplasia). These problems can occur at both a very young age, and during the early stage of breast growth.

Breast cancer also has to be added to the list of potential problems. It increasingly seems that a transwoman who starts hormone therapy in her teens is as likely to die from breast cancer as a ciswomen - there hasn't been enough research done to date to say if the probabity is more or less.

Transwomen must examine their breasts regularly for signs of problems

All transwomen taking hormones should regularly cheack their breasts. 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 have regular mammography screening.

Summary

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.

In 2001 I suggested in an early version of this page that a transwoman's best possible breast development from hormones was one bra-cup size less than her mother or sisters - and this was soon being widely quoted. However, this was based on taking at face value the substantial bust development claimed by many transwomen after taking hormones for even just a few months. I now realise that these claims include a considerable element of optimistic rounding up.

Chanel, pictured in 2017 age 23. It's unclear when she started hormone therapy, but her breast development well above average from hormones alone.

It's now undisputable that the earlier in life that oestrogen therapy begins the better the results will be, but some girls who began treatment as young as 16 still have have only Tanner II/III type budding years later.

A substantial proportion of young transwoman starting hormones before age 18 do 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 the visual appearance is still often unsatisfactory.

Transsexual women starting hormone treatment over the age of 18 will be 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 in Europe is actually only "C".

Overall, most transwomen are disappointed with their breast development from taking hormones, and as a result breast augmentation surgery is commonly sought. Whilst there are exceptional cases such as Jazz Jennings (left), one study of 60 transwomen states that 58 ultimately had breast augmentation surgery.

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.

Examples
The following ladies are all believed to be transsexual women with natural breasts developed from hormone use alone. I have attempted to classify the breasts using the Tanner stages, but this system is arguably less relevant to transwomen who start hormones after a male puberty. Notice the small areali in almost all the pictures. This is very common with transsexual women, even if hormones were started at an early age and the overall breast development is good.

Please contact me if you have any comments.


Early Tanner II budding	Tanner II	Tanner III - typical final type breast development when starting hormones in 40's

Tanner III, started hormones age 25, after 18 months use	Arguably a Tanner III, but the scale doesn't apply well to some transwomen	Tanner IV, started hormones early 20's

Tanner IV, probably started hormones as a young teenager	Small Tanner V, started hormones about age 19 and pictured late 40's	Possible Tanner V, started hormones age 13 but may have had implants

Hypoplastic tubular breasts don't conform to the Tanner model	Tanner III, as good as it gets for many transwomen	Slightly enhanced breasts after a month on hormones, Tanner II

Tanner V - very rare. A pre-SRS 34-year old transwoman after four years on hormones	Another pre-SRS transwoman, Tanner IV, nearly V	Another very hard to classify case, Tanner III is closest

Tanner II	Tanner I	Tanner III (just)