Transgender lactogenesis

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Registered: 03-26-2003
Transgender lactogenesis
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Wed, 07-21-2010 - 12:57am

http://etransgender.com/viewtopic.php?f=1&t=410

The natural purpose of the female human breast is to provide sustenance and nourishment to young children. While transsexual woman proudly regard their breasts as an important sign of their femininity and womanhood, they rarely consider their biological purpose.

Some years ago an English national newspaper published a story about a young woman who was breast-feeding her baby. Nothing extra-ordinary about this except that the woman in question was a male-to-female transsexual who had begun female hormone treatment simultaneously with his/her wife becoming pregnant. She was now happily and enjoyably sharing nursing duties, even in public places such as a busy restaurant. The story was inevitably intended to be rather sensationalist, but probably even many transsexual women reading it were rather surprised to learn that their breasts may well be capable of the natural function that they are intended and designed for.

The breasts of a transsexual woman are in fact quite capable of producing milk ("lactation") given the following circumstances:

The breast has not been badly damaged internally by breast augmentation implants
A sufficiently developed breast structure
Suitable stimuli to start and maintain the production of milk
Motivation
Inducing lactation is not easy, it will often take a lot of time and a lot of effort over a long period. The necessary motivation is essential or failure is almost inevitable.

One study of 27 genetic women who undertook a lactation induction programme found that 24 (89 per cent) were successfully breast feeding well nourished children. All 11 women who had never previously lactated were successful.

While such a high success rate would not be achieved with M2F transsexual women, there's no doubt that given a high degree of motivation combined with medication, support, and encouragement, lactation induction can still be often successful in transsexual women.

Breast Augmentation

A majority of transsexual women have had breast augmentation (implants), but fortunately the chances are good that the implants in themselves will not prevent lactation. Studies show that only about 10% of genetic XX woman with implants are unable to breast feed due to damage to their breasts caused by the implants. However, unfortunately TS women usually have breast augmentation because of small and underdeveloped (hypoplastic) breasts. Although breast augmentation surgery will improve the appearance of such underdeveloped breasts and perhaps give the appearance of fully developed and filled out Tanner V breasts, it can not solve the underlying milk supply problem and it will still be difficult for the woman to produce milk and nurse.

With a breast that has been surgically enlarged with implants, the nipple may be more or less sensitive than normal. If the nerves around the areola were not cut or damaged during the surgery then it should still be possible to nurse fully or partially. Nerves are vital to breastfeeding since they trigger the brain to release prolactin and oxytocin, two hormones that affect milk production. The chances of breastfeeding also improve if the milk duct system is intact. It's impossible to know the full extent of damage — if any — until a woman tries to make and express milk. Once lactation starts, implants may also cause exaggerated breast engorgement with more intense than usual pain, fever, and chills.

The likelihood that implants cause serious lactation and milk production problems depends directly upon the kind of surgery had. Incisions that were made under the fold of the breast (inframammary) or through the armpit (transaxillary ) shouldn't cause any trouble. However, the popular periareolar method, making a "smile" incision around the areola, has greater risk of problems.

There's absolutely no evidence that silicone from silicone implants leaks into breast milk, but even if it did, it probably wouldn't harm a baby. Silicone is very similar to a substance used to treat a baby's stomach gas.

Breast Development

In order to be able to produce milk internally the breast must have certain structures in place, but fortunately these are present at birth in every human, whether genetically male or female. It's also worth noting that highly visible factors such as breast size and areala diameter that are often of great importance to transsexual women in fact have relatively little effect on the breasts potential ability to lactate and the quantity and quality of the milk that will be produced. Whatever the size of her breasts, a M2F transsexual woman can still potentially breastfeed if the internal structures are in place and undamaged.

Stages of Mammary Development
At birth the rudiments of the functional mammary gland are in place: 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 the advent of estrogen secretion by the ovaries brings about the first stage of the four stages of mammary development: mammogenesis, lactogenesis, lactation and involution.

