Did you know that you start making breast milk even before the baby is born? This early milk is called colostrum, and production begins mid-pregnancy when you’re around 12 to 16 weeks. By the third trimester, you may even start leaking colostrum. (Don’t worry if you don’t – not everyone does!)

Moms have posted videos on TikTok and Instagram of collecting colostrum in late pregnancy and saving it for their babies. You may also be wondering if you should.

It’s a common question and one that has grown in popularity over the past few years, according to Jessica Madden, MD, a pediatrician, neonatologist, and International Board Certified Lactation Consultant (IBCLC).

“Although pregnant women in other parts of the world have been doing prenatal milk expression for a long time, it has only recently gained popularity in the US,” she says. The lack of infant formula a few years ago really sparked the conversation, adds Dr. Madden, and now she recommends it more than she did in the past.

Here’s the evidence on prenatal expressing, who it may benefit from, the potential risks, and a guide to prenatal expressing if it makes sense for you.

What is prenatal milk expression?

Simply put, prenatal milk expression (also known as prenatal breast milk expression) is when you give colostrum while you’re still pregnant. Colostrum is the yellowish-orange milk you produce starting in mid-pregnancy. “It’s expressed in small amounts, it’s thicker than mature breast milk and it’s full of antibodies,” says Dr. Madden.

Moms-to-be get this milk by hand expressing and scooping (a small amount) of the colostrum they produce into a container.

It is advised that you should only try prenatal milk expression with your doctor’s approval Jenelle FerryOpens a new windowMD, board certified neonatologist and director of infant feeding, nutrition and development at Pediatrix Medical Group in Florida. They can let you know when to start the practice (as there is a small chance that prenatal milk secretion can cause premature labor) and how to do it.

What are the benefits of prenatal milk expression?

Unfortunately, there is very limited data from the US on the benefits of prenatal expressing. “Many of the studies done were observational or reported on what the mothers did and what their results were,” says Dr. Ferry.

However, there is limited evidence that prenatal milk expression may increase the likelihood that mothers will successfully breastfeed. Women who express milk prenatally and save it for their babies are also less likely to use formula in the hospital, another study found.

That’s because prenatal milk expression can “help a mother’s breast milk ‘come in’ earlier,” says Dr. Madden. This expressed milk can also be used in the hospital to supplement breastfeeding after birth.

There are a few specific scenarios when prenatal milk flushing is more helpful, such as if you had supply or feeding problems with a previous baby or if your baby is at risk for low blood sugar after birth, adds Dr. Madden.

Are there risks of prenatal milk spillage?

Since there has not been much research on prenatal milk secretion, its risks are not well known, points out Dr. Ferry. The main concern is the possibility of premature birth.

This is because every time your breast tissue is stimulated, the hormone oxytocin is released. Oxytocin can stimulate uterine contractions, which, in theory, could lead to labor. For this reason, most providers suggest waiting to express until after 36 weeks, when the risk of preterm labor ends, says Dr. Madden.

But again, there just aren’t enough studies to say if this will happen if you express milk during pregnancy. It’s best to consult with your doctor to discuss your own individual risks and benefits before trying to express your milk prenatally.

Is it a good idea to express milk during pregnancy?

First things first: You definitely don’t need to express milk during pregnancy. Your body does not need any additional preparation to prepare milk. And since there isn’t a lot of research right now, it’s not something that all providers even advise doing.

“The limited data we have makes it difficult to support a particular recommendation,” says Dr. Ferry. However, the practice may be beneficial after 36 to 37 weeks of pregnancy for moms with high-risk pregnancies, who may present some difficulty with breastfeeding, or moms who expect to wean their baby after birth and want to provide colostrum.

There are several other situations in which Dr. Madden recommended:

If any of these scenarios apply to you, talk to your doctor first before trying to express your milk prenatally.

How to do prenatal milk expression

If you’re interested in prenatal expressing and your provider has signed off on it, here’s how to get started, according to Centers for Disease Control and PreventionOpens a new window (CDC).

1. First, wash your hands with soap and water. (Prenatal milk expression is best done by hand rather than using a pump, says Dr. Madden.)
2. Find a clean, disposable container with a wide mouth to collect the colostrum.
3. Get into a comfortable position and lean forward slightly to help gravity.
4. Place your thumb and fingers in a “C” shape above and below the nipple
5. Gently press your thumb and fingers towards your chest.
6. Gently squeeze your thumb and fingers together to release the milk. Continue the compression and release and collect the expressed milk.

Give yourself time to practice manually expressing colostrum and be patient, says Dr. Madden. Here are some more tips to help:

• Plan to manually express your breasts once a day, starting around week 37 of your pregnancy. Hand express for about two to three minutes at a time, max.
• Before standing out, warm up the chest for about ten minutes. You can use a heating pad, a warm compress or a warm shower.
• Don’t expect a lot of colostrum to come out; the average yield will be 0.5 to 1 milliliter (ml) from both breasts combined.
• Store the colostrum in small 1 or 2 ml syringes and then freeze it, storing it after delivery.
• Try watching a hand expression video. dr. Madden recommends this tutorialOpens a new window by Maya Bolman, IBCLC.

Again, prenatal expressing is not a requirement, nor is it something that is right for every mom. At the same time, it may be a good option for you. If you are interested, discuss the details of prenatal milk expression with your doctor.