Surprising Reasons Why Women’s Breasts are Getting Larger

Surprising Reasons Why Women's Breasts are Getting Larger

Breasts that are getting larger is a normal part of the growth process that happens during adolescence and into womanhood. However, throughout their adult life, many women’s breasts continue to grow and get larger. The reasons why some women experience changes in the size of their breasts can vary. Pregnancy almost always causes breasts to get bigger. But sometimes, breasts can grow larger without being pregnant. For example, weight gain and hormonal fluctuations can also cause breasts to get larger. Whatever the reason, it is only natural to be concerned if you experience a sudden increase in breast size.

In most cases, breasts that are getting bigger isn’t a sign of any serious medical condition. In this article, I will look at what causes breasts to continue growing even after your breasts have become fully developed. You will also find out when you should see a doctor if one or both of your breasts starts increasing in size.

Reasons Why Breasts Get Larger


Breasts that get larger could be one of the first signs that you are pregnant. The onset of pregnancy causes many changes in a woman’s hormones and this affects the size of the breasts.

The American Pregnancy Association reports that enlargement of the breasts, tenderness, and a darkening around the nipples are some of the changes to expect if you are pregnant.1 As the breasts grow in size, you may also experience itchiness as the skin stretches and stretch marks may also appear on the breasts. Another sign of pregnancy is sore and tender nipples.

The reason for breast enlargement during pregnancy is because milk glands become larger and fat builds up in the breasts. This happens very quickly and you could find that within the first 6 weeks of pregnancy, your breasts have grown a whole cup size larger.

According to research published in the American Journal of Human Biology, women who are expecting boys tend to have slightly larger breasts during pregnancy than those who are expecting girls.2

Menstrual cycle

Most women find that their breasts get larger and swollen during their menstrual cycle. However, this increase in breast size usually disappears once menstruation starts.

The John Hopkins School of Medicine explains that these normal changes in breast size happen because estrogen causes the milk ducts in the breast to enlarge, which in turn, cause the breasts to get larger. Some women also experience lumpy, painful breasts just before menstruation.3 These symptoms usually go away when your period starts.

Oral contraceptive

Taking the oral contraceptive pill is one reason for breast growth other than pregnancy. If you are on oral contraceptives then you could find that your breasts grow in size. However, if your breasts get bigger or not is dependent on your hormones and the type of oral contraceptive that you take.

A study carried out on the role of oral contraceptive use and their relation to breast size found a connection between hormone levels and larger breast sizes. The study reported that during the menstrual cycle, some women had larger breast sizes when they were taking the contraceptive pill.4

The American Family Physician also reports that certain types of hormonal contraceptive pills can increase breast tenderness after your period or at other times in your menstrual cycle.11

Fibrocystic Breast Changes

Many women have fibrocystic breast changes which can cause breast swelling or thickening. This is a harmless condition that causes a woman’s breasts to feel lumpy and sometimes painful.

Authority in obstetrics and gynecology, Dr. Nivin Todd says that fibrocystic breast changes are caused by thickened breast tissue that is firm to touch or fluid-filled cysts that form in the breasts. Fibrocystic breasts cause symptoms like larger breasts, lumps, tender breasts, and pain which tend to fluctuate during the menstrual cycle and are affected by your hormones.5

Dr. Todd recommends that if you find a lump in your breast, you should make an appointment to see your doctor to have a check-up.


Some women get bigger breasts during the menopause. Many women find that when they are in their 50s, their breasts start to grow and they have to buy a larger bra.

Studies into the physical changes that happen to women during the menopause found that about one in five women experienced breast growth. However, the study showed that larger breast sizes in older women weren’t all connected with hormonal changes. With many women, the increase in breast size was directly associated with an increase in weight.6

There are many nutritional supplements you can take to alleviate many of the symptoms of the menopause. In my article about the different supplements that can help during the menopause, you can learn about the top 10 supplements to take.

Weight Gain

Weight gain is one possible reason why your breasts are getting bigger and continuing to grow. Fat content is one of the main reasons for breast size.

According to the Mayo Clinic, most women have the same number of milk ducts in their breasts. However, it is the amount of fat in your breast that determines their size.10

Much is dependent on the structure of each woman’s individual breasts, therefore, not all women who put on weight experience breast growth. But, if you do put on weight, you will develop more fat in all places in your body, including your breasts.

This also explains why, when some people lose weight, they notice that their breast size also reduces.

Abscesses or inflammation in the breast

Inflammation or an abscess in the breast can sometimes affect women who are breastfeeding and this can cause the breasts to swell even more and become tender.

Dr. Hayley Willacy on says that the inflammation can occur when milk accumulates in the milk ducts and causes the breasts to become larger. If bacteria start to grow in the accumulated milk this can cause an infection to develop and this cause pain and tenderness in the affected breast.7 If left untreated, the inflammation can develop into an abscess.

If you experience pain and tenderness in your breasts while breastfeeding, it’s important to speak with your healthcare practitioner who can carry out an examination and check your milk for the presence of bacteria.


The side effects of taking certain medication could cause breast changes, one of them being that your breasts grow larger.

Professor of medicine, Dr. Sandhya Pruthi from the Mayo Clinic warns that breast enlargement can be a side effect of taking certain medications. For example, some antidepressants, hormone therapy treatments, and birth control pills are all known to cause breasts to grow larger in some women.8

Hormonal changes

One simple reason for breasts getting larger is hormonal changes in your body. Just because you discover that your breasts are growing without any other explanation isn’t always a reason for concern. Any changes in the size of your breasts can be a normal part of life and probably isn’t anything to worry about.

When to See a Doctor

It’s important that all women check the health of their breasts and are aware of any changes that they notice. This can help you identify any lumps or changes in your breast which could be a sign of a more serious condition like breast cancer.

Specialist in breast cancer, Dr. Debra G. Wechter advises all women to perform a breast self-exam once a month about 3-5 days after the start of their period.9

There are some other reasons to visit your doctor for a checkup if changes in your breast size are causing you concern. For example, if you notice that one breast is growing larger than the other one, or if you experience pain and tenderness in your breasts that won’t go away, then a visit to your health practitioner will help to put your mind at rest.

Read these related articles:
1. Unconventional Signs of Breast Cancer
2. How to Make Breasts Smaller: Effective Natural Ways that Really Work
3. The Best Exercises To Firm And Lift Your Breasts
4. How to Get Rid Of A Rash Under Breasts

Article Sources

  1. American Pregnancy Association Breast changes during pregnancy
  2. Am J Hum Biol. 2015 Sep-Oct;27(5):690-6
  3. Johns Hopkins Medicine Normal breast development and changes
  4. Am J Epidemiol. 1997 Apr 1;145(7):571-80
  5. WebMd Fibrocystic breast changes
  6. 2004 May 28;48(1):51-7
  7. Patient. Info. Puerperal mastitis
  8. Mayo Clinic. Women’s health
  9. MedlinePlus. Breast self-exam
  10. Mayo Clinic. Female Breast Anatomy
  11. American Family Physician Managing Adverse Effects of Hormonal Contraceptives

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