Mammogenesis commences at puberty with the onset of oestrogen secretion by the ovaries, usually between the ages of 10 and 12 in the girl. Oestrogen causes 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. About 40% of male children also initiate mammary development during puberty due to the tendency of the testis to secrete significant quantities of estrogens in early phases of its development. As testosterone secretion increases this function is lost.

Oestrogen stimulates breast growth by acting on the mammary tissue. With the onset of the menstrual cycle the presence of progesterone stimulates the partial development of mammary alveoli, so that by the age of 20 the mammary gland in the woman who has not been pregnant consists of a fat pad through which course 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.

Mammogenesis is completed during pregnancy, with the gland becoming able to secrete milk sometime after mid-pregnancy.

Lactogenesis (referred to as the time when the milk "comes in") starts about 40 hours after birth of the infant and is largely complete within five days.

When nursing has ceased the gland undergoes partial involution, losing many of its milk producing cells and structures, a process which is only completed after menopause.

Breast Development in the Transsexual Woman
A combination of supportive tissue, milk glands, and protective fat makes up a large portion of every woman's breasts (or mammary glands). Every person is born with milk ducts — a network of canals that transport milk through the breasts — present from birth. In the male-to-female transsexual woman the mammary glands stay quiet until commencing female hormone treatment releases a flood of oestrogens, causing them to grow and swell in what is effectively a female puberty and thus initiating the first phase of mammogenesis.

The amount of hormone induced breast development achieved in the genetically XY male transsexual woman is very age dependent. Young boy-to-girls who start female treatment during their normal puberty years (i.e. about age 12-16) are likely to reach near normal breast development. But unfortunately the amount of development that can be expected rapidly tails off as the age of the commencement of hormone increases, and older transsexual women will commonly suffer from underdeveloped (hypoplastic) breasts.

Breast development is categorised by the "Tanner Stages" scale which goes from I to V. It can again be emphasized that there is really NO minimum degree of breast development in order to be able to lactate, there are well documented instances of even men with minimal Tanner I breasts producing some milk and breast feeding without using hormones. On the other hand there is no doubt that the higher the development stage, the easier it will usually be to start lactation and the greater the likely quantity of milk produced. In general, well developed Tanner IV or V type breasts are really required for successful nursing of a baby, perhaps a majority of the girls who start hormone treatment by age 25 are likely to achieve this but most older woman will achieve no more than Tanner III or even II breast development. Such hypoplastic breasts are very small or narrow, lack normal fullness, and may seem bulbous or swollen at the tip. They are also likely to be widely spaced and one breast may be larger than the other. Hypoplastic breasts don't develop and grow in response to any additional hormones given in order to simulate pregnancy and prepare the breast for lactation. Breasts of this kind have fewer milk glands than normal, leading to milk-production problems.

Breast Development During Pregnancy

It is is necessary to understand how the human breast develops and prepares for milk production during a woman's pregnancy.

Mammogenesis is completed during pregnancy - indeed pregnancy is the period of greatest mammary growth. Extensive lobular and alveolar development occurs only during pregnancy, also milk secretory cells only develop during pregnancy, therefore this period is extremely important in determining the number of secretory cells in the lactating gland and the subsequent production of milk. Mammary growth (of the mother) accelerates throughout pregnancy and is fastest during the later stages of pregnancy, which coincides with the most rapid period of fetal growth.

Breast Structure of a Pregnant Woman
A pregnant woman will certainly notice a huge metamorphosis occurring in her bra cups. These physical changes include:

tender, swollen breasts
darkened nipples and areolas (the circle of skin surrounding the nipple)
the appearance of tiny bumps around the areola called the Glands of Montgomery
But perhaps even more remarkable than this visible transformation is the extensive changes taking place inside her breasts, primarily under the stimulation of high levels of oestrogen and progesterone, combined with the rising levels of prolactin from the pituitary and human placental lactogen (HPL) from the placenta.

Nestled amid the breasts fat cells and glandular tissue is an intricate network of channels or canals called milk ducts. The additional hormones released during pregnancy cause the cells of the mammary fat pad to diminish in size and their place is taken by the developing ducts and alveoli.

