Came across this article about progesterone and trans women, DISCUSS.
The Lowdown on Progesterone
By Dr. Richard J. Curtis
10th July 2009
The London Gender Clinic
Progesterone is a hormone naturally produced by the female reproductive tract. Many trans
women believe it has value in the physical transition process and particularly in relation to the
development of breast tissue. However, in the trans arena, there is much misinformation about its
benefits, little information on its adverse effects and little understanding of its action in the genetic
female.
Progesterone Physiology
Prior to the start of menstruation – usually around 12 years old1 – girls do not have any
appreciable level of progesterone. In the early years of menstruation, oestrogen levels fluctuate
but the typical monthly profile is not yet established and periods tend to be irregular in frequency
and duration. Early cycles do not result in ovulation, i.e. no egg is released from the ovary.
After 2 years of non-fertile menstruation – at around 14 years old – ovulation starts to occur and
an egg is released from the ovary.
Only when this occurs, do progesterone levels begin to rise from their low baseline during the
second two weeks of the menstrual cycle (Figure 1).
They are highest during the week prior to menstruation and rapidly decline contributing to the
stimulus for bleeding to occur. However, the average levels of progesterone during the full
monthly cycle are very low.
Figure 1: Progesterone levels in the 28 day menstrual cycle, once ovulation has
started, at approximately 14 years old.
It can therefore be seen that in genetic women, there is no progesterone before approximately 14
years of age. Consider this fact with the stages of natural breast development.
1 Chronological ages given throughout this paper are all based on averages. The variation in start times of
menses is wide and varies between populations.
Days
Breast Development
The average age at which a genetic girl commences breast development is 10 years old and
occurs according to well-defined milestones called Tanner stages.
Tanner Stage Average. Age
1 10 Increased nipple size
2 10 ½ Increased areola as well. Breast bud (small tender lump
behind the nipple)
3 11 ½ Nipple – areola complex increases. Breast size increases
4 12 The areola is a separate mound above the breast
5 13 ½ The areola becomes confluent with the breast leaving only
the nipple proud
Figure 2: Tanner stages and approximate ages of development prompted by oestrogen
It takes approximately two to three years to achieve the majority of breast growth at age 13. Until
stage 4, the growth of the breast in a girl takes place with the same oestrogen level as an adult
male, i.e. < 150pmol/litre, as periods have not yet started. (The reason teenage boys do not
develop breasts is because testosterone inhibits the effect of oestrogen. The development of
small breasts in teenage boys can occur; this is called gynaecomastia and is caused by the overconversion
of low levels of testosterone to oestrogen.)
As progesterone does not exist in genetic girls until age 14, it is clear that progesterone cannot
possibly have any effect on breast development in the genetic female.
To be clear, there is no direct involvement of progesterone in determining the size of breasts.
Oestrogen is the primary enabler of breast growth. And there is no reason to suppose that the
development of the breast in trans women is different.
Puberty is a complex process and, in addition to oestrogen, there are many other hormones
which regulate it. These include prolactin, insulin and growth hormone. Breast tissue is composed
of 80% fat. Prior to puberty, girls have slightly more body fat than boys. Therefore, women have a
head start in the breast fat accumulation race compared to the aspiring development in trans
women. At puberty, the effect of oestrogen further increases fat deposition. An adult female has
10 – 15% more body fat than an adult male, of which a proportion is obviously on the breasts.
The average breast size of a woman in the UK is a 'B' Cup. In fact, the average amount of breast
growth in a trans woman is also an 'A /B' cup. However, the reason it does not look the same is
due to the relatively larger frame of a trans woman.
9 10 11 12 13 14 15
Tanner stages
periods start ovulation starts
years old
progesterone
levels
1 2 3 4 5
The actions of progesterone in the natal female are:
o cerebral: causing mood change;
o uterine: to prepare the uterus for implantation;
o pregnancy: to maintain pregnancy;
o breast: enabling duct formation for lactation. N.b. Ducts are very small and contribute little to
breast size.
The first of these effects is undesirable, and the latter three actions are not relevant in trans
women who do not become pregnant and have no need for breastfeeding.
Myth
There is a commonly perceived myth that progesterone increases breast size, or improves shape
in the trans woman. This comes, in part, from a paper published some years ago documenting
the microscopic appearance of breast tissue. It indicated that progesterone increased the size of
the lactating ducts. Hence, this is in accordance with the functions detailed above. The paper is
not saying that breasts are bigger.
Further facts about Progesterone
Progesterone is produced in small quantities, in men and women, in the adrenal glands. It acts as
a precursor to the formation of testosterone. ANY form of progesterone, whether naturally
produced or artificially administered has the propensity for conversion into testosterone.
Commonly available progesterones / progestins.
