How Much Do Boobs Grow During Pregnancy?

pregnant woman holding her stomach

During the third trimester, your breasts are fully developed and ready to produce milk. The hormones oestrogen and progesterone stimulate further breast growth, as well as the development of milk ducts and glands. The areolas also become larger and darker in colour.

This enlargement can begin as early as the eight-week mark, and will continue throughout pregnancy. It’s common to go up a bra cup size during this time, especially for first-time mothers.


Pregnancy is full of many changes, and one of the most noticeable ones happens to your breasts. This is because pregnancy hormones—primarily estrogen and progesterone—stimulate the growth of mammary glands and milk ducts in preparation for breastfeeding. These hormonal changes can cause your boobs to grow in size as well as feel tender, sensitive, and fuller.

Your nipples and areolas—the skin around your nipples—may also darken due to increased blood flow, and your nipple muscles may become more prominent as a result of the changes in your breast tissue. You may also experience colostrum leakage, which is a yellowish liquid that signals the start of milk production in your nipples.

Women often notice their breasts getting bigger in the first trimester, and they may even find that they need to go up a bra size during this time. This is normal, and your boobs will continue to increase in size throughout the remainder of your pregnancy.

You may also notice that your boobs don’t grow equally in size, or that one side of your nipples is larger than the other. This can be caused by the position of your nipples and is a common part of pregnancy. If this is a concern, consider wearing a support bra or using a nipple extender. After your baby is born, it’s possible that your breasts will return to their original size if you choose not to breastfeed, though this can vary from person to person.

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During the first trimester, pregnancy hormones like estrogen and progesterone start raising milk-producing glandular and duct tissue to prepare the breasts for breastfeeding. This increase in tissue can make a woman’s breasts feel full or heavy as early as the second week of pregnancy, and is completely normal.

Breasts are made up of lobules (which produce milk), ducts, and fibrous and fatty tissue that give them their size and shape. The darker area that surrounds the nipple is called the areola, and it’s unique to every woman. It can change in color and size during pregnancy, and no two areolas are the same.

In the second trimester, increased estrogen levels can make a woman’s breasts appear larger and heavier, and they may begin to ache or hurt. The nipples can also darken and become more erect as the glandular tissue grows in preparation for milk production. This is also when a mother might begin to leak colostrum, the first form of milk she’ll feed her baby after birth.

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It’s important to note that not all women experience these kinds of changes to their breasts, and that’s completely okay! Many women’s boobs do not grow at all during pregnancy, or they might grow only a cup size or two. It’s also possible for one side of the breast to grow faster than the other, and this is completely normal as well.


For many women, breast changes – including a change in size and nipple sensitivity – are one of the first signs that they’re pregnant. This is because soaring hormones pack on extra fatty tissue and increase blood flow to the area in preparation for breastfeeding when the baby arrives.

The early breast growth can make your nipples feel sensitive and tender, which is completely normal. It can also lead to a leaking of colostrum, which is a thick, sticky fluid that acts as an early form of breast milk. This can be uncomfortable, and if you’re worried about wet spots on your clothes, you can wear nursing pads inside your bra.

By the time you reach the second trimester, your nipples are often fuller and more firm. This is because the increased progesterone levels help the mammary glands and milk ducts grow, as well as stimulate other organs to prepare for breastfeeding. During this period, some women find their breasts grow by up to a cup size and a width size, making it easier to fit into maternity bras.

Your nipples will continue to grow until you’re six weeks past the due date, and you’ll likely be able to breastfeed the baby by this point. If you’re planning on breastfeeding, you should start shopping for a larger-sized bra by this point.

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Stretch Marks

Stretch marks are wrinkly, raised streaks that can be red, purple, pink, reddish-brown or dark brown and appear on the breasts during and after pregnancy. They usually fade and change to a silvery color with time. If you have them, don’t let them detract from your beauty, as they are a natural part of the process. Many women get them during puberty, pregnancy and rapid weight gain. Wearing a soft, breathable bra and moisturizing daily can help reduce their appearance.

Breast growth during early pregnancy is triggered by the influx of progesterone and estrogen, which help the milk glands and mammary tissue grow. This is why nipple sensitivity and an increase in breast size are often the first signs that you’re pregnant.

Swelling of the breasts and nipples is also normal, as your body retains fluid to prepare for breastfeeding. This swell can also cause itching of the breasts, which is caused by the skin stretching. Using a gentle moisturizer can soothe itching. You may also develop stretch marks, as they are a common result of pregnancy and rapid weight gain. These marks, however, can be difficult to get rid of once they’ve formed. If you’re able to, Massick suggests framing them as “badges of motherhood” rather than a negative feature.