During the first three months of pregnancy the milk ducts increase in number and size; the ducts starting to branch off into smaller canals near the chest wall called ductules. During the mid-three months a cluster of small, grape like, sacs called alveoli appear at the end of each ductule. A cluster of alveoli is called a lobule; a cluster of lobules is called a lobe. Each breast contains between 15 and 20 lobes, with one milk duct for every lobe. During the last three months of pregnancy the alveoli grow and mature.

Milk is produced inside the alveoli, which are surrounded by tiny muscles that squeeze the glands and push milk out into the ductules. Those ductules lead to a bigger duct that widens into a milk pool or milk sinus directly beneath the areola. Milk pools (also know as sinus) act as reservoirs that hold milk until a baby suckles it through tiny openings in the nipple. Essentially the 15 or 20 milk ducts act as individual straws that all end at the tip of the nipple and deliver milk into a baby's mouth.

The mammary gland becomes able to secrete milk sometime after mid-pregnancy, and begins to produce small amounts of a protein- and fat-rich secretion sometimes referred to as precolostrum. It seems likely that mammary development continues through the duration of pregnancy since milk secretion by mothers of premature infants often appears to be diminished. The onset of copious milk secretion (or lactogenesis) is held in check by the high levels of circulating progesterone until after child birth.

Differentiation of the breast to its mature status occurs by the third month of pregnancy, although it will take about 6 months for the breast system to fully develop and become functional for lactation. Indeed, mammary growth will continue right up to birth, and even after if nursing. In a pregnant woman, by time the baby is born, glandular tissue has replaced most of the fat cells and accounts for the much enlarged breast. The increase in size varies greatly with the individual, ranging from zero to 800 cc of volume (and 1� lb of weight!) per breast; the average being about 400 cc. It is normal for women to increase by one or two cup sizes during pregnancy, although this will decline (sometimes dramatically) after the cessation of lactation.

Oestrogen and Progesterone
Optimal mammary growth requires both oestrogen and progesterone hormones. Together, these result in growth of the lobular and alveolar system. Both hormones are elevated during pregnancy, which is why there is no such "lobuloalveolar" growth during a woman's estrus (fertility) cycle, when only one of these hormones is elevated at a time. Progesterone is elevated throughout gestation (required for maintenance of pregnancy), while oestrogen is particularly elevated during the second half of gestation. Consequently, most of the mammary growth during the first half of gestation is mainly ductal growth and lobular formation. In the second half of gestation, ductal growth continues, but most growth is lobuloalveolar.

Oestrogen and progesterone together establish the conditions needed for geometric cell multiplication to occur. For example, from one original cell, 8 cell divisions yields 128 cells.
During pregnancy, the mammary tissue has estrogen receptors and progesterone receptors. During lactation the mammary gland has oestrogen receptors, but not progesterone receptors.

Other hormones
As well as the oestrogen and progesterone hormones well known to transsexual women, there are several other hormones important to breast development and milk production. Indeed, mammary development in the pregnant woman takes place under the influence of an extraordinarily complex mix of hormones, including:- prolactin, human placental lactogen, estradiol (a type of oestrogen), progesterone, insulin, cortisol, growth hormone, thyroid hormones ...

Prolactin is a protein hormone secreted from the anterior pituitary gland, as well as assisting in breast development, it stimulates and controls the actual production of milk.

In a pregnant woman, the placenta produces an important hormone called Human Placental Lactogen (HPL) which adjusts the maternal metabolism. One of its functions is similar to prolactin, i.e. stimulation of milk production by the mammary glands. HPL seems to work with oestrogen and progesterone to increase the number of alveoli in mammary glands and also plays a role in making the alveoli functional (capable of producing milk). It's thought that the level of HPL hormone activity in the maternal blood regulates the extent of mammary development during late pregnancy. HPL also causes the secretion of a form of milk called colostrum from about the fifth month of pregnancy.

Yet another, and apparently unimportant, hormone is secreted by the pituitary gland of a pregnant woman, Melanocyte Stimulating Hormone (MSH). Its only known effect is to stimulate the skin to produce pigmentation, causing the aeroli to enlarge and darken.

