Starting estrogen and other E+ medications is an exciting moment. Whatever your transition goals, you can expect estrogen to create a profound transformation in your body and your emotions. One of the changes that many people look forward to is breast growth. While not everyone who uses estrogen/E+ medications wants to develop breasts, many trans women, transfeminine people, nonbinary people, and genderfluid folks are excited to experience this transition milestone.

Estrogen, which is sometimes called a “feminizing” hormone when used as gender-affirming hormone therapy (GAHT), can shift body fat to create a more feminine body shape. Understanding how your body will change on estrogen, including chest or breast development, is important and can help you make better decisions about your health and reach your transition goals. While everyone’s gender transition is different, understanding the clinical effects of estrogen is good for anyone interested in using GAHT.

Estrogen is a powerful hormone that can transform your body and create gender euphoria—the sense of bliss that people experience when their gender expression matches their gender identity. One of the most obvious physical changes from estrogen is breast growth. Estrogen stimulates the breast tissue and, combined with body fat redistribution, can cause someone to grow natural breasts.

Estrogen influences the way that certain body tissues behave. When people born with ovaries begin puberty, their body typically produces more estrogen. This causes breast tissue to grow. It also redistributes body fat tissue, creating a different body shape that might look more “feminine” or more mature. For people taking estrogen as part of their gender transition, breast growth typically begins within three months of starting GAHT. Breast growth or changes in sensation tends to increase dramatically within the first six to twelve months. After this period, many people notice that their breast growth slows down, but the breasts continue to develop and change in appearance for many years. Some trans women shared that their breast growth continued up to five years on GAHT and beyond.

During breast development, trans women and others taking estrogen also notice changing nipple sensations. The nipple grows larger and more sensitive, and breast ducts appear on the nipple. If you are taking E+ medications such as blockers or progesterone, your nipples may be very sensitive—and even sore at first.

How big will my breasts grow on estrogen? 

The stages of breast growth are different for everyone because each person’s body responds differently to estrogen. Every person notices some changes. For some people, those changes are subtle, while others see dramatic transformation. A study published in 2021 in The Journal of Clinical Endocrinology & Metabolism studied the breast tissue changes that 69 transgender women experienced while taking estrogen with a T-blocker for three years. Breast size growth was not associated with hormone levels in the blood, which means that higher levels of estrogen didn’t mean greater growth.

The women in the study were age 21-38, with a median age of 26. A substantial majority of the women developed less than an A-cup, but others noticed a significant increase in their cup size. After 36 months of consistently taking estrogen:

Bra cup size
Percent of women in the study whose breast development increased to this bra cup size
Smaller than A cup
A cup
B cup
C cup
E cup

The same study also measured how much the nipples changed in size. On average, people noticed an increase in the diameter of the areola, which is the soft circular area that makes up the outer ring of the nipple. The areola grew from an average of 24.1 mm to 28.6 mm, which is about the size of a quarter. However, areola growth was very personal to each of the study participants. Nipple size varied between 15.8 mm (slightly smaller than a dime) and 41.4 mm (slightly larger than a silver dollar). 

How soon will my breasts start developing?

Most people notice breast development within the first three months of beginning estrogen. This is around the same time that other physical changes appear. Depending on the person, the first changes that estrogen causes might be mood changes, appetite changes, or minor changes in how your body fat is distributed. Estrogen works over time and most people get the best results from taking their GAHT as consistently as possible, as prescribed. Consistency is more important than dosage—so, taking a higher dose of estrogen does not automatically translate to faster physical development.

Breast development is very exciting, and you may wonder how quickly your chest will grow. Don’t be discouraged if your body needs some time. These changes can be extremely subtle at first. You may notice tingles or aching in your nipples prior to developing a breast bud. You may also notice increased sensitivity within the first few months.  

To encourage breast growth, patience is the secret ingredient. However, there are some factors that can make your breasts look larger or more obvious. Push-ups will build the muscular wall behind your breasts and cause them to seem “lifted.” Some people also report that taking fenugreek as a dietary supplement has helped them grow their breasts. (This is anecdotal research, not clinically supported by data.) 

There is no such thing as a “breast growth pill,” so avoid taking supplements or miracle pills that promise quick results. Everyone feels differently about their breast growth—at the three-year point, 58 percent of women were happy with their breast development, and approximately 75 percent were happy with the size and shape of their nipples.  If you are unhappy with your breast development and you are considering breast augmentation, Plume can write you a letter in support of that gender-affirming surgery.

If I am older, will I still experience breast growth on estrogen?

People who are over 50 and using estrogen experience breast growth, too. Taking hormones as part of your gender transition will have a profound impact on your body regardless of your age. You’re never too old to transition, and people who are in their golden years report having positive experiences with gender-affirming hormone therapy.

The 2021 published in The Journal of Clinical Endocrinology & Metabolism reported that older trans women experienced breast growth, just like younger women. The study found “no associations” between increase in breast volume and age, BMI, tobacco use, treatment regimen, and serum hormone levels. That means that all people who take estrogen as GAHT, regardless of their age, weight, or medications, will develop breasts. The size or volume of the breast tissue may not be easy to predict, but every trans woman in the study noticed development of some kind.

Your body is beautiful and should be celebrated at every phase of your gender journey. Whether you are at the beginning of your gender transition, or more than one year, you deserve to feel happy and whole.

Your development is as unique as you are, and it will happen in time. Rather than compare yourself to others, enjoy the changes you are experiencing. From new sensations to exciting shifts in your appearance, you have lots to look forward to. If you have specific questions about your estrogen/E+ prescriptions, or you want to know more about how estrogen affects breast development, reach out to your healthcare provider at Plume.