Does Pregnancy Cause Your Milk Supply to Drop? Understanding the Changes

Posted on April 09, 2026

Introduction
The Hormonal Shift: Why Supply Changes
What to Expect: The Timeline of Change
The Shift to Colostrum: Liquid Gold for Your Toddler
Managing Nipple Sensitivity and Nursing Aversion
Nutrition for Three: Supporting Your Body
Herbal Support and Safety
Is it Safe to Breastfeed While Pregnant?
The Toddler Transition: To Wean or Not to Wean?
Looking Ahead: Tandem Nursing
Practical Tips for the Journey
Summary of Key Takeaways
Frequently Asked Questions
You’ve Got This, Mama!

Introduction

You just saw those two pink lines on a pregnancy test, and while your heart might be racing with excitement, your mind is likely spinning with a million questions. If you are currently breastfeeding an older child, one of the first things you might wonder—or perhaps you’ve already started to feel it—is: "Can pregnancy cause your milk supply drop?" It is a moment of profound realization when you recognize that your body is now performing the incredible feat of nourishing a child at your breast while simultaneously weaving together the delicate threads of a new life in your womb.

Many mothers worry that they are "running out" of milk or that their body isn't strong enough to handle both tasks. We want to start by telling you: you are doing an amazing job. Your body was literally created to feed human babies, and it is capable of extraordinary things. However, it is a biological reality that pregnancy brings about significant shifts in lactation. In this post, we are going to explore the science behind why milk supply often decreases during pregnancy, what you can expect in terms of taste and composition changes, and how you can support your own physical and emotional well-being during this transition. We will cover everything from hormonal shifts to the transition into colostrum, managing nipple sensitivity, and preparing for the possibility of tandem nursing. Our goal is to provide you with the evidence-based information and compassionate support you need to navigate this journey, because every drop counts—and your well-being matters just as much as the little ones you are nurturing.

The Hormonal Shift: Why Supply Changes

When you are not pregnant, your milk supply is primarily a game of "supply and demand." The more milk is removed by your baby or a pump, the more prolactin (the milk-making hormone) your brain releases to signal your breasts to make more. It is a beautiful, self-regulating loop.

However, pregnancy introduces a powerful new player into the mix: progesterone. Produced in high quantities by the placenta, progesterone is the "pregnancy-maintaining" hormone. While it is essential for keeping your developing baby safe and growing, it acts as a significant biological "brake" on milk production.

The Progesterone Brake

Even though your prolactin levels remain high while you are pregnant, the high levels of progesterone effectively block the prolactin from fully engaging with the milk-producing cells in your breasts. Think of it like a car where the engine is running (prolactin), but the emergency brake is pulled tight (progesterone). No matter how much your older child nurses—no matter how much "demand" there is—the biological "brake" of pregnancy hormones will usually prevent your body from maintaining the same volume of mature milk.

The "Leaky Alveoli" Theory

Research suggests that progesterone also changes the physical structure of the milk-producing cells, known as alveoli. During pregnancy, these cells may become more permeable or "leaky." This means they are less efficient at storing mature milk, leading to a noticeable drop in volume. For most mothers, this decrease begins as early as the first month of pregnancy, but it often becomes most dramatic during the second trimester, specifically between the fourth and fifth months.

What to Expect: The Timeline of Change

Every pregnancy is unique, and every breastfeeding relationship is different. However, there is a general pattern that many mothers experience when nursing through a new pregnancy.

The First Trimester

During the first few weeks, you might not notice a change in volume, but you might notice a change in how nursing feels. Nipple tenderness is often one of the very first signs of pregnancy. Hormonal shifts can make your nipples feel incredibly sensitive, making the initial latch or the duration of a feeding feel uncomfortable. During this stage, your supply might hold steady, but the physical challenge of nursing might increase.

The Second Trimester

This is typically when the "drop" becomes most apparent. Around the fourth or fifth month, the volume of mature milk decreases significantly for the majority of women. You might notice your child nursing more frequently to try and "signal" for more milk, or they might get frustrated with a slower flow. At the same time, your body is beginning to transition from mature milk to colostrum.

The Third Trimester

By the third trimester, your milk has usually fully transitioned into colostrum—the "liquid gold" your newborn will need in those first few days. Colostrum is produced in smaller quantities than mature milk, but it is incredibly dense in nutrients and antibodies. Some older nurslings will continue to nurse through this, while others may lose interest due to the very low volume and the change in flavor.

The Shift to Colostrum: Liquid Gold for Your Toddler

A common concern we hear is: "Will my older child eat all the colostrum before the baby arrives?" The answer is a resounding no! Colostrum is produced under hormonal influence during pregnancy. It is not a finite "tank" that can be emptied. Your body will continue to produce colostrum throughout the end of your pregnancy, and the act of your older child removing it will not leave your newborn without.