Breast Stimulation in the Transsexual Woman
Hormonal Stimulation
The transsexual woman attempting to stimulate lactation may try to initiate the necessary changes in her breasts by simulating pregnancy using hormones.

Lacking the hormone producing ovaries and placenta present in a pregnant woman, the transsexual woman must take by some means (oral, injection, patches, etc.) high doses of oestrogen and progesterone hormones for a sustained period of at least six months. This may stimulate her breast in to developing and preparing for lactation, but unfortunately transsexual women with underdeveloped hypoplastic breasts are unlikely to succeed in this endeavor as their breasts will fail to respond to the additional hormones.

Also, in a pregnant woman her production of the estriol type of oestrogen greatly increases and it becomes the dominant type of oestrogen in her body. When present in high levels (unlike the non-pregnant lower levels), one of its effects is to help prepare the breast for milk production. However, the "weak" estriol oestrogen is rarely taken by transsexual women as part of their hormone therapy, instead standard oestrogen prescriptions are either of the estradiol (e.g the Estrace brand) or estrone (e.g. the popular Premarin brand) types. Unfortunately, prolonged taking of large doses of these "strong" oestrogen types, as is common with transsexual women, seems to desensitize the body to estriol, making stimulating the breast to prepare for lactation via hormones much more difficult.

Assuming that the hormones have an effect, the period of the most rapid breast growth is often during the first eight weeks of treatment. This enlargement is due primarily to engorgement of the blood vessels, enabling increased circulation to the breasts. Thereafter, the oestrogen hormones stimulates cell mitosis and growth of the ductal system, while growth development and differentiation of the glandular tissue (lobules and alveoli) is dependent on progesterone, breast fat accretion seems to require both.

Regarding the other hormones found in pregnant woman:

Some prolactin may be produced naturally by the woman's pituitary gland which is helpful but probably insufficient. Currently, there is no prolactin medication on the market but prolactin-inducing drugs are readily available and these can be taken to increase prolactin production to normal levels.
HPL is valuable aid to breast development and lactation, but it's not naturally produced in the body of a transsexual woman. Highly purified HPL is available but unfortunately it's hard to obtain, very expensive (a course would cost several hundred dollars a day), and is very rarely used as a medication.
MSH is not believed to be necessary and is unlikely to be present in a transsexual women.
Mechanical Stimulation
If it not possible to take additional female hormones in order to stimulate the breasts in to preparing for lactation, or if (as is commonly the case) the hormones have no effect due to hyperplasic breasts, don't panic, all is far from lost. This is because prolactin and oxytocin, the hormones which govern lactation, are pituitary, not ovarian (or "female") hormones. Both prolactin, the milk-making hormone, and oxytocin, the milk-releasing hormone, are produced in response to nipple stimulation. Many women can induce lactation to some extent with only mechanical stimulation. This consists of breast massage, nipple manipulation, and sucking - the later either by a baby or by expressing using a good quality electric breast-pump with a double pump kit (realistically expression by hand, or even with a hand pump, is simply not a practical alternative to an electric double breast-pump given the frequent and prolonged sucking required on each breast).

A possible expressing regime: Begin by expressing each breast for about five minutes, three times a day. Increase the length of the pumping session as you become more comfortable, until you are expressing for a total of about 15 to 20 minutes on each breast every two to three hours during the day. Expressing both breasts simultaneously by double-pumping obviously saves a lot of time every day by this point! You must include nighttime pumping sessions, allowing just one long 4-5 hours period of sleep.

Constant expressing will soon get to become hard work, when after a week you still haven't seen any milk at all, try not to become discouraged or concerned, unfortunately it may well take four to six weeks for the breasts to begin producing milk this way. Some dedicated women have reported only finally achieving some success after two or three months pumping!
Stress, tension, and fatigue all produce hormones that can reduce let-down. Avoid smoking and excessive alcohol and caffeine - these are known to inhibit a mother's milk production and let-down.

