You can expect certain things during pregnancy: You may be queasy, your feet might swell, and you’ll have various aches, pains, and discomforts as your belly grows.

But other pregnancy experiences may take you by surprise. For example, did you know that you may leak breast milk during pregnancy?

Leaking milk during pregnancy — or finding dried breast milk on your nipples — is a strange but perfectly typical part of pregnancy. This happens because your breasts begin to produce colostrum as your body prepares for nursing.

Colostrum is a form of milk that is more nutrient-dense than mature breast milk. It also contains a variety of antibodies, including an important one called immunoglobulin A (IgA). IgA helps protect baby from infection and develop their immune system.

Toward the end of pregnancy, some of this colostrum may leak out of the nipples.

Here’s what to know about leaking breast milk during pregnancy — why it happens, when it happens, and what to do if it happens to you.

Leaking breast milk during pregnancy isn’t something that’s talked about often. You usually think of milk leaking as an event that happens after your baby is born.

But the changes that your breasts go through during pregnancy mean that your body starts making milk even before baby arrives. Starting at the mid-point in pregnancy, your body produces colostrum, according to 2021 research.

Colostrum is considered your baby’s first milk because it ensures that your little one will get that milk as soon as they start suckling after birth. It makes sense to plan ahead, right?

So the short answer is: Yes, milk can and does often leak during pregnancy. Not every expectant parent leaks milk during pregnancy, but many do.

This doesn’t mean that milk leaks all over the place and is plentiful at this point. But many people will find little whitish or yellowish drops of colostrum on their nipples, the American Academy of Pediatrics (AAP) explains. Often, this milk is dried and crusted on your nipples or the inside of your bra or shirt.

Soon after — or sometimes even before — you get your positive pregnancy test result, you may notice changes in your breasts. In fact, breast changes are often the first indication that you are pregnant.

Usually, by the 5th or 6th week of pregnancy, your breasts begin to feel heavy, sore, and tender to the touch. Your nipples may darken and you may notice tiny little bumps on your areolas, called Montgomery’s glands.

All these changes have to do with the fact that your breasts are getting ready to become milk-making factories.

Hormones like estrogen and progesterone lead to changes inside your breasts, too. Milk glands and ducts start to form and multiply.

Between the 12th and 16th week, alveolar cells in your breasts start to produce colostrum. Usually, though, any leaking of colostrum doesn’t happen until sometime in the third trimester of pregnancy, according to 2021 research.

During pregnancy, your body is doing everything it can to prepare for the upcoming birth of your baby. As your second trimester ends and your third trimester begins, your breasts are ready to feed your baby in case they arrive earlier than expected.

The colostrum your body is producing will be “on tap” as soon as your little one is born. At times, it may leak even before baby makes their appearance.

It’s not clear why some people leak more colostrum than others. You may leak colostrum but not notice it until you see yellowish stains on your nipples or find dried up specks of colostrum on your nipples. Usually, there isn’t a large amount of liquid.

It’s important to note that leaking colostrum during pregnancy doesn’t mean that you will have too much milk once your baby is born. And not leaking milk during pregnancy doesn’t mean you will have less milk when baby arrives.

All bodies are different, and some people just seem to leak more milk than others — during pregnancy and after.

As mentioned, if you do find yourself leaking milk during pregnancy, you are seeing colostrum. This sticky, yellowish-orangish substance is the first milk that your baby will drink, and it will be ready as soon as they are born. Colostrum is small in amount but full of nutrition and immune-boosting goodness for your baby.

Colostrum has some special features that distinguish it from the mature milk that baby will receive a few days after birth when your milk “comes in.” For example, colostrum:

  • is higher in protein and lower in fat and carbohydrates than mature milk
  • shields your baby from infection, in part because of increased amounts of secretory IgA
  • protects your baby’s gut and helps establish a healthy microbiome

When you are producing colostrum, your breasts will not be especially full yet. That’s completely typical. As long as you nurse frequently (8 to 12 times per day is best), your baby will get all they need.

About 3 to 5 days after giving birth, you will notice that your breasts feel fuller. This means your body is transitioning to more mature milk, which will be whiter in color and much more abundant.

If you notice some leaking milk during pregnancy, don’t panic. It may catch you off guard, especially if you weren’t aware of this as a common phenomenon in pregnancy, but it’s typical and happens frequently.

Still, you may have concerns about what’s happening. You may worry that you have too much leaking milk or not enough. Again, the amount you leak — or whether you leak at all — does not relate to what your milk supply will be like after your baby is born. Every person is different when it comes to leaking milk during pregnancy.

If you have any questions or concerns about what is happening, contact your OB-GYN, midwife, or a lactation consultant.

Breast milk leakage during pregnancy may include yellow, orange, or whitish milk. This milk may leak on its own or when you roll or squeeze your areola.

You may find stains or dried up flakes on your clothing or bra. You may also find flakes on your nipples. All of that is par for the course during pregnancy.

However, you should speak to your healthcare professional about certain breast changes. If you notice blood leaking from your breasts or staining your clothing, alert your doctor or midwife.

In rare instances, you may show signs of breast cancer during pregnancy, according to 2020 research. According to ACOG, symptoms may include:

  • warmth, reddening, and dimpled skin
  • blistering of the breast skin (ulcers)
  • ongoing crusting or scaling of the nipple skin (not to be confused with crusted milk, which can be cleaned off)
  • changes in nipple shape

Still, most changes in the breast — including size increases, soreness, darkening of areolas, and milk leakage — are expected during pregnancy and not a cause for alarm.

Finding breast milk on your nipples or on your bra or clothes during pregnancy can certainly come as a surprise. You may worry that something is wrong with your pregnancy or with your body.

These are natural concerns, but leaking milk during pregnancy is very common. It’s a promising sign that your body is getting ready to produce breast milk for baby!

If you have any further questions about leaking milk during pregnancy or any other changes your body is going through to prepare for birth and breastfeeding or chestfeeding, don’t hesitate to reach out to your doctor or midwife.