Breasts can grow in response to hormones estrogen and progesterone, as well as pathological conditions such as benign and cancerous breast tumors and certain medications.
Breast changes continue to occur throughout a woman’s life. The first thing to develop are lobes, followed by mammary glands, which are influenced by hormones activated in puberty. Shrinkage of the milk ducts is the final major change that occurs in the breast tissue, which typically starts at about age 35.
What are the physiological causes of breast growth?
As a girl approaches her teen years, the first visible signs of breast development begin. When the ovaries start to produce and release estrogen, fat in the connective tissue starts to collect, causing the breasts to enlarge. The duct system starts to grow. Often, these breast changes occur at the same time pubic and armpit hair appear.
Once ovulation and menstruation begin, maturing of the breasts begins with the formation of secretory glands at the end of the milk ducts. The breasts and duct system continue to grow and mature, with the development of glands and lobules. The rate at which breasts grow is different for each person.
Each month, women go through hormonal changes during the menstrual cycle. The hormone estrogen is produced by the ovaries in the first half of the menstrual cycle and stimulates the growth of milk ducts in the breasts. Increased levels of estrogen lead to ovulation halfway through the cycle. Progesterone then takes over in the second half of the cycle and stimulates the formation of the milk glands. Progesterone is responsible for cyclical changes that many women feel in their breasts just before menstruation, such as swelling, pain, and soreness.
During menstruation, many women have changes in breast texture. For example, their breasts may feel lumpy, because the glands in the breast are enlarging to get ready for a possible pregnancy. If pregnancy does not occur, breast size goes back to normal. Once menstruation starts, the cycle begins again.
Pregnancy and lactation
Many doctors believe the breasts are not fully mature until a woman has given birth and produces milk. Breast changes are one of the earliest signs of pregnancy caused by progesterone. For example the dark areas of skin around the nipples (areolas) may begin to swell. This is followed by rapid swelling and expansion of the breasts. Most pregnant women feel soreness down the sides of the breasts and tingling or soreness in the nipples because of the growth of the milk duct system and formation of many more lobules.
By months 5 or 6 of pregnancy, the breasts are fully capable of producing milk. As in puberty, estrogen controls the growth of the ducts, and progesterone controls the growth of the glandular buds. Many other hormones play vital roles in milk production. These include follicle-stimulating hormone, luteinizing hormone, prolactin, oxytocin, and human placental lactogen.
Other physical changes may also occur, such as the blood vessels in the breast becoming more visible and areolas getting larger and darker. All these changes are in preparation for breastfeeding the baby after birth.
Perimenopause typically starts or is underway by the time a woman reaches her late 40s and early 50s. At this time, estrogen and progesterone levels begin to change. Estrogen levels dramatically decrease, leading to many of the symptoms commonly linked to menopause. Without estrogen, the breast’s connective tissue becomes dehydrated and is no longer elastic. Breast tissue begins to shrink and lose shape.
Women who undergo hormone therapy may have symptoms similar to menstruation symptoms such as breasts soreness and swelling. However, if a woman’s breasts were saggy before menopause, this will not change with hormone therapy.
Because most breast tissue is made up of fats, an increase in body fat leads to accumulation of fats in the breasts, giving them a fuller appearance. Therefore, if increased food or calorie intake may result in the enlargement of one's breast.
What are other causes of breast growth?
Breast expansion can also occur due to pathological causes that include:
- Breast carcinoma (malignant tumors in the breast can lead to breast enlargement)
- Benign hypertrophy, which is usually bilateral
- Giant fibroadenoma (noncancerous tumors)
- Fibrocystic breast disease
- Sarcoma (connective tissue cancer of the breasts)
- Colloid carcinoma
- Filariasis of the breasts
- Drugs (oral contraceptives, diuretics, anabolic drug overuse, and antacids)
- Injury to the breasts due to inflammation
Traumas such as a blow to the breasts, rough handling of the breasts, and surgery can lead to breast expansion, making breasts tender and more swollen. The reason behind this expansion is that due to inflammation, breast capillaries become permeable. Fluid seeps through the capillaries and accumulates within the breast tissues.