In order to pump effectively and increase milk supply it is essential to relax and stimulate as much as possible the milk let-down response crucial to milk expression. Suitable mental or environmental stimuli such as baby photo's, imagining yourself breast feeding, direct sucking stimulation of the nipples and immediately surrounding tissue, playing a tape of the cries of a hungry baby, ... etc, are essential aids to milk production. And a partner can greatly assist with sexually arousing mental stimulation and manual manipulation of the woman's body before, and even during, her expression period.

Here are some tips to help pumping:

Set up a regular milk expression schedule.
Allow enough time so you don't feel rushed.
Relax for 15 minutes before expressing, watch TV, listen to music, enjoy the occasional class of wine.
Try to minimize distractions - take the phone off the hook, etc.
Try to express milk in a familiar and comfortable setting - privacy and comfortable seating promotes relaxation, which enhances let-down.
Follow a pre-expression routine: Use warmth to relax and stimulate milk flow by applying a warm compress to your breasts for 5 minutes or putting a warm wrap around your shoulders; relax with deep breathing and visualizations.
Encourage milk let-down by using an oxytocin nasal spray 2 or 3 minutes before using the breast pump - costly but worth it.
Think about babies - look at pictures of a baby and imagine him at your breast while you are expressing your milk. Play a tape of a hungry baby.
Before pumping stimulate your breasts and nipples through massage as illustrated right.
While pumping help "push" the milk towards the nipple - place your thumb opposite the fingers on either side of the areola (positioned as the pump allows), then rhythmically press your hand in towards your chest, gently squeezing the thumb and forefinger together. Rotate the fingers to get all the milk ducts. With practice you can do both breasts simultaneously.
Interrupt your pumping several times to pause and massage your breasts more.

To massage your breast, place one hand underneath your breast, the other on top. Slide the palm of one or both hands from the chest gently towards the nipple and apply mild pressure. Rotate your hands around the breast and repeat in order to reach all the milk ducts.

Milk Production in a Maternal Mother

Lactogenesis
In a human mother lactogenesis, or the onset of copious milk secretion, (also referred to as the time when the milk "comes in") starts about 40-48 hours after child birth and is largely complete within five days. Milk secreted during the period between colostrum secretion and mature milk is called transition milk.

Lactogenesis is associated with an abrupt increase in milk volume secretion, which goes from a mean of about 50 ml per day on day 2 of lactation to about 500 ml per day on day 4. After this time there is a gradual volume increase to about 850 ml/day by three months postpartum. There are also profound changes in milk composition during the early post child birth period as the production of milk products comes into high gear. By 10 days after child birth the milk has assumed the composition characteristic of mature milk. There are minor composition changes that continue throughout lactation. Full lactation, or the secretion of mature milk, continues as long as the demand is there, up to three to four years for infants in some cultures.

Three factors are necessary for successful lactogenesis: a developed mammary gland, continued high plasma prolactin levels, and a fall in progesterone and oestrogen levels that otherwise inhibit lactation - it can therefore be partially inhibited by high doses of oestrogen. It is important to note that the milk "comes in" at the same rate whether the infant suckles during the first 48 hours or not. Thus the onset of milk secretion depends, not on milk removal from the breast, but on the changes in hormonal status associated with child birth. However, continued milk secretion depends on milk removal from the breast, the involutional process sets in after only 3 to 4 days if breast-feeding is not initiated.

Milk Production in the Transsexual Woman

Lactogenesis
A genetic woman who's given birth also expels the hormone-producing placenta, and the estrogen and progesterone levels in her body suddenly drop. In a transsexual woman, ceasing an additional high oestrogen and progesterone dosage that's been taken for several months will have the same affect if the hormones have worked. Recognising that the "birth" has happened, the pituitary gland now signals the body to make lots of milk in order to nourish the baby by increasing its output of the hormone prolactin, and the changes in hormone levels thus cause milk production to begin.
At this point mechanical breast stimulation, particularly sucking (with a breastpump or by a baby) should be started and a oxytocin nasal spray used to stimulate milk release. If not already begun a course of a prolactin enhancing drug such as domperidone (brandname Motilium is highly recommended to help milk production.

