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Changes to the breasts are one of the earliest signs of pregnancy. Caused by hormonal changes, your breasts will continue to change as your pregnancy progresses.

Pregnancy affects levels of the hormones estrogen and progesterone in your body. These hormones play an important role in readying the breasts for lactation and are responsible for many of the changes you may experience.

Estrogen stimulates growth of the breast duct cells and generates the secretion of prolactin, another hormone. Prolactin stimulates breast enlargement and milk production. Progesterone supports the formation and growth of milk-producing cells within the glands of the breasts.

After delivery, estrogen and progesterone levels plummet, and prolactin levels rise, allowing lactation to occur.

Read on to learn what changes to your breasts you should expect during and after pregnancy.

Early signs of pregnancy

Breast changes often start before you are far enough along in your pregnancy for a positive pregnancy test. Changes may include:

  • breast swelling
  • soreness or tenderness
  • heavy feeling, or a feeling of fullness in your breasts

Your breasts will continue to change and grow heavy throughout the first trimester.

Is it pregnancy or PMS?

Many early pregnancy symptoms mimic those associated with premenstrual syndrome (PMS). During the second half of the menstrual cycle, you may have sore, heavy, or tender breasts as a symptom of PMS. Your breasts may feel lumpy or ache. As with early pregnancy, these physical symptoms are generated by the production of hormones, such as progesterone.

Changes in the first trimester

During the first trimester, your body’s blood volume starts to increase to meet the developmental needs of the growing fetus. This may cause the veins on your breasts to become larger, bluer, and more visible. Your breasts will also continue to grow in size. They may feel tender and swollen, although these symptoms often dissipate within the first few weeks of pregnancy as your body adjusts to the hormonal changes you’re experiencing. You may feel an ache right up into your armpits. That area has breast tissue called the Tail of Spence.

You may also notice changes to your nipples. They may become larger and more sensitive, and you may notice a darkening of the areola. You may also begin to develop Montgomery tubercles in the areola. These small, painless bumps have antiseptic and lubricating qualities, and help support breastfeeding.

Changes in the second trimester

During the second trimester, estrogen levels continue to rise. Your breasts will continue feeling heavy or full as the milk ducts develop, and you may need to purchase a larger bra at this time to accommodate your growing size. You may only go up one cup size, or you may go up several.

Consider getting fitted so that you can find the right bra size for you. Even though your breasts will continue to change, and you may only be in a new bra size for a short amount of time, wearing a bra that fits will help keep you more comfortable.

Your breasts will also start to produce colostrum during the first few weeks of the second trimester. Colostrum is the first form of breast milk. You may not be aware that your body is producing colostrum, or you may begin to experience leakage of breast milk at this time. It’s fine to check to see if there is colostrum coming out, but avoid overstimulating the nipple as it could put you into premature labor.

Changes in the third trimester

As your body continues to get ready to give birth, your breasts will become even heavier and denser. Your nipples will become larger and more pronounced. They may also change shape. Your nipples and areola may continue to darken significantly.

As the skin on your breasts stretches to accommodate their growing size, you may experience itching or dryness. If so, using a gentle moisturizer will help. You may also develop stretch marks.

When do you start producing milk?

Your breasts will continue to make colostrum for a short period of time after your baby’s birth. Colostrum is nutrition-dense and full of antibodies. It’s thicker, darker, and stickier than the breast milk you will express in greater amounts once colostrum production stops.

You may leak colostrum during pregnancy, although not all pregnant women experience leakage. Don’t be concerned that you are “using up” your baby’s colostrum if you do leak. If you don’t leak colostrum during pregnancy, that doesn’t mean that you’ll have a low supply of breast milk, either. Every woman’s body responds differently to pregnancy.

Leakage can be uncomfortable during pregnancy. Try inserting nursing pads into your bra to absorb milk and prevent stains or wet spots from seeping through to your clothing. Pads are available in either disposable or environmentally friendly reusable varieties.

No matter what your current breast size, your breasts will grow and change during pregnancy and breastfeeding. These changes don’t indicate what your milk supply will be like or your ability to nurse.

Bras and pregnancy

You will probably be ready to start shopping for larger-sized bras as early as the end of your first trimester, if not before.

Comfort, support, and ease of use are all important factors to consider when choosing pregnancy and nursing bras. Keep in mind that your breasts will continue to get larger and heavier as your pregnancy progresses, and larger again once your milk supply comes in. Opt for bras that easily adjust to size changes, or consider buying several bras in multiple sizes. If you’re uncertain what size or type to buy, consider going to a store that specializes in bras. The sales associates should be able to fit you and offer guidance for your bra needs throughout your pregnancy.

Consider purchasing a few sleep bras as well. Your breasts will be tender and heavy throughout pregnancy, and sleeping with a bra may be more comfortable than sleeping without one. Many pregnancy sleep bras provide light support in easy-to-recline-in styles, such as wraps. They’re often designed to let you nurse easily during nighttime hours, as well.

You can also start wearing nursing bras during your pregnancy, if you choose. Many of these are functional as well as attractive, featuring front clasps and turn-down cups in quick-dry, breathable fabrics.

When purchasing bras during pregnancy:

  • choose soft, natural fabrics, such as cotton
  • look for bras that feature a snug, supportive band under the bust line and wide shoulder straps
  • avoid underwire, which may be uncomfortable for your sensitive breasts

If you have leaking breasts, look for bra styles that easily accommodate nursing pads while providing ample coverage.

Stretch marks on the breasts during pregnancy

It’s not unusual to get stretch marks on the sides or front of your breasts during pregnancy. To avoid this, plus keep your skin as supple as possible, rub on a good moisturizing cream or oil at least once a day and before bed. No stretch-mark cream is a tried-and-true miracle, but keeping skin moisturized may help reduce stretch marks, and eliminate dryness and itching.

How will breasts change after pregnancy?

Pregnancy creates dramatic changes to your breasts. After delivery, your breasts will remain large as they continue to produce breast milk. You may experience engorgement if your breasts become overly full or produce more milk than you are able to express. Breastfeeding or pumping often will help reduce engorgement.

Some women’s breasts “snap back” to their original size and shape once they stop producing breast milk. Others remain larger or lose some of their elasticity. These changes may be determined, in part, by many factors, including:

  • the length of time you breastfeed
  • genetics
  • weight fluctuations during and after pregnancy

Your nipples may or may not go back to their original size and shape. They will become lighter in color over time after you stop breastfeeding.

The takeaway

The hormonal changes of pregnancy help get your breasts ready for lactation. Your breasts will become heavier and denser during this time. Your nipples will also darken.

The changes your breasts go through don’t predict the type of milk production you’ll have. Some women’s breasts go back to their original size and shape after pregnancy. Others remain changed, staying larger or more lax.