When Does Lactation Start?

Understanding how lactation starts can be confusing for many new parents. The concept of milk “coming in” can create a misconception that breast milk production is sudden. However, the process is much more gradual and complex.

Lactation begins during pregnancy, with colostrum production, and continues after birth as hormonal shifts and breastfeeding cues play a role in transitioning to mature milk. The varying experiences of individuals, including differences in colostrum visibility and breast changes, further contribute to the confusion. By unraveling the intricacies of lactation and dispelling common misconceptions, parents can better understand this natural process and feel more empowered in their breastfeeding journey.


Phase 1: Pregnancy

During pregnancy, lactation begins as early as 12-18 weeks. Hormones produced by your pituitary gland and your baby’s placenta stimulate the growth of milk-making tissue. The first milk you produce is called colostrum, which appears thick, sticky, and varies in color. While some may notice colostrum leaking or can squeeze some out, it’s important to note that every experience is different and does not predict future lactation capabilities.


Phase 2: The First 72 Hours

After giving birth, the delivery of the placenta triggers a hormonal shift that stimulates lactation. During the first 72 hours postpartum, frequent breastfeeding or expressing colostrum is crucial for establishing long-term milk production. Your baby’s demand for milk plays a vital role in transitioning from colostrum to mature milk.

It’s normal for breasts to feel heavy and tender, and nipple lactation or leakage can vary. Over time, colostrum transitions into thinner, whiter mature milk, and volume increases.

Skin-to-skin contact and feeding cues from your baby are essential during this phase.


Phase 3: The Early Days

After the initial postpartum period, milk production shifts from being hormone-driven to maintenance-driven. In the first two weeks, establishing a breastfeeding routine or expressing milk regularly (at least 8 times in 24 hours) helps maintain milk production.

As your baby grows, their feeding patterns will change, and you can follow their cues. Adequate weight gain and dirty diapers are signs that your baby is getting enough milk. Remember that milk needs will vary, and as your baby starts solid foods around six months, their milk intake will decrease.


Seek support from a lactation consultant if you have any concerns or questions about milk production. Remember, every breastfeeding experience is unique, and with the right knowledge and support, you can nourish your baby and enjoy this special bonding time.

Some mothers may experience difficulty with milk production, particularly in cases of medical complications such as postpartum hemorrhage. It’s important to recognize that not all moms will have their milk come in immediately and/or may have a low supply. While this can lead to feelings of inadequacy and frustration, combo feeding and formula feeding are perfectly nutritious options. Every parent and baby’s journey is unique; the most important thing is that baby receives proper nutrition and care. Fed is best.

About the Author

Sarah Quigley, MA, IBCLC

International Board Certified Lactation Consultant