Relative changes in some of a mothers
hormone levels in the days around child birth. (The amount of a-lactalbumin in the mammary tissue is an indicator of lactogenesis.)

Success is not guaranteed, but some milk production can be expected in a majority of cases. Milk production typically begins between 1-4 weeks after initiating stimulation using prolactin enhancing drugs, although it can be as little as 2-3 days if hormones were taken and were effective, or as long as 4-6 weeks if relying purely on mechanical stimulation.

One study of induced lactation using enhancing medications describes the onset of milk production being between 5-13 days. At first, the woman may see only drops. During the time that milk production is building, women may notice changes in the color of the nipples and areolar tissue. Breasts may become tender and fuller. Some women report increased thirst, and changes in their menstrual cycle or libido.
As the body readies itself for lactation, it pumps extra blood into the alveoli, making the breasts firm and full. Swollen blood vessels, combined with an abundance of milk, may make the breasts temporarily painful and engorged, but nursing or expressing frequently in the first few days will help relieve any discomfort.

Milk Release
In order to maintain production it is necessary to frequently stimulate the milk-ejection reflex (MER) or "let-down" secretion, i.e. release milk from the internal alveoli.

Obviously the best and most natural way to enhance let-down is by nursing a baby. As a baby sucks a nipple he stimulates the woman's pituitary gland to release oxytocin (as well as prolactin) into her bloodstream. If a baby is not handy, the let-down reflex can also be encouraged by using an oxytocin nasal spray such as Syntocinon which can be prescribed by a doctor.
When it reaches her breast, the oxytocin causes the tiny muscles around the milk-filled alveoli to contract and squeeze. The milk is emptied into the ducts, which transport it to the milk pools just below the areola. When he suckles the nursing infant presses the milk from the pools into his mouth.

As the milk flow increases, the lactating woman may feel some tingling, stinging, burning, or prickling in her breasts. The milk may drip or even spray during letdown.
A benefit of oxytocin is that it the nursing woman may feel calm, satisfied, and even joyful as she nurses or expresses.

Maintaining Lactation
The volume of milk produced is primarily a function of demand and is unaffected by maternal factors such as nutrition or age. Not a lot of milk will be produced unless suckling (natural or artificial) is frequent and consistent, the milk itself contains an inhibitor of milk production that builds up if the milk remains in the mammary gland for a prolonged period of time. Adequate milk removal from the breast is absolutely necessary for continued milk production.

If nursing an infant is not immediately and regularly possible then in order to maintain milk flow it will be necessary to artificially stimulate let-down by expression using a breast pump.

The more you nurse or express, the more milk that will be produced - nursing 10 to 15 minutes per breast every 2-3 hours (day and night!) is the target! Less frequent stimulation than once every 5-8 hours, will result in dramatically less milk production, although some milk production will continue so long as an infant is suckled or milk is expressed at least twice per day. Less than that will result in complete cessation of milk production some one to three weeks later. But with sufficient and regular stimulation, it is quite possible to maintain lactation for months, even years.
Two hormones are necessary for this continued production: oxytocin and prolactin. As mentioned above, oxytocin is necessary for the milk ejection reflex that extrudes milk from the alveolar lumen. Prolactin is necessary for continued milk production by the mammary alveoli. The secretion of both hormones is promoted by the afferent nerve impulses sent to the hypothalamus by the process of suckling. However, whereas the secretion of oxytocin is highly influenced by the activity of higher brain centers, prolactin secretion appears to be determined primarily by the strength and duration of the suckling stimulus. Although prolactin levels fall with prolonged lactation, at least some basal level appears to be necessary for continued milk production. There appears to be no direct relation between prolactin levels and milk production and therefore it is thought that the rate of milk production depends on control mechanisms localized within the mammary gland.

Involution
Although there is a reduction in milk production during gradual weaning, the term involution is restricted to the changes in the mammary gland that occur after complete cessation of lactation. These change appear to involve a gradual replacement of ducts and alveoli with stromal and fat tissue and the reversion of the mammary alveolar cells to a less differentiated state. There is substantial loss of epithelial cells, probably through apoptosis (programmed cell death). Suckling or mechanical stimulation alone may promote reinduction of lactation in this state.