Levenorgestrel (testosterone analogue) Most androgenic
Norethisterone (testosterone analogue)
Mexdroxyprogesterone Acetate (progesterone analogue)
Dydrogesterone (progesterone analogue) Least androgenic
Drospirenone (spironolactone derivative) Antiandrogen
Cyproterone Acetate (synthetic progesterone) Antiandrogen
Progesterone reduces the effectiveness of oestrogen as it:
a) increases the breakdown of oestrogen in the liver;
b) reduces the number of oestrogen receptors in the breast (oestrogen must bind to receptors in
order to work. Even if there are good oestrogen levels in the bloodstream, if there are no
receptors, it cannot work);
c) is converted into testosterone which inhibits the actions of oestrogen.
The following table shows the common side effects associated with progesterone; the
testosterone derived effects of progesterone are underlined.
Progesterone-only contraceptives stop menstruation and ovulation by inhibiting the actions of
oestrogen. Therefore, high doses of progesterone in trans women will also inhibit the actions of
oestrogen and thus hinder feminisation. All commercially available forms of progesterone are
'high doses' as they are made to inhibit the actions of oestrogen in natal women.
Bloating Nausea Fluid retention Body Hair Growth
Breast tenderness Headache Weight gain Loss of head hair
Dizziness Drowsiness Acne Increased
cholesterol
Depression Itching Jaundice
Optimising Breast Growth
In the trans woman, breast growth occurs due to oestrogen. It is achievable at low plasma levels
of oestrogen. It is thought that too high a dosage too soon can stunt breast development so that
only the early Tanner stages are achieved causing a conical effect with poor nipple growth. In a
pubertal girl, oestrogen levels increase very slowly over many months.
It is well known that the some trans women believe that more oestrogen is better. This would be
feasible if the body had more oestrogen receptors, but unfortunately, there are not a great
number of oestrogen receptors. However, they will soak up any available oestrogen from the
bloodstream.
Therefore, genetic predisposition largely determines the number of receptors and thus the
likelihood of breast growth. Oestrogen stimulates receptor synthesis with relatively low levels of
oestrogen in the natal woman pre-menstruation. There is a strong argument for commencing at
low dosage and gradually increasing towards typical adult female levels.
Breast growth takes 2-3 years as stated earlier. The body can only change slowly. Patience is
required and the understanding that growth is also phasic that is, there are periods when it is
active and periods when nothing occurs. N.b. breast / nipple tenderness does not always indicate
growth is occurring.
Growth occurs because oestrogen induces formation of glandular tissue and fat. Glandular tissue
is hard and nodular. It constitutes 20% of the size. 80% of breast size is due to the oestrogen
induced accumulation of fat. Simplistically, in pubertal girls, the calories eaten will preferentially
be laid down as fat, whereas in the pubertal boy, calories contribute to muscle accumulation. In
the trans woman, the effect of the taking oestrogen is to help to re-dress this physiological
difference.
Many women experience an increased appetite whilst taking oestrogen and those who feminise
well tend to put on weight, typically ½ stone to a stone. As an oestrogen dominant individual, this
will manifest as gaining fat, at least some of which will be laid down on the breasts (as long as
there is the genetic predisposition) and some will accumulate on the hips / legs to create the
rounded female shape.
Therefore, to optimise the development of the female shape, trans women should avoid
excessive calorie restriction or large amounts of cardiovascular exercise at this point, because
this will lead to a suboptimal outcome, particularly in individuals who are very lean to start with.
The bottom line is that oestrogen alone grows breasts as long as other factors are favourable.
Progesterone and Trans women
Many trans women have a wish to take progesterone. For several reasons:
1) they feel they should because menstruating females have progesterone for two weeks in the
month,
2) they think it will make their breasts bigger
3) they are influenced by their friends
4) they want to feel more like a genetic woman
With regard to 1) the average age of presentation of trans women is 42 years old. Natal women
undergo the menopause at approximately 50 years old, after which time their progesterone is all
but zero and their oestrogen levels are the same as a man. So if 1) were desirable, NO trans
woman should be taking any progesterone, (or any oestrogen for that matter after the age of 50).
As already explained 2) is a fallacy.
Point 3) is a reflection of the pressure many trans women feel, and may put their friends under,
having accepted as true the many postings on the internet on the topic of the benefits of
progesterone. The majority of what is written on the internet about hormones is rubbish. It is
frequently written by non-medical people, who have copied and pasted their information from
other uninformed sources. The advice is laden with myth, out of date information and personal
opinion. Even the sites that seem to be written by 'doctors' are usually not actually medical
doctors. A science PhD does not indicate medical competence.
Sites abroad are also seldom written by doctors and very few sources are written by any who
have a reasonable degree of actual experience in dealing with the administration of hormones in
trans people.
Point 4) is understandable but somewhat bizarre since most genetic women would prefer not to
experience the effects of progesterone. Progesterone is largely what causes premenstrual
tension (PMT). It greatly affects mood, causing a whole array of mood destabilising effects;
anxiety, aggression, depression. The susceptible genetic woman will explain that these feelings
are neither pleasant nor desirable. Feeling bloated and spotty with painful breasts just prior to a
period is not welcomed by natal women. I believe trans women have a high placebo effect where
this scenario is concerned.
