When Do Pregnant Women Start Producing Milk?

While people often reference the roller-coaster ride of pregnancy hormones, these chemicals play a vital role in dictating the timeline of events. For instance, human placental lactogen is responsible for preparing the body for breastfeeding. Surprisingly, pregnant women start producing milk long before birth, around week 20. For some people, production starts a couple of weeks later. At the other end of the spectrum, production can even start in week 13.

However, this early breast milk, called colostrum, is a little different in color and composition. Ranging from yellow to orange in hue, only about a teaspoon at a time is needed to meet a baby's earliest needs for nutrition and immune system support. Colostrum's also essential for digestive development, since it delivers beneficial bacteria while helping the baby start pooping and eliminating waste from their time in utero.

Although colostrum is produced for weeks during pregnancy, its production is very limited after birth, lasting just a few days. From there, milk gradually evolves over the first two weeks, becoming a more familiar color and consistency. Newborns grow quickly, and a week after birth, their stomachs have grown, too, moving from the size of a cherry to the size of an apricot. While colostrum is ideal for filling that tiny stomach, babies still need to breastfeed at least every few hours, or anytime the baby makes hunger cues, like rooting for a nipple or putting their hands in their mouth.

Although colostrum production may have been underway for weeks during a pregnancy, not everyone will experience outward evidence. If leaking does occur, it's different than the more pronounced leaking that can happen when a breastfeeding mom's letdown reflex is unexpectedly initiated in the weeks after birth. It's much less noticeable and often dries pretty quickly. In addition, leaking colostrum isn't connected with how much milk a mother will produce when breastfeeding. After birth, the baby's suckling acts as communication with the mother's body, sending messages to ramp up milk production to meet the growing baby's needs.

While some women may be curious to know if they've started producing colostrum, it's a good idea to consult a medical provider before trying to express milk during pregnancy, due to concerns this action could trigger early labor. No matter when your body initiates colostrum production, this robust milk will be available at birth.

However, expressing colostrum could be beneficial in certain cases, like for mothers with diabetes (this "liquid gold" can help stabilize a baby's blood sugar) or babies with a cleft lip or palate who may struggle with latching. If you do express colostrum, the amounts are far smaller, just a tenth of an ounce or less, compared to the .5 to 4 ounces per session once breastfeeding is well established. Good hygiene during collecting colostrum is important to keep germs out. Although the storage guidelines are the same for storing colostrum and mature milk in the fridge or freezer, since newborn babies eat a tiny amount, colostrum is typically stored in feeding syringes rather than breast milk bottles or bags.