What causes breast expansion in men?
Breast enlargement in men is called gynecomastia, which is hypertrophy of the male breast tissue that occurs due to estrogen overload or androgen deficiency. The condition can affect a single breast or both the breasts and be symmetrical or asymmetrical.
Causes of gynecomastia include:
Top What Causes Breast to Expand? Related Articles
Breast AnatomyThe breast, or mammary gland is made up of lobules, milk producing glands, and a system of ducts to transport milk. Both males and females have breasts. Abnormal enlargement of breasts in men is referred to as gynecomastia. In women, during pregnancy the breasts grow larger and produce milk. Common medical conditions that affect the breasts include breast cancer, breast lumps, fibrocystic changes and cysts, mastitis, and benign tumors (fibroadenomas).
Breast Anatomy PictureThe breast refers to the front of the chest or, more specifically, to the mammary gland. See a picture of Breast Anatomy and learn more about the health topic.
Breast Augmentation and ImplantsBreast augmentation refers to the surgical implantation of a silicone or saline implant to give the breast a fuller appearance. Potential complications of the procedure include
- asymmetry, and
- hardening of the breast.
Young Women & Breast CancerIs breast cancer genetic? Should I get tested for the BRCA gene? What every young women should know about breast cancer. Discover the signs and symptoms of breast cancer and other crucial breast cancer facts.
Breast Cancer SlidesLearn about breast cancer causes, symptoms, tests, recovery, and prevention. Discover the types of treatments such as surgery and drug therapies as well as the survival rate for breast cancer.
Breast Cancer QuizThis Breast Cancer Quiz features signs, symptoms, facts, causes, common forms, terms, risk factors, statistics, and more. Increase your awareness of breast cancer now!
Breast ReconstructionAfter a mastectomy, breast reconstruction is performed to replace the skin, breast tissue, and the nipple. A patient's goals, medical conditions, cancer treatment, and previous surgery affect the type and timing of the reconstructive surgery.
Breast Self-ExamA woman can use a breast self-exam to check for changes, lumps, or thickenings, in her breasts. Any unusual changes should be reported to the doctor. A breast self-exam is one way to detect lumps that may be cancerous. Early detection and treatment of breast cancer greatly increases the likelihood for survival.
Breastfeeding (and Formula Feeding)It's important to know whether you will breastfeed or bottle-feed your baby prior to delivery, as the breasts' ability to produce milk diminishes soon after childbirth without the stimulation of breastfeeding. Breast milk is easily digested by babies and contains infection-fighting antibodies and cholesterol, which promotes brain growth. Formula-fed babies actually need to eat somewhat less often since formula is less readily digested by the baby than human milk. This article explores the advantages and disadvantages of both forms of feeding.
Can a 7-Year-Old Develop Breasts?The development of breast buds is one of the first signs of puberty in a girl. The beginning of adult breast development is called thelarche. As the breasts start to develop, a girl will have small, firm lumps under the nipples called breast buds, which may sometimes be tender.
What Are Polycystic Ovarian Syndrome (PCOS) Symptoms?Polycystic ovarian syndrome (PCOS), also known by the name Stein-Leventhal syndrome, is a hormonal problem that causes women to have a variety of symptoms including irregular or no menstrual periods, acne, obesity, and excess hair growth. Treatment of PCOS depends partially on the woman's stage of life and the symptoms of PCOS.
What Are the Types of Breast Implants?Breast implants are U.S. Food and Drug Administration (FDA)-approved devices that are fitted into your breasts to enhance the look, shape, and feel of your breasts. The different types include saline, silicone, gummy bear, round, smooth, and textured implants.
When to Worry About Breast PainThe easiest way to tell whether breast pain is something to worry about or not is to determine whether it is cyclic or noncyclic.
Why Do Your Breasts Get Bigger Before Your Period?Many women may notice that their breasts become larger just before a week of menses, whereas others may not experience such symptoms. Breast swelling and tenderness occur due to a surge in hormones during the menstrual cycle.