When Does Breast Milk Come in?

When does your milk come in, and what will it feel like? Here, get the lowdown from experts.
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If you’re expecting baby’s arrival soon, or if you just recently gave birth, you may be wondering, “When does breast milk come in?” What you may not know is that our bodies like to be prepared for baby well before their arrival. Women start producing baby’s first food midway through pregnancy and continue on to make different types of breast milk over the course of those first couple weeks postpartum. Keep reading to learn about the types of breast milk a mother makes and how long it takes for milk to come in, plus what to do if your breast milk is delayed.

When Does Breast Milk Come in During Pregnancy?

If you’re pregnant, you may be making early breast milk and not even know it! Milk production generally begins around the midpoint of pregnancy, somewhere between weeks 16 and 22. At this stage your body is producing what’s known as colostrum—a yellowish milk that’s rich in calories and disease-fighting antibodies—which will serve as baby’s first food after birth. Some moms-to-be may even notice faint yellow or orange stains in their bra during the second or third trimester, a sign that their nipples are leaking colostrum. (If they never leak, that’s fine too.)

When Does Breast Milk Come in After Birth?

From the moment baby is born, your body is prepped and ready to deliver colostrum. This is true whether you delivered vaginally or via cesarean. “It’s a hormonal process, meaning that breast milk would come in regardless of whether baby ever breastfed or if Mom pumped in those first few days,” says Carrie Bruno, RN, IBCLC, a lactation consultant and founder of The Mama Coach.

As baby gets the hang of feeding and their needs evolve, your body will begin to cycle through the three stages of breast milk: colostrum, transitional milk and, finally, mature breast milk. Keep reading to learn more about each type of milk and how long it takes milk to come in.


Since your body starts producing colostrum during pregnancy, that first type of breast milk has already come in by the time baby is born. Your newborn will only get a few drops of colostrum at each of those first feedings, but it’ll give them plenty of nutrients. What it lacks in quantity, it makes up for in quality—which makes perfect sense, given that “when babies are born, their stomachs are small, like a marble!” Bruno explains. “This makes colostrum the perfect first milk” Colostrum also works as a laxative to help baby pass their first stool, known as meconium, and helps prep baby’s intestines for the arrival of mature breast milk.

Transitional milk

Transitional milk typically comes in two to five days after birth. This period is commonly referred to as “milk coming in”—as your body ramps up breast milk production to fill baby’s expanding belly, your breasts will start to feel full.

Transitional milk will look thinner and whiter than colostrum, according to Sherry Ross, MD, a women’s health expert and author of She-ology: The Definitive Guide to Women’s Intimate Health. It provides baby with more energy, Bruno adds, as it’s higher in fat and carbohydrates. Transitional milk can last for up to 10 to 14 days after birth.

Mature breast milk

Toward the end of the second week, moms can expect their mature breast milk to come in. Mature breast milk is the milk baby will continue to drink until Mom and baby want to wean. “Breastmilk composition changes throughout the breastfeeding relationship to match exactly what the baby needs,” Bruno says. “Breast milk contains two types of proteins: whey and casein. Over time, this ratio of casein and whey changes. Whey is high in immunoglobulins and easier to digest, whereas casein helps baby feel full longer. In the beginning, with colostrum, the ratio of whey to casein is 90:10, and after a month it’s 60:40. If Mom breastfeeds for over a year, it’s closer to 50:50.”

Signs Your Milk Is Coming In

So you now have a sense for when breast milk comes in—but what does it feel like when your milk comes in? Here are a couple common signs that your milk is in:

Your breasts become engorged

According to Bruno, the most common sign is a feeling of fullness and engorgement. “Breasts physically fill with milk, which can feel heavy and sore. Breasts can feel hard to the touch, warm and tingly,” she says. “Mom may also notice her breasts leaking in between feeds.”

Engorgement when milk comes in can be painful. Luckily, there are ways to help decrease the discomfort:

  • Breastfeed often. One of the best things moms can do to help with engorgement is keep up a regular feeding or pumping schedule, Bruno says, as that will help empty the breasts and avoid clogged milk ducts. You can even massage your breasts while nursing

  • Express by hand. “If moms are finding it hard to latch their baby due to the engorgement (sometimes breasts can feel so full the nipple flattens), it can be helpful to hand express for a few minutes to soften the breast, which will help the baby to latch easier,” she explains.