Anecdotal Findings
Many of my patients have reported their experience taking progesterone (not prescribed by me
and usually before they see me).
Their experience falls into 3 categories:
• Some tell me it made no difference at all, neither good nor bad.
• Many describe the side effects, particularly on mood as well as the full complement of effects
listed in table 3.
• Some report an increase in breast growth. In some individuals, this may be the case and I
suspect that this is due to two things:
1) The individual's appetite is greatly increased. This causes increased fat accumulation in a
straightforward calorie excess dependent fashion.
2) A sub-optimal oestrogen regime. Just because a person takes the dosages detailed on the
internet, does not equate to an optimised regime. Many women do not absorb oestrogen well.
There is no substitute for a professionally monitored oestrogen regime by someone who
understands oestrogen physiology and drug administration. Oestrogen levels need
interpretation in the context of the individual's observed effects, the regime administered and
the dynamics of drug administration.
Consider this. In my past life:
If I weighed 57kg (9 stone) my breasts were less than an A-cup.
If I weighed 60kg, they were a proper A-cup.
If I weighed 63kg or over, I was a B-cup.
This was regardless of hormone status and only depended upon how much I ate or exercised.
The Problems Associated with Progesterone
The forms of progesterone available to trans women are all DRUGS. Regardless of how they are
taken or what they are called, these drugs are not the same as a naturally occurring progesterone
hormone. ALL drugs have side effects.
The side effects of progesterone are significant and MUST NOT be dismissed.
Anyone with the following pre-existing conditions should be extremely cautious about taking
progesterone.
Cautions Epilepsy High blood pressure
Migraine Asthma
Heart disease Kidney disease
Abnormal liver function History of jaundice
Thrombosis (DVT / PE) Depression
Diabetes
Progesterone is contraindicated in people who have, or who have had, any of the following:
liver dysfunction, breast cancer, heart disease, stroke, arterial disease.
In the natal woman, progesterone is given largely in three scenarios;
1. as a contraceptive;
2. to suppress menstrual blood loss;
3. to protect the uterus from developing cancer.
Trans women have none of these issues therefore, progesterone administration is not indicated.
With regard to protecting the uterus from cancer, this is the only reason a post menopausal
woman is given progesterone as well as oestrogen as part of her hormone replacement therapy
(HRT) regime. Otherwise, if there is no uterus, oestrogen only is given, regardless of patient age.
The reason for not giving progesterone unless absolutely necessary, is because of the risk. The
most serious of which are breast cancer and thrombosis.
Studies and observation show well documented evidence for a significant contribution from
progesterone in the above. Of itself, oestrogen increases the risk of venous thrombosis and
breast cancer. Progesterone further contributes independently of oestrogen.
For Thrombosis (DVT):
50-59 years old 60-69 years old
No HRT 10 cases in 1000 women 20 in 1000
+ Oestrogen 11 in 1000 24 in 1000
Oestrogen + progesterone 15 in 1000 33 in 1000
These figures indicate that in the 50-59 age group, 4 more women in a 1000 will have a venous
thrombosis when progesterone is part of their regime.
And for breast cancer:
50-59 years old 60-69 years old
No HRT 14 in 1000 31 in 1000
+ Oestrogen 15 in 1000 31 in 1000
Oestrogen + progesterone 20 in 1000 35 in 1000
Venous thrombosis and breast cancer are obviously serious problems. Be aware that no one
knows the true incidence of breast cancer in trans women. There are no data on this. Figures
cannot be collected accurately as many women cease to attend gender clinics, and positive
diagnoses in trans women (where the trans history is disclosed) are not, in any case, ascribed to
a transgender category.
Another Myth
It is wrong to believe that venous thrombosis will not occur if aspirin is taken.
ASPIRIN WILL NOT PREVENT VENOUS THROMBOSIS.
The clotting processes which occur in veins are different to those in the arteries. Aspirin protects
the arteries.
Conclusion
The above are the reason the risk-benefit ratio associated with progesterone renders it unethical
to prescribe. The benefits of it are extremely limited and unproven.
Hormone protocols from well-informed gender clinics around the world do not routinely use
progesterone and ethical doctors who are up to date in their knowledge will not prescribe it.
It should NOT be self-prescribed and is only done by foolish, misinformed, risk taking individuals.
The overall effect of it with regard to feminisation is a negative one.
If progesterone contributed to breast growth it would be evident in natal women when they take
progesterone preparations. This is not the case. Any increase in breast size in natal women is
due to general weight gain.
Therefore the same effect in feminisation can be gained by exercising less, and a modest degree
of caloric over-consumption.
For those who wish bigger breasts, save your money, reduce the side effects and longer term risk
and just eat more pies. Without making yourself obese, feminisation is greatly dependent on the
oestrogen assisted accumulation of body fat which does not come out of the ether.
If you are disappointed with the eventual size of the breasts resign yourself to the fact that you
may need a breast augmentation; a procedure increasingly sought by non-trans women and
undertaken in 50% of trans women after two years on hormones.
Stardust
