What to Know About the Start of Breast Milk Production


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Most of us are familiar with the idea of our milk “coming in” after our baby is born. But what you may not realize is that milk production actually starts during pregnancy, whether you plan to breastfeed or not. Turning your breasts into milk-making factories requires preparation, and while you may or may not notice it, throughout your pregnancy, your body is working hard to make this happen.

Here's what to know about the start of breast milk production, including when it happens, what the signs of it are, and what to do about possible leakage.

When Does Milk Production Start?

Your breasts begin the preparation for breastfeeding pretty much as soon as you get pregnant, even if they aren’t making milk quite yet.

“Parents may notice that their breast/chest tissues are getting bigger and changing color, usually getting darker,” Laura Howells, IBCLC, a lactation consultant in private practice. “One of the first symptoms of pregnancy can be tenderness in the breast/chest area, this is some of the hormonal work of human milk production beginning.”

It might surprise you, but by the time you are 12-16 weeks pregnant, your breasts are able to secrete colostrum, though many parents won’t see it till much later. Howells says that most parents will start to see colostrum at around 20 weeks, though that can vary from one pregnant person to another, with some parents not seeing any signs of milk production till their baby is born.

Whether you are seeing signs or not, you can rest assured that it’s happening, Howells says.

What Are Signs That Milk Production Has Started?

Colostrum, AKA the milk that’s produced during pregnancy, is the same milk your baby receives at birth, before your mature milk comes in. Colostrum is yellowish in color, and is often referred to as “liquid gold” because of how healthy it is for your baby.

While you don’t produce a ton of colostrum—mature milk is more abundant in terms of ounces—it’s chock full of good stuff for your newborn. It’s high in protein, high in antibodies, and helps establish a strong gut microbiome for your baby. Colostrum also has laxative prosperities that will help your baby take their first poop.

You might start to see colostrum toward the middle of your pregnancy. But some parents don’t notice it until the very end of pregnancy, or even after they've given birth, says Naomi Hambleton, IBCLC, lactation consultant at A2Z Lactation.

As milk production gears up toward the middle of pregnancy, you may also probably notice that your breasts are larger and heavier. “Cup size usually goes up during pregnancy and can continue to grow in early breastfeeding or pumping days,” says Hambleton.

According to the Academy of American Pediatrics (AAP), if you do see colostrum during pregnancy, it will usually show up as a crusty yellow substance on your nipple, or inside your bra or clothes. If you gently squeeze your breast or your areola, a few drops may appear. You may also notice colostrum leaking after you’ve had a warm shower, or after sex, explains Molly Peterson, IBCLC, lactation consultant at Peterson Lactation Services.

This has to do with the release of the hormone oxytocin, often referred to as “the love hormone,” says Peterson. “When your baby arrives, it signals to your body to ‘let down’ or release the milk so they can drink,” she describes. “However, oxytocin can be triggered even when your baby isn't present, like during intimacy or whenever you feel that warm fuzzy feeling.”

How to Manage Leaking

There is a huge range of normalcy when it comes to colostrum production during pregnancy, with some parents seeing it frequently, and some not seeing it at all. In some cases, you may leak quite a bit—this is nothing to worry about, but it can get messy!

Leaking is more common if you’ve been pregnant before, says Peterson. “Some [parents] find that with subsequent pregnancies, they notice an increase in breast size, tenderness, and leaking colostrum earlier in their pregnancy, but it really varies person to person,” she says.

If you find yourself leaking a lot, wearing reusable or disposable breast pads can help, Peterson suggests. “Additionally, you can try and collect some of the colostrum that you have leaked and save it for after your baby is born,” she says. “It's liquid gold!”

Should You Pump Your Colostrum?

You may be wondering if pumping your colostrum during pregnancy is something that you should do. The answer is different for every expectant parent, but pumping your colostrum is not strictly necessary. After your baby is born, if you breastfeed frequently, your baby will get all the colostrum they need, before your mature milk comes in a few days later (usually about 2-5 days after birth).

Still, there are some circumstances where it might make sense to have a stash of colostrum at the ready once your baby is born. Having a history of gestational diabetes or surgery/injury to the breast may be a reason to have some extra colostrum available after birth, says Howells.

Additionally, if your baby has health complications and will need to be separated from you, this may be a reason to collect colostrum beforehand. Parents with a previous history of low milk supply or a delay in their milk coming in may want to consider this as well, Howells recommends.

“It can be helpful for parents who are anxious about breastfeeding or chestfeeding, or who are delivering at hospitals who are less knowledgeable about the natural progression of breastfeeding or chestfeeding,” Howells offers.

Importantly, if you are considering expressing your colostrum during pregnancy, you should speak to your healthcare provider first. In some cases, breast stimulation can jump start labor, so you should ask your doctor or midwife if you are a good candidate for this, and what the safest way is to do it.

A Word From Verywell

The way that the human body prepares to welcome a child into the world is pretty amazing when you think about it—and the process of milk production is no exception.

Your body starts to rev up its milk almost as soon as you become pregnant, so that you have the ability to feed your baby as soon as they are born. If you have any questions about what is happening with your milk production during pregnancy, or general questions about breastfeeding your baby after birth, please reach out to your doctor or midwife.

7 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. American Academy of Pediatrics. How Your Body Prepares For Breastfeeding.

  3. National Health Service. Leaking from your nipples.

  4. Nibali SC. Breastfeeding and the second baby. Lancet. 2002;359(9303):P358-359. doi:10.1016/S0140-6736(02)07521-9

  5. American Academy of Pediatrics. Colostrum: Your Baby's First Meal.

  6. National Health Service. Collecting your colostrum while you are pregnant.

  7. Demirel G, Guler H. The Effect of Uterine and Nipple Stimulation on Induction With Oxytocin and the Labor Process. Worldviews on Evidence-Based Nursing. 2015;12(5):273-280. doi:10.1111/wvn.12116

Additional Reading

By Wendy Wisner
Wendy Wisner is a lactation consultant and writer covering maternal/child health, parenting, general health and wellness, and mental health. She has worked with breastfeeding parents for over a decade, and is a mom to two boys.