  • Apply ice. “If mom is still sore after feeding, applying ice for a few minutes after feeding can provide some relief,” Bruno says.

  • Apply heat. Ross also recommends using a warm compress or taking a warm shower in between feedings.

Baby starts gulping

Another telltale sign to look for when your milk comes in? Baby will start to take longer gulps. “Baby’s feeding patterns will change,” Bruno explains. “Mom will start to notice baby staying longer at the breast, and be able to hear audible swallows of milk.”

Moms may also see milk dribbling out of the corner of baby’s mouth. In fact, after the first few feedings of fast-flowing milk, baby may look the way you do after Thanksgiving dinner—full and sleepy, an expression moms humorously refer to as “milk drunk.”

Why Your Milk Might Be Delayed Coming In

There are several reasons milk may be delayed coming in, and they could be related to your medical history, birth experience or something else entirely, like simply being a first-time mom. According to Bruno and Ross, some possible reasons include:

  • Having a c-section delivery
  • Traumatic birth
  • Excessive blood loss during birth
  • Postpartum hemorrhage
  • Premature birth
  • Maternal obesity
  • Diabetes
  • Thyroid abnormalities
  • Polycystic ovarian syndrome (PCOS)
  • Significant stress
  • If mom has an infection with fever
  • Retained placental tissue
  • If baby is unable to latch properly
  • Previous breast surgery (reductions or augmentation)

What to Do If Your Milk Is Delayed

You know when breast milk generally comes in and the signs look out for—but what happens if the milk just isn’t coming? Here, a few tips on how to get breast milk to come in if it’s a bit behind schedule.

Talk to a professional

First and foremost, Bruno recommends reaching out to your doctor or a lactation consultant to ensure there aren’t any medical reasons for the delay. Together, you can build a plan for how to help your milk come in. “Sometimes, while moms wait for their milk to come in, there is a need for supplementation,” she adds. “This should be decided in conjunction with your healthcare provider, as they can help a mom decide if their baby needs it and how much, and will help build a plan to get baby solely breastfeeding if that is what Mom decides.”

Stimulate your breasts around the clock

For how to get milk to come in faster, Bruno recommends stimulating your breasts every three hours, around the clock (even the middle of the night), either by breastfeeding or hand-expressing and pumping to help build up a supply. “Research shows that if Mom feeds baby frequently or hand-expresses and pumps, it does increase a woman’s milk supply,” she says. “Every mom is different. Just because it’s delayed doesn’t mean it isn’t coming.”

To ensure baby is getting enough milk, listen for big sucks and swallows during feedings, and look for an appropriate number of wet and dirty diapers.

Stay positive and try your best

Above all, both Bruno and Ross encourage moms to stay positive. “Breastfeeding is extremely challenging, and every woman experiences it differently,” Ross says. “Be patient, use your resources and know it does get better with time. It’s completely worth the effort for you and your baby.”

Bruno adds that breastfeeding “can feel like a roller coaster, which is hard to navigate after you have just run the marathon of birth!” To help reduce anxiety around potential challenges, she recommends reaching out to a lactation consultant even before birth. “This way a plan is in place,” she says. “And if you’re a new mom and feel like you’re struggling with breastfeeding, I would encourage you to find support. There are solutions to what you are moving through and you shouldn’t have to do it alone.”

About the experts:

Carrie Bruno, RN, IBCLC, graduated from nursing school at MacEwan University in Alberta, Canada in 2005. She worked as a labor and delivery nurse for 10 years before starting her own company, The Mama Coach in 2015. In the past six years, the Mama Coach has grown to a team of over 40 registered nurses that provide prenatal education, newborn support, lactation counselling, sleep coaching and allergy navigation.

Sherry A. Ross, MD, FACOG, is an ob-gyn with more than 25 years of experience and currently practices at Providence St. John’s Hospital in Santa Monica, California. She’s also the author of She-ology: The Definitive Guide to Women’s Intimate Health. Period.

Please note: The Bump and the materials and information it contains are not intended to, and do not constitute, medical or other health advice or diagnosis and should not be used as such. You should always consult with a qualified physician or health professional about your specific circumstances.

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