Your Milk “Coming In”: What’s Actually Happening?
One of the most common things new parents hear after birth is:
“Has your milk come in yet?”
But that phrase can make breastfeeding sound like an on/off switch — as if your body suddenly starts making milk days after birth.
That’s not actually what’s happening.
Your body has already been making milk. The real shift is that milk volume increases significantly in the first few days postpartum as hormones change and your baby begins feeding frequently.
Let’s break down what “milk coming in” really means, when it usually happens, what you may feel physically, how your baby may respond, and what supports healthy milk production early on.
First: You Already Have Milk
During pregnancy, your body begins producing colostrum — the thick golden milk often called “liquid gold.”
Colostrum is:
• Highly concentrated
• Rich in antibodies and immune factors
• Produced in small volumes
• Perfectly designed for a newborn’s tiny stomach
This is why newborns do not need large amounts of milk in the first couple of days. Small amounts are biologically normal.
So What Does “Milk Coming In” Mean?
After birth, hormone levels shift dramatically — especially after the placenta is delivered.
As progesterone levels drop, your body receives the signal to increase milk production. This transition from colostrum to larger volumes of mature milk is called lactogenesis II.
For most families, this happens around 48–72 hours postpartum. But there is a wide range of normal. Some parents notice changes sooner. Some later.
What Does It Feel Like?
When milk volume increases, you may notice:
• Breasts feeling fuller or heavier
• Warmth
• Tingling sensations
• Swelling or leaking
• Firmness or engorgement
Some people experience dramatic fullness. Others notice only subtle changes. Neither automatically tells us how much milk you are making.
How Does Baby Usually Respond?
As milk volume increases, babies often:
• Feed frequently — sometimes very frequently
• Begin swallowing more audibly
• Have more wet and dirty diapers
• Seem more satisfied after feeds
• Start gaining weight more consistently
Cluster feeding is especially common during this transition. And while it can feel overwhelming, frequent feeding is actually one of the ways babies help establish milk supply.
Your Baby Helps Build Your Supply
Milk production works on supply and demand. The more effectively and frequently milk is removed from the breast, the stronger the signal your body receives to continue producing milk. This is why early feeding patterns matter.
Things that support milk production in those early days:
• Frequent feeding
• Skin-to-skin contact
• Deep latch and effective milk transfer
• Avoiding unnecessary separation
• Hand expression when needed
• Getting skilled feeding support early
What Can Delay Milk Coming In?
Sometimes milk volume increases later than expected. Possible reasons include:
• Significant blood loss during birth
• Retained placenta fragments
• Hormonal or endocrine conditions
• Cesarean birth
• Long labor or birth complications
• Limited milk removal or separation from baby
• Certain medications
A delay does not mean your body has failed. It simply means additional support and assessment may be helpful.
When Should You Reach Out for Help?
Seek support if:
• Baby is excessively sleepy and difficult to wake for feeds
• Diaper output is low
• Weight loss is a concern
• Feeding is extremely painful
• Baby is not transferring milk effectively
• You feel severely engorged
• Milk has not noticeably increased after several days postpartum
Early support can make a huge difference — and you don’t have to wait until something feels seriously wrong to ask for help.
Final Thoughts
“Milk coming in” is not a magical moment where your body suddenly starts working. It’s a hormonal transition supported by frequent feeding, milk removal, and close contact between parent and baby.
Your newborn’s constant feeding in those early days is not usually a sign that your body is failing. More often, it’s part of the biological process of building supply.
And you don’t have to figure it out alone.
If you’re in those early days and feeling unsure — whether feeding feels off, your baby seems unsettled, or you just want someone to tell you you’re doing it right — that’s exactly what we’re here for.
My team of IBCLCs serves families across the entire Phoenix Valley — in your home and in our offices — and via telehealth anywhere in the United States. Most visits are covered by insurance.
Click here to check your coverage and book with my team: https://www.azbreastfedbabies.com/appointments
I’m Amey Fields, RN IBCLC — an 18-year labor and delivery nurse and board-certified lactation consultant. I own AZ Breastfed Babies, a team of 18 IBCLCs supporting families across the Phoenix Valley and nationwide via telehealth. I am an IBCLC but not YOUR IBCLC (yet 🧡). Information shared here is not individualized advice. Personalized guidance is provided through one-on-one consults only.