Changes in Taste and Consistency

Colostrum is very different from the mature milk your child is used to. It is:

Thicker and more concentrated.
Yellow or golden in color.
Higher in protein and sodium (salty).
Lower in lactose (less sweet).

Because of these changes, many toddlers will comment on the taste. They might say the milk is "salty" or "different." Some children love it, while others may naturally begin to wean at this point.

The Laxative Effect

Colostrum has a natural laxative effect, designed to help a newborn baby pass their first stools (meconium). If your older child is still nursing frequently when your colostrum comes in, you might notice that their stools become looser or more frequent. This is normal and is simply a result of the high nutrient and antibody density in the colostrum.

Managing Nipple Sensitivity and Nursing Aversion

Nursing while pregnant isn't always easy. In fact, it can be quite taxing both physically and emotionally. Nipple soreness is a very common side effect of the hormonal changes of pregnancy.

Coping with Nipple Pain

To manage the discomfort, we often suggest:

Checking the latch: Even an older toddler can get "lazy" with their latch. Remind them to open wide.
Shortening sessions: You can use a timer or a "counting game" to limit how long they nurse.
Breathing exercises: Using the same breathing techniques you might use in labor can help you relax through the initial "let-down" discomfort.
Safe nipple creams: Keeping the skin moisturized can help prevent further irritation.

Understanding Nursing Aversion

Some mothers experience something called "nursing aversion" or "nursing agitation" during pregnancy. This is a sudden, intense feeling of irritability, skin-crawling, or an urgent desire to have the child stop nursing immediately. It is a physiological response, likely driven by hormones and the body’s focus on the new pregnancy.

If you experience this, please know that you are not alone and you are not a bad mother. It is okay to set boundaries. You might say, "Mommy's milkies need a break right now," and offer a snuggle or a story instead. Protecting your mental health is vital for your entire family.

Nutrition for Three: Supporting Your Body

When you are pregnant and breastfeeding, your nutritional needs are significantly higher. You are essentially "eating for three"—yourself, the baby in your womb, and the child at your breast.

Caloric Intake

It is estimated that breastfeeding burns about 500 calories a day, and pregnancy requires additional calories to support fetal growth. It is not the time for restrictive dieting. Focus on nutrient-dense foods like avocados, nuts, seeds, lean proteins, and whole grains.

Many of our Milky Mama families love our Emergency Brownies or our Oatmeal Chocolate Chip Cookies as a delicious way to get in some extra calories and lactation-supporting ingredients like oats and flax. Having a "stash" of easy-to-grab snacks can be a lifesaver when the "pregnancy hunger" hits.

Vital Nutrients

Calcium: Your body will prioritize the baby in the womb, so if you don't consume enough calcium, your body may pull it from your own bones. Focus on leafy greens, sardines, and fortified foods.
Vitamin D: This is crucial for immune health and bone development.
Hydration: This is perhaps the most important factor you can control. Dehydration can exacerbate pregnancy fatigue and further impact your milk volume. We recommend keeping a water bottle with you at all times. If you struggle with plain water, our Lactation LeMOOnade™ or Pumpin Punch™ are excellent options to help you stay hydrated while providing a refreshing treat.

Herbal Support and Safety

Many mothers turn to herbal supplements to help bolster their supply. While many herbs are safe and effective, pregnancy changes the landscape.

Choosing the Right Supplements

Certain herbs that are excellent for milk production when you are not pregnant might not be recommended during pregnancy because they could potentially stimulate the uterus. At Milky Mama, we offer a range of herbal supplements designed to support different stages of the breastfeeding journey.

Products like Lady Leche™, Dairy Duchess™, Pumping Queen™, and Pump Hero™ are favorites among our community. However, it is absolutely essential to consult with your OB-GYN, midwife, or healthcare provider before starting any herbal supplement while you are pregnant. They can help you determine which ingredients are safe for your specific health history and pregnancy.

Disclaimer: This product is not intended to diagnose, treat, cure, or prevent any disease. Consult with your healthcare provider for medical advice.

Is it Safe to Breastfeed While Pregnant?

The short answer is yes, for the vast majority of healthy pregnancies, breastfeeding is perfectly safe.

The Question of Oxytocin

Some people worry that the oxytocin released during breastfeeding (the hormone that causes the milk to "let down") might cause the uterus to contract and lead to miscarriage or preterm labor. However, in a healthy pregnancy, the uterus is not very sensitive to oxytocin until quite late in the third trimester. Furthermore, the amount of oxytocin released during a typical nursing session is similar to what is released during sexual activity, which is also generally considered safe during pregnancy.

When to Use Caution

There are certain circumstances where your healthcare provider might advise you to wean or reduce nursing sessions:

If you are carrying multiples (twins, triplets).
If you have a history of preterm labor or late-term miscarriage.
If you are experiencing unexplained bleeding or uterine pain.
If you are not gaining adequate weight due to the high caloric demand.