Additional Information

Breastpumps
If you don't have a baby or young child to nurse then hiring or buying a good quality, fully automated, electric breastpump that closely imitates the natural rate and rhythm of a baby's suck pattern is essential in order to regularly artificially stimulate let-down and express milk. Some automatic pumps can "double pump" (i.e. pump both breasts at once) thereby increasing prolactin levels and milk production while at the same time decreasing the amount of time a pumping session takes by about half to about 15 minutes.

Medela "Classic" pump

Unfortunately while a breast hand pump intended for occasional expression may seem initially very attractive given its low cost of just $15-20, this will usually be a big mistake. Hand pumping each breast in turn 6 or 7 times a day for 15 or 20 minutes for perhaps several months is just not realistic for most people. Instead a good quality electrical pump with a double pumping capability is simply essential. The best option is a hospital grade breast pump such as the "large" Medela (Classic) or the Ameda-Egnel Elite, unlike most cheaper pumps these test and regulate pressure, they cost perhaps $40-$50 a month to rent. If you have problems finding a rental agent then try contacting the LeLeche League for help.
If you want to actually buy your pump, then a popular high-end option is the Medela Lactina at perhaps $500 (it can also often be rented for about $30-35 a month) , while one entry level option is the Medela Pump-in-Style for around $300. Remember to get the double pump kit and accessories.

Medela Lactina

Medela Pump in Style

Lactation Enhancing Drugs
Prolactin and oxytocin, the hormones which actually govern lactation, are pituitary, not ovarian hormones (such as oestrogen). There are currently no human prolactin medications available, but Domperidone (brandname Motilium) is a drug which has, as a side effect, the increased production of the hormone prolactin by the pituitary gland, thus helping develop a more abundant milk supply faster as prolactin is the hormone which stimulates the cells in the mother's breast to produce milk. Another related but older medication is metoclopramide (brandnames Maxeran and Reglan), this is also known to increase milk production but it has frequent side effects which have made its use for many nursing mothers unacceptable (fatigue, irritability, depression). Domperidone has many fewer side effects because it does not enter the brain tissue in significant amounts.

Genetic women trying to start lactation are advised that prolactin enhancing drugs should only be started only after the ending of any oestrogen treatment as oestrogen, particularly those types found in contraceptive pills, can retard the start of lactation. However transsexual women can still gain considerable benefits from the breast developing effects of prolactin so should not be deterred.

In many countries domperidone tablets are available without prescription. Generally, start at 20 milligrammes (two 10 mg tablets) four times a day, i.e. about every 6 hours. After starting domperidone, it may take three or four days before any effect is noticed, though sometimes women notice an effect within 24 hours. It appears to take two to three weeks to get a maximum effect. Most women take the domperidone for 3 to 8 weeks, but women who are nursing adopted babies may have to take the drug much longer in order to maintain lactation.
Motilium 10mg tablets, produced by Janssen Pharmaceutica

Some women also find that herbal seed capsules such Blessed Thistle and Fenugreek help increase their lactation, and these are commonly taken.

Hormone Regimen
I have been repeatedly asked for typical regimen for hormonal stimulation of the breast for lactation. I am not a medical practitioner, and there are many factors that must be taken in to account when determining the best regime and these must all be discussed with your doctor. As an example only, and derived from just limited evidence, the following daily regimen may be appropriate for a post-SRS woman under 40 years:

1 x Cyclogest 400 pessary from Cox Pharmaceuticals, containing 400mg Progesterone PhEur, daily
1 x Duphaston tablet from Solvat Pharmaceuticals, containing 10mg Dydrogesterone, twice daily
1 x Premarin tablet from Wyeth-Ayerst, containing 1.25mg Conjugated Estrogens, twice daily
1 or 2 or 3 Ovestin tablets from Organon, each containing 1 mg Estriol, 4 times daily
(i.e. about every 6 hours)
1 or 2 or 3 Motilium tablets from Janssen, each containing 10 mg domperidone maleate, 4 times daily
A Syntocinon nasal spray from Sandoz Pharmaceuticals, containing oxytocin (use just before pumping
or nursing to help elicit milk let-down)
also, 1 x 150mg Aspirin tablet, daily

Notes:

The regimen should be followed for at least 3 months, preferably 6 months, but no more than 9 months before attempted lactogensis.

