Pregnancy & Preparation

Exploring Breast Changes During Pregnancy: What Happens in the First Trimester?

Time to read: 2 min.

Some women find that the first thing they notice about being pregnant is the breast changes they are experiencing.

Many women who are having their second or third baby have told me how they knew they were pregnant before even doing the test because they recognised the feelings in their breasts...

The breasts have a huge amount of work to do throughout your pregnancy, in order to be fully prepared to feed your baby for 18-24 months or longer in many cultures. Many women don’t realise that their breasts are changing on the inside and outside as much as their growing bumps, but they are!

Let’s have a look at what is going on in this first 12 weeks of pregnancy (the 1st trimester):

Blood Supply

The blood supply is rapidly increasing inside the breast from this point and you may notice your breasts feel tender, or that your nipples and areolas are tingling.

Breastmilk Production

Your body is now starting to produce the milk-making cells in abundance and lengthen and increase the ductal branch-like system. The best way to visualise the inside of a lactating breast is to imagine a bunch of grapes.

The grapes represent clusters of the milk-making cells and the branches coming off the grapes are your ductal system which leads your milk down to your nipple.

Breast Changes During Pregnancy

As the weeks go by you may feel that your breasts feel like they would when you were pre-menstrual; fuller and heavier. Your nipples may have become more prominent and the skin around your nipples (areola) has started to get darker. It is believed that by making your areolae darker it helps your baby see the nipple clearer which is easier to find and feed from.

Some women, particularly with fair skin, will notice veins appear on the skin of their breasts. Or you may see small bumps, known as Montgomery’s Tubercles, appear on your areola. These are very normal, they are there to release a sebum (oil); an antibacterial, helping to keep your nipple area clean and healthy, and a scent, known to be recognisable to babies.

The Roles of Oestrogen, Progesterone, and Human Placental Lactogen

All of this development and growth of the breast tissue is happening because of certain hormones called oestrogen, progesterone, and human placental lactogen that are abundant once you become pregnant.

Not Every Woman Experiences the Same Breast Changes During Pregnancy

Every woman has a different growth pattern throughout the 3 trimesters of pregnancy. Some women may find that their breast size rapidly increases in the first few weeks of pregnancy but then minimal changes seem to occur from then on.

Whilst other women will notice a slow gradual change over the whole pregnancy and other women may find most changes in size happen in the 3rd trimester.

We are all different, that’s for sure, but our bodies are working hard to develop our breasts into super milk-making organs!

Continue to Check Your Breasts!

It is still really important to continue to check your breasts as you would do normally each month for lumps and unusual changes. Knowing how your breasts feel now will help you when you are checking your breasts in the 2nd and third trimester too.

If you do notice any new lumps, skin or nipple changes (not discussed above) or any coloured substance from your nipple then it is advised you discuss this with your doctor.

What questions or thoughts do you have about the breast changes you have noticed? Please join the conversation on the Medela Australia Facebook page.