When Does Breast Milk Come In: What You Need to Know

The term milk “coming in” actually refers to the maturation and volume development of breastmilk. In other words, the milk changes from colostrum to the white milk we think of, causing breasts to feel fuller and is easier to pump out. The technical term for this is Lactogenesis II- the creation of milk, part two. This change and the timeline are important for both families and professionals to understand as this understanding helps:

  • Prevent delays in putting the baby to the breast in the early days of baby’s birth, or waiting to “feel milk.” Many first-time moms are unaware of the presence of colostrum at birth or the importance of providing it.
  • Provide encouragement and understanding on what it means to have and achieve “enough milk."
  • Screen for medical problems in the mother.
    • Retained placental fragments
    • Delayed lactogenesis II
    • Insufficient glandular tissue (IGT)
    • Hormonally-related; PCOS, T1,2 Diabetus, Thyroid dysfunction
  • Identify Milk Transfer Issues
    • Dehydration
    • Insufficient stools, no change in color and composition
    • Tongue tie/ankyloglossia, lip and buccal ties
    • Positional discomfort


Colostrum goes by many names, such as “Liquid Gold” and “First Milk.” It is made during the second trimester, weeks 14+, by the hormone, progesterone (pro-gestation/pregnancy). This hormone is released by the placental sac. The purpose is to have milk ready from that point forward to be available for the birth of the baby immediately on-hand.

If the new baby is premature, needing NICU care, or if otherwise unable to feed directly from the breast, colostrum can be expressed by hand and fed with a medicine cup or syringe. This practice is commonly found in the NICU setting to minimize energy expenditure while also preventing the feeding process to be too rapid or too much at once.

The composition of colostrum is a concentration of immunologic factors and antibodies, nutrients, calories, and growth factors, and is quite sticky and sweet, all contributing to that golden color. The volume, or amounts, of colostrum are low and highly concentrated in its ingredients. This is to help a newborn take in the necessary calories with little effort, but also for another interesting fact: The stomach can only hold up to 10 ml of fluid until then.

Newborn’s stomachs are tiny, and do not have the capability to stretch until 3+ days of age! The baby needs small, frequent feedings as opposed to large, space-out feedings. Colostrum is also a great laxative, speeding up and easing the passing of meconium, the first stool, which is particularly tar-like and black.

Transitional Milk

This segues into the next stage: transition. Transition technically takes place the moment the placenta leaves the mother’s body, no matter the method of birth. It is incredibly important for the entirety of the placenta to be removed, so as the drop in progesterone hormone can happen, triggering the rise in hormones, oxytocin and prolactin (pro-lactation), but to also avoid infection and hemorrhaging. The stage lasts 3-5 days postpartum, and can be observed by:

  • Mecomium passing
  • Mecomium passing
  • Stools changing in color from black, to dark green, to mustard yellow with flecks, as well as amounts/frequency
  • Urine output increasing by at least one additional diaper a day, 4 by day 4
  • Milk color changing from gold, to creamy yellow, to variants of white/clear blue tones
  • Milk volume slightly increasing

When to Call the Lactation Consultant

Engorgement and Mastitis

Developing mature milk status is also when engorgement, excessive swelling and milk retention, may happen. This is due to poor milk transfer, or even overproduction, in most cases. Engorgement is not comfortable and may lead to other issues, such as mastitis from lack of milk flow flushing bacteria out, or supplementation/cessation of breastfeeding, as the internal pressure makes it quite difficult for the baby to suckle.

Pain, Pinching, and “Seams”

While pain is always a red flag, it is not always present during a shallow latch. Other signs for shallow latching can be clamped nipples, often seen with a “seam” around the tip, as well as blanching or lipstick shapes. All of these point to the clamping off of milk production. It could be something as simple as an adjustment needed in the positioning of the baby to get a good latch and nurse more effectively, or a more complex issue such as anatomical anomalies, such as “tongue-tie.”

Inadequate Output and Weight Gain

By day 4, there should be four or more moderately wet diapers a day. Stools should be increasing in number and amounts, as well. This is a great reflection of both change in breast milk composition and breast milk supply, but also how baby is transferring the milk to gain weight. A drop in birth weight by 10% or more is in need of a lactation plan, if not sooner than that, or if baby's weight has plateaued.

No Color Change in Stools

By day 2-3, all black meconium should be gone. Stools need to be reflecting the change in type of milk and adequate intake by changing to green, and later mustard yellow. Lack of change could mean lack of change in the mother and inadequate milk intake, most often due to something on the infant’s end of things: poor latching, lethargic, jaundiced, etc.

Maternal Hemorrhaging or Abnormal Clots Postpartum

This can be a sign of retained placental fragments, and may very well prevent the milk-making process. It also can cause iron anemia, which can directly affect the mother’s ability to produce or do so adequately.

When in Doubt Seek Breastfeeding Support

An IBCLC is the new mother’s best advocate, and also a great detective when it comes to troubleshooting breastfeeding. They can provide reassuring and helpful guidance, as well as resources.


ABM Clinical Protocol #3: Hospital guidelines for the use of supplementary feedings in the healthy term breastfed neonate, revised 2009. Breastfeed Med. 2009;4(3):175-82.

Ballard O, Morrow AL. Human milk composition: nutrients and bioactive factors. Pediatr Clin North Am. 2013;60(1):49-74. doi:10.1016/j.pcl.2012.10.002

Chapman DJ, Pérez-escamilla R. Maternal perception of the onset of lactation is a valid, public health indicator of lactogenesis stage II. J Nutr. 2000;130(12):2972-80.

About the Author

Ashley Georgakopoulos is an International Board Certified Lactation Consultant (IBCLC) that specializes in the clinical management of breastfeeding and an expert in the field of lactation. Ashley is from Knoxville, TN, and is a mother who has dealt with the obstacles and joys of breastfeeding. As the owner of Genesis Lactation, she educates families, connects them to resources, and helps the next generation be as healthy as possible: nutritionally and sustainably.

All content published on the Motif Medical site is credited for information purposes only. This information should not substitute as medical advice, diagnosis, or treatment. Always consult your doctor or qualified health professional with any questions regarding the health of you or your baby.


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