Typically, milk comes in a few days after birth and regulates around four weeks after delivery

Breastfeeding can be one of the most natural things your body does. But it can be difficult at times. And it can feel shrouded in mystery.

Somehow, your breasts go from these things that are just ... there ... to the very tools that you’re using day and night to keep your baby healthy.

But how does that happen? When does your milk “come in”? How does milk supply get established? When does your breast milk supply regulate? And how do you know if you’re making enough milk?

These are common and valid questions.

“It’s very natural to worry about your milk supply and want to know what’s going on in your body,” says Kam Lam, MD, a breastfeeding medicine physician. “The first few weeks of breastfeeding are very important to setting the stage for establishing a healthy milk supply that will nourish your baby.”

We talked with Dr. Lam about what you need to know about your milk supply so you can know what to expect.

When milk supply regulates: A timeline

When milk will come in, how much milk will be made and how well breastfeeding will go can vary from person to person.

But as a general timeframe, you can expect that your milk supply will increase substantially in the first two weeks and will be established by about four weeks after delivery.

“Milk supply can be a finicky thing,” Dr. Lam reports. “Lactation is affected by a lot of things, like how often you nurse, how well the baby latches, your health and more. So, it’s important to recognize that your experience may be different from others'.”

But typically, your body will begin the process of producing breast milk during the second trimester of your pregnancy and continue to make milk for as long as your baby needs it.

Here’s a general idea of what to expect.

Stage 1: Colostrum forms during pregnancy

Your body starts gearing up to breastfeed long before you even give birth. That’s usually around week 16 of your pregnancy.

“You may feel a little more fullness in your breasts around that time and may even have a bit of leaking in the third trimester,” Dr. Lam says.

This is called “stage one lactogenesis.” It’s essentially a time when your body begins to make milk to feed your baby.

During this stage, you’ll begin making colostrum. Colostrum is the first kind of milk you’ll make. It’s highly concentrated and full of nutrients, antioxidants and antibodies that will build your baby’s immune system in their first few days of life. Colostrum is thicker than milk and has a yellowish color.

During your second and third trimester, you may notice some other changes to your breasts to get ready for breastfeeding, too, like:

  • Your nipples may get darker.
  • Your areolas may become larger.
  • The small bumps on your areolas (Montgomery glands) may secrete oil to lubricate your nipples.

Stage 2: The first days after delivery

In the first few days after delivering your baby, you’ll continue to make colostrum. And then, a switch will come. You may hear this referred to as your milk “coming in.” Your healthcare teams call it “second-stage lactogenesis.” And it typically happens between two and seven days after delivery.

You may notice the change from colostrum to milk because it can cause some discomfort in your breasts. This is called breast engorgement, and it could make your breasts feel tender, swollen, full, hard and even painful. You may also leak milk when your milk comes in.

While it might feel like something is “off,” it’s natural to experience mild engorgement when your milk comes in. It’s a good sign that your milk supply is becoming established.

“Mild engorgement is a normal physiological process to making breastmilk, but it can be quite surprising, especially if you're lactating for the first time,” Dr. Lam reassures. “It typically lasts a few days, up to about a week. As your body starts to recognize how much milk you need, it starts to level out.”

Severe engorgement should be managed by a lactation consultant to investigate underlying causes and ensure it doesn’t progress to mastitis or cause a drop in your supply.

You can help to calm down the discomforts of mild engorgement by:

  • Feeding your baby on demand.
  • Resisting the temptation to over-pump. The more milk you remove from your breasts, the more your body will make. Dr. Lam suggests that pumps should be used to remove the amount of milk needed for your baby to feed. They’re best used if your baby isn’t latching well or removing milk well or if direct breastfeeding isn’t possible or preferred.
  • Wearing a supportive bra.
  • Applying cold compresses, like a cold washcloth or ice pack (wrapped in a towel) to your breasts.
  • Reversing the pressure in your breasts before baby latches. Here’s how: Place your fingers around the base of your nipple and press inward toward your chest wall. Keep steady pressure in the area as you count slowly to 50. Continue until you feel that your areola is soft.
  • Trying over-the-counter pain medications like ibuprofen (Advil®) or acetaminophen (Tylenol®), if approved by your healthcare provider.

Again, everyone’s body is different. You may feel the effects of engorgement when your milk comes in. You may not. And it may take your milk longer to make the change from colostrum. Some factors that can delay the transition from colostrum to milk include:

Stage 3: Week two and beyond

After that initial rush of milk coming in, your body starts to operate a little differently. Your milk supply becomes established based on supply and demand and relies less on hormones.

How?

As your baby nurses (and/or you pump milk), your body takes notice. It recognizes how much you use each day to feed your baby, and it adjusts accordingly. It’s less likely now to overproduce and fill your breasts to the point of pain or discomfort. But you’ll make enough to keep your baby healthy.

This is the third and final stage of lactogenesis. It’s the sweet spot of breastfeeding when your body becomes in tune with baby’s needs.

It’s at this point where you might consider your milk supply “regulated.” But remember that even an established milk supply is a moving target.

“I like to say, The baby makes the milk. Because after your milk comes in, breastfeeding works on the principles of supply and demand,” Dr. Lam explains. “As you remove milk from the breast, your body makes more to keep up with baby’s needs.”

In other words, the more milk you use, the more you’ll make. And vice versa. So it’s important to your supply that you remove the milk you need. Not more. Not less.

Dr. Lam offers these tips for establishing and maintaining your milk supply:

  • Feed your baby on demand. Remember, most newborns need to be fed eight to 12 times per day. (That includes nighttime feedings, which are important to keeping up your supply.)
  • Feed your baby at your breast, rather than pumped milk, if that’s an option. Most babies are more efficient than pumps at removing milk from your breasts.
  • Practice skin-to-skin time with your baby.
  • Make sure your baby is latching properly to feed efficiently and effectively. Remember, a good latch won’t hurt. But a poor latch can.
  • Try out different breastfeeding positions to find what works best for you and your baby.

Signs of established milk supply

How will you know that your milk supply is regulated? (And that your baby is getting what they need?) Dr. Lam suggests looking for these signs that your breast milk has regulated and is meeting your baby’s needs:

  • Your breasts begin to feel a little full or hard when it’s time for your baby’s feeding.
  • Your baby nurses on both breasts at most or all feedings.
  • You can see your baby’s jaw move and hear them swallowing as they nurse.
  • Your baby is gaining weight appropriately.
  • Your baby has six or more wet diapers per day.

What to do if you’re concerned about your milk supply

If you’re worried about your breast milk supply, you’re far from alone. It’s not easy to spot what’s going on inside your breasts after all.

Dr. Lam advocates for reaching out to a healthcare professional, like a lactation consultant or breastfeeding medicine physician, early if you have any questions or concerns.

“The earlier the intervention, the better. The first few days and weeks of breastfeeding are critical for establishing a healthy supply, so getting the support you need early on can make a big difference in successful breastfeeding.”