Pregnancy brings significant and rapid changes to the breasts, changes that are entirely normal and reflect the body preparing for the demands of feeding a newborn.

For most women, these changes are expected and manageable. But pregnancy also makes the breasts harder to self-examine and can occasionally mask an underlying breast condition. Knowing what to expect, and what to look out for,  is important throughout pregnancy and into the breastfeeding period.

At Breast & Surgical Oncology at The Poche Centre, we see pregnant and breastfeeding women with breast concerns regularly. If you've noticed something that doesn't feel quite right, or your GP or midwife has identified a breast change that needs specialist review, we're here to assess it promptly and expertly.

Normal Breast Changes Throughout Pregnancy

The breast changes of pregnancy are driven by surging levels of oestrogen, progesterone, and prolactin — the hormones that stimulate glandular growth and milk production. These changes begin very early, often before a pregnancy is confirmed, and continue through to birth and beyond.

First Trimester

For many women, breast tenderness or soreness is one of the very first signs of pregnancy, sometimes appearing before a missed period. As hormone levels rise rapidly in the first weeks, the breasts may feel heavy, swollen, and unusually sensitive to touch. The increased blood flow to the breasts can cause a visible network of blue veins beneath the skin, and the breasts may begin to increase in size as the glandular tissue starts to proliferate.

The nipples and areolae often become more sensitive, and the small bumps on the areola — known as Montgomery's glands — may become more prominent. These glands secrete a lubricating fluid that protects the nipple during breastfeeding.

Second Trimester

By the second trimester, many of the early discomforts ease as the body adjusts to the hormonal changes. The areolae continue to darken and widen, and the nipples may become more prominent and protrude further than before. Some women notice a thin, yellowish fluid called colostrum beginning to leak from the nipples — this is entirely normal and signals that the breasts are beginning to prepare for milk production.

Breast lumps are relatively common during pregnancy due to the significant structural changes occurring in the glandular tissue. The most common lumps found during pregnancy are galactoceles (milk-filled cysts), fibroadenomas (which may enlarge under hormonal stimulation), and cysts. While the vast majority of lumps found during pregnancy are benign, any new lump should always be assessed by a specialist — pregnancy does not eliminate the possibility of breast cancer.

Third Trimester

The breasts continue to grow through the third trimester and may increase significantly in size — often by one to two cup sizes or more across the course of a pregnancy. Stretch marks may develop as the skin stretches to accommodate this growth. The production of colostrum may increase, and some women experience spontaneous leakage. The nipples and areolae are typically at their darkest and most prominent at this stage.

During Breastfeeding

Once the baby is born and breastfeeding is established, milk production increases under the influence of prolactin. The breasts may feel engorged — particularly in the first days as supply adjusts to demand — firm, warm, and heavy. Blocked milk ducts are common and present as a tender, localised area of firmness or a palpable lump. Most blocked ducts resolve with continued breastfeeding, warmth, massage, and rest.

Managing the Physical Changes of Pregnancy and Breastfeeding

Supportive bra — investing in well-fitted maternity or nursing bras throughout pregnancy and breastfeeding is one of the most effective ways to manage breast discomfort. As the breasts change size rapidly, regular re-fitting is worthwhile. A soft, wireless bra worn at night can also help with overnight tenderness and engorgement. A properly fitted sports bra provides essential support during exercise.

Breast tenderness — in the first trimester particularly, breast tenderness can be significant. Avoiding tight clothing, wearing a supportive bra day and night, and being gentle when sleeping (a pillow for support can help) are all practical measures. The tenderness typically eases as the first trimester progresses.

Nipple care — keeping the nipple and areola moisturised during pregnancy and breastfeeding can help reduce dryness and cracking. Lanolin-based nipple creams are widely used and safe during pregnancy and breastfeeding.

Stretch marks — while there is limited strong evidence that topical creams prevent stretch marks, keeping the skin well moisturised throughout pregnancy is a reasonable measure. Stretch marks typically fade in colour over time after birth.