Ideally HPL should also be taken, but this is usually impractical as well as very costly.

The dosage of Ovestin and Motilium should be doubled to 2 tablets half way through the regimen.

The dosage of Ovestin and Motilium should be increased again to 3 tablets three days before attempted lactogensis.

Premarin is just one possible oestrogen, if in any doubt stick with your normal oestrogen proscription instead of Premarin, but add the Ovestin or similar. The Premarin/Ovestin combination would be very unlikely if the woman has already been taking Premarin for a prolonged period. There is some anecdotal evidence that an Estradiol Valerate (e.g. Progynon-Depot from Schering) delivered by intramuscular injection may be an effective alternative to Premarin.

For a pre-SRS woman the dosages may need be much higher.

Syntocinon and other oxytocin nasal spays may not be currently available in the USA.

Some "morning sickness" and nausea is very probable at first, if more severe side effects are experienced then medical help should be sought immediately. Long term use of such high dosage levels should be avoided, and if it's clear that no beneficial effects are occurring within 6-8 weeks then the regimen should be abandoned and the previous hormone regimen reverted to.

"Attempted lactogensis" means reverting to the prior hormonal regimen in order stimulate the start of milk producion and lactation, this must involve a considerable reduction in oestrogen and progesterone hormone intake, in pre-SRS women it may actually require a reduction to less than their normal regimen. If a baby is to be nursed then medical advice should be sought as to what hormones can still be safely taken and in what dosage, and any anti-androgens being taken must be stopped. Prolactin-enhancing drugs should continue to be taken, e.g. 2 Motilium tablets every 6 hours, each containing 10 mg domperidone maleate.

Antiandrogens may also be helpful to a pre-SRS transsexual women trying to induce lactation, although they should never be taken by a pregnant woman, or subsequently if breast feeding. The most commonly used antiandrogens are spironolactone (brand name Aldactone), flutamide (Eulexin) and cyproterone acetate (Androcur). Spironolactone, in a dosage of 25 to 100 mg administered twice daily, is the most commonly used antiandrogen because of its safety, availability and low cost. Flutamide is usually given in a dosage of 250 mg twice daily, and cyproterone is given in a dosage of 25 to 50 mg per day. Pre-SRS women may well already be taking much higher dosages of antiandrogens and these should not be increased - indeed in some cases it may be advisable to change the drug or reduce the dosage to the levels given here.

Nutritional Value of Induced Milk
Milk released by a mother during the first few days of lactation after giving birth is called colostrum; it is richer in proteins, minerals, and immunoglobulins and is lower in calories and fat than the mature milk that develops over the following few weeks. The level of fats, lactose, and B vitamins gradually increases in breast milk during the first month of lactation. Mature breast milk is rich in the mother's white blood cells and hormones and substances such as immunoglobulins, which protect the infant against bacteria and other infectious agents.

Using a SNS
The milk brought in by inducement skips the colostral phase, instead it more closely resembles transitional and mature breastmilk. It is thus not ideal for new-born babies, but studies of non-maternal women nursing after induced lactation indicate that that their infants are well-nourished. However, it must be noted that many women felt they were only providing about 50-70% of the nutrition their babies needed with breast milk alone. If a transsexual woman is nursing it is therefore also very likely that she will be able to produce only a portion of the breast milk the baby needs, and it will be necessary to boost the baby's milk intake with formula. For this a Supplemental Nursing System (SNS) is valuable alternative to the traditional bottle. The device consists of a plastic pouch to hold breast milk or formula and attached thin, flexible tubes that run down each breast to the nipple. Since the baby takes both nipple and tube into his mouth when he suckles, he benefits from all the breast milk that is available.