Always have an open conversation with your healthcare team about your desire to continue breastfeeding.

The Toddler Transition: To Wean or Not to Wean?

As your supply drops and the taste changes, your older child will likely have a reaction.

Natural Weaning

Some children will naturally lose interest. If the flow is too slow or the taste is too salty for their liking, they may simply stop asking. If this happens, it can be an emotional time for Mom. You might feel a sense of relief mixed with a bit of sadness. This is completely normal.

Continuing to Nurse

Other children are "nursing focused" and will continue to nurse for comfort regardless of how much milk they are getting. In this case, nursing becomes more about the emotional bond and the "snuggle time" than the actual nutrition. If your child is under 12 months old and your supply drops significantly, you must work closely with a pediatrician to ensure they are getting enough nutrition from other sources, as milk (breast milk or formula) should remain their primary source of nutrition until age one.

Looking Ahead: Tandem Nursing

If you choose to continue nursing throughout your pregnancy, you may find yourself "tandem nursing"—breastfeeding both your newborn and your older child.

Benefits of Tandem Nursing

Many mothers find that tandem nursing helps the older child adjust to the new baby. It provides a shared "safe space" and can help reduce sibling rivalry. Additionally, having an older child who is an "expert" at removing milk can actually help your milk come in faster and manage engorgement in those early days after birth.

Priorities After Birth

Once the new baby arrives, the general rule is to give the newborn first preference. The newborn relies on the colostrum and early milk for their entire nutritional intake, whereas your older child is likely eating solid foods. You can nurse them together (one on each side) or nurse the baby first and then let the older child "finish up."

Practical Tips for the Journey

Navigating a pregnancy while breastfeeding requires a lot of "moms-eye" planning. Here are some practical steps to make it easier:

Hydrate Early and Often: Don't wait until you're thirsty. Sip on Milky Melon™ or water throughout the day.
Rest When You Can: Nursing is a great excuse to sit down. Use nursing sessions as a time to put your feet up and read a book with your older child.
Encourage Solids for Toddlers: If your supply is dropping, ensure your toddler is getting plenty of nutrient-dense solid foods and staying hydrated with water or other age-appropriate drinks.
Join a Community: You don't have to do this alone. The Official Milky Mama Lactation Support Group on Facebook is a wonderful place to connect with other moms who are tandem nursing or breastfeeding through pregnancy.
Get Professional Support: If you are struggling with pain, supply concerns, or the decision to wean, a virtual lactation consultation can provide personalized guidance tailored to your specific needs.

Summary of Key Takeaways

Pregnancy hormones (progesterone) are the primary cause of a milk supply drop.
Most mothers notice a decrease in volume by the fourth or fifth month of pregnancy.
Milk transitions to colostrum during the second and third trimesters, which changes the taste and consistency.
Breastfeeding during pregnancy is generally safe for healthy, low-risk pregnancies.
Nipple sensitivity and nursing aversion are common challenges that can be managed with boundaries and latch checks.
Nutrition and hydration are critical when supporting yourself, a pregnancy, and a nursing child.
Every family’s journey is different; whether you nurse through pregnancy or choose to wean, you are doing what is best for your family.

Frequently Asked Questions

1. Can I use a breast pump to increase my supply back to normal while pregnant? In most cases, no. Because the drop in supply during pregnancy is caused by hormonal shifts (specifically high progesterone) rather than a lack of stimulation, extra pumping usually won't bring a mature milk supply back to pre-pregnancy levels. Your body is prioritizing the pregnancy. However, pumping can still be useful for some moms to maintain some level of stimulation or to provide what little milk is available to their child.

2. Is it true that breastfeeding will cause me to have a miscarriage? For the vast majority of women with a healthy, low-risk pregnancy, the answer is no. The oxytocin released during nursing is generally not enough to cause the cervix to dilate or trigger preterm labor in a healthy pregnancy. However, if you are at high risk for preterm labor or have other complications, your doctor may advise you to stop. Always consult your healthcare provider.

3. Will my toddler "steal" the colostrum that my newborn needs? No! Your body does not have a "limited supply" of colostrum stored in a tank. It is produced continuously during the latter half of pregnancy and the first few days after birth. Your older child can nurse as much as they like, and your body will continue to produce colostrum for the newborn.

4. Why does my nursing toddler have diarrhea now that I’m pregnant? It is likely not true diarrhea, but rather a change in stool consistency due to the colostrum. Colostrum has a natural laxative effect. If your child is nursing frequently and consuming a significant amount of colostrum, their stools may become looser, more frequent, or change in color. This is normal and usually resolves once your milk "comes in" and transitions back to mature milk after the birth.