Blocked ducts and engorgement — if breastfeeding, continuing to feed regularly and ensuring a good latch is the most important measure. Warmth before feeding, gentle massage during feeding, and cold compresses between feeds can all help manage engorgement and blocked ducts.

When a Breast Change During Pregnancy Needs Specialist Review

Because pregnancy causes significant, rapid changes to the breast tissue, it can be more difficult to detect an underlying problem through self-examination. The glandular tissue becomes denser and lumpier, which can mask a new lump or make it harder to distinguish from normal pregnancy-related changes. For this reason, any new, persistent, or unexplained breast lump or change noticed during pregnancy or breastfeeding should always be assessed by a specialist promptly — not waited on.

Signs that warrant prompt assessment include:

• A new lump or area of thickening that does not resolve within a week or two
• A lump that feels different from general pregnancy-related lumpiness — harder, fixed, or irregular
• Skin changes such as redness, dimpling, or puckering
• A localised area of persistent redness or warmth not associated with a blocked duct or mastitis
• Nipple discharge that is bloodstained or from one side only
• Swelling or a lump in the armpit
• A lump that persists despite treatment of suspected mastitis

Breast Lumps During Pregnancy. Can It Be Cancer?

This is a question many pregnant women are afraid to ask — but it is an important one. Breast cancer diagnosed during pregnancy or within one year of giving birth is known as pregnancy-associated breast cancer (PABC). It is rare but not uncommon — it is the most common cancer diagnosed during pregnancy, affecting approximately 1 in 3,000 pregnancies.

PABC presents particular challenges because the normal changes of pregnancy can obscure or delay recognition of a suspicious lump, and because some investigations and treatments need to be modified to protect the baby. Mammography can be performed safely during pregnancy with abdominal shielding. Ultrasound is the preferred initial imaging modality as it involves no radiation and is excellent for characterising lumps in young, dense breast tissue. Core biopsy can also be safely performed during pregnancy under local anaesthetic.

Critically, a diagnosis of breast cancer during pregnancy does not mean termination is necessary, and most treatment — including surgery and some chemotherapy — can be carried out safely during pregnancy with appropriate specialist co-ordination.

The key is not to delay. A lump found during pregnancy should be assessed with the same urgency as a lump found at any other time. The fact that you are pregnant is never a reason to wait.

Mastitis and Breast Abscess During Breastfeeding

Mastitis (infection of the breast tissue) is one of the most common breast problems affecting breastfeeding women, occurring in up to 1 in 5 women in the first three months after birth. It presents as a painful, red, warm, swollen area of the breast, often accompanied by flu-like symptoms including fever, chills, and fatigue.

Mastitis is caused most commonly by a blocked milk duct that becomes infected, often with Staphylococcus aureus bacteria. Treatment involves continuing to breastfeed or express regularly (stopping abruptly worsens engorgement), antibiotics prescribed by a GP, rest, warmth, and pain relief.

If mastitis does not resolve promptly with antibiotics, or if a painful lump remains, a breast abscess may have formed — a collection of pus within the breast tissue. A breast abscess requires drainage, which can usually be performed under ultrasound guidance in the outpatient setting under local anaesthetic. Surgical drainage is occasionally required for larger or complex abscesses.

It is important to note that mastitis and breast abscess, while painful and debilitating, are benign conditions and do not increase breast cancer risk. However, if a firm lump persists after a course of antibiotics and a clinical episode of mastitis has resolved, it should be assessed further to exclude an underlying breast condition.

Specialist Breast Care During Pregnancy in North Sydney

Our team has extensive experience assessing breast changes during pregnancy and breastfeeding, and in the management of pregnancy-associated breast cancer. We understand that concerns about your breasts during pregnancy carry particular emotional weight, and we provide prompt, expert, and compassionate assessment for all women who are referred to us during this time.

Urgent appointments are available when clinically needed.