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Breast growth during the first year of HRT: what can I expect?

Posted January 31st 2019
Breast growth during the first year of HRT: what can I expect?

Attention:

We do not provide HRT at the 2pass Clinic. Please contact your doctor or specialist for more information.F

For many transgender individuals looking to see breast growth, the main question is: “How much breast development can I expect on HRT, and when will it start?”. Let’s take a look at breast development during the first year on anti-androgens and estrogen.

This article is describes the findings of the first scientific study on breast development after HRT in trans women (Breast Development in Transwomen After 1 Year of Cross-Sex Hormone Therapy: Results of a Prospective Multicenter Study (2017)– Christel Josefa Maria de Blok en co-authors)

This detailed study was performed on 229 trans women who completed their first year of Hormone Replacement Therapy. Their ages ranged from 18 to 69, the median age being 28 years at the start of the study.

When will my breasts start growing after starting on HRT?

Breast development mostly occurred during the first 6 months on Hormone Replacement Therapy. The average increase over the first 3 months being 1.8 cm, and another 1.3 cm over the following 3 months. During the last 6 months, the average total growth was only 0.5 cm. It can hereby be concluded that main breast growth takes place in 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 on HRT?

After one year of HRT, the average increase in breast growth was 3.8 cm. When translating this to bra cup size, this meant around 50% of all participating women had less than an AAA cup after one year. Less than 5% of all women gained a cup size larger than an A cup.

More follow-up research is needed to be able to accurately predict breast growth in the following year(s) of HRT.

Do factors like smoking, BMI, weight change, age,… influence breast development?

The short answer is: no.

In the study:

  • Breast growth does not vary in 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 months of HRT, but total breast-chest difference after 12 months was the same in normal weight, overweight and obese trans women.
  • Breast growth does not vary in smokers versus non-smokers.
  • Breast growth had a faster increase in trans women treated with transdermal estradiol for the first six months, but total breast development after one year saw no difference between the intake of oral or transdermal estradiol.

So we can conclude that the current study shows a modest increase in breast-chest difference after 1 year of CHT, mainly resulting in less than an AAA bra cup size. Age, weight change, smoking, BMI, serum estradiol levels, and estrogen administration route did not predict total breast development after 1 year of CHT.

Because of the modest results of HRT on breast development, many trans women seek to get a breast augmentation. It is advised to wait with surgery until you have been on HRT for 18 months.


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