Transmen can get bigger

Breast Growth In The First Year Of Hormone Oral Therapy: What Can I Expect?


We do not offer HRT (hormone replacement therapy) in the 2pass Clinic. Please contact your doctor or specialist for more information.

We do not offer HRT (hormone replacement therapy) in the 2pass clinic. Contact your doctor or specialist for more information.

For many trans women who want breast growth, the main question is: "How much breast development can I expect from HRT and when will it start?" Let's look at breast development in the first year from antiandrogens and estrogens.

This article describes the findings of the first scientific study on breast development after HRT in trans women (Breast development in trans women after 1 year of hormone replacement: results of a prospective multicenter study(2017)- Christel Josefa Maria de Blok and co-authors)

This detailed study was conducted on 229 trans women who completed their first year of hormone replacement therapy. Their ages ranged from 18 to 69 years, the mean age at the start of the study was 28 years.

When will my breasts start growing after starting HRT?

Breast development occurred mainly in the first 6 months of hormone replacement therapy. The average growth was 1.8 cm in the first 3 months and another 1.3 cm in the following 3 months. In the past 6 months, the average total growth was only 0.5 cm. It can be deduced from this that the main breast growth occurs within the first six months of HRT.

For most trans women, the size of the breast, nipple, and areola will increase somewhat.

How much breast development can I expect from HRT?

After one year of HRT, the mean breast size growth was 3.8 cm. When applied to bra sizes, this means that around 50% of all participating women had a cup size smaller than AAA after one year. Less than 5% of all women achieved a cup size larger than A.

Further follow-up studies are needed to accurately predict breast growth in the following year or years of HRT.

Do factors such as smoking, BMI, weight change or age influence breast development?

The short answer is no.

In the study:

  • Breast growth does not vary in the different age groups.
  • Breast growth does not vary based on weight change, weight gain, or weight loss.
  • Obese trans women showed faster growth in the first few months of HRT, but the overall breast difference after 12 months remained the same, regardless of whether they were normal, overweight, or obese trans women.
  • Breast growth does not vary in smokers compared to non-smokers.
  • Breast growth increased faster in those trans women treated with transdermal estradiol in the first six months, but there was no difference in overall breast growth after one year between taking oral estradiol and using transdermal estradiol.

From this we can conclude that the current study shows a modest difference in breast size after 1 year of HRT, mainly giving a cup size less than AAA. Age, weight change, smoking, BMI, serum estradiol levels and the method of administration of the estrogen did not affect the predicted overall development of the breast after 1 year of HRT.

Because of HRT's modest results on breast development, many trans women want breast augmentation. It is recommended that you wait until you have had HRT for 18 months